Burning a bit of oil.....

[PatHeald]

I've noticed that she puts out a bit of oily smoke, usually the first time you give her some stick after she has been idle for a while.

The motor has only done 23500 miles, so I'd be surprised if it was the bottom end. I also find it hard to believe that the valve guides are worn at this mileage.

Maybe the turbo is the culprit?

The oil is currently Mobil 1 0W-40 and is less than 1000 miles old.

Suggestions on a postcard, please.....

Cheers

Pat.

[lotusguy]

PatHeald said:

I've noticed that she puts out a bit of oily smoke, usually the first time you give her some stick after she has been idle for a while. The motor has only done 23500 miles, so I'd be surprised if it was the bottom end. I also find it hard to believe that the valve guides are worn at this mileage. Maybe the turbo is the culprit? The oil is currently Mobil 1 0W-40 and is less than 1000 miles old. Suggestions on a postcard, please..... Cheers Pat.

Pat,

Most likely some oil seepage down past the guides. Especially once the engine cools and all the parts contract. Should disappear though once you warm up to temp. BTW, 0W-40 seems a little lightweight to me, I'd go w/ heavier oil, at least 5W-50. I use 15W-50. With synthetics, especially Mobil1, you are very safe choosing this weight, in fact, it's what Lotus recommends. Happy Motoring! ...Jim'85TE

[NJGSX96]

Sounds like valve seals in the head to me. usually is when you can idle/coast down a hill and then hit the gas and see smoke.

It doesn't plume out, right? Only puffs after idle for too long and that's it, right? Find a nice long downgrade and coast down it. After a bit, give it some gas again, see if it smokes. If so, most likely it's the seals in the head.

>> Edited by NJGSX96 on Thursday 4th March 00:55

[lotusespritworld]

Jim's right! The Lotus engine is an older design with larger tolerances than more modern engines. So you'll need a thicker oil, as you're just burning the thinner stuff way. You won't be causing any long term damage, it will just cost you in oil.

I was running with Mobile One 0w40 after an oil change and using quite a bit of oil. Topped it up with Mobile One 15w50 after a bit research and haven't used any since.

This goes for all 4 cylinder engines and all older engines in general. I'm currently writing a piece of this and other lubrications for LEW.

kato
Lotus Esprit World

[lotusguy]

NJGSX96 said:

Sounds like valve seals in the head to me. usually is when you can idle/coast down a hill and then hit the gas and see smoke. It doesn't plume out, right? Only puffs after idle for too long and that's it, right? Find a nice long downgrade and coast down it. After a bit, give it some gas again, see if it smokes. If so, most likely it's the seals in the head. >> Edited by NJGSX96 on Thursday 4th March 00:55

Hi,

Just F.Y.I, on the Lotus 9XX engines, there are no valve seals, their function is performed by the guides. The stock bronze guides wear at about 35k-40k mi. and some seepage can/will occur. If replacing, switch to the much harder bronze/silica type. This will extend their life considerably for just a couple bucks more. Happy Motoring! ...Jim'85TE

[danny tattersall]

Lotus Guy - You stole my thunder when I scrolled down this post and found that you had already mentioned the fact that the 9XX engines do not use valve stem oil seals!! Good to have you on board in this forum and I hope that, if you do stray onto the dark side and eventually buy the Mercedes, that you keep sharing your knowledge with us.

All the best,

Danny Tattersall.

[lotusguy]

danny tattersall said:

Lotus Guy - You stole my thunder when I scrolled down this post and found that you had already mentioned the fact that the 9XX engines do not use valve stem oil seals!! Good to have you on board in this forum and I hope that, if you do stray onto the dark side and eventually buy the Mercedes, that you keep sharing your knowledge with us. All the best, Danny Tattersall.

Danny,

Sorry about that... Next time clue me in ahead of time, but thanks anyway for the kind words. I freely admit that my knowledge is not all-encompassing, or that I am the sole source of knowledge on this forum, it's great to have everyone contribute.

