Smoke from Tail Pipe

[Lotus49]

It's really starting to look like my recently purchased 1974 Elan Plus 2 might have been a bad idea.

In addition to the suspension issues described elsewhere in this forum, I'm now seeing smoke coming out of the tail pipe. It's light during idle but extremely noticeable at 2,000 rpms and higher.

I have no idea what constitutes normal for a car this old. I've never owned a car older than 1988. Regardless, I'm pretty sure that what I am seeing, and smelling, indicates a problem.

How serious a problem is what I am wondering. To me it smells like burning oil. Would this indicate a gasket needs to be replaced?

The car starts up and runs fine, just with smoke in the tail pipe. All cylinders hold compression well.

I'm waiting for a September service appointment so want to get the forum's feedback while this wait is occurring.

What's a worse case scenario here?

Thank you for your feedback.

[pabbage]

Never a bad idea don't worry… like any old car or house they'll need some money here and there.

So are you using oil? And what do your spark plugs look like? That would be an easy first check.

[david.g.chapman]

Check the colour of the smoke first. If its black then you just have a rich mixture. Adjusting/rebuilding the carburetors should clear the smoke.
If it's blue then the engine is burning oil. It could be coming past the piston rings due to bore wear, or it could be tricking down the valve guides, particularly the exhaust guides.

I would go on a road test and floor the throttle. If you see blue smoke coming out of the exhaust from inside the car, then there is a fair amount of smoke being ejected and you probably have a bore wear problem. Head off first, then assess bores by measuring. I would get the pistons out as well and check for broken rings. Search this forum for the next steps, depending of what you find.

if you don't get the smoke on full throttle, idle the engine for a few minutes, then snap the throttle open. Smoke at this time could well be from the valve guides. Head off to refurbish and check the bores as well while the head is off.

Having said all this, if the engine is not making any strange noises and is not using too much oil (more than 250 miles/pint) then you could just carry on driving it for now.

Hopefully others will chip in as well.

Dave Chapman.

[Lotus49]

Check the colour of the smoke first. If its black then you just have a rich mixture. Adjusting/rebuilding the carburetors should clear the smoke.
If it's blue then the engine is burning oil. It could be coming past the piston rings due to bore wear, or it could be tricking down the valve guides, particularly the exhaust guides.

I would go on a road test and floor the throttle. If you see blue smoke coming out of the exhaust from inside the car, then there is a fair amount of smoke being ejected and you probably have a bore wear problem. Head off first, then assess bores by measuring. I would get the pistons out as well and check for broken rings. Search this forum for the next steps, depending of what you find.

if you don't get the smoke on full throttle, idle the engine for a few minutes, then snap the throttle open. Smoke at this time could well be from the valve guides. Head off to refurbish and check the bores as well while the head is off.

Having said all this, if the engine is not making any strange noises and is not using too much oil (more than 250 miles/pint) then you could just carry on driving it for now.

Hopefully others will chip in as well.

Dave Chapman.

Thanks for the reply Dave. Unfortunately, my car is not drivable now due to an issue with one of the rear wheel hubs. I have a Sept. appointment to get this fixed. The car will have to be trailered into the shop to get this work done. Fixing the wheel hub, installing new tires, and converting from doughnuts to CV joints was on my agenda. Now with this smoke coming out of the tail pipe, I fear my repair bill is going to be absolutely massive.

[alanr]

You need to accept that owning a 50year old classic car, particularly a Lotus is going to be expensive! Particularly so if you are unable to carry out work yourself.
Personally if I were in your shoes I think I would get someone with good Lotus knowledge to give you a complete overall mechanical condition assesssment of this car that you have purchased. You will then be in a position to perhaps budget and prioritise what work the car needs doing now and what will it need in the future.

I also think if I were in your shoes that I would forget converting doughnuts to CV joints. Providing the doughnuts are in a satisfactory shape then swapping them out for CV joints is an unnecessary expense at a time when you you have more important things on the car that obviously need money spending on.

So, to the smoke issue .Any smoke out of the exhaust is not obviously not good!
Blue smoke is burning oil. Black smoke is rich mixture( Carburation).
The blue smoke absolute worst case scenario could be a complete engine rebuild! It may not come to that but you may not know until at least the cylinder head is removed.
A long shot though re smoke out of the exhaust is if the car has a brake servo is that the seals in the brake servo have gone bad and the engine is sucking in and burning brake fluid.That would also give you exhaust smoke.Usually clouds of it. Obviously this would be a less expensive scenario just meaning the brake servo needs an overhaul.

Diagnosis by forum, as you can probably appreciate though, most of the time is just guesswork.

Alan.

