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MG MGF Technical - Air sensor control device/lambda sensor

The recently purchased VVC has a dial control (variable resistor type) fitted by the PO, which is situated under the dash. This is apparently connected to the air sensor system. Does anyone have any idea what this does and would it likely have any effect on the lambda sensor? - which is currently suspect as the EM warning light is on.

Also, what is the part number of the post cat sensor on my MY 2001 VVC (and is it the same as the TF)? - as I've had a rummage around the internet and can only find post cat (or rear units) listed for the TF.

Chris.

Chris Bond

I believe some people have fitted these variable sensors as a secondary control for the heater - supposedly more reliable than the MG fitted resistor pack.

I think the lambda is totally separate from any form of manual control BUT I suppose it is not beyond the wit of man (or woman) to put in some sort intervention device.
Ted Newman

Difficult to know what has been done here, without knowing where the wiring goes. If it is to the Lambda sensor, then I suspect that it'll do the grand total of the square root of bugger-all. The lambda-signal is not voltage-dependent.

However, if on the in-take temperature sensor circuit, then it'll be working along the same lines as those infamous eBay adverts of "Get +15bhp!". It'll fool the engine management into thinking that the air intake is cooler than it actually is, and subsequently feed more fuel to make use of the presumed denser air.

Again, I doubt that there would be any significant difference would be noted, but it could be potentially damaging by over-fuelling.

Other than that? No idea. Maybe this is cleverer than we think. Or not.

I'd be tempted to trace the wires and figure out exactly what is going on.
Rob Bell

Dieter's EPC is a very useful resource - http://translate.google.com/translate?u=http://www.mgfcar.de/index.htm&langpair=deen&hl=de&prev=/language_tools
bandit

Try http://www.lame-delegation.de/mgfcar.de/epc
Geoff F
Geoff Farthing

Thanks Guys.

Regarding the rheostat, I think it is on the in-take sensor circuit and probably does as Rob says.
I cant understand the reasoning behind just enriching the fuel mixture? Surely to increase HP you have to get increased fuel and oxygen in there.

Could this enriched mixture have damaged the lambda sensor in anyway?

Anyway, I'll remove this rheostat and reconnect the wires together.

And thanks to Bandit and Geoff for the link to Dieters site


Chris

Chris Bond

It is certainly possible the sensor has taken offence to having fuel-rich exhaust gas present on a long-term basis, and the catalytic converter may have suffered too. Rather depends on how much faith the previous owner had in the utter hogwash claims made by the retailer of the rheostat... You're spot on, shoving extra fuel into a standard K Series will result in less power and shorter life - the standard ECU does a very good job of getting the fuel/air mix exactly right and upsetting that balance is a Bad Thing. If you increase the breathing, i.e. ported & polished inlet tract and maybe larger high-flow valves, longer duration camshaft etc then you'll need more fuel, and if you've really gone to town then the standard ECU may reach its limits and an aftermarket programmable version like the Emerald chip becomes necessary.

I'm not certain how the sensor / ECU / warning light process works, but it seems possible that removing the over-fuelling will restore correct mixture and consequently the sensor will see 'within scope' conditions, but the ECU will persist with the warning light until it is re-set. If that's the case, you may not need to start buying new bits just yet. Might be something in the archives - happy hunting ;o)
bandit

Thanks (again) bandit,

Crawled underneath the engine today and took a look at the lambda sensor and it's brand new, so dont suspect the sensor. I'll try an ECU re-set and keep my fingers crossed.
Chris Bond

Also check the Lambda sensor wiring loom. It's rather vulnerable to the heat of the exhaust manifold and can become damaged.
Rob Bell

Update-April

MOT test failed on emissions but I was expecting this as the engine warning light had been on since a couple of weeks after the head gasket was done. Garage said it needed a new cat and it will all be fine. And it was for about 3 weeks (until yesterday) when the good old warning light re-appeared.

It is back in on Wednesday but I'd like to know what is causing this, I don't think its the lambda sensor as it is clearly a recent item (still shiny & new looking) and the wire loom is OK.

