1996 850 Turbo, Rough idle, new PCV didn't fix it...

futureboycolin · Post by **futureboycolin** » 06 Oct 2013, 12:49

I towed the trailer back at the end of February, it was running fine before then. I had just replaced the timing belt, tensioner and pulleys, water pump, serpentine belt, wheels, tires, brake pads, front wheel bearings, radiator and all coolant hoses, heater core and catalytic converter. I did all that work myself, and I'd hate to see all that time and money spent completely wasted.

After the trip I let it sit for awhile, and have only been driving it since mid-July with the miss. I started work on the car again once I started driving it again.

So you don't think it's a stuck valve but a burned valve? I'll check out the local pick n pulls for Volvos, not sure how plentiful they are in Chicago. Are there any upgrades I can do for more hp while I'm doing the head? NA cams?

futureboycolin · Post by **futureboycolin** » 06 Oct 2013, 13:08

Too late on staying under 55 on the highway. After putting in the seafoam, I've been taking it on late night, crazy fast highway pulls on 90/94. Was up near 100mph 2 nights ago...hoping to unstick the valve.

On a side note, most of the work that I did on the car before I pulled the trailer was back in NYC in the dead of winter in an unheated garage. Let me tell you how much it sucks to work in a parka with a scarf around your face, pulling a space heater around behind you the whole time. All of the work I've done on the 850 here in Chicago has been in the parking lot behind my apartment building. I don't have a the space to do a drawn out job like a head swap. I guess I could fin someone with a garage, but "Winter is Coming." So I'd like to be able to do this sooner than later if I pull the trigger.

Would I feasibly be able to complete this job outdoors in a day if I start at 8am? It took me 2 hours to do the PCV, and now I could probably strip the engine of all hoses, intake manifold, air box, coolant tank, drain coolant, oil and pull plugs in about 2 hours.

Post by **erikv11** » 06 Oct 2013, 13:21

About the stuck lifter: as I understand it, that will often break free with driving. Remember that you can inspect the lifters by pulling the cam cover, you don't have to actually pull the head. For perspective: on the forums I can recall seeing posted zero stuck lifters, a couple dozen burnt valves, one broken valve spring, maybe one stuck valve.

Oil additives are not going to fix this problem.

I would never put in a high mileage junkyard head if I knew the only problem with my existing high mileage head was valves or even lifters. The junkyard head is 15+ years old and I can guarantee you has bad valve stem seals, in short order you will be right back where you started. I just see no benefit in that move.

I agree the compression numbers seem fine - they didn't jump with oil, so the low value must be the gauge. Almost no way they are truly that low, so uniformly across the board.

A key move now would be a leak down test. Just to totally rule out a piston/ring problem. If the leakdown points to exhaust valves on #1 (but test them all), then it is time to bite the bullet and pull the head. If it points to pistons then you need to do some more figuring before diving in (or abandoning ship).

If you want to go the route of pulling the head, which makes sense with all you've put into the car, then I would replace the bad valve, put in new valve stem seals, and know you can expect zero top end problems moving forward. That's what I'd do, but only after the leakdown test.

Post by **erikv11** » 06 Oct 2013, 13:30

Just now seeing your last post ...

If you need to do the head swap quick then you will need to have a head ready to go back in right away, my advice to rebuild your existing one won't work. In that case get a junkyard head but I would never put it on without first sending it to the machine shop for new valve stem seals and a valve job.

I have done a few head swaps I can't fathom getting it done in one day in a parking lot. If you really crank at it, you could perhaps get it done in two.

Teardown - Maybe 5 hours, there is always something that hangs you up e.g. exhaust manifold or that PITA little pipe on the firewall side of the head.
Cleaning - 3 hours.
Disappeared time - 3 hours. Where does it go?
Assembly - Maybe 5 hours.

Usually what slows me down is the one or two parts I didn't know I would need, and I have to order. Things break, you find new problems when you get in there, etc. You need a pretty full set of tools for this job.

