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MG MGF Technical - Incipient HGF?

I'm pretty sure I'm panicking unnecessarily...

Checked coolant level last night prior to fitting new K&N (more of that later). Couldn't really tell in poor light, but checking again this morning, thelevel has dropped noticably over the last three or four days - maybe by half an inch in the reservoir. Also a dry chalky deposit on the cap. Rivet *might* have moved sideways, but if so it's certainly not far. How far does a blown cap's rivet move?

No other hgf signs - oil is clean as a whistle on the dipstick, exhausts are clean, engine temp might be running a tad higher than usual, but I've gunned her a few times over the last few days (only when warmed up according to oil temp!) so probably nothing.

What do I do? Run her to local (ok-ish but not really trusted, certainly not for mgf diagnostics) mgr dealer, get new expansion cap and some replacement coolant, keep a really close eye on it for the next few days? And is there an easy way to accurately check the coolant level? I find estimating the amount by peering into that little hole tricky.

ALSO (do seem to be getting my money's worth from the bbs these days!) fitted K&N last night - just picked it up and figured that, even if there was a coolant leak, it wouldn't do any harm. Obviously didn't give it the brisk road test I would have otherwise, though.
It's quiet to the point of unnoticeability when cruising (as advertised) and sounds like a wounded bull elephant in the boot when foot down hard (as advertised) but there is an intermediate stage - accelerating hard but not too hard - when there is no roar but a really striking whooshing noise. I assume that this is air going through the induction tubes, and it's drowned out when the cone starts to resonate. But is this normal? I'm reasonably sure I fitted it correctly. Should I be able to bring on the induction roar without putting pedal *all* the way to the metal?

Sorry for the length...

Jamie
Jamie

I would start with a new expansion cap. re-fill when COLD the expansion bottle to seam and keep an eye on it.
Mike
Mike (@home)

If it's only 1/2 inch then use plain water, a new cap is a couple of quid from Halfords.

The wosh is the air rushing past the throttle plate, so at all apart from full throttle there is quite a lot of stuff preventing noise getting back from the engine (think of how the noise gets back to you from the valves). Air doesn't pass thru tubes fast enough to make any significant noise
Will Munns

"If it's only 1/2 inch then use plain water, a new cap is a couple of quid from Halfords" "and keep an eye on it"

Right - will do. Suppose I should treat this as a reason to get some coolant anyway!



"wosh is the air rushing past the throttle plate"

So how come I couldn't hear it before? It really is LOTS louder than any air-like noise I had before. And do I really have to put pedal all the way to metal to get the *nice* noise?

Thanks for all your help, guys.

Jamie
Jamie

The K&N is very non-restrictive, on the standard F, there is a long ribbed pipe to a large hard walled box, then a restrictive thick paper element, then another ribbed tube which ends up on the opposite side of the engine, most of the way down (about as far as you can get from your ears).
The K&N is a short pipe with smooth sides, leading to a thin layer of foam, exiting fairly close to your head -

Remember that noise is just vibrations in the air, 'heavy' things block it.

I prefer the slurp to the hammer of tappets, but I guess I'll just have to get used to it (todays MOT failure is trivial!!) - oh oh another thread!
Will Munns

Update - went to local MGR dealer and bought a new cap. Went home and let the car cool down a bit. Under his intructions I looked at the coolant (all fine, nice and green), topped it up with distilled water, and ran the engine with the cap off for ten minutes (slightly surprised by the jet of coolant coming back in, but after thinking about it for a minute, that's normal, isn't it?).

Turned engine off. Coolant level had actaually risen a tad. Noted the *tiniest* amount of an oily residue on the surface of the coolant. It was a white-ish colour.

Replaced (new) cap. Chainsmoked for an hour or two. Looked again before going to bed, and again this morning - no sign of the residue.

Help? Is it going? Still no sign of anything in the oil, no increase in smoking from exhaust (always been a little, but that subsides after ten seconds), oil and coolant temps aren't going higher than normal.

Thanks,
Jamie
Jamie

Jamie, I don't think that you've got any serious problems there - but do keep an eye on the 'average' coolant level. As you've spotted, it can fluctuate a little - but if you are loosing coolant, it'll be pretty obvious in terms of a level drop.

Does a coolant level drop mean HGF? Fortunately not. You've already considered, quite rightly, the coolant cap. If the cap is leaking, you can sometimes see a congealed or dried coolant residue either around the cap or under the grille inspection cap. Remember that just because the cap is new it doesn't mean that it's okay - there have been plenty of quality control issues with these caps in the past - and hence the appearance of the 'white dot'... But other 'favourite' sources of coolant leakage are the coolant rubber and underbody metal pipes and the radiator.

Fingers crossed, but to me it doesn't sound as though you have any particular problem :o)
Rob Bell

>But other 'favourite' sources of coolant leakage are the coolant rubber...

You're so fickle, just cause yours popped, a couple of months ago it was rusty rads ;-)

Jamie, Don't open the cap with the engine so much as warm, and don't run the engine with the cap off (it's designed to run a little pressure). That asside it sounds like your engine is running peachy, and look here, It's the summer - Get out in it!
Will Munns

Depends how old your car is Will.

4-5 years and the under body coolant pipes start to cause problems
5-6 years and the rad becomes a culprit.
7-8 years then there is a good chance that the engine hoses will start to fail.

Other than the underbody pipes, I've been there, done that. I didn't want to bother with the T-shirt.

;o)
Rob Bell

Thanks, guys. Much appreciated!

So I don't need to worry about a touch of oily stuff in the coolant tank? It was actually on the surface of the coolant liquid.

Have new radiator and very recently checked pipework (by TechSpeed) so will assume it was the cap, unless it continues to drop.

"don't run the engine with the cap off" - sounded odd. Typical dodgy MGR advice, then? This is the same dealer who managed to give me the orange coolant rather than the green after specifically asking me which colour I needed...

See y'all on Tuesday then :-)

Jamie
Jamie

> sounded odd. Typical dodgy MGR advice, then?

running with the cap off is usually done to look for HGF exaust gasses getting into the coolant, usually causes a stream of bubbles - but for the cooling system to run properly it ought to be pressurised (I knwo - you weren't really pushing it I give you that)

If the car has had HGF in the past, oil is very difficult to compleatly remove from the cooling system, so enough to put a very slight film on the water surface is 'expected'
Will Munns

Ah - makes sense now. Certainly no stream of bubbles seen. One or two at the start.

I don't know if the car's had an HGF before - evil dodgy dealer gave me no service history (despite promises - at least the small claims court came down on my side). Will assume that it has, then.

cheers,
Jamie
Jamie

This thread was discussed between 30/03/2004 and 31/03/2004

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