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Having completed my winter project- building an uprated engine for my 4, I spent a greasy weekend doing the swapover. Engine runs beautifully but----- there is a slight weep of coolant from the rear of the head at the joint. My heart sank. I was meticulous in checking the protrusion of the liners and after much thought used wellseal in conjunction with the new gasket. I have managed to torque the head down a little more and have added a bottle of barrs leaks (desparate times etc) Is this a commonplace thing?- am I really going to have to lift the head? I look forward to your suggestions folks.

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When you put a steel ruler on top of the liners, you will find that you can slide feeler gauges of different thickness between the ruler and the top of the engine block, depending on were you check the protrusion of the liners. This is due on the upper surface of the block not being perfect straight.

So probably you haven't done anything wrong. The Wellseal can't do any harm I suppose (Wellseal should be diluted with something like tetra- or tri-ethyl chloride, brushed on sparingly on the 4 surfaces and leaving it like that for several hours before mounting the gasket, otherwise it it less effective).

Perhaps you can wait, don't know if the leak will disappear though.

If you have to take the head off, you could use blue Hylomar, but only around the suspect area's.

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Some additional information would help.

 

Did you use a steel head gasket (ie sold) or a composition one? Solid head gaskets are very unforgiving if the head is even slightly warped.

 

Did you check the cylinder head to make sure it wasn't warped? I checked mine a few times with a metal straight-edge and thought it was OK, but when it kept blowing head gaskets, I had it skinned - 10 thou only. You could see from the skimming that the head had been very slightly high in the middle, even though I could't detect this with a straigt-edge.

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I used a copper gasket and did check the head was true but as yousay its hard to judge absolutely accurately. There was no apparent damage to the upper edge of the block. Its not gushing water by any means but under pressure there is a bubbling and then a small puddle just forward of the bell housing. I guess I might have to bite the bullet and lift it

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I used a copper gasket and did check the head was true but as yousay its hard to judge absolutely accurately. There was no apparent damage to the upper edge of the block. Its not gushing water by any means but under pressure there is a bubbling and then a small puddle just forward of the bell housing. I guess I might have to bite the bullet and lift it

Is it a plain copper gasket, or a compound one? The plain copper ones are more difficult.

Did you check the water isn't leaking from the core plug in the cylinder head that is facing the bulkhead?

The water apertures are close to the liners : it's a bit strange that the liners are tight and water is leaking.

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Maybe the block is cracked?

That's really another possibility, I experienced this two times with my TR3, once with a newly cast cylinderhead (fault in the casting process) and ones during a race : a water jacked cracked and a lot of water leaked towards the an exhaust port under pressure evaporationg immediately by the hot exhaust gases: an enourmous cloud of steam escaped via the tail pipe : just like Raikonen blowing another Mercedes F1 engine.

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It is the compound type copper gasket that I fitted and you can observe the tiny bubbles on the head to block joint which makes me doubt cracking. Is it worth another couple of pounds of torque?

I suppose chances are minimal that further torqueing will stop the leak. Did you try already some 'Leak Stop'? Perhaps you can make this work more effective by pouring little bits in the water outlet to the heater? But generally I think these products are not recommended : the products remain as lumps somewhere in the cooling system. I suppose you will have to lift the head anyway to find and rectify the culprit

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Thanks for all the suggestions. Having stepped away from the job and gone back refreshed, I started the car and watched again carefully from the leak. On closer inspection, it appears that the core plug on the back of the head is leaking. Fingers crossed that thats where its all coming from but given the care and agony in assembly I would have been surprised at a leak on the joint. Keep your fingers crossed for me and thanks again

Julian

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