Also, finally got around to having a look at the rheostat under the dash.
As you can see from the attached pic the stat has 2 wires leading from it which I've traced back to the sensor on the inlet manifold (but not sure which one - could be the air intake temperature sensor?). The thing that I need to know, before I cut the wires to the stat, is how do I put it back to standard? The 2 twin wires hanging down in the pic (1 black/white & black, the other black/red & black), appear come from the loom - the PO has just cut them off and taped up. Assuming that these are the original wires which he has disabled, where should they be connected to?

This should be another thread but here goes.....
The other thing that troubles me is that after 1500 miles since the head gasket was done, there is still signs of mayo on the dipstick. The garage says it is sweating but there are very conflicting signs!
Firstly it is losing coolant - from maximum to minimum level in the header tank in about 100 miles (which would account for the amount of mayo in oil). But the coolant system remains pressurised after 24+hrs of being stationary (not run). So what gives? - is it possible for the HG (or any other area) to leak coolant into the oil but for the coolant system to hold pressure for this length of time (I'd would'nt expect this from perfectly healthy system).

I'd appreciate your views before I take back in on Wednesday.

Chris.

Chris Bond

The white/black and red/black wires look like stereo speaker cables - and don't relate to the car's harness. If wired to the inlet manifold sensor, then I would think that you're right: it's the inlet manifold air temperature sensor - and one of those classic eBay bodges (+15bhp they'll have you believe!!! Yeah, right...)

Presumably one end of that wire is from the sensor's loom, and the other to the sensor plug? If one end is completely disconnected, then presumably the ECU is not getting any signal whatsoever from the inlet air temperature sensor??? It'd certainly be one potential explanation as to why you're getting the illumination of the engine Malfunction Indicator Lamp (MIL). Also bear in mind that there is also a post-cat lambda on 2001 and later cars. Running the fueling too rich (which by disconnecting the air temperature sensor will be prone to causing) will cause problems with the catalyst - which could be permanent, but hopefully, if the problem is rectified, could be recovered with an "Italian tune-up" to get some decent heat into the cat and burn off any residues...

With regard to water loss and mayo, well, erm, it does rather indicate a problem with the head gasket I am afraid. How much may are you finding in the coolant? It is also true to say that after a HGF, the mayo can take a while to leave the system. The coolant loss could be from another source - and a leaking hose should be excluded. A pressure test might be helpful?

BTW I've seen the films. Cut the red wire. No, hang on a moment, the black. No, the red... ;oD LOL
Rob Bell

Depends whether the rheostat is supposed to modify the sensor feed, or 'replace' it. Perhaps as simple as cutting the red & black wires upstream of the fuse and joining them together? I'd agree that the twin wires are more likely to be speaker feeds, so perhaps a red herring in this case.

It is feasible for pressure to remain in the coolant circuit despite there being a leak across into the oilways, not uncommon for a gasket leak to only manifest itself when the engine is running. Your garage are being super-optimistic I feel, after 1500 miles I'd be fairly confident that residual mayo wouldn't still be visible.
bandit

Thanks Rob & bandit.

Rob,
Yes, now you mention it, of course they look like speaker cables. I'd just got fixated with the rheostat/sensor issue.
Regarding the wires from the stat - both wires appear to go to the sensor, although I haven't been able to get a visual of the sensor to confirm where they connect.

I'll try cutting the wires and joining them together as bandit suggests.

Thanks for your post from the Register forum - I'm hoping you are right and bandit is wrong but we will see.

Bandit,
I'd updated the info on Register forum and as stated there are no other signs - no oil visible in the coolant, no temperature or heater issues and no coolant blowing past the pressure cap. The other thing is that the mayo content is (currently) small and seems to constant - neither increases or decreases - and it is in the oil rather wholly part of it (ie there is oil on the bottom of the dipstick that is not contaminated, although further up the dip stick it looks like the mayo has been sprayed on).

I'll get the garage to carry out a pressure test and a sniffer test on Wednesday and maybe we'll get a answer one way or another.

Chris.


Chris Bond

If the two wires are spliced onto the wires on the sensor then simply removing them completely should put the configuration back to standard.

