Lotus Elan

PROOF and two vital pictures + DIAGNOSIS

PostPost by: el-saturn » Sun Jun 09, 2019 10:16 am

somehow the gasket at cylinder 4's bore is slightly crushed and the nearby crack has something to do with it. at first the oil stayed clear and at 1000ks i changed oil and it was already slightly getting creamy. at that point the gasket DRIPPED water into the combustion chamber creating the emulsion. thereafter it opened up more and let the water channel fill cylinder 3 + 4 W H Y B O T H????? sandy very grateful for more insight
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PostPost by: promotor » Sun Jun 09, 2019 10:37 am

Maybe the gasket fire ring has been pulled out of shape by the piston - it looks like the pistons are very near to the gasket - if the pistons protrude above the block top (or are very close) you could see some contact.
What size bore have you got? Looks like 83.5mm - 84mm? The Ajusa gaskets are usually 84mm - is that what's fitted?
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PostPost by: el-saturn » Sun Jun 09, 2019 10:55 am

yes - i think the pistons are 83.65 and a 84mm ajusa - you see the disturbed area and the crack, right --- the gasket was "open" (not bonded to the surface at all) where the water channels (triangular ones) are and that's where the water got into the combustion chamber AS I SEE IT - do you agree? should i go to a larger dia gasket? much appreciated sandy
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PostPost by: 2cams70 » Sun Jun 09, 2019 12:14 pm

What compression ratio are you running. Looks awfully high with those domed Pistons. Are you running a special cam?
Did you retorque the head after bed in?
What head bolts are you using and what is their condition like?
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PostPost by: el-saturn » Sun Jun 09, 2019 12:57 pm

the cams have a lift of close to 11mm, compression is around 11:1 - all i need to know if, using another gasket, if my diagnosis is correct. so this time i wanna try reusing a cometic (2nd use and only used fo 3000miles) using this copper gasket spray by prematex ----------- what do you think, fellas?? sandy ps: + race springs for the valves
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PostPost by: 2cams70 » Sun Jun 09, 2019 2:12 pm

What is the block surface like under the gasket where the break is?
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PostPost by: el-saturn » Sun Jun 09, 2019 2:59 pm

a N7 (i think DIN standard) which is 600 in sandpaper, if that helps. i intend to try using a cometic gasket for the second time using permatex copper spray on both sides. there's folks which have used em 4-5 times all using copper spray. sandy
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PostPost by: nmauduit » Sun Jun 09, 2019 4:44 pm

well, short of an expert point of view of I'll give you my 2 cents...

I see 2 cracks in the fiberglass at about the 2 places where the metal fire ring of the gasket is bent (and corresponding part of the gasket pushed outside) : If you are quite sure that the gasket was not damaged prior to or during installation, esp. in these locations, and has not moved before torquing (using 2 guides at opposite corners when lowering the head and still being careful), I would

Get the head lightly skimmed to make sure it is flat (and possibly has the adequate surface smoothness for proper gasket grasp)
Get the block face cleaned and check it for flatness (if in doubt have it checked)
Get an new identical (composite, here Ajusa) gasket and apply Wellseal or equivalent (Permatex etc) to both sides during reassembly (make sure to follow the torque/retorque procedure)

I would not use a MLS Cometic, probably harder to seal a block that has already proven difficult.

good luck !
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PostPost by: el-saturn » Sun Jun 09, 2019 5:06 pm

ive got a a feeler gauge (0,05mm) and a foot long straight edge and the thinist feeler is way too thick for both head and block the surface roughness (-es) are almost as new and no scratches.

MY MAIN question is/was: did i analyse the symptom or reason for this leak properly? the gasket didn't stick to the surface near cylinder 4 on the length of the entire 85mm + 30 at the end and 10+ towards cyl. 3: everywhere else it stuck very well to the block (none to head)

S O did this cause the (A) the emulsion (at the beginning, when it started to leak) and (B) the water filled chambers of cylinder 3 AND 4? OR is there any likelyhood that the waterpump caused these problems (very very unlikely! ) sandy
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PostPost by: nmauduit » Sun Jun 09, 2019 5:21 pm

el-saturn wrote:ive got a a feeler gauge (0,05mm) and a foot long straight edge and the thinist feeler is way too thick for both head and block the surface roughness (-es) are almost as new and no scratches.

MY MAIN question is/was: did i analyse the symptom or reason for this leak properly? the gasket didn't stick to the surface near cylinder 4 on the length of the entire 85mm + 30 at the end and 10+ towards cyl. 3: everywhere else it stuck very well to the block (none to head)

S O did this cause the (A) the emulsion (at the beginning, when it started to leak) and (B) the water filled chambers of cylinder 3 AND 4? OR is there any likelyhood that the waterpump caused these problems (very very unlikely! ) sandy


A good use of a straight edge and light would do (it takes some practice though) but you need one as long as the block ideally; feeler gauge would be of no use (anything measurable with a feeler would be way too large here) : again, if in doubt, and apparently you are, have it checked. Most likely planarity issues are to be expected from the head though, but block not proprely cleaned (or deburred if marred when opened, etc.) can cause issues as well.

The actual reason for the gasket leak is sometimes difficult to pinpoint, and careful opening is key in getting clues : something only you can know. Lack of flatness of head ar/or block is a common cause for poor sealing (all else being perfect, gasket positioning, cleanliness, torque and retorque etc).

In any case, what I would do after having sealing difficulties on an engine is ramping up the effort for sealing, as described in my post above.
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PostPost by: elanfan1 » Sun Jun 09, 2019 5:49 pm

Have you thought of asking JonB?
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PostPost by: elanfan1 » Sun Jun 09, 2019 5:51 pm

Double post
Last edited by elanfan1 on Mon Jun 10, 2019 1:15 am, edited 1 time in total.
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PostPost by: el-saturn » Sun Jun 09, 2019 6:21 pm

i can hardy see light thru the straight edge and as far as i remember if its like "closed" (visible light) you're talking about 0,001mm i'm way under 0,01mm Sandy (both head and block)
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PostPost by: nmauduit » Sun Jun 09, 2019 7:36 pm

el-saturn wrote:i can hardy see light thru the straight edge and as far as i remember if its like "closed" (visible light) you're talking about 0,001mm i'm way under 0,01mm Sandy (both head and block)


if it's only a foot long and you're only checking transversally, you theoretically could have a dip at one end (say it was machined when pulled unevenly)... most chances are the head is where the leak occurs, so that is why I would get it lightly skimmed (takes less than an hour, you can bring it to your machine shop and back if in a rush).

If you intend to install the MLS Cometic (maybe only for a few days and are desperate to get the car running for an event, till you get a new Ajusa), you should double check the surface roughness expected for a good seal, and inform your machinist of that requirement (too smooth or too rough would not do).
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PostPost by: el-saturn » Sun Jun 09, 2019 8:25 pm

thanks chaps! as a retired person hrs are a commodity which you no longer have to consider, SO ill take the risk and use this copper gasket spray. i think the ajusa i used was dropped or something and i sometimes don't need glasses and as a very pragmatic fella, stuff which comes perfect IS perfect, unless you dont look carefully (=no glasses) ................. so i could loose 6L of oil (now the flush type), a few gaskets and 2 x three to four hours of unpaid labour and good music - then i can agree with all these folks (lots of corvettes and dragsters) in the US who have used their cometics up to 5 times - so i have hardly anything tto loose. just imagine how much i saved: no bent rods, no cracked block, no corrosion, and no machine shop bills sandy
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