[Lotus49]

You need to accept that owning a 50year old classic car, particularly a Lotus is going to be expensive! Particularly so if you are unable to carry out work yourself.
Personally if I were in your shoes I think I would get someone with good Lotus knowledge to give you a complete overall mechanical condition assesssment of this car that you have purchased. You will then be in a position to perhaps budget and prioritise what work the car needs doing now and what will it need in the future.

I also think if I were in your shoes that I would forget converting doughnuts to CV joints. Providing the doughnuts are in a satisfactory shape then swapping them out for CV joints is an unnecessary expense at a time when you you have more important things on the car that obviously need money spending on.

So, to the smoke issue .Any smoke out of the exhaust is not obviously not good!
Blue smoke is burning oil. Black smoke is rich mixture( Carburation).
The blue smoke absolute worst case scenario could be a complete engine rebuild! It may not come to that but you may not know until at least the cylinder head is removed.
A long shot though re smoke out of the exhaust is if the car has a brake servo is that the seals in the brake servo have gone bad and the engine is sucking in and burning brake fluid.That would also give you exhaust smoke.Usually clouds of it. Obviously this would be a less expensive scenario just meaning the brake servo needs an overhaul.

Diagnosis by forum, as you can probably appreciate though, most of the time is just guesswork.

Alan.

Hi Alan and thanks for your reply. Yes, understood about the guess work. I appreciate you giving me details to think about. My doughnuts are likely shot so that's why a CV conversion is in the cards. I have a September appointment with a Lotus specialist who will truly go over this car with a fine tooth comb. The engine runs very smooth despite the smoke so I'm hoping a rebuild is not the cards.

Thanks again.

tom

[JonB]

There's a couple of videos on BAT of the car performing cold starts. Zero smoke visible.

https://youtu.be/UyXbBI3K0Jw and https://youtu.be/d6bjTGdONGQ

Based on that, I'd have to conclude that your problem is may be something trivial. The difficulty in starting in the first video is normal - it's caused by fuel evaporation from the carburettors, leading to long cold start cranking so the (mechanical) pump can refill the carburettors.

Tom, can you do the tests that have been mentioned and let us know what the result is, please?

By the way, in the driving video, you can hear the engine note sort of wowwowowowowing when he accelerates, this is caused by doughnut windup and the description says the doughnuts are worn. You're wise to consider CV joints.

Lovely car I have to say. It has been nicely restored and I cannot believe that the previous owners went to that expense without also overhauling the engine.

[elans3]

Blue smoke = burning oil, reasons listed above.
Black smoke = rich mixture, also see above.
White smoke = servo (brake fluid being sucked into the inlet manifold and being burnt off in the exhaust.

last two are easy, (and much cheaper) to sort out.

What colour is the smoke ?

[StressCraxx]

I really hope all of this "worst case scenario" doesn't put you off owning a lotus.

ALL twincams produce some smoke at startup, and on overrun from the lack of valve guide seals.

"They all do that, Sir."

If the smoke is coming out the tailpipe all of the time during driving, it could simply be a stuck oil control ring. A pint of Marvel Mystery Oil may easily free up the offending stuck ring. I hope you are able to get your rear hub and drive pins get repaired properly, inspect the other three corners for their integrity and then have fun with your Elan.

Best wishes to you.

[Sadbrewer]

It's really starting to look like my recently purchased 1974 Elan Plus 2 might have been a bad idea.

In addition to the suspension issues described elsewhere in this forum, I'm now seeing smoke coming out of the tail pipe. It's light during idle but extremely noticeable at 2,000 rpms and higher.

I have no idea what constitutes normal for a car this old. I've never owned a car older than 1988. Regardless, I'm pretty sure that what I am seeing, and smelling, indicates a problem.

How serious a problem is what I am wondering. To me it smells like burning oil. Would this indicate a gasket needs to be replaced?

The car starts up and runs fine, just with smoke in the tail pipe. All cylinders hold compression well.

I'm waiting for a September service appointment so want to get the forum's feedback while this wait is occurring.

What's a worse case scenario here?

Thank you for your feedback.

Tom, don't panic...see my reply on your wheel thread.
As Dave G and Elans3 have pointed out, you need to identify the colour of the smoke, your garage will do that, if it's oil burning , no Gasket will solve this, it's natural engine wear...mine did several thousand miles, reliably on a bloody smokey exhaust..eventually the rear end was so black I got fed up of cleaning it off and decided to get round to putting it right,... It will have to be sorted as I explained on the other thread...OK you didn't bargain on the cost, but tbf a smokey engine can be seen ( if you know how to look) when you buy any car not just Lotus..so put that down to experience and look at it now as an opportunity to give yourself a well sorted engine for the long term.