A common culprit for coolant loss after head unbolting is a rubber hose connection not fully sealing, as I think Rob suggested, so fingers crossed that's what it turns out to be. It should be noted that despite repeated and sustained efforts to wring the last ounces of oomph out of every K Series I've owned, only once has coolant ever escaped and that was to atmosphere and visible to the point of being spectacular, so I'm really not qualified to judge the likely lifespan of mayo. A fair few half-used jars of Hellmans have ended up in my bin, further evidence I should be ignored I suspect...
bandit

>> common culprit for coolant loss after head unbolting is a rubber hose connection not fully sealing <<

You're right Bandit. And these hoses also split - as I have found to my cost in the past. But also the hoses do age, and don't seal well to the outlet stub, a problem that is not helped by the earlier design that doesn't seem to give much for the hose to grip onto - there are more pictures of what I mean here: http://mgf.ultimatemg.com/group1/info/journal/blog/index.htm

Hopefully the solution won't be too expensive!
Rob Bell

Apparently I'm worrying unnecessarily - "just sweating - it'll disappear when the weather warms up" and the coolant loss is down to "the level fluctuating on these systems" - we shall see!

But it looks like the MIL warning light was down to the rheostat, I took it out the night before and connected the 2 wires together. This clearly sent the wrong signal, as they told me that the diagnostic (testbook) was showing and open circuit. I told them to put it back to standard and it cost me a new plug, as the old one was apparently butchered.

Fingers crossed - just the water leak to deal with now!

Chris.
Chris Bond

Obviously, I did not have my fingers crossed enough!

One week one from the the fix and the MIL light is back on!

There is a pattern here, as every time it has been in the garage and sorted (1st time the HGF fix, 2nd time the MOT and 3rd time the intake sensor plug) it has lasted around a week before the MIL light comes back on. So what gives?

Another thing that occurred last weekend, which may be related, we went to the Pride of Longbridge rally (some irony here methinks) and sitting in the queue to get in I noticed the temp gauge going up. Initially I was unconcerned as the rad fans had been working fine prior to the visit to the garage. But they did not kick in and eventually we had pull over and cut the engine (by this time the temp gauge is well in the red).

Took things easy going home and checked the fan fuse when we got back, which was fine. So I decided to run the engine up to see what would happen and as soon as the temp gauge hit half way the fans kicked in.

Could both these intermittent faults be down to a faulty ECU?


Chris.
Chris Bond

I think that we now need to know what fault codes have been logged by the ECU. IIRC, 2001 MGFs will have an OBD2 compliant socket, which can be read by aftermarket fault readers (plenty on eBay) - which may be cheaper than popping into the main stealer. That said, if they have a Testbook diagnostics set up, you'll be able to get more detail on the Rover-specific error codes.

Intermittent faults are the worst, but at least knowing what faults are being logged may help associate a link between the non-functioning of the cooling fan (poor or damaged connection to the water temperature sensor?) and the triggering of the MIL (mis-fire?).

What is evident is that the wiring loom has been modified. It is therefore possible that there is an intermittent short arrising from that modification.

Equally, the problem may be entirely separate - the cat may be damaged (second post-cat lambda logging the problem) or perhaps needs a bit more of the "Italian tune" to burn off residue that may have built up on the matrix. This wouldn't explain the overheating, but it may be possible to have two separate problems...
Rob Bell

Thanks Rob,

It is booked back in on Monday (and I will not be handing over any cash this time) so I'll try and get the error codes from them - and some answers.

Re the wiring loom, I was hopeful that I had resolved that issue but you could well be right. I'm still not sure about those 'speaker wires' as all the speakers function and they do not appear to be aftermarket ones, as they appear to come out of the loom.

I'm less convinced it is the cat, as they've just fitted a new one and the problem occurred identically, prior to it being fitted (which of course begs the question did it need replacing).

I've tried a few 'Italian tune ups' in the past, to no avail.

One question, can the ECU be reset by disconnecting the battery for a few minutes, or is this a myth?

Chris Bond

I'd not be surprised to hear that Testbook isn't revealing an error code, on the assumption that if there was a code associated with the warning light the garage would have informed you - no reason not to. The possibility that's due to the ECU not functioning correctly is definitely there, and is strengthened by what appears to be an inconsistent reaction to coolant sensor inputs - the brown coolant sensor sends a feed to the ECU, and the ECU switches on the radiator fan when necessary. A failing sensor will usually cause high idle speeds as the ECU applies the cold-running fuelling map - is the idle constant at circa 900rpm regardless of temperature?

