Burning oil downhill.

TransAmDan

TransAmDan

Forum Admin
Staff member
Okay so on last club night we went on a cruise, someone mentioned when I was going down hill they saw blue smoke from my pipes.

Last Sunday going downhill again someone else mentioned the blue smoke.

Well I know about burning oil up hill as it leaks out the back of the sump, so that's okay, but down hill got me thinking.

Going downhill I use gears to control speed so I'm not on the brakes like auto's. So this is putting the intake in a vacuum, sucking oil vapour from the heads. This gets collected in the oil catch can. Hang on when did I last check that, gotta be 6months.
IMAG1571.jpg
Oh dear, it's full, that would explain things, enough vacuum is pulling oil into the intake and burning it.
 
Like the use of electrical tape :thumb:

what the open pipe in the back of picture for looks a tad rusty?
 
saleen 192 said:
Like the use of electrical tape :thumb:

what the open pipe in the back of picture for looks a tad rusty?
Click to expand...

Not rust that intake is plastic. That is where the catch can gets connected to. Insulation tape was mainly to test for vacuum leaks, I'll make that one pipe between the intake and catch can.
 
Went out for a little drive and data logging. Looking at full throttle between 3000 and 5500 rpm thr fuel delivery looks spot on still. A few things I may need to tweak, like when cold it's open loop it's need more fuel on pulling away.
 
Have you also checked plugs see if foulled up as well. And oil level in engine?
 
saleen 192 said:
Have you also checked plugs see if foulled up as well. And oil level in engine?
Click to expand...

I check oil level with every trip. Just over 3/4's full which will be enough for Worthing tomorrow. Plugs seem to fire okay, but not taking them out.
 
Oil loss is good, and manageable.

Symptoms are when going up hill, and my window is open a crack I have smoke coming in the car through the gearbox tunnel, very little but you can smell oil, it dosn't do it on every hill.

Checking the block under the car, there is no visible oil, everywhere feels dry, no drips on the floor. The transmission may have a light residue of oil at the bottom.

Conclusion, oil getting out the back of the engine, either though the back of the sump or main seal. Oil maybe hitting back of flywheel and turning to smoke. Its not visible without taking the gearbox and flywheel off.
 
The last two sump bolts around where the crank exits, are not dry bolts. As in they tap into the oil galleries. You did put sealant on them?
 
It may be something like that. I know we were careful of any holes that were not blind, but maybe we missed something. Thanks for the idea.

The plan is to whip out the engine at some point. As then I can seal the sump, and get to the back of the block.
 
Wow that sounds drastic but sometimes the only way to go, or are you taking it out for other reasons?
 
There isn';t a lot holding the engine in To get to the main oil leak it may be revealed by taking out the grearbox, clutch and flywheel. But to change the sump gasket need to drop the front suspension while holding the engine up, as the crank is a longer throw now, there is a chance that I cannot remove the sump to change the one piece gasket.

So it may be worth while just taking the engine out, 3 bolts and a few wires are all that hold the engine and gearbox in the car. A good chance for a good inspection all over.
 
Well the oil leak hasn't been fully addressed yet. This is partly the reason why I wanted the garage built. I can then take the car apart either if dropping the front suspension or engine out to check the sump seal.

Anyway, during tuning sessions I have covered around 20miles, a lot of it being hard on the throttle, uphills and downhills, this used to use more oil. In 100 miles I used to put in around half a litre of oil. In those 20miles I have used no measurable oil at all. I'll keep and eye on things. The oil I'm using is different brand of oil with a high temperature before it turns to mist. I wonder if my oil oil was getting hot, exiting through a gap in the sump.

I'll still do the sump investigation, I'll also carry on keeping an eye on oil until then.
 
You must log in or register to reply here.

Similar threads

A
Alfa Romeo Stelvio’s toughest test
Replies
0
Views
555
Auto Express
A
Back
Top