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MG MGF Technical - HGF permanent solution

We really must work out an official Club wide solution or at least avoidance strategy for the HGF problem that seems to be plaguing our cars! The MGF will go down in history as a pretty but fragile and difficult to work on classic. This accordingy will keep residuals low even into the long term, despite the latent demand for the car. It will also keep us busy fixing dead heads.

Despite a million angry voices MGR, to their eternal shame never engineered the problem out, indicative of their fate I suppose.

All I think we can do is set alarms for the events leading to HGF. And that is fit a B&G water level alarm and a much bigger reservoir tank and provide a list of checks you should do to avoid HGF

Neil

Neil,

Your post has inspired me to arrange having the coolent sensor fitted at B&G. I'll have to shelve the TB for minute.

Thanks.

Oh and how's my TT coming along?

Merry Christmas

martin
Martin

That won't help avoid all hgf, but it will help stop it spiraling out of control with steam everywhere.
Will Munns

The water level alarm and check list is certainly a very good idea but the reasons for failure can be complex. I had an HGF at 23k but there was no problem with the cooling system and it would seem to be 'green engine syndrome' (I have included an explanation from Roger Parker just in case some people haven't seen it) so failures with new cars are probably the same when no obvious fault can be found. The good news is that having had one there is less likelihood of having another!


From Roger P
On the head gasket issue i would add that the repeat failure rate is so low because of two specific issues. 1, is that the design if the engine leads to full clamping loads not being achieved until after the engine has gone through one full thermal cycle to reach normal operating temperature and then cool.
2, is related to the 'green' unmatured castings in a new engine. Virgin castings mature with use and stresses inside will often lead to slight movement away from the original. This can then apply additional stresses during use and these seem to have a habit of showing up when an engine has covered around 25k miles approx.

Most will also know that the best race engines are built using used main castings as in use these will have had all the stresses eased out of them so when they are machined and reassembled they are now far less reactive and more inert. This leads to greater reliability. Applied to a K series engine and the main element comes from the release of the sandwich of castins that are held together by the through bolts, but is often assisted by a very light head face skim. (Although this is not meant to indicate that head skimming is mandatory - just that if there is any hint of warp, even when in tolerance it is a good move.)
Once the engine is reassembled it doesn't have the internal stress and so needs far more abuse to push it over the edge of a repeat gasket failure. Here though pushing over the edge is possible if a fundamental issue with coolant leaks and airlocks exists.

Blue Pocket Rocket

Following your question for HGF-preventing measures I would without any obligation give you info about my own precausions for the "Green Frog" -97 VVC.

1. IMO a separate thermostat system is a must. Can be any well-built type that are on the market. I use my DIY system as shown on Dieters site. Has served well for many years now,both on road and track.

2. The often overlooked exthaust bracket is a good thing to prevent any movement of the head, especially if lightly shunted from behind and forces gets thru the exthaust system...

3.Never over 3000 rev/min on a cold engine,nor "lugging" the engine on low revs when cold.

4. Any signaling system that alerts on low water-level and / or high temps in the system. As we all know the original water temp readout is useless. Personally I use a "steak thermometer" (!) with settable alarm temp. Works great ! But hesitate to tell about it to the Miata friends in the Racing Club ;O). / Carl.
Carl

As all engine castings are " Green " at the time of manufacture, are we saying that the design of the K series is more likely to lead to probs', as opposed to other engine designs?

Bit late in the day, but would it not have been possible for MGR to have had a water heat/level sensor connected to the ECU to shut it down at the first sign of trouble?

P.S. off topic, but interesting, just been reading that the engine of the Alfa 159 G.P. car of the fifties was so highly developed from the original design that it became a " 5 " stroke, using one stroke to put fuel in the engine to help cool it.
roy bridge

>>>
2. The often overlooked exthaust bracket is a good thing to prevent any movement of the head, especially if lightly shunted from behind and forces gets thru the exthaust system...
<<<
Good point, good old bracket ! However it didn't help me from having 2 HGF's. On the other hand, it will be removed once I install the 4-2-1, right ?

In general, I find it very hard to handle the thought I will be struggling with HGF's on my beloved F 'till the end of its days.
Erik

Hi,

<.. would it not have been possible to have a water heat/level sensor connected to the ECU to shut it down at the first sign of trouble? ..>

Just too dangerous.

<.. off topic, but interesting, just been reading that the engine of the Alfa 159 G.P. car of the fifties was so highly developed from the original design that it became a " 5 " stroke, using one stroke to put fuel in the engine to help cool it. ..>

Tell me more! A brief precis. I'm just interested for it's own sake, not for MGF application.

Regards, Kes.
Kes

I suffered hgf at 41k miles and 90k miles,I have looked at the idea of fitting an auxillary electric water pump in the heater water circuit governed by a turbo timer ,or electric thermostat.i believe fitting this pump may add to help in the cooling down process of the engine , smoothing out hotspots.What do you think?

ps, my k series engine is fitted in a fx4 type Taxi working the streets of London,

pps, electric water heater pumps are fitted the x300 Jaguar ,volvo 480 ,to my knowledge.

Simon
Simon

HGF permanent solution:
Very easy: GET A GOOD OLD MX5!!!
A. PINTER

Kes, bit late in the day.
Go to www.grandprixhistory.org the details are there, along with brief historic/technical pages on all the historic G.P. cars. It doesn't go into the details of how the 5'th stroke worked, valve timing, ignition etc. You'll have to dig a bit deeper for that!

regards.
roy bridge

> GET A GOOD OLD MX5!!!

Hey boys, looks like we got ourself a troll. Y'all remember what we did with the last one?
Chris Reeves

P.S. think 8w.forix.com is a bit more " in depth ". Or if you have MP3 there's loads of sound clips, just put " brm v16 loud pass" for one e.g., in google.

My B-in-Law's just got an MX5, seems to spend all his time and money trying to make it look like my TF.

Reliable........Yes

Everything else..No

regards

roy bridge

Let's see what the changes the Chinese takeover produces!

options

1. Nothing ( good chance of this)
2. Small production of mgtfs in Longbridge using K series = same old HGF issues.
3. Small production of TFs retooled to fit an alternative engine = cure to HGF!

K series could have been one of the best engines in the world, but seems to be destined to be forever associated with HGF a problem that should have been engineered out 10 years ago, as I have often ranted!

So perhaps a Honda or VW engine would be the best permamnent cure for new Fs!!!

Neil

This thread was discussed between 20/12/2005 and 29/12/2005

MG MGF Technical index

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