Disconnecting the battery for a period won't I believe 're-set' the ECU to the point of wiping the fault logs or extinguishing warning lamps, but removing power for an hour will reboot it so no harm in giving that a shot. If the radio is OE, that will need the code re-entering afterwards.

Cables that are paired usually suggest they feed a device that does not earth to the car body. Does yours have speakers in the doors & the rear T-bar, or just the doors?
bandit

Hi bandit,

No, the idle is constant at 900rpm whatever the temp, so I guess that eliminates the coolant sensor. The fans were still kicking in yesterday, in the warm weather, so good news!

Been busy on other things today so didn't get to disconnect the battery but have invested in some diagnostic software and a cable from flea-bay, as per Robs suggestion.

Speakers are in the doors & T bar, all are working.

We'll see what the garage says tomorrow.
Chris Bond

Right then, update post garage visit. Apparently the intake manifold sensor was playing up and they have swapped it (no charge too!).

So far so good, but what happened on the way home has made me think again regarding the overheating/cooling fan issue.

I took it nice and steady on the way back from the garage (about 15 miles), sun out, top down and no hurry. A typical day of late, sunny but only warm. All OK on the move as usual but when I got home the rad fans kicked in as I parked up. So I let it tick over with the fans running but the temp gauge continued to climb. Once it had got over half way (and still climbing) I cut the engine, only to hear the burbling from the rear, which was hot (boiling) coolant rushing back into the header tank from the overflow pipe. The header was virtually full and a small amount of coolant had come out of the cap but within half an hour this had returned to normal.

This has made me think again about the other weekend, maybe the fans had kicked in then and we did not hear them. At the time we had a young ZS driver behind us with obligatory boom box on board, so perhaps they were working after all.

So what's occurring - why wont the fan keep the engine at normal temperature during tickover? One thing that seemed odd was that when the fan was on there seemed to be air pressure at the front grill - could the fan be pushing and not pulling air through the rad? Or is this a cooling system issue - but if so why is it maintaining temperature on the move?

Chris Bond

When stopping after a gentle amble I'd only expect the fans to run if it was a very hot day, so indications are that the cooling system isn't shedding heat as well as it should. I suspect the fan is pulling air through the rad, but the hot air hits the spare wheel well and gets squeezed, resulting in some being pushed upwards and out of the nose vents.

Is the radiator in good condition? An elderly rad that has lost a fair number of cooling fins will struggle to transfer enough heat, and if some of the veins are bunged up with oil then efficiency drops even further. If you remove the black plastic shroud in the front compartment and reach down past the washer reservoir, you should be able to feel a marked difference in temperature between the feed & return pipes.

While you're at at (but when the engine has cooled), open the bleed points on the radiator & heater matrix and check only coolant comes out, then do the same on the bleed point near the cylinder head. If the excess pressure in the system is just steam, then it will condense back to liquid as it cools. If air appears at any of the bleed points, then it's not just steam...
bandit

Hi bandit,

The fans do seem to come on quite regularly and nearly always as soon as you stop or are in a queue. We have overcome this on a few occasions by putting the heater and fan on full, which will bring the temperature back down. I guess that suggests that the rad is not doing its job.

Yes the rad is a recent replacement (by PO) and looks in very good order (externally), but I'll investigate further this weekend.

I'll check the bleed points also and hope its not air - I take it this would this mean the HG is suspect?
Chris Bond

If you have to run the heater on full to save the engine from boiling over, then something is definitely awry. Did the HG repair include flushing out the radiator? Once oil gets in there it's a bu99er to get out again, needs strong detergent and plenty of hot water to loosen it, taking it out so you can do a cocktail-shaker technique helps a lot, and saves having to put detergent through the rest of the cooling system.

