Lotus Elan

S2 smokes (a lot) on start up (again)

PostPost by: ftsoft » Mon Oct 16, 2017 2:55 pm

First a little history. I've owned this car since 1967 and raced and autocrossed in the Mohawk-Hudson region for a few years in the 60's. I drove the car as my main transportation until around 1975. From 1975 until the mid 80's it saw some use, but not a lot. After the mid 80's, it sat for really long periods and started deteriorating a little. Around 2010 I decided to rehab the car and did what I could, but the big problem was the water pump of course. so I bit the bullet and had a classic car shop here in Ohio rebuild the engine and clutch. The engine needed a lot of work, bearings, rings, new camshaft (one of the cams was broken in half), valves etc. When I got it back it ran really well, except that it now smokes a lot on start up (and I mean really a lot) The smoke goes away after a few minutes and you don't see it again until the next start up. Someone here said that "oh they all do that", which is nonsense, since it never did it before the rebuild. I'm assuming that there was something neglected in the valve guides or valve seat inserts on rebuild, but I was wondering what expertise the forum could bring to this problem. The shop that did the work does a lot of custom engine work for classic British cars, so I can work with them to resolve the problem (it was a riot to see the elan sitting in between a couple on 30's Rolls Royces and some other exotica). Any way thanks for any help.

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PostPost by: RogerFrench » Mon Oct 16, 2017 3:30 pm

The first thing to know is the colour of the smoke, that will help to identify what's burning.
Black smoke is fuel, blue smoke is oil, white smoke isn't really smoke but water vapour.
From that, we can start to narrow down the cause.
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PostPost by: ftsoft » Mon Oct 16, 2017 4:49 pm

Good point. I should have said that it is blue smoke.
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PostPost by: ftsoft » Mon Oct 16, 2017 4:50 pm

Good point. I should have said that it is blue smoke.
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PostPost by: Mr.Gale » Mon Oct 16, 2017 5:08 pm

Probably worn intake valve guides. When the car sits for awhile the oil is running down the valve stems and past the guides and when you start the engine it sucks in the the oil.

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PostPost by: memini55 » Mon Oct 16, 2017 5:13 pm

I would strongly suggest you have a visit with your engine builder to see what was done with the valve guides? Standard guides are always bad and will leak oil down into camber and burn on start up. I always use guide from DB Engeering in bronze.
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PostPost by: memini55 » Mon Oct 16, 2017 5:45 pm

A little more detail about guides that leak, when you run a TC and oil builds up around valve train and then you stop and park. The oil leaks down guides as a drain out of the valve train. It sits on the piston tops until you start motor and burns oil off. Very common to have a bit of smoke but should not be what you discribe and worn guides will do this as you discribe.
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PostPost by: Davidb » Mon Oct 16, 2017 5:48 pm

Has anybody, apart from John McCoy, figured out how to fit valve guide seals?
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PostPost by: ftsoft » Mon Oct 16, 2017 6:25 pm

Thanks for the replies. I'll check with my engine builder and perhaps get it done when I replace the transmission bearings next year.

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PostPost by: RichardHawkins » Mon Oct 16, 2017 9:33 pm

Frank,

One of your countrymen Keith Franck runs two web sites, sidedraft central and vintage technology garage. He has previously had trouble with trolls and only allows polite correspondence. He has successfully fitted seals to his Elan valve guides.

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PostPost by: lotusS2guy » Mon Oct 16, 2017 11:52 pm

Richard beat me to it. Keith has a thread on the Yahoo group Vintage Technology Garage on fitting valve stem seals. I haven't done it, but it looks like a big job.

Re: blue smoke at start up. Several decades ago, I analyzed the problem to be the exhaust side of #4 cylinder. The oil on the exhaust side drains back to the sump by running forward to the chain housing. There is a pocket on the #4 cylinder that traps oil so that the valve guide is immersed and oil finds it way into that combustion chamber after the car sits for a while.I have drilled a hole and installed a threaded fitting there with an external hose back to the sump to empty this pocket. (You cannot do this with the engine in place.) Result - no more startup smoke.
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PostPost by: elancoupe » Tue Oct 17, 2017 1:01 am

If you have access to a copy of Dave Bean's Elan parts manual, his thoughts on valve seals are worth considering.
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PostPost by: cbguerrajr » Tue Oct 17, 2017 1:47 am

i had a similar problem. paid lots of $ to a renowned restoration shop in Stratford, CT to rebuild the twin cam head. but after about 2,000miles, lots of smoke as you described. turns out the valve guides were installed incorrectly, the OD was too small, the ID too large and some of them were dropping down!
Luckily, a friend introduced me to Olsen Engines in Nyack, NY who rebuilt the head again, and because of the damage already done, there were no standard valve guides that would fit with the required precision, so he machined new bronze guides from scratch. no smoking except a tiny amount at the start.

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PostPost by: rgh0 » Tue Oct 17, 2017 1:56 am

The early heads had the problem of the oil pooling at the No 4 cylinder on the exhaust side. It is worse if you park on a slope with the nose uphill. The later heads had a cross drilling to drain the exhaust side to the inlet side. If you have that cross drilling there will be a plug just above and just to the right of No 4 exhaust port.

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PostPost by: types26/36 » Tue Oct 17, 2017 12:31 pm

I fitted seals, there is a bit of work modifying the guide and the valve gear and I dont think it could be done on an engine with higher lift cams then the Sprint cam or it would crush the seals, there is not a lot of room in there.
It worked for me and now I get no smoke even on start up.
Attachments
seal-guide-modified.jpg and
seal-guide-fitted.jpg and
seal-fitted.jpg and
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