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Coolant weeping from head gasket joint

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Esprit S2.2 - I have coolant weeping from the head gasket joint below the exhaust manifold - not much but noticeable drops on the garage floor. No coolant in the oil or apparent reduction in performance so I guess compression is being maintained. I'm assuming I have a local HGF (which is frustrating as the head was off just over 1000 miles ago for a partial rebuild). I'd appreciate any advice, is this a common problem, how urgent is the need to fix the leak? Presumably the solution is a replacement head gasket ...appreciate any advice thanks - John.

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Its not that unusual and I wouldn't be overly concerned - i.e. I don't think it will get any worse. Certain Jaguars and Scoobies also suffered from this and the official fix was a branded Radweld type product. That's what I would try in the first instance... The alternaitive may be to try retorquing your current HG (That would be my plan B). Plan C would be to replace HG, but then you may check your nip and decide its not quite spot on... then you are into a complete rebuild.

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you may check your nip and decide its not quite spot on... then you are into a complete rebuild.

I had an S3 with HGF an put it into Paul Matty's who diagnosed incorrect liner nip & fixed the problem without removing the engine by shaving the block using a steel scraper. Worked great :thumbsup:

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If it's leaking between the head and the block, scraping the block won't help. If you had a head gasket leak around one of the liners, then lowering the block by scraping could increase the liner nip and thus the compression of the head gasket, stopping the leak from the cylinder. I would agree with Steve...try some Radweld type sealant...but don't put it into the normal header tank. Add it directly to the engine block...pour it in through the heater takeoff at the rear of the head on the carb. side, this gets the gloop straight into where you need it. I'd be inclined to run the engine for a bit with the heater takeoff and heater hose blocked off....to try and keep said gloop from the heater matrix. Once the gloop has done it's job, reconnect the heater. Might think of changing the coolant at the same time, using plain water when the gloop is being introduced and going back to proper antifreeze coolant once the job's done.

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It's worth checking compression anyway. If it is also leaking coolant into the liner, it'll eventually cause the piston to break up - I know I'm speaking from experience!

If as I suspect, the problem lies (as this is quite common) with some HG's (Goetz in particular), and is therefore not related to liner nip. Then as has been suggested use a form of Radweld.

It's now recommended and SOP in certain Lotus circles to use Wellseal on the HG before fitting, to get round the problem.

I would also caution against using a steel scraper - blocks need to be carefully machined as flat as possible, otherwise you could end up amking the problem worse.

Good luck!

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Thank you all for your advice - I will try the redweld route first and let you know how it goes - hopefully this will fix the leak.

Cheers John.

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Just referring to Pauls comment, head gaskets need to be fitted dry. There is a small water hole near the edge of the block which used to cause water seepage problems but Goetz headgaskets have a silicon type edge around this hole. They recommend however a small smear of Wellseal at this point. I agree Radweld is probably the answer although I did notice something made by Holts which claimed to be for this very purpose and also sealed any seeps around hose clips.

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Mike, you're right about dry fitment. However, the advice comes from a Lotus engine builder who's had over 30years experience on these 900 series engines and I personally trust him.

There are numerous other ways of sealing troublesome HG's, such as spraying with clear coat laquer, or alli paint.

But it'll be a smear of Wellseal around the perimeter on both sides for me.

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Update - tried the radwelled route with a product called K-Seal - Permanent Coolant Leak Repair "Permanently seals most leaks in engine blocks, cylinder heads, head gaskes...... it was initially successful - however after 200 miles the leak was back so not quite as permanent as the manufactures claim.

Next step re torque the head bolts?

Cheers John.

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Not sure about the S2 but i think you will need to take off the cam towers to access the bolts. That means removing the cambelt etc.

Might as well go the rest of the way and remove the head to see why the gasket has gone after such small mileage

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Exactly, if you're that far in, might as well go ahead and fix it...

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I can't believe so many have reccomended radweld type products. They are never a permanent solution to leaking. I would guess when you had the head off last time it wasn't skimmed? You need to take it off and do this for a successful fix.

Trevor.

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Bear in mind you can rapidly scrap a 907/910 head by skimming, (maximum allowable skim specified in manual is 'nil') I would only do this if an expert says it is required. In reality you have upto .015 to play with. If its flat dont do it. Its also a tricky head to do properly as they are 'floppy' and dont have a flat edge opposite the head face. Should ideally be done with cam towers bolted on

Edited by 910Esprit

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Did you do a compression test? Although it does sound like its just a coolant sealing issue.

You could try Irontite ceramic engine sealant which I understand has been successful in most circumstances.

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The head could be bowed, leaving a gap in the middle between head and block. The liner nip could be wrong, with the liners projecting too far and thus preventing the head from sealing properly on the block. As long as you have good compression and no sign of leakage of coolant into the cylinders, your only problem is a bit of a leak. Not a head gasket failure per se; I think I'd try to seal the little leak rather than take the head off with all the subsequent hassles....

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I agree with not having the head skimmed. When mine was at the engineering shop they checked it for flatness and said it was ok but advised against skimming, not because of the amount you can take off but the sheer problem of setting up a flat edge to enable a skim. I took their advice and later discovered on the Forum how lucky I had been.

Try running the car for a bit longer, the product may reseal itself.

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So if the head is not flat, what you you recommend?

Trevor.

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Bear in mind you can rapidly scrap a 907/910 head by skimming, (maximum allowable skim specified in manual is 'nil') I would only do this if an expert says it is required. In reality you have upto .015 to play with. If its flat dont do it. Its also a tricky head to do properly as they are 'floppy' and dont have a flat edge opposite the head face. Should ideally be done with cam towers bolted on

I have never had any issues with head skim.. I always do it before refitting a head.

