free hit
counters
'81 Dry Sump - coolant in oil - Engine/Ancilliaries - The Lotus Forums Jump to content
Steve4012

'81 Dry Sump - coolant in oil

Recommended Posts

I've been having some running temperature issues with my dry sump the last couple of months. Under normal driving it was fine but as soon as I gave it some boost the temperature would climb to somewhere between 90 and the next line on the gauge and not come back down for the rest of the journey whether flowing traffic or not. I changed the thermostat and found a small leak also but it still persisted. This morning upon start up I noticed the oil pressure was low. You can't just look at the dipstick on a dry sump to check, it needs to be run then checked and not wanting to do this I topped the oil up a little and started the car. Oil pressure was still low and looking into the oil tank the level was high but the oil was also very frothy and of a thin consistency. I believe I'm losing coolant into the oil. I've drained the oil and it seems very thin. I've boiled the oil in a pan and it sizzles and crackles more than new oil so I presume that confirms coolant is present so I think it's looking like head gasket failure. Ps a combustion check with the blue liquid does not indicate this but it's probably possible to get coolant into oil, without gasses into coolant(?)

Anyway if anyone has any words of wisdom I'm all ears, is it a case of taking the head off and inspecting the head gasket and if so leave the engine in or remove from car? 

Thanks in advance,  Steve. 

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.

Just done a compression test. Car was cold, throttle fully open: Cylinders 1-4 113,115,111,109 psi

Share this post


Link to post
Share on other sites

Some good info from moley on this thread.

 

Share this post


Link to post
Share on other sites

Steve

I had 121-123 psi when I had my dry sump as was concerned with a bit of blue smoke on start up. I tested it warm (Not hot) so not a true comparison.

How many miles has yours done now?
 

Dave :) 
 

 


Do or do not, there is no try! 

 

Share this post


Link to post
Share on other sites

Hi Dave,

The car has done 117k miles but the engine is a bit of an unknown quantity. It's had the main bearing panel mod as I saw this when I had the crank out to repair the spigot bearing/ input shaft issue. I replaced the main bearings and big end shells at that time (the originals were still pretty good) but the top end I don't know about. I'm not sure how much the readings would increase with a hot engine. 

Share this post


Link to post
Share on other sites

I’m not sure Steve but the normal way is at operating temp, it may be worth pulling the head off and checking for wear, at 117k I would be inclined to give it a good refresh if you have no rebuild history. Not cheap once you start mind so feel for you, the readings do seem a bit low though. 🥺

Dave 🙂


Do or do not, there is no try! 

 

Share this post


Link to post
Share on other sites

Cheers Dave. If it needs a refresh that's ok and I'll get it done.  I'm just mindful I don't want to start dismantling when the problem still maybe elsewhere. I'm tempted to simply renew the oil so I can then run up to temp and redo the compression test. Also try and find out what's in the oil to make its viscosity lower, be it coolant, fuel or whatever else may have happened to it.

  • Like 1

Share this post


Link to post
Share on other sites

Steve

I am with you as nothing much to lose other than the cost of oil and filter. Are you losing any water or nothing you’d notice?
Definitely worth doing a little more investigating especially if it’s been driving fine until recently, I take it you haven’t been thrashing recently be an old girl these days?

Fingers crossed its ok but if not after a rebuild you will have a great car again.

Dave :) 


Do or do not, there is no try! 

 

Share this post


Link to post
Share on other sites

Nope no thrashing Dave! 😆

I've been losing a little coolant but I did have a leak in a coolant pipe which I replaced along with the thermostat so it's difficult to tell if it being lost there or not. The car drives faultlessly, no hesitation or misfires of any kind anywhere in the rev range.

I'll do the oil which will hopefully bring the oil pressure back up and run to temp and retest and go from there. 

Cheers, Steve. 

  • Like 1

Share this post


Link to post
Share on other sites
19 hours ago, Steve4012 said:

I've been having some running temperature issues with my dry sump the last couple of months. Under normal driving it was fine but as soon as I gave it some boost the temperature would climb to somewhere between 90 and the next line on the gauge and not come back down for the rest of the journey whether flowing traffic or not.

Have you checked the radiator isn't clogged with debris? They normally need clearing out every few years as they pick up all kinds of crap. First sign of water in the oil is mayonnaise is the filler cap which you've not mentioned so why not get a leak tester to put your mind at rest? :thumbup:

  • Like 1

Cheers,

John W

http://jonwatkins.co.uk

Share this post


Link to post
Share on other sites

Hi Jon.

