Smoke on over-run (7K RPM, no throttle) - free stuck rings..
Dec 20, 2021 14:50:39 GMT
wannabe and scottydugg like this
Post by atlex on Dec 20, 2021 14:50:39 GMT
This worked for me and I've now been smoke free for the best part of a year. Oil consumption is down.
Context:
I'd done my valve stem seals as part of a head job and this didn't solve my high-RPM smoke cloud problem. if I revved the engine up to 7.5K it'd smoke on deceleration until about 6K. Or until I changed gears.
Evidently it was never valve stem seals and honestly I don't know how so much oil could come through a valve stem even if it were.
So the thinking is that this is caused by the oil control rings and related piston holes/gaps getting gummed up, if you don't use the car enough for a few months (or 3 separate 6 month period in my case) this happens and the oil control rings stop controlling oil.
A friend of mine worked on another MX5 where he and the owner thought it was valve stems, replaced them TWICE never was, but the car drove fine and they continued to compete.
Also on our cars the oil squirters facing the gap in the oil control area doesn't help :-) This maybe contributes to the problem.
Method:
The thing to do is take your time, be quite careful with the relevant chemicals. Get your car up and ready to drain and make sure you keep the stuff within your pan but not overflowing it. You DO NOT want this stuff going over the 'full sump' line.
So drain your oil first, then drain the stuff that leaks down.
Use some chopsticks or other small sticks of equal length with the plugs out so you get the cylinders all to half way. (they all line up heh) - this gives you 200ml of fluid to fill each cylinder. 1600 motor, 400 cylinder at half way.. 200ml.
That way you can put a good dose down and then come back in a few hours to put more down.
The thing is this, you're putting down volatile hydrocarbons. Those will happily soften whatever is stuck to the rings or in the ring lands. But you need _flow_ to actually move the dissolved stuff, so you will end up putting about a litre past each piston ring.
The "big idea" is that those volatiles will flow down past the rings and take some of the deposits with them as they go to the sump, while also softening the deposites further. The varnish will be hard at the start and soft at the end. Ideally you put through enough that a good portion gets solvated into the volatile solvents and _flows_ down the cylinder walls.
If you're going to do the compressed air thing, do it at the end, not at the start, that way you're 'forcing' more solvated carbon past now that it is really softened, if there is any deposit left.
Don't rotate the engine for a good while, while putting the chemicals in.
When you're done, make sure all the cylinders are empty, then put a teaspoon of motor oil down so the rings are lubricated again before startup, then drain the sump, put in new engine oil and optionally change the filter.
The TSP of oil won't flow out quite as fast as the volatiles, I suggest cranking by hand a few times and then firing it up and taking it for a hard drive.
## The chemicals to look out for for doing the softening are..
Toluene
Xylene
Kerosene / Napftha / Parafin
MEK (Methyl Ethyl Ketones)
Acetone
Any 'bulk' carb cleaner would contain something like these. You don't want pressurized stuff as the quantities aren't enough and it evaporates as soon as you try to use it.
You need Litres, uncompressed, not in spray form.
You could also use Gasoline and Diesel. Diesel is a great solvent not that different from Kerosene. And cheap. Gasoline evaporates a bit too fast imo, but I recon it'd work too.
These are common in varnish removers and paint thinners and they aren't actually that different from actual Fuel. Toluene is common in fuel and was somewhat responsible for the turbo era of F1.
The stuff on your pistons is varnish, which is why Acetone is so good. Acetone is also probably the least carcinogenic of the chemicals mentioned, although it's still flammable.
I recon over 24 hours you could run through 4L of the above chemicals. 200ML every few hours, per cylinder.
You can put the spark plugs back in to stop evaporation through the plug holes but there is no need to put them in tight.
Be bloody careful. These chemicals aren't a joke.
Context:
I'd done my valve stem seals as part of a head job and this didn't solve my high-RPM smoke cloud problem. if I revved the engine up to 7.5K it'd smoke on deceleration until about 6K. Or until I changed gears.
Evidently it was never valve stem seals and honestly I don't know how so much oil could come through a valve stem even if it were.
So the thinking is that this is caused by the oil control rings and related piston holes/gaps getting gummed up, if you don't use the car enough for a few months (or 3 separate 6 month period in my case) this happens and the oil control rings stop controlling oil.
A friend of mine worked on another MX5 where he and the owner thought it was valve stems, replaced them TWICE never was, but the car drove fine and they continued to compete.
Also on our cars the oil squirters facing the gap in the oil control area doesn't help :-) This maybe contributes to the problem.
Method:
The thing to do is take your time, be quite careful with the relevant chemicals. Get your car up and ready to drain and make sure you keep the stuff within your pan but not overflowing it. You DO NOT want this stuff going over the 'full sump' line.
So drain your oil first, then drain the stuff that leaks down.
Use some chopsticks or other small sticks of equal length with the plugs out so you get the cylinders all to half way. (they all line up heh) - this gives you 200ml of fluid to fill each cylinder. 1600 motor, 400 cylinder at half way.. 200ml.
That way you can put a good dose down and then come back in a few hours to put more down.
The thing is this, you're putting down volatile hydrocarbons. Those will happily soften whatever is stuck to the rings or in the ring lands. But you need _flow_ to actually move the dissolved stuff, so you will end up putting about a litre past each piston ring.
The "big idea" is that those volatiles will flow down past the rings and take some of the deposits with them as they go to the sump, while also softening the deposites further. The varnish will be hard at the start and soft at the end. Ideally you put through enough that a good portion gets solvated into the volatile solvents and _flows_ down the cylinder walls.
If you're going to do the compressed air thing, do it at the end, not at the start, that way you're 'forcing' more solvated carbon past now that it is really softened, if there is any deposit left.
Don't rotate the engine for a good while, while putting the chemicals in.
When you're done, make sure all the cylinders are empty, then put a teaspoon of motor oil down so the rings are lubricated again before startup, then drain the sump, put in new engine oil and optionally change the filter.
The TSP of oil won't flow out quite as fast as the volatiles, I suggest cranking by hand a few times and then firing it up and taking it for a hard drive.
## The chemicals to look out for for doing the softening are..
Toluene
Xylene
Kerosene / Napftha / Parafin
MEK (Methyl Ethyl Ketones)
Acetone
Any 'bulk' carb cleaner would contain something like these. You don't want pressurized stuff as the quantities aren't enough and it evaporates as soon as you try to use it.
You need Litres, uncompressed, not in spray form.
You could also use Gasoline and Diesel. Diesel is a great solvent not that different from Kerosene. And cheap. Gasoline evaporates a bit too fast imo, but I recon it'd work too.
These are common in varnish removers and paint thinners and they aren't actually that different from actual Fuel. Toluene is common in fuel and was somewhat responsible for the turbo era of F1.
The stuff on your pistons is varnish, which is why Acetone is so good. Acetone is also probably the least carcinogenic of the chemicals mentioned, although it's still flammable.
I recon over 24 hours you could run through 4L of the above chemicals. 200ML every few hours, per cylinder.
You can put the spark plugs back in to stop evaporation through the plug holes but there is no need to put them in tight.
Be bloody careful. These chemicals aren't a joke.
le sigh