BrickBoard Archives
The files contained in this listing have been automatically archived from the active forums. Because the vast majority of posts are now in one place, this archive is considered legacy. You should use the SEARCH feature OR choose your topic and select date tabs within the forum you choose.
white smoke from exhuast[120-130/1967] posted by James Genus Jr. on
Wednesday, 6 October 1999, at 9:56 a.m.
Here's the short of it...I have a 1967 122s that runs like a charm other thatn the following problem. When I lift off the accelerator in gear, I see a plume of smoke exit from the exhaust pipe. When I take the car out of gear, the smoke does not appear.
I noticed the problem after I started using a lead additive in the gasoline. I have since stopped using the additive. Has anyone else had this kind of problem? Hopefully, I haven't done too much engine damage here....
Thanks,
James
James
Re: white smoke from exhuast[120-130/1967] posted by Steve Seekins on
Wednesday, 6 October 1999, at 10:58 a.m.
The most likely problem is that your valve guides are worn and the valve seals are shot. When over-running the engine (decelerating with clutch engaged and foot off the gas), the cylinder vacuum pulls oil from the valve cover area past the valve guides into the cylinder - then smoke. This usually does not happen under load. The other possibility is badly worn, broken rings or a stuck oil ring on the pistons allowing some oil to be sucked up past them into the cylinder. The most serious of these conditions would be a broken ring which could be causing damage to your cylinder walls. Try doing a compression check - if all cylinders are good, then it is likely a valve guide problem - and not particularly critical except that it is annoying, somewhat embarrasing, and can cause failed emissions tests (visible smoke, high HC). Solution is top end rebuild. And while you are at it, have the valve seats replaced with hardened ones so that you do not need fuel additives, use bronze valve guides and the new style teflon valve seals for longer life.
--Steve Seekins
Re: white smoke from exhuast[120-130/1967] posted by James Genus Jr. on
Wednesday, 6 October 1999, at 1:17 p.m.
Steve,
Thanks for your answers to my query. When I purchased the car, the previous owner said the compression across 4 cylinders was the same. I don't remember the figure though.
I'll check around to see what is required for a compression check, since I've never done one myself.
The engine is a transplanted B20B, 1970. From what I've seen the CR should be at 9.3 @ 3500 RPM.
I bought this car so I could learn...so I'll really have to break out the Haynes manual. Thanks again for your help!
James
--James
Re: white smoke from exhuast[120-130/1967] posted by Steve Seekins on
Wednesday, 6 October 1999, at 3:37 p.m.
You will not measure the compression ratio directly, but rather the compression in psi. This is done with the spark plugs removed using the starter motor to turn the engine - I doubt that you can find a Volvo starter to turn a B20 at 3500! You can get a compression tester for relativeloy little money from Sears or most discount parts places. Be sure to get one that has a fitting that screws into the spark plug hole - will probably have a couple of different adapters for different engines - and a quick disconnect at the gage. Simply screw the adapter into the spark plug holes in order, attach the gage and crank the engine - usually at least 4 complete cycles (8 revolutions). Just watch the gage - when it stops rising you are done. Write down the reading, release the pressure in the gage and repeat. If the reading is essentially the same, move on to the next cylinder. This will constitute a set of "dry" readings. When you have all four measured, squirt a little engine oil into each cylinder and crank the engine over several times. Then repeat all the readings. This will give you "wet" readings. If the wet readings are noticeably higher than the dry ones, then you have ring wear. If you have one or more low cylinders and the pressure does not change between wet and dry, then you have either bad valves or leaky head gasket. All the cylinders should be within about 5-10psi of each other for adjacent cylinders. Overall variation should not be more than about 20-25psi. Do not worry if the wet readings are 20-25psi more than the dry ones as long as all four cylinders are roughly equal - it just means that the rings are evenly worn. Check your manual for the correct range of readings - probably in the 150 - 175 psi range. You can get more data to track down specific problems with a leak-down test, but this will require a different tester.
--Steve Seekins