If you get a junkyard head, get the cam cover too, you don't know if yours will fit properly. Yes, a good time for NA cams.

futureboycolin · Post by **futureboycolin** » 06 Oct 2013, 14:21

Well that's a bummer. I guess I'll try and find someone with a garage where I can lay up the car for a week. I don't know too many people in Chicago though. That's beside the point though...

Would I be better served by buying a couple new exhaust valves and lapping them into my current head? Is that easier/less time consuming than swapping? I suppose if I do find somewhere to leave the car while I do this, I could also send off my head to be machined and cleaned.

Post by **rspi** » 06 Oct 2013, 15:11

I wasn't sure if that was you or not that did all that work before making that move.

If you drive it any more, keep it under 55. Less strain on the rest of the motor. Low rpm's will help you do less damage to the motor. I seriously doubt you have a stuck valve or lifter. The motor would make a lot of noise with the lifter trying to do it's job. You likely have a small chip, doesn't really matter it's large enough to bleed by your compression.

I replaced our head in the parking lot of an apartment complex. I think it is a 9 to 12 hour job. Cleaning the head and block takes time. I stacked everything in the trunk while doing the work.

Yes it sucks working in freezing cold, about as much as working in 100 degree heat. Can't pick up tools that are sitting in the sun.

NA cams would be a good upgrade. Not sure how to time them to get the extra hp yet, others can tell you.

Post by **rspi** » 06 Oct 2013, 15:24

There is a chance to find a car in the junk yard with a reconditioned head. Maybe it was over heated a year or so back. When you pull the intake manifold and look into the intake of the head, you will see how clean it looks. If it looks clean, it's likely been rebuilt with new valve stem seals. Exhaust stems are not cheep. You can send a used head to a shop to be cleaned and new steal installed but that will cost about $275. Having my head straightened and new seals being installed cost me $435. A guy on VolvoForums gets these 850's for $450 or less, swaps heads from junk yards and keeps on moving.

Yes there is a big chance that the head has leaking valve stem seals but I believe these motors are built to last 500,000 miles so you may be ok if the PO used Volvo oil filters. You can tell by how the car looks in the yard if it was maintained or neglected. Torn up seats, torn CV axles, super dirty motor with evidence of leaks, it was likely neglected. Might want to look at a different motor.

Post by **erikv11** » 06 Oct 2013, 15:39

To lap in new valves, the head must be pulled.

I think that is good advice to unplug the #1 injector lead, you can drive it a long time like that.

taupehat · Post by **taupehat** » 06 Oct 2013, 16:59

erikv11 wrote:To lap in new valves, the head must be pulled.

I think that is good advice to unplug the #1 injector lead, you can drive it a long time like that.

Agreed on this. You'll have a 4-banger, which is what most people drive anyhow.

When a teenager I was doing an oil change on a 120 for work, noticed coolant leaking down the block. Showed my boss who called the owner who had no idea. Boss told him the price and said "Drive 'till it quits."

Car came in on a hook six months later. Volvos are amazing.

Post by **MoVolvos** » 06 Oct 2013, 17:10

**

My mentioning of the stuck lifter is that the 502 is especially good at cleaning out the motor besides resealing the rings. What ever has caused the #1 cylinder to be low on compression is not known at this time but we do know that it is dirty inside and running it hot only helps to cake the inside further including valve seats. Prolong raw fuel in the cylinder could cause the low compression as it is diluting the oil from the top of the Pistons and causing it not seal properly. That in combination with the dirty valves not seating is bad news in the long run and hurting the CAT for sure. Go ahead and try to clean it up before embarking on such a long and expensive job. So much money and time has been put into the previous work and to go over it again and find just the valves not seating

.

Buy the 502 and change to some DINO 5W-30 and add 503 to half a tank of gas. If your car improves you know it is dirty valves not seating. In the old days with Carburetors (what's that) you would rev the motor and pour water directly into it to rid the combustion chamber of carbon deposits. Perhaps you can do that as with the SeaFoam but I have not seen it done. Pepboys will not have the 502 and 503. You'll need to call your local high performance repair or builder (Porsche or Ferrari) and check if they have it or get it online. You have very little to lose at this point especially if you can't get to the work because of weather. What ever you do run the 90 plus gas nothing less.

Blessings,

BKM

**