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MG MGF Technical - Porous Cylinder Head - A Cry For Help

Hi Guys,

Apologies for gate-crashing your BBS but my '96 Elise (with 30k on the clock) has just expired in a cloud of steam and smoke on the M25. Symptoms were typical of head gasket failure. However, it turns out that there is a problem with the head. It's being tested at the moment but they suspect either a porous or cracked head.

I wondered if any of you had experienced or heard about this problem. Can't get any joy from the Elise BBS because there aren't so many 30K Elises about.

I've had a new head fitted (along with some nice Piper BP270 Cams to cheer myself up) but I was wondering whether this was a known problem with earlier engines and one worth bashing on Rover's door about?

Sorry if I'm going over old ground.





sorry about your problems. We haven't (IMO) found here the one and only reason for several blown headgaskets (our common short word here is 'HGF' or 'CGF').

I'm not that english mother language guy but recommend this non representativ consumption site for getting knowledge of some of our thoughts of the last year.


Porous head! No that is a new one to the MGF BBS, head gasket failure isn't so new.

However if the head is porous then I would have thought that Rover/Lotus would be responsible.

Ted Newman

If you do have a 'porous head' or indeed block (which I assume is due to a porous casting) then you should get the whole lot replaced free. If your dealer complains, mention the phrase 'latent defect of manufacturing' and see what happens. At the very worst, they should pay for the bits, and you the labour.

N837 OGF

Yes, having a broader base than owning an F I have heard of this before. It was mentioned I think by Roger Parker - try hunting through the Subjectarea ' 16V K series midgets and Bs' further down the list. Also have a look at Dave Andrews' K series site, might be something there too.
David Smith

The problem may be corrosion pitting. I have seen this go deep around the HG fire ring and near where the silicon rubber track touches and can be mistaken for porosity. This has been so bad as to cause either leaks to the out side or leaks at the fire ring (either blowing combustion gas into the cooling system or/and sucking water into the comustion chamber). It can be put down to running the engine without proper antifreeze levels. This contains important inhibitors which prevent corrosion. Age or overheating results in loss/degradation of the inhibitor pack to the point at which corrosion can set in.
Terry Cox

hello Becker

when you refer to porosity of the head has the coolant gone into the oil or has it gone oil into coolant, oil going into coolant could be movement of the piston liner in the cylinder block the only cure for that is a new engine. if the problem is coolant into oil the problem could be some thing as simple as a failed inlet manifold gasket Rover/Mg are modified dont know about lotus presume that is the same porous heads do exist but are not as common as hgf failures
mark the tech

I have previously mentioned porous K series block castings and not head castings. With the block an antifreeze trail left a stalagtite like residue from the middle area of the casting on the back of the block, and when the engine was hot a clear wet dribble emerged like a spring out of a hillside. This was a very early 1.6 litre K series engine.

I haven't come across porosity of the head casting and would favour one of the more common gasket failures, especially the inlet to head face one.

Roger Parker

A friend has just had the same problem on the K-series in his Caterham (porous and/or cracked head). It's been repaired using a resin dip process. Apparently this process is applied to all the magnesium gearbox casings used by F1 teams prior to assembly, just to ensure that there will be no porousity problems.

It's not *that* unusual for ali heads to suffer this way, the Vauxhall 16v XE engine is well known for it.

Mike Bees

Many thanks for all te help and advice.

I'm afraid things have gone progressively down hill since my last message:

I collected Reg last night with his new cylinder head (the third btw) and cams. It turned out that the original head was warped but not porous or cracked so, none the wiser, I drove him to work this morning only to find him overheating, lots of steam from the exhaust, lost all coolant from the expansion tank and lots of lovely mayo on the dipstick and filler cap.
So back to square one!!

Motobuild, who replaced the head, now want to replace the block too but, obviously, I'm reluctant to fork out any more hard earned cash until I know exactly what the problem is.
But how the hell do I find out. Could it be the new gasket, the liners or the block itself???

When it first went the symptoms were loss of coolant (not from outside the engine though), mayo on the dipstick and, strangely, oil dripping from the throttle body. No real loss of compression though.

The second time, again loss of coolant with lots of steam from the exhaust (suggesting the water is getting into the chambers). No loss of coolant or oil outside the engine and no loss of compression though.

So still crying for help, just considerably more skint than last time.



My god :(

Diiirkyyyy, can you count that all ?


If there was a guarantee on the previous work, I'd try and invoke that. It would be to the long-term benefit of the garage that replaced the head if they find out themselves what caused it - and a bit of financial prodding should help......

If you've had water in the cylinders, I think that block replacement is a good idea. Water tends to be incompressible. Otherwise could be HGF. Has the waterpump been checked?

N837 OGF

Hello again Becker

sounds very much like a block problem you see what happens is the seal at the bottom of the piston liner moves and lets water /coolant leak past the seal and into the sump unfortunatly the only way forward is anew block, this is avery common problem on the K series engine with our dealership alone changing on average one a week. With regards to cost the original diagnoses wasnt correct so some cost must be taken on board by the garage doing the work they should at least refund your original cost on the head rework let me know how you get on cheers .
mark the tech

Cheers Mark,

You've been a big help. I came to the same conclusion last night whilst thumbing through the K16 manual that comes with the Elise service notes, but it's good(?!) to hear it from someone in the know. Motobuild say they have a block from a low mileage MGF VVC and I'll be looking at about 800 (bearing in mind the money already spent). This doesn't seem unreasonable, but what do you think?

Also, would it be worth trying to recover some of the cost from Lotus/Rover, bearing in mind the reasonably low mileage?



This thread was discussed between 18/04/2000 and 20/04/2000

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