A radiator that looks ok from above doesn't always look so good on the lower half, so worth having a thorough inspection. Sadly there's not really any way to determine whether there is oil present other than dismounting & draining it, but if you have access to a multitester with thermocouple function that may point to whether there is a section of the rad staying cool when the rest is up to running temperature. If you have the means to clamp the radiator hoses, I'd be inclined to take the radiator out and flush it regardless as that could well solve the overheating, which could well cure the coolant loss (i.e. steam being vented by relief valve)



bandit

So todays investigation revealed the following:
Hot water entering the rad and much cooler water leaving it - good news.
Cool down period, then..
Open rad bleed tap and low and behold - lots of air!
Open heater bleed nipple and.... nothing! So gave it poke and out came a small amount of air (bubbles).
By now I'm thinking that aforementioned "MGR specialist' are full of BS and decide to bleed the engine valve (is there an easy way to get to those 3 cover bolts under the T bar?). The good news here ( i hope) is there is no air at this valve.
Mrs B was on expansion tank top up duty the whole time, so no problems in that area.

End result - 15 minutes plus on tick over with temp gauge never getting above 1/3 mark and fan did not even kick in (I'd ran it up prior and temp gauge went straight up and fan did no good at cooling as usual).

So I had a rad half full of air - the question is, (apart from why didn't I check it earlier) was it always there because the system was never bled properly (heater bleed valve suggest so) or do I have HG blow by?

If it's not chucking it down tomorrow we'll be off to Abingdon meet, so it will have a good run followed by another bleed check- and I'll be talking to the garage on Tuesday!
Chris Bond

A 10mm ratchet spanner is the best tool for the engine cover bolts, agreed they're a pain in the butt. I had a couple of MGFs from new that duly went to dealerships to have their spannering done during the warranty period, and many was the time I got the car back with those 3 bolts just finger tight.

I suspect the air has arrived since the garage bled the system after the gasket repair, however it's worth giving them the benefit of the doubt for now and see if more air appears, probably accompanied with wayward temperature gauge readings & lots of fan activity. If it does, the air is almost certainly gas from the combustion process, but the clincher on that would be a sniffer test for hydrocarbons.

A blocked bleed point on the heater matrix isn't uncommon, and although it does appear they went to no trouble to unblock it I'm not convinced that it's a factor here. If you've been successfully cooling the engine down by running the heater & fan, there clearly isn't a shortage of coolant passing through the heater matrix so the evidence is increasingly pointing to the new gasket not doing its job properly 8-(
bandit

I'd take the car for a quick run, get the engine speed up, see what happens to the engine temperature, and then re-check the bleed points. If lots of air again, then a pessimistic view should be taken of the head gasket - or even the cylinder head (may be a porosity past the fire ring).

If on the other hand, all's well, then a watch and wait approach could be taken.

Fingers crossed!
Rob Bell

Just to bring things up to date.

We went to Abingdon (it didn't rain but was bl**dy freezing!). No problems on route but pulled up to look at the map to find the airfield and within a minute or so the temp gauge goes off the scale, with steam from the expansion tank. When we got back home, checked the the rad bleed valve and air/gas present again.

Followed this up with a sniffer test at a local garage and this was positive (not really a surprise by now).

It is now back at the MGR specialist where they are 'investigating' the cause (they are still refusing to accept that it is the HG). The head is currently being crack tested an I'm awaiting the result.

I'm just concerned that they will now try to blame it on a cracked head, to try and avoid the replacing the HG at their cost. If so, shouldn't they have spotted this when they did the HG?

Chris Bond

Well, clearly exhaust gas is escaping past the fire rings. This can be due to porosity of the cylinder head. If not previously skimmed, the head can be recovered by peening the fire ring landing on the cylinder head, and then skimming it flat again. Or you can use a head-saver shim if the head's already been skimmed...

Another potential problem is the liner heights - if a liner has sunk into the block, it may not be clamping the fire rings adequately, allowing the leak. And similarly, if one of the liners is too high, then the head may not be tensioned down adaquately onto adjacent liners...

So not only does the head need to be investigated, so does the block/ cylinder liner heights.
Rob Bell

Hi Rob,

Actually it turns out to be a cracked liner (no 4 cylinder).

I called round there on the way home and spoke to the mechanic, who showed me the steam cleaned no. 4 piston.
Obviously they had a negative result on the head, as he was saying that it wasn't a conclusive test due to porosity etc etc. At this point he started saying that he'd looked at the cylinder liner and it was fine but then stopped mid sentence, whipped out a pocket torch and shone it in the cylinder. There as plain as day was a 2" crack in the liner.