In most cases its just a touch to clean it up and check its flat. As far as how much it can

go is debatable.. On my engine i took 0.040+ off , The valves when seated were higher

than the face.... Of cause some of you will say what about compression ratio, This can be

compensated for when chambering, Others will refer to cam timing which can be an issue,

however as long as it stays inside the original and 104' then there is no issue, If you are

still concerned then fit vernier cam gears and set spot on...This is always the best option.

As far as it being a difficult head to do....Poppy cock...A good experienced engine machinist

will have no problems and will have done loads before.

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What Dave said. Anyone claiming head skins are difficult shouldn't be touching a car. Same goes for any kind of 'miracle' sealing product. Don't be tightening the head down either. Just do the job properly.

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Well I know I will get seriously flamed now - but the suggestion that you can take 40 thou from a 910 head and simply bolt it back up is not good advice - you would get uncontrollable detonation (no idea what the valve to piston clearance is as standard, but there wont be a huge amount spare) As I say, its a head that requires careful setup as there is no parallel flat face to the head surface. Like anything, such work needs entrusting to someone that is prepared to take the time.

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If the head is not flat then you have no option other than a skim. However it should be checked first rather than skimmed as skimming is not that easy with the head shaped the way it is. The engineering firm I used asked if I had the cam towers with me but then said unless it was bowed they would not recommend a skim as it was relying on the surface of the cam towers being true and they wouldnt give me a warranty on their work because of this.

However if there is a leak after only 1000 miles then you have to question whether the job was done properly or there is a real problem and as I said earlier its not worth just tightening the head, you might as well do the job properly.

From a point of interest I think you used to be able to get head gaskets which compensated for skimming but I dont see these anymore. But, isnt the Goetz gasket a bit thicker than the original Coppers gasket which should in theory compensate for a small skim.

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If your head is shaped like a banana, you have little choice but to find a competent machine shop to skim the thing. As has been said (!) this isn't easy, as the cross sectional shape of the head means that there is no parallel surface to use to get the head mounted on machine tools. If the cam towers are fitted, then that will add stiffness to the assembly...but the major problem is locating the thing with the head surface parallel to the plane of the machine. The head does have a machined face from which to take measurements for skimming purposes...but I have never been able to find any specification showing what is allowable.

To get back to the actual problem in this instance, we seem to have an engine where the seal between the head and the cylinder liners is perfect, and it's just the seal between the head and the side of the water bath in which the liners sit that is leaking a bit. And that's all that needs fixing...hence I still support some gloop, sealant, patent wundastuff or suchlike to cure this weeping. I would caution against filling the cooling system up with this sort of stuff...but the right stuff in the water bath around the liners ought to fix the problem, without going down the total top end/head gasket replacement route....even if the gasket was replaced, there's no guarantee that that would cure the weeping.

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Well I know I will get seriously flamed now - but the suggestion that you can take 40 thou from a 910 head and simply bolt it back up is not good advice - you would get uncontrollable detonation (no idea what the valve to piston clearance is as standard, but there wont be a huge amount spare) As I say, its a head that requires careful setup as there is no parallel flat face to the head surface. Like anything, such work needs entrusting to someone that is prepared to take the time.

:blob fire::ermm:

I did not suggest you can whip 0.040 off a head and just bolt it on bolt it on, But basically that is what I did with mine.. Of cause there is a little bit of maths and combustion engineering involved. It was not a case of machine it fit it and hope...there are quite a few calculations and measurements to do to insure it will do what it was designed for...... and it certainly did its part to produce drivable 424 bhp at 1.52 bar.. :)

You should never need to remove this much material. This was done as part of the project to achieve an objective with different specification. Plus see what could be done...

Exploring the extremes if you like... The results speak for them selves.

A small warning if anyone wants to replicate this you will be machining the face into the valve seat which needs a different cutting head and procedure. Plus a few other checks and changes may be required.

As for uncontrollable deternation, ''what's that when its at home''.!!! Do the maths first and understand the principals , you won't have any problems.... :rtfm:

There is far to much...oooh you can't do that by people who have not done it...or don't know how to....you may be surprised what can and can't be done... The trick is knowing who and where..

The fact is to properly test if a head is flat , you need to set it up square for a touch probe or DTI.. This i have done on the miller bed which is set up for it... It can be a little fiddly to shim and clamp but it ain't rocket science 20 min max... Once checked its another 15 min max to nip the top off to give a true clean finish... Also i never have the cam carriers fitted when skimming, i want the head to be in its natural relaxed state as it will be when fitted to the block. The cam carrier mating faces should be checked, measured and matched as a separate procedure and should have zero influence on head distortion..

If you still have doubts take the head to you local m/sport engine builder he will know a guy who will do it for you..

A good clean flat face will isolate your problems...

post-10519-0-02504800-1352646237.jpg

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Dave - I always knew I was backing a loser when 'debating' wiith someone with your results.... I think one of the problems is finding a machine shop you can trust, when you are doing this sort of stuff on an infrequent basis, with a head they don't see every day (that's the voice of (bad) experience of using a very well established engine shop in Rochdale....). NB The 0.015 max was given to me directly by Lotus Techical, however, as you say, anything is possible with the right knowledge. NB by 'uncontrolled detonation', I simply mean 'pinking' as (for anyone else who is interested) the increase compression will increase the charge temperature. On a carb turbo there are not really any 'tricks' for dealing with this. (mine went from 135 to 155psi with a total cut of no more than 0.015. I'm already a little uncomfortable with that, but there is no mechanical evidence of any problems so far.

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