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MG MGF Technical - Cracked Engine Block

Wanting to canvas opinions advice. I have 2 questsion, but first I should give some background:

June 2005: Bought a second hand MGF 1.8i, 2000 SE model with 35900 miles on the clock.

July 2005: Engine began to overheat in traffic jam on a very hot day. Front radiator fuse blown. Turns out that front radiator fan was sticking. This was repaired. No evidence of head gasket failure at this point, but check coolant regularly just in case...

April 21, 2006: Notice mayonaisse in coolant. Sh*t. Take MGF into garage to have head gasket, cam belt, bolts replaced. Car has done approx 3500 miles since purchased.

May 26, 2006: 100 miles into my first long distance journey since head gasket replaced, engine overheats only this time my eye wasn't on the temperature gauge, so caught it way too late. Engine cooked. Front radiator fan fuse did not blow this time (so that is unlikely to be the cause.)(My only journeys prior to this probably amounted to 150 miles at most. I also regularly checked for any evidence of any oil in the coolant, either from being flushed through the pipes or from a new leak.) Engine block is now cracked and I'm up for a new engine 250 miles or so after having the head gasket replaced.

The garage that replaced the head gasket claims that it isn't their fault and that the crack in the engine block was a pre-existing weakness. I must admit that I find the temporal proximity of the head gasket being replaced and the engine overheating just a wee bit suspicious. I'm also doubtful that the engine block cracking was the cause of the coolant loss/overheating. It seems more likely that this occured as the engine cooled down after overheating. (i.e. is a symptom not a cause.) Water was poured into the coolant tank, but not until 2 hours after the car had been stopped.

So, my questions are:
(1) Any ideas as to what the likely cause could be? What could the garage have done wrong (if anything) when they replaced the head gasket that could cause what happened on the first proper run after it being fitted. (There was no evidence of coolant loss over the preceding month, btw.)

(2) If it is likely that this has been caused by poor workmanship, how the heck can I prove it? What recourse do I have? Does anyone else have experience of MGF HGFs/Engine failure occuring in quick succession like this?

I obviously don't want to hit the garage if it isn't their fault, but I find it hard to believe that the HG replacement and the engine overheating aren't linked given that it was the first trip ofmore than 3 or 4 miles since the HG was replaced.

Many thanks for your advice in advance,

Steve Siller
Steve Siller

Sorry to hear about this Steve.

I have not heard of an engine block cracking before and I've been reading this BB for 7 or 8 years now.

The radiator fans don't run all the time as they are just an aid to the existing cooling system when the air flow through the radiator is low.

The fact the you suffered an HGF not long after you bought the car unfortunately means you do not know the history of how long a problem existed. Do you know if it had a head gasket replaced before you owned it ?

However, if the head had been off before and skimmed an experienced mg service centre should have been able to spot this and make a judement on its future robustness.

If you want to source an engine try who broker all the car breakers, I remember being offered a whole VVC engine with 36000 miles and 30 day warrenty for less than a new x part cylinder head.
Jon Baker

Car was second hand and supposedly came with full service and repair history...but who knows. The cracked block happened the first proper trip AFTER the head gasket was replaced. I do not know if it was the cause of the second engine overheating, or a symptom of the engine having over heated. I suspect the latter, but the garage suggests the former.

The initial over heating that perhaps precipitated the HGF happened 3500 miles before the head gasket began to show signs. The head gasket was replaced (along with the head being skimmed, cam belt replaced and bolts) when I noticed oil in the coolant. As I said above, it was immediately after this work was done that the over heating leading to the engine block cracking occured.


Steve Siller

You have not said where in the block you have a crack.
Any casting can have a 'core shift' resulting in a thin wall section. A crack may then develop causing coolant loss and the first HGF. No mechanic can be expected to crack detect the block when repairing an HGF therefore unless it is abvious, then it will not be seen.
It may be interesting if your local technical college would like to take the block to cut up and investigate it. It may be another cause such as an inclusion or mis-machining during manufacture.
Geoff F.
G. Farthing

A cracked block? Crickey. As Jon says, this is not something that's cropped up on the BBS before that I recall.

Falls into the "really bad luck" category. And Geoff's right - this is very likely to be a very rare problem that a mechanic would think to look for and wouldn't really be expected to search for.

Hopefully you can find a new warrantied engine reasonably cheaply.
Rob Bell

It comes back to Geoff Farthing's point about where the crack happened, or to put it another way, would it be reasonable to expect the engineer to spot it during a quick visual check when they had the head off?


From far left field: my vvc coupe had hgf in March, still leaked coolant in June, so took it back to the garage. Found a small crack across the edge of the combustion chamber and the flat (interface with the block) which looked like someone pushed their fingernail into it...

Can't really see it happening from overtightening/uneven tightening of the head bolts as its in the strongest part of the casting, so I suspect a manufacture time flaw.

Anyway, have tracked down a second hand head which looks ok, and am now waiting for the garage to fit it (hopefully by wednesday)...

So its not necessarily all that rare, thought the garage said it was the first they had ever seen.

-- Andrew
Andrew Haigh

Andrew, you had a cracked head has been reported before rather than a cracked block.
Jon Baker

This thread was discussed between 09/06/2006 and 18/06/2006

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