He then started talking about the cost of a single piston/liner versus a complete set - is there any benefit it fitting a complete set?

In my view this has been the problem from day one and explains all of the symptoms - coolant loss, gas in the coolant, the small amounts of mayo etc. Could it also be the issue behind the cat failure and MIL warning light through water contamination in the exhaust gas?
I'm now not convinced that the head gasket needed changing.

One question, am being unreasonable in believing that this cracked liner should have been spotted by them back in January, when the HG diagnosed and repaired?
Chris Bond

Well, that'd certainly explain everything - and I think you're right, that's been the problem since day one. Should it have been picked up earlier? Well I guess that the answer to that is self evident in a way, but it isn't necessarily the commonest mode of gasket failure, and moreover the crack is likely to have gotten larger over time... In other words, it would have been very easy to overlook.

A new gasket is needed now anyway - they are one use only.

The discussion regarding liner/cylinder sets - they're usually replaced as a set. Probably because they're matched and all are of a known quanitity, being new. Talking to an engine guru like Dave Andrews may give you some more insights - but I suspect that he'd recommend changing all four at the same time. He'd also say take particular note of liner stand-proud of the block - they should all be within a thou or two of one another; if they're not, then HGF is more likely.

Bad news/good news: bad news that the liner has cracked, and you're facing a rebuild bill. Good news that this should solve the problem!

If you have the budget, if this were me, I'd be getting the engine balanced by Vibration free (the engine will be stripped anyway, and it costs about 100 quid or so to balance the engine) and get the cylinder head ported. That way, when it all gets put together, not only will the engine not just work, but it'll be smoother and more powerful - and thus more pleasant to use ;o) But then, this is the Darkside calling: don't listen to me! LOL Mahmahmahmhahahaha! ;o)
Rob Bell

The lure of the Darkside gets ever stronger, one option would be to fit the 1900cc liners & pistons - ok a fair bit higher cost than OE 1800 spec but no time like the present ;o)

I'd not expect the relatively small quantities of coolant going down the exhaust to have had much effect on the cat or sensors, but it is certainly possible that it has been a factor. The debate over whether cylinder liners should have been investigated during the previous repair is a common one, perhaps worth suggesting to the garage that a goodwill gesture might be in order on the labour charge at least - it is the responsibility of the repairer to use 'reasonable endeavours' to determine what the cause was, and checking for cracks isn't difficult or time-consuming.
bandit

Hi both,

Please stop getting carried away - all I can see now is pound signs in front of my eyes!

1900cc liners, engine balancing and head porting - this is primarily the missus's run around guys.

I'm supposed to be spending my small amount of disposable income on the MGA - which is destined to be the quick one.

Seriously though, being a true believer of the adage 'if want something doing properly...', is this the time to collect it on a trailer and sort it myself. Is the cylinder liner replacement do-able at home or not?

One thing that jumped into my mind when we got to this situation, was fitting the LR oil rail kit - whats your view on this?
Chris Bond

Chris - you mention the oil rail kit...

Had this changed on mine when the HGF was 'sorted' recently (3 times) :o)

Seriously though, there were three parts to the original Landrover solution; the multi layered gasket, a separate thin stainless steel shim, one side of which is pre-treated with a bonding agent to stick to the head face, and a new lower, strengthened oil rail that fits to the underside of the engine and which is what the stretch bolts screw into.

The the new oil rail is clearly very different and much obviously stiffer than the original. It is probably some 20% heavier, due primarily to the additional strengthening webs. This is supposed to improve the overall stiffness of the engine. That said, the stretch bolts and torquing procedure remain the same, so not exactly certain how that works, but it is certainly the recommended option by everyone I have spoken to.

Mike Hall

Hmm - 1900cc option - now you're talking Bandit! :oD Scholar reckon 450 quid for a short block - but of course, there's all the other sundries; it quickly mounts up!

