just about one year ago ,i had to have a exhuast valve replace on cyl 4 this year a valve is bad on cyl. 2 ill bet its an exhuast valve what gives? the check eng. light was on for a vac leak, any help would be great 96 850 GLT NON TURBO 150.000 MILES

It could be sparkplugs chipping..what kind do you have?

Also, I find that lean conditions in the fuel can be caused by neglecting the routine fuel filter changes..this will eventually harm the valves. Fuel filters should really be changed every 10k miles, more if possible. I do mine every 3rd oil change. Lean conditions in the fuel system will also harm the water and fuel pump.

I had a 94 BMW 320. One day the fuel pump cracked and sprayed fuel all over the inside of the engine compartment, a few of the valves blew out as a result..I didn't know this and dropped 550 dollars on a new pump and various other damaged hoses...I couldn't recover the engine from the valve damage and ended up parting out the entire car. From that moment on, I get my fuel filter done regularly.

Fuel filter every 10K miles??....never heard of such...I always replace mine by 100K miles, but I know I should probably replace it earlier...say, 70-80K miles, but not every 10K miles. Where do you live? Is the fuel there really that contaminated? There are filters on the fuel lines at U.S. gas stations, so really, contaminants from fuel we buy is minimal if at all. If you don't live where there are certain standards for clean fuel, or if you buy from a station because they are cheap and have a reputation of say, sludge or water in their fuel, then I would understand.

See here's where it shows that changing the fuel filter on our cars used to be a 50K interval, but now it's 100K miles:
http://www.volvospeed.com/Repair/fuelfilter.php
Regards,
MIJ
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.

I had the same thing happen at about 49K miles--tooling down the freeway at 70mph and it was like someone pulled a plug wire. Took it to the dealer, both exhaust valves burned on #4, one of them had a small chip on the rim, all others pristine. Since it was just out of warranty, got Volvo to pay half the $1500 cost. No problems since (now at 115K miles and I've owned the car since new).

A later discussion with a respected local indy (Volvos only, certified tech)pointed the finger at Bosch platinum plugs--he said he had seen the same problem several times with Bosch platinums. He believed that the insulators on the plug tip tended to break. I had installed the Bosch's about 20K miles previously. I went back to the standard Bosch copper plugs and have had no problems since. Hard to know if Bosch platinums were really the problem, but I'm not willing to experiment with them anymore.
--
96 850T, Bilstein HD, IPD swaybars

Interesting i had new Bosch platinum plugs installed before and after the first valve job i also think i will replace all the exhaust valves this time, THANKS TO EVERYONE FOR THEIR INPUT

Tbone,
You are not alone with a valve problem. Others on this site have had the same issue, some have swapped engines with a junk yard (cheap) and others have bought new cars. I never knew that these heads could have a single valve replaced, reliably. Usually, if the head is off, you clean and replace all of the valves.
A lean condition is the normal cause of burned/dropped valves. That is a side benefit of the CEL, a warning to get the condition fixed. I agree that most CELs are for emission control, but they all need to be attended to.
We can't tell you what to do with your engine/car. If you like it, fix it. If you think an upgrade is in order, then get a new car. You are the one in the driver's seat. It depends on how much the car is worth to you and your bank account.
BTW, I consider someone going 65-70mph slow and should be in the right lane!

Klaus
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(1975 164, 1995 854T, 1998 V70R)

i notice its 2 and 4, wonder if its any significance, has the wastegate setting been played with (or the car been rechipped)?

my firt inclination woul be somepnes played with the engine....(or you just get in an rev the nuts off it when its cold!)

I know jags were prone to this if you didnt ketthe engines warm up BEFORE stoping on the loud pedel (freind of mine went through 2 engine rebuilds before he worked it out!)

Never read of anyone else haveing any 850 burned valve problems. Do the plugs look like they're running hot? Do you use any fuel additives? Do you always buy the same gas? What brand? Maybe a plugged catalytic converter could contribute to this? Check the accordian air intake duct. I've seen where those can crack and cause a lean running condition.

Was the original problem overconsumption of oil? How was it concluded that a valve was bad in each case? Also isn't it typical when there is a problem with valves and/or guides to rebuild or replace the entire cylinder head? This would be especially so at 150K miles when you might expect some wear to have set in on all the valves, seals, and guides. I had heard that Volvo does not sell parts for rebuilds but only sells remanufactured heads? Can any one confirm or deny this? This could help lots of people as our cars move into the age (10+ years) and mileage (150K+) where this kind of issue might come up.

SAME FUEL, NO FUEL ADDATIVES, NO OIL CONSUMPTION, NO COMPRESSION IN CYL.4 LAST YEAR, NO COMPRESSION IN CYL 2 THIS. YEAR WOULDN'T A LEAN FUEL MIX TURN THE CHECK ENG. LIGHT ON ,THE CODES SHOWED A VAC LEAK

My 850 had a cracked fresh air intake bellows and it did indeed set the check engine light. I don't know what the code was since the crack was obvious and the light went out when I changed the hose.

What was the original symptom or problem that led you to check the compression (this time or the last time)?

driving the car you could feel the valve blow it was like a plug wire came off