7 replies to this topic

[Angus 850]

I have been having problems recently with my 850, with wet plugs and damp cylinders. I thought that it was caused by running rich but now I am not so sure. After very helpful advice from TMF, I cleaned the carb and float chamber, fitted an inline fuel filter and a fresh tank of fuel. The car runs much better now.
The only problem is that there is a very tiny leak between the head and block. There is a wet patch coming from the head gasket on the left corner (flywheel side). Obviously the wet patch increases the longer i run the engine. I did a compression test and all four cylinders are between 135-140.
Is it possible that the head gasket can leak on the edge of the head without actually entering the cylinders?

[Spider]

Is it possible that the head gasket can leak on the edge of the head without actually entering the cylinders?

 

Yes, but if the car's been sitting for a very extended period without running at all, I wouldn't rush in to changing it if it's only 'noticeable' but not dripping or running out. If you have coolant in the system, drain it and run it on straight water for a few days while monitoring it, if it dries up, then go back to coolant, if it's still noticeable, then off with it's head.

[Angus 850]

Is it possible that the head gasket can leak on the edge of the head without actually entering the cylinders?

 
Yes, but if the car's been sitting for a very extended period without running at all, I wouldn't rush in to changing it if it's only 'noticeable' but not dripping or running out. If you have coolant in the system, drain it and run it on straight water for a few days while monitoring it, if it dries up, then go back to coolant, if it's still noticeable, then off with it's head.

It could well be the coolant. I flushed out the system a few days ago and added coolant for the cold winter. I will take your advice and hopefully it will work, otherwise I will remove the head.
Thanks

[tiger99]

I have seen various cars, including a Mini, leak like that, with no immediate sign of leakage into or between cylinders. It usually means that the head needs a light skim because it has warped due to overheating. But Mini heads don't warp all that easily. Iron, not ali.

 

But spilled coolant, or leakage from the water pump or top hose, does have a nasty habit of creeping around the ledge formed where the block and/or gasket protrude from under the head. You also get oil lying there, from various possible sources.

 

I agree with Moke Spider, and suggest that if the area is clean and dry you may be able to detect where it is coming from, and it may be a trivial source such as a hose clip needing to be tightened.

 

Another old favourite is leaking round the head studs, which in some blocks penetrate into the water space. That can always be fixed by using sealant on the thread. Theoretically you need to drain the water to below the top of the block, sompletely de-torque the head, remove the offending studs, coat the end with sealant, re-fit, re-torque the head, re-set the valve clearances, and refil with coolant. Note that I did not say fit a new gasket. You can often get away with re-use on the lesser engines, standard 998 for instance. You "may" get away with just removing the offending studs, one at a time, applying sealant and refitting, but don't balame me if it goes wrong and the gasket fails.

 

That goes for other occasions, such as fitting lifting brackets, where you may want to de-torque one or two studs only. Like the coil bracket on some early Minis, such things "should" be fitted only to a slightly longer stud, using an extra nut, so the main head nut is not disturbed when removing the bracket.

 

But this is going off topic. As I said, a good clean and dry, and watch for the first signs of wetness appearing....

[Stevie W]

Hi,

 

Antifreeze or coolant is very good at finding small or fine leaks. Follow the above good advice.

 

I had a MkII Fiesta years ago that had the coolant changed and the water pump seal started leaking soon afterwards!

 

Cheers, Steve.

[sonikk4]

Could be a poor HG seal due to a cheap copper gasket. There have been a spate of these recently and by replacing the copper for a Payne HG cures the problem. No skimming needed.

I had this problem last year. Compression good but a seep from the back and front of the head. Used a Payen gasket and cured it instantly.

I used a good quality straight edge to check for trueness on the head face and block.

[pusb]

I had this, not long after I first got my Mini, an 850 as well. It drove fine, and I only noticed it by chance while looking at the engine while it was running. New HG and it was fine.

[Angus 850]

Could be a poor HG seal due to a cheap copper gasket. There have been a spate of these recently and by replacing the copper for a Payne HG cures the problem. No skimming needed.
I had this problem last year. Compression good but a seep from the back and front of the head. Used a Payen gasket and cured it instantly.
I used a good quality straight edge to check for trueness on the head face and block.

I was thinking the same thing. If I do have to replace the head gasket, which Payen hg would you recommend?