Question about 1988 Volvo 740
I have a 1988 Volvo 740. Recently, I have been having an issue of oil leaking from the fill cap (I think it started happening after I used STP Leak Stop). The mechanic cleaned out some vacuum hoses at the oil change and it basically stopped. Now it is leaking a little from one of the bolts on top of the engine, but there is also smoke coming out of the cap when I open it, and from the dipstick hole when the stick is out. There are also fumes in the car, and I have to leave the windows open. I spoke to a mechanic yesterday on the phone, and he told me that I should replace the flametrap and the plastic pieces that go with it, and possibly the breather box, and it should resolve my problem. I mentioned this to my local mechanic today, and he said that because when he takes off the vacuum hose, there is a blueish gas smoke from the compressor coming out, he knows that the engine is finished (probably piston rings), and has nothing to do with blockage.
The smoke coming from the valve cover and dipstick is called blowby. It is combustion gases the have passes by the piston rings . A small amount of blowby is normal on all engines. The PCV system(Positve Crankcase Ventilation)pulls the gases out and directs them back into the egine to be burnt again. I would first check the PCV system to make sure it is working proper. Also a compression test of the engine will tell you which cylinder is not sealing proper. If the compression test is ok, a leak down check of the cylinders will determine if the engine is wore out.
Posted on Mar 12, 2009
Good morning and welcome to fixya
you can try a couple of little tricks, try taking the pcv valve out and cleaning it or replacing it. try cleaning the fuel injection and look for carbon build up on or around the egr valve. you can also do a compression check on the engine and take readings see which one has a major loss spray wd-40 in the hole and recheck to see if compression changes, you might be able to fix just that cylinder if you dont want to fix everything else. good luck and let me know
Posted on Mar 12, 2009
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