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Engine blowing up, sort of.

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
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abscate
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Re: Engine blowing up, sort of.

Post by abscate »

Almost sounds like you are getting fuel into the crankcase somehow. I'm worried you havemajor mechanical problems in the bottom end and should be looking at motor options. Large crankcase pressure isn't good. There is no way you want this thing to start until you figure this out,
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Post by j-dawg »

I don't think your only problem is the PCV. Have you checked fuel and spark?

The problem may include but not be limited to your PCV.
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FLXC90
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Post by FLXC90 »

Try disconnecting the hose from the oil trap box to the cam cover. (in between spark plugs, see if that is where the white smoke is coming from. while doing the diagnosis, pull your fuel pump relay and coil wire, then check and see if cranking pressure is coming from the upper hose, and if the dipstick tube and oil cap stop smoking.

This will just show that the crankcase is pressurizing the system. Sounds like a compression check is in order, like a LOT of pressure is going through PCV, may indicate weak rings. Or may not.
Also, before you do PCV, read cn90's thread on DIY PCV hose redo, If you have a lot of blow-by, but not too low of compression, this might be the ticket for you..
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Post by PeteB »

Or a hole in a piston?

TripleEight
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Post by TripleEight »

Thanks for all the input guys, I'll check cn90's pcv redo, search feature isn't recognizing anything with less that 4 letters....

So I got the pcv kit from fcpeuro, most parts Volvo genuine, the trap looked different (a bit compact) but ended up fitting perfectly. Long story short, still getting smoke coming out of the oil fill and dipstick like a steam engine.

I'm only cranking the car for 5 seconds intervals as I'm afraid of the explosion.

Also I'm not sure is if it was smoking from the crankcase before the problem, or it's because of this problem as I never checked.

Old oil trap was clogged at the bottom but it seems like it wasn't the problem as there's enough space for gas to get through. Cleaned out the hole where the trap connects to the block, Cleaned out EGR which was completely blocked. Everything else was fine just caked on carbon here and there.

I haven't checked the timing yet.

So is there anything else other than the piston ring seal that would spit smoke? As i will have to give up on the car if it was the ring seal.

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Post by TripleEight »

Im gonna check again if I'm getting actual sparks from every plugs.

But there must be something igniting in the cylinders if I'm getting smoke from a freezing cold engine right?

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Post by TripleEight »

So I checked the Sparks and they are all igniting dull orange, probably due to low battery.

I decided to crank the car for a while and just see what happens and it started! for a couple of seconds and stopped, very excited I tuned the engine again and it goes POOM!! White smoke everywhere again, oil all over the cover, top pcv tube blown off. (And this is with the dipstick out and oil fill cap half tight)

The smoke smells kind of like burnt rubber but not unburned fuel and the initial smoke or vapor that pumps out of the dipstick before the explosion also smells like burnt something.

Before this all happened I also tried cranking without the fuel injectors plugged and/or the spark unplugged and I still saw smoke coming out of the oil fill mouth.

Yes, i tried unplugging the top pcv pipe only and it had blow by gas/smoke pumping out just like the dipstick hole and oil fill hole.

I read n90s pcv fix after I did my pcv job :| . But I doubt that the small tube is at fault for the huge pressure build up and the explosion, not to mention with the dipstick being pulled out and oil fill cap loose.

Now I'm just stumped. :?:

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Post by tryingbe »

Sounds like there is a hole in the piston. Did you do a compression test yet?
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TripleEight
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Post by TripleEight »

I will grab an compression test kit at autozone today if they have them, thanks

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Post by erikv11 »

tryingbe wrote: ... Did you do a compression test yet?
Good advice.
'95 854 T-5R, Motronic 4.4, 185k
'98 V70, T5 tune-injectors-turbo, LPT engine, 304k, daily driver
'06 S60 R, 197k
'07 XC70, black, 205k
'07 XC70, willow green, 212k
'99 Camry V6 :shock: 153k
gone: '96 NA 850 210k, '98 NA V70 182k, '98 S70 NA 225k, '96 855 NA 169k

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