Chris, since this is the "sensible" car, then keeping standard and DIY makes sense. The liners are a DIY proposition. I'd recommend you get a copy of the K-series manual, which will be invaluable. It's bundled with the MGF/TF workshop manual, if you buy it from the MGF Register shop (and a number of reputable booksellers).
I'd also suggest you chat to Dave Andrews for advice (http://www.dvapower.com/) - especially regarding liner stand-proud tolerances etc.

Regarding the LR oil ladder, yes, go for it if you've got a multilayer shim gasket. As Mike says, it forms part of a package, so it makes most sense to do everything together.
Rob Bell

Well, every now and then you get a result!

There was I ready to be hit with a big bucks cost for the fitting the liners (and preparing to take it home on a trailer), when I get the call from the garage to say that they are only going to charge me for parts but not any labour. Obviously my continual questions relating to the issues that have been occurring since January have been noted.

But fair play to them as many garages would have charged full price for this regardless of my protestations.

I've asked them to put a full set of liners & pistons in and hopefully we can look forward to some stress-free, top down summer motoring.

One of the re-assuring things is that the mechanic that is fixing it, drives a TF.

Thanks to all those who have responded to this ridiculously long thread, especially bandit and Rob, (good luck with project Shed by the way). I really do hope this is now the last entry relating to this issue (tempting fate there).

Now, I've just got to fix that water leak, front suspension clunk, replace the clock........
Chris Bond

Fingers crossed Chris!

Project Shed is currently suffering from a lack of time available to work on it. But crucially, I now have a replacement, good second hand front subframe to disassemble, paint, rebuild with new bushes etc etc

Oh, and I've now also got a very sheddy looking GRP bonnet... :o) Weighs quite a lot less than the original steel item, and I shan't be too fussy about cutting a great hole in it to vent the radiator, ala mgtf200HPD :o)

Hopefully no more diasters to be found, and it'll be a case of putting everything together again. Well, here's hoping that Shed won't put up more of a fight... ;o)
Rob Bell

That's excellent news Chris, you clearly chose a garage that still understand the concept of Good Customer Service.

Rob, if tweak-able front camber is a desirable option for Shed then Superflex now do (after some light coercion...) camber-adjustable lower wishbone bushes. Sadly their price tag is just high enough for me to be looking into alternatives, i.e. replacing the centre-drilled inserts with off-centre versions so the same can be achieved with Powerflex bushes.
bandit

Hmm - that's interesting! Thanks for the heads up on that Bandit. Is this an off-set drilled bush? Mighten it be reasonably simple to do something similar with a blank blush, 'freeze it' and drill?

What I probably need to do is to check the geometry of the front suspension and work out what's needed. Lowering the ride height often gives some useful negative camber anyway - up to a degree. I guess about 2 degrees of negative camber is probably what many would aim for though.

On this slight tangent, I am also thinking of checking the bump-steer of the front suspension. Since I am rebuilding the front subframe and suspension anyway. I might do this. Need a laser pointer, a sheet of graph paper and a spot of trigonometry. I recall that Ian Pogson mentioned this when discussing the TF85LE, but wish I had the geometry detail... Perhaps this is another call to Al Philips and Andy Kitson...?
Rob Bell

I have the insert from a Powerflex bush on my desk right now and some stainless bar on its way to me. The headache will be how to lock the insert so it can't be rotated by the wishbone movement. The Superflex version has the eccentric bolt hole, but I'm not sure whether its design prevents rotation. I'm half-way through CAD modelling the front suspension, with the intention of seeing what the options are, and what can be done to improve the steering angles for lower ride heights. The VHS modified steering arm might well prove to be a quicker solution to that though, my CAD skills are struggling a bit...

Avoid the cheapest laser spirit levels like the plague, horrible diffusion and utterly useless 8-( There's one Toolstation sell for 9 odd that is up to the task though, I used these for my laser alignment rig and a 30k state-of-the-art kit confirmed the results to be spot-on 8-)
bandit

Nice to know that it is possible to DIY a rig equivalent to 30k worth of professional kit :oD

I'm holding out for that VHS kit too - for both of my MGFs! :o) Very interested to hear about your CAD modeling of MGF suspension - look forward to hearing the results :o)
Rob Bell

This thread was discussed between 18/01/2010 and 14/05/2010

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