Don't worry, once I get my merc, I'll still be lurking on the lists, if for no other reason than to stay abreast of how y'all are doing. Happy Motoring! ...Jim'85TE

[PatHeald]

lotusguy said:

Most likely some oil seepage down past the guides. Especially once the engine cools and all the parts contract. Should disappear though once you warm up to temp. BTW, 0W-40 seems a little lightweight to me, I'd go w/ heavier oil, at least 5W-50. I use 15W-50. With synthetics, especially Mobil1, you are very safe choosing this weight, in fact, it's what Lotus recommends

I had reservations about the oil when I put it in....

In fairness to the motor, it is only putting out a bit of smoke following a cold start, or when you first really crack on after warming up.

This is only something that I have noticed since the last oil change, so maybe a change in viscosity is in order next time.

Presumably giving the instrument binnacle a thump isn't going to sort the problem out...

Cheers

Pat.

[lotusguy]

PatHeald said:

...Presumably giving the instrument binnacle a thump isn't going to sort the problem out... Cheers Pat.

Hey,

You jest, and I do admit it does seem a funny procedure to perform on a World Class SuperCar, but hey, it works and has worked for numerous owners having instrument problems.

Don't laugh, but this was also the fix on the ALS (Automatic Landing System, a sort of automatic throttle) on the McDonnell/Dousglas F4. I can't tell you how many times a smack on the dash would settle the speed out on landing approach. And this from a $20mil. aircraft!

Don't worry, I take it all in the spirit in which it was intended. Happy Motoring!... Jim'85TE

>> Edited by lotusguy on Friday 5th March 00:14

[NJGSX96]

lotusguy said:

Just F.Y.I, on the Lotus 9XX engines, there are no valve seals, their function is performed by the guides. The stock bronze guides wear at about 35k-40k mi. and some seepage can/will occur. If replacing, switch to the much harder bronze/silica type. This will extend their life considerably for just a couple bucks more. Happy Motoring! ...Jim'85TE

Learn something new every day! Thanks. Thanks for the info and I apologize for thinking I knew what I was talking about! I have been working on DSMs for 9 years now so my thought process usually follows what I have learned on them or pertains to them.

[PatHeald]

Just done a compression test to check the bores/rings and guides.

The motor is a 1987 nicasil lined HC Turbo on 45mm carbs. It has only covered 24500 miles.

The results run as follows:

Dry:

1: 161psi
2: 163psi
3: 165psi
4: 164psi

Wet:

1: 171psi
2: 170psi
3: 174psi
4: 169psi

The dry figures were averaged over three tests and are probably accurate. The wet figures are the result of one test, with a completely arbitrary dose of oil squirted in. Nevertheless, I don't think these seem so bad. What do you reckon?

In view of these figures, I'm hoping that the bit of smoke that I get on cold starts is nothing more than using 0W-40 which is too thin and gets past the guides when the car has been standing for a few days.

Cheers

Pat

[kylie]

Hi Pat, I had the same problem, when I first bought my car I treated it to everything and put the best grade of oil out there in thinking I was doing the right thing this model car, which was a very thin oil. I have since put 15w50 in and the problem went away.

My engine is due for a rebuild as the miles are up there, but this little change of oil put my money back in my pocket for a while anyway Don't get me wrong my baby will never be neglected and plan on a rebuild soon.

Kylie
89 Carbed Turbo

[lotusguy]

PatHeald said:

Just done a compression test to check the bores/rings and guides. The motor is a 1987 nicasil lined HC Turbo on 45mm carbs. It has only covered 24500 miles. The results run as follows: Dry: 1: 161psi 2: 163psi 3: 165psi 4: 164psi Wet: 1: 171psi 2: 170psi 3: 174psi 4: 169psi The dry figures were averaged over three tests and are probably accurate. The wet figures are the result of one test, with a completely arbitrary dose of oil squirted in. Nevertheless, I don't think these seem so bad. What do you reckon? In view of these figures, I'm hoping that the bit of smoke that I get on cold starts is nothing more than using 0W-40 which is too thin and gets past the guides when the car has been standing for a few days. Cheers Pat

Pat,

Those compression numbers are pretty much exactly in the middle of the spec range, meaning you are well within spec. for an '87 they are really quite good.

I agree with your conclusion that the lightweight oil is most likely the source of your problem.

Get that nasty thin oil out of there so you can keep those comp numbers for another 17 years! Happy Motoring! ...Jim'85TE