Engine issues

[Tic's60]

Trying to figure this out. An BBC engine I got recently was told is was rebuilt about 3k ago and I have been tinkering with it for the last few months.

Here's the issue

On start up it smokes slightly

on ilde it's clean

normal acceleration it's clean

on rev up it smokes - BAD

no fouled plugs on any cylinders - all tan


I changed the PVC valve all vacuum hoses oil three four times. I am thinking the rings are gone as well as the valve seals.
Ideas?

 

[LITTLE JOE-59]

your smoker

sounds like you may have 1 or more oil control rings that are stuck,how long has the engine been sitting before you installed it?if this is the case i have a suggestion thay may work.

 

[Tic's60]

It had been sitting for 6 months. What's you idea?

 

[Nuts]

Tic,

Sorry to hear you are having issues with the motor.... Don't despair, things will work out for you I'm sure. Can't wait to see that car out and about in the near future....

 

[Tic's60]

Makes sense now. If they are stuck hwo do I un-stick them? Tranny fluid or?

Your diag was dead on though exspecialy after reading this.

"As for the oil consumption, it's most likely a sticking or weak scraper and/or oil control ring on the piston. Why doesn't a bad scraper or oil ring show up during a compression test? Because these parts don't have much involvement in sealing the cylinder. That's the job of the top compression ring. Oil control is performed by the two rings located below the compression ring. If the compression ring is doing its job compression will test great but the engine can still burn oil. Why don't you see blue smoke bellowing out the exhaust? Well there are a couple of reasons. The scraper and oil ring really don't have to work until the engine RPM is up, like at highway speed. At highway speed the wind inside the engine, caused by the spinning parts, is like a hurricane. This hurricane sends oil flying as well. That is when the scraper and oil rings have to really get down to business. If they don't, oil moves past and into the cylinder where it is burned. The compression ring has no oil control ability so it's no help at all. Then there's the catalytic converter. At highway speed the converter is cooking and it has no problem toasting the smoke made by the oil. The end result is little to no blue smoke out the exhaust to be seen."

Better to fix it now themn to wreck a cylinder wall!

thanks

M:-)