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MG MGF Technical - head gasket

losing coolent and overheated last week. oil seems a bit different in colour but still above minimum , also a slight ticking noise from engine when running , does this mean head gasket or is there a chance its something else. its a vvc but has only done 42000 ,surely not the gasket already? could i be losing the coolent from somewere else? were should i look to see if it is something else? dealer wants 450 to do the gasket!!!!! thanks all.

Guy, first things first.

1. Do you have mayo (white stuff) on the dip stick. If you do you'll know all about it is'll be all the way up.

2. Look in the coolant tank and see if there is any white goo in there too.

3. remove the spark plugs shine a torch in and see if the top of the pistons look shiny or covered in carbon. (if shiny then water is getting in somewhere). If the cylinder nearest the alternator show sign of water ingress then it may simple be the inlet manifold gasket if the car is an MPi.

With the engine cover off and the engine running look to see if there is a fine jet of water coming form the head gasket. HGF comes in two flavours innies and outies. Innies are a bit more serious as they can cause hydraulic lock if water enters the combustion chamber. A different type of innie is if one of the headgasket seals around an oil way fails.

Don't jump to the HGF conclusion just yet..

You ticking noise may be very well be a hydraulic follower which has got blocked. I have just read a thread on this over on the Lotus BBS. There solution to clear the follower was to drive the car in third from 2000rpm to 6000rpm and then let the car return to 2000. repeat this a couple of times and it can have the effect of pumping up the follower with oil. The Lotus boys seem to find that this worked. Of course if you do have to have a head gasket replaced at any stage then this is the time to replace them.
tim woolcott

Sound advice from Tim.

>> 3. remove the spark plugs shine a torch in and see if the top of the pistons look shiny or covered in carbon. (if shiny then water is getting in somewhere). If the cylinder nearest the alternator show sign of water ingress then it may simple be the inlet manifold gasket if the car is an MPi. <<

If the top of the piston nearest the expansion tank is shiney, could be the inlet manifold gasket on a VVC too.

I had this on Scarlet, she has a VVC inlet plenum and manifold and the return pipe to the expansion tank is cast into the manifold. This means that if the gasket goes, coolant will be sucked passed it into pot 1 (the one nearest the expansion tank).

'Mayo' is a sure sign that the oil and coolant are mixing. As the head gasket is the main separating membrane between the two it is a clasic indicator of HGF. The mayonaisse is actually an emulsion of coolant and oil, it is a coffee and cream colour and tends to stick to surfaces so it'll look like a residue rather than a floating mass.

Another way to tell is hydrocarbons in the expansion tank. You garage can do this test by putting an MOT exhaust 'sniffer' in the top of the tank and testing for hydrocarbons. It is looking for evidence of oil which is carbon based in the coolant which is water and alcahol based.

Good luck

Scarlet Fever

M8 I just had my first HGF on my 99 VVC with 36,000 on the clock cost me 849:48 all in with the cam belts changed as well. MG main dealer that is
P Durrant

Hello Guy
I am also an unfortunate victim of HGF the first in Bermuda i beleive i have researched this turns out the car was in the garage last week for overheating and loss of coolant at that time i checked for all tell tale signs of HGF but did not find any after a day at the garage i picked the F up and it was fine until last night when we came to a stop sign and whoosh there went the gauge again pulled over checked the oil and tru enuff mayo and there was steam coming out the K+N as well maybe someone can elaborate on this anyhow its in the garage now and i am NOT paying for the fix, anyhow will keep u updated.
Bermuda's first HGF :(
Luis Pereira

This is a long posting but worth the read. (for everyone)

Mmmmm, this is an unfortunate one..... It is not uncommon for HGF after a trip to the garage especially for work to the coolant system. We know that the system is a bit delicate and requires careful attention and correct bleeding. I may just be that the gasket was about to go however if a large air pocket develped in the coolant system when refilling this would lead to HGF, very difficult to prove though.
A tip which might be adviseable if in doubt of a garages competence, is to tactfully ask the mechanic if they know the correct bleeding proceedure. Ask to be shown all of the bleeding points. Top of radiator, Heater matrix bleed point in front bulkhead under wiper mechanism and a third on a coolant pipe underneath the K&N (beside the regular airbox). When taking the car to the garage make sure the heater is on 'HOT' this will ensure the heater matrix is drained and filled correctly. Luis, if you received the car back and the heater was on 'COLD' then they may not have done this.

If still in doubt, when you get the car home raise the front end of the car and allow air to collect at the top of the radiator and then bleed it out.

There is actually a fourth automatic bleed value, called a jiggle value in the inlet manifold.

Sometimes this jiggle valve can become stuck and will not allow air to escape from the coolant from the top of the engine. It has been advised (by Roger Parker I seem to remember) to check this periodically.

Roger Parkers text.
In addition to the three manually opened bleed points on the cooling system (water rail, heater and radiator) I think a timely reminder is of use to introduce a periodic test by owners to ensure the little jiggle valve in the inlet manifold of all MGF engines remains free and so allows air circulated up in the engine to automatically escape to the header tank.

Both plastic and alloy manifolds have a small bore hose that connects to a stub at the cam belt end of the manifold flange. This valve consists of nothing more than a plastic ball which is heavier than air and lighter than water. When the cooling system has no air this ball is held on a seat and so closes the path for coolant to the header tank from this direction. If any air percolates to the top of the engine, which it will if any is there, then the ball falls away from the seat and the air escapes to the header tank. As soon as coolant arrives the ball reseats.

It has become more and more apparent as cars age that this valve sticks on it's seat and so any air remains trapped in the upper part of the engine. This as we all know can cause spot overheating and even cause interuption to coolant flow and the results can be ....... unpleasant and costly!!!

A simple check periodically can ensure that the valve remains working properly. This involves removing the existing hose and I suggest it be squeezed with a brake pipe clamp or other similar device to prevent unnecessary coolant loss. Then have to hand a length of the same bore hose that can be simply pushed onto the manifold stub and long enough for you to be able to blow into it.

If the valve is free then you will be able to blow past the valve. If it is stuck then you won't be able to blow into the system. Loosening the valve involves removing you blow hose and poking a blunt probe down the manifold stub to dislodge the ball. Check again by blowing down to confirm it is now clear. Remember that the valve will stop any coolant loss so you only have to worry about the hose from the header tank.

Removing and carrying out this will not lose any coolant, other than a few drips and confirms that a safety valve to help prevent HGF is actually working.
tim woolcott

Proud owner of an mgf for 3 months.
Unfortunately it broke down last night.
Today's diagnosis is a HGF (25k on the clock) with a cost of 584 (dealer). I'm not mechanically competent so have no idea if this a fair deal or not.
Sad to see others in the same boat.


Basic HGF's range between 400 and 600 quid. Seems to be the right kinda price. Really sorry to hear that it's happened to you too.
tim woolcott

If you brought from a grage then the car is not 'fit for purpose' and they should refund you or replace the HG free of charge, if you did not buy from a garage then you have only the comfort of knowing that you saved more than the HGF will cost you.
Will Munns

This thread was discussed between 12/06/2003 and 18/06/2003

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