I had the radiator out 2 years ago and it was quite new with no debris in the fins and I flushed through also so pretty confident on that. There is no mayonnaise on the oil tank cap. Yes as mentioned above I have done a leak test (twice) and both were negative. 

Share this post


Link to post
Share on other sites

First port of call is the oil test. Find out exactly whats in the oil. Water will show up. Then go from there. The new thermostat I installed works perfectly so now you have that installed you can rule that out as a overheat probelm.

  • Like 1

Share this post


Link to post
Share on other sites

Steve,

I'm with JW in thinking that coolant would leave visible evidence if getting mixed in with the oil, in fact serious contamination typically manifests as a foamy, light coloured emulsion in the sump so not hard to spot. You report frothy, thin oil consistent with this condition I'm afraid. The mayonnaise under cap is symptomatic of chronic operation below temperatures sufficient to boil off routine condensation, solution here being to give the thing a hard run rather than poodling around off boost. Thin oil can be a result of excessively rich mixtures over time and, if this is the case, an odour of fuel in the tank should be apparent. You are right to be most cautious under the circumstances. 

  • Like 1

Share this post


Link to post
Share on other sites

A cooling system pressure test kit is a very useful thing to have, quite cheap on Ebay.

You can pump up the system and see if it holds pressure on the gauge. This can be done with the system empty or filled. If it loses pressure there is a leak and if no visible leak it could be into the engine.

The compression test figures look OK though on a cold LC engine.

  • Like 2

Share this post


Link to post
Share on other sites

Many thanks Andy, great idea. I've ordered a test kit. I'll not rush into taking the engine apart and this test along with a hot compression test and finding out why the oil is thin should give me some info to go on.

Share this post


Link to post
Share on other sites

Thanks for the replies. I'm making progress (I think). I'm 99% certain the oil is fuel contaminated. I've sent a sample off to confirm. Coolant pressure test holds steady at 11psi along with previous negative combustion test. I've also put fuel and coolant separately into a new oil samples and the colour and smell of the oil from the car matches the fuel sample. Taking the top off the carbs the fuel in the bowl is low after the car has been standing. I belive it's draining when the car is not running and I've since discovered a number of threads called 'Dellorto drip' which I'm still researching. As a test last night I manually topped both bowls up with fuel and checked the level this morning. The front carb level had reduced by 8mm and the rear 5mm. The tops had been put back on the prevent evaporation.  This can't be right can it?? I've now removed the carbs and there is fuel evidence in the intake, in the plenum and on the block. Can this be draining whilst sitting overnight? Any thoughts appreciated. 

Share this post


Link to post
Share on other sites

Before my engine rebuild my car smelt of fuel. I believe it was because the pump jet adjustment was so far out. Can’t explain the draining though on yours. At least its not coolant! Fuel problem can be fixed far more easily.

Ohh you could check the fuel pressure regulator is still adjusted correctly and putting out the correct pressure. Not sure if too high pressure could cause the fuel to drain?

Share this post


Link to post
Share on other sites

Cheers Fab. I tested the fuel pressure a few days ago and was actually slightly low at 3.5psi so I upped to 4psi just to make it on spec. Agreed re prefer fuel contamination to coolant! 

  • Like 1

Share this post


Link to post
Share on other sites

I think some evaporation from the float chambers would be normal. They are not closed containers, there is a large vent which opens into the plenum, just next to one of the intakes, so in effect open to the whole intake and the turbo.

Share this post


Link to post
Share on other sites

FYI on my turbo when I compression test it cold I got 10 / 10 / 9.8 / 10. All in bar. This is a rebuilt engine.  I guess its the spread rather than the absolute numbers you are looking at.

Share this post


Link to post
Share on other sites

I think you're right Andy. I've just topped up the carbs with fuel and left off the car on clean cardboard and no leaks. So I think  I'm looking at fuel delivery quantity and/or pump jet operation. When this all started I was adjusting the handbrake which needed a lot of 20 yard journeys up my steep driveway to test and maybe starting the car so many for tiny journeys had an effect. @Lotusfab do you still have @LOTUSMAN33 pump jet test set up and would it be OK for me to borrow Dave if so?

Thanks for the figures C43.

Share this post


Link to post
Share on other sites

Hi Steve

No problem, PM me your address and I will mail it to you.

Do you have a Carbtune balancer as well or do you want to borrow mine?

Dave :) 


Do or do not, there is no try! 

 

Share this post


Link to post
Share on other sites

Brilliant,  many thanks Dave will do now. I have a Carbtune 👍

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...