The 'E' Type Forum

Yes, the topic seems old and familiar, but after 50 years of wrenching, this is new. Finished a concours restoration on my '63 FHC. Motor overhauled. Started beautifully. No smoke. Put 450 highway miles on it with no smoke, then drained the 10-30W break in oil, and put in Castroil GTX 20-50. Immediately got a big cloud of blue smoke out of left exhaust. After 3 minutes it stopped. 20 miles at highway speed produced no more smoke, nor at idle when I returned to shop. Next day, same thing. And the next, etc. A big cloud at start, but goes away after warmup. Compression is 150 psi at 5,000 ft in all six cylinders. Mixture is correct. Engine smooth and quiet. Doesn't smoke on the road, or during letup on accelerator. I've overhauled more than a few engines, including Porsches and Austin-Healeys. This is new and a mystery. Could the oil be too heavy for new tighter clearances, leaving residue on rings overnight? Bore scope shows light oil coating on piston tops in all six cylinders.

I suspect that there is a valve stem problem. Mis machined guide, forgotten stem seals.

Something like that.

Isn't 20-50 oil a bit heavy for a brand new engine, I would have thought 20W-40 would have been more suitable.

Garry

I've always had a different, but similar, occurrence. On starting, gloops of black would come out of both exhausts. Had to put sheets of cardboard behind the pipes to protect the garage. But no smoke, ran very well, etc. Had the head off, completely re-furbished, rings ok, started up and no gloop! Then within a few weeks, the gloop was back. Still runs superbly, no smoke, so just stick with the cardboard!
BTW, the gloop looks a bit like an oily carbon.
Just don't worry about it now!

Are you getting blue smoke on closing the throttle while running ? If so, that would confirm Andrew Bowie's suggestion that it is oil seeping down the valve guides at a standstill - even if it doesn't happen on the overrun, his is still the most likely scenario in my view

Sorry , just read your post again confirming no smoke on overrun ( although this is difficult to see through a mirror if it is just a puff on upward changes )

malcolm wrote: ↑

Thu Dec 17, 2020 9:27 am

I've always had a different, but similar, occurrence. On starting, gloops of black would come out of both exhausts. Had to put sheets of cardboard behind the pipes to protect the garage. But no smoke, ran very well, etc. Had the head off, completely re-furbished, rings ok, started up and no gloop! Then within a few weeks, the gloop was back. Still runs superbly, no smoke, so just stick with the cardboard!
BTW, the gloop looks a bit like an oily carbon.
Just don't worry about it now!

Gloop is most likely wet carbon-i.e. condensed water in the exhaust pipes blown out on a cold start up. Once the exhaust is up to temp, the water becomes vapor and no more gloop.

Most people forget that water is one of the by products of normal combustion, and that there is always water present in the exhaust, just more commonly in the form of invisible water vapor.

I deal with the inevitable gloop by hanging a towel out of the hatch (FHC) to collect the carbon on a cold start in the garage. Otherwise the carbon ends up on the wall or dribbled across the floor (I park back end first).

Thanks Steve, you're probably right. Perhaps I've been running a little rich, so carbon in the exhaust, then condensation spits it out? Mind you, I've been getting 24mpg so wouldn't think so. Maybe just build up in exhaust from starting on choke? I park back in, so have my sheets of cardboard fixed against the wall behind it for starting.

tbone wrote: ↑

Wed Dec 16, 2020 10:28 pm

... put in Castroil GTX 20-50. Immediately got a big cloud of blue smoke out of left exhaust. After 3 minutes it stopped.

Compression is 150 psi at 5,000 ft in all six cylinders..

Maybe Castroil smokes more than Castrol?

Left exhaust repeatedly and never right means cylinders or valves of 4, 5 & 6 on a short wheelbase. That in turn means front or centre carb but you’re sure all mixtures are correct.

As everything is new I’d inspect inside the front manifold before a cold start and again as soon as heavy smoke starts.

Get someone to drive the car while you follow, or vice versa while they video, using phones to capture specific provocations to check the true colour and occurrence. You need full and firm data.

I’ve never measured anything at 5000 feet, I’m always next to the engine

Check for heavy blowby into the plenum between front two carbs. Piston seal imoroves with heat - hence no recurrence until next cold start. Run the breather to a catch tank and your smoke will likely disappear. When engine is fully broken in (HARD if it has typical 3.8 chrome rings) it will hopefully stop without glaze busting and a re-ring.

How about putting the break in oil back in and see if it disappears?
This will tell you if its unburnt fuel and steam from using the choke on first start up or an oil problem
My guess its just a rich mixture from the choke
My car steams like a kettle on cold start which slowly goes away
Joe

I am interested in the 5000 feet altitude. At that level it is highly likely that the engine is being significantly over-fuelled, particularly when on choke, unless weaker than standard needles are being used . What are they ?

My thanks to all who responded to this post. I checked the vacuum and it's steady (no pulsing, indicating a problem in one cylinder) at about 13-14 inches, which corrected for 5,000 ft is about right. I went to the trouble of draining the 20-50wt oil and put 10-30wt in, which is the same weight as the break in oil. Voila! No more huge cloud of blue smoke. There is a bit when the engine is cold, having just used the choke, and I "blip" the throttle. But, considering that the engine still has only 500 miles on it, it's probably not broken in yet. Interesting that the 20-50wt oil, notwithstanding that it only had 50 miles on it, was black as coal upon draining.

I put the 20-50-wt oil in following the procedure of a well-known XK engine rebuilder that has a website. But, that obviously didn't work for me on this engine. Plus, my piston skirt clearance was on the tight side (but acceptable) when I rebuilt the engine. So, who knows what went on. Thick oil obviously made the engine unhappy. I obviously learned my lesson; you can teach an old dog new tricks, I guess.

Interesting.

When I was a young man commuting between Derby and Birmingham I would thrape my Cooper S along the A38 dual carriageway. I ran the car on Duckhams Q, at the time considered a good oil but it would get through several pints between 3000 mile oil changes.

I changed to Castrol GTX and it stopped using oil.

I'm running my S2 4.2 on Castrol Classic XL 20W-50 and it produces quite a lot of smoke when hot and peddled hard so I was considering changing to GTX next time, particularly as my original Jaguar handbook lists Castrol GTX as a preferred engine oil.

Trouble is, I bought a 20 litre container of the XL - 2 more changes yet to finish it

I don't want to sound like the voice of doom but I'm not convinced that there is no problem with your engine.

I'm not a world expert but I have been involved in building and commissioning more than 20 E Type engines over the last 10 years. None of them are burning oil in the way you describe.

What you describe is oil smoke that occurs when the car is cold, after it has been sitting. Sure, it was worse when you changed oils but regardless that oil still had to get into the combustion chamber in order to get burned.

I would still suspect that there is something amiss with one or more of your valve stem seals. While the smoking has now improved I'd just keep that in the back of your mind in case it rears its head again in the future.

Hi ive just had the same problem on a honda cbx1000 motorcycle .I rebuilt the engine into NOS casings perfect for about 200 miles then i changed the oil then just like your e type blue smoke on startup ,It was a low mileage engine i removed the head and replaced the valve guide oil seals with viton ones. I had fitted new seals that came in the gasket set but no good, again rubbish parts its perfect now the seals i took off looked good and nice and tight on the valves but when fitted over the guide it stretched them so they were slack on the valves/ lesson learnt from now on quality viton seals hope this helps
Regards Rob