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MG MGF Technical - water leak

hi had head gasket done a few months ago new bolts new gasket head skim land rover bottom rail belts and tensioners and rad basically everything done lost some water leaking by oil filter took it back to garage and they retightened bolts just took it for mot (passed)and thought while i was there would check up behind alternater and found a drip of antifreeze off bolt coming off bolt in block taking it back to garage wed am shifts allowing for trhem to look at any advice please getting cheesed off now
tg hardwick

Sorry tg, can't help but thought somebody should respond, good luck!
Russ68

AFAIK the through bolts are "stretch" and at the specified torque they are at their yield point. So no point in retightening them and it may even cause damage. Is the garage a K engins specialist? The head may need skimming and the block may be porouse I have read elswhere that peening can sure this but its going to be beyond someone who doesnt understand these very clever units..
Stan Best

We've replaced many F and TF head gaskets at the Classic Car Clinic but I have one that is a pain...! The symptons are exactly as above...
Head skimmed (to dress it only and finished to the 'correct' surface finish), latest triple layer gasket, new bolts (of course), new (latest spec) bottom end rail, new water pump etc etc.... I still have the leak that TG has.
I've researched this but with no conclusions. The problem appears to be more prominant with the Land Rovers fitted with the same engine, but again, nobody has the answer.
Just to compound the problem, we've replaced the H/G three times now, the first time the client has paid, subsiquent times, we've stood the cost (Ouch...!). As I see it, he's not to blame, but neither are we... The situation is ammicable between us and I certainly don't want to fall out with anyone, but as things are going, I can see he's getting to the end of his tether.
I'm looking for some firm sugestions as to what the hell may be causing this.
Not that it'll make any difference, the car is a 2004 TF with VVC and only 34000Kms on the clock. Japanese import into Aus. And me... 35+ years in the profession... :-)

Mark.
M T Boldry

Hi Mark,
if I understand TG well, than at his engine the drops were visible. So, that must be a interesting lead towards the devil.
But what about your engine: do you see any drops or is the point of leaking still a mystery?
Greetings, Huib
Huib Bruijstens

No, I can see the drops exactly the same as TG.... Looks like it's leaking from the head / block joint below the exhaust manifold at the alternator end....

I'm really struggling with this one....!

Mark.
M T Boldry

My experience last year when my head gasket let go last year was that the polymer beads got "tired" and let go in a tiny section on one side, and let water into the oil. Fortunately I had a low coolant alarm and stopped the engine immediately.
Stripping the head revealed no problems at all, clean bores with honing marks still visible (54k miles)and a good gasket except for that little patch.
One of the major problems people seem to have is in appreciating how important the liner stand proud above the block is. I had 3/4 thou on every liner, no steam funnel effect and everything else looked fine. I used a Land Rover multishim gasket, no bottom rail.
If the liner height is not sufficient at cold, the differential coefficients of expansion could mean that the liner ends up below the block at working temperature. Any gasket is going to struggle then!
If liner heights are not to spec, a polymer bead gasket would probably be the best bet to seal the block/head.
Liner heights in spec would benefit from a multishim gasket, as I believe the polymer bond to the stainless steel gasket sheet is very fragile and age/ excess temperatures/ anything else can make the gasket fail.
Coolant dripping from above the alternator is a classic leak point when the polymer seals have failed.
Retightening the bolts is a big no-no as well. If everything is to spec, there is no need to touch the head bolts ever again.
Skimming the head is another dubious thing to do, as there is a heat treated "skin" which may be machined away. If the head has got too hot, it may have gone completely soft and be scrap.
Sorry for such a long rant, but the engine is good if maintained properly and does not take kindly to being treated like any other modern alloy engine because of it's unique construction.
My jaundiced view of garages is that I would not get them to change a light bulb.
All above just my views on working on the engine.
Jerry Herbert

Jerry, I'm with you on this... The liner heights are ok on this engine, I'm begining to believe that the few thou off the head face may be the cause of the problem. Although a hardness test shows it to be good all over the machined face.
I guess finding a good S/H VVC head is the next option for my client.

Mark.
M T Boldry

Have you penetrant crack detected and pressure tested the head.
Geoff F.
Geoff Farthing

I've not Die Pen'd it but it has been pressure tested showing NO faults.

Mark.
M T Boldry

mine never overheated or lost water just saw oil in water so got it done asap will be checking under car next weekend because havent used it much the last few weeks
tg hardwick

This thread was discussed between 15/10/2010 and 21/11/2010

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