98 V70 GLT no comp on cyl 5-need some guidance

shadetree_v70 · Post by **shadetree_v70** » 03 Apr 2014, 10:53

Hi All,
1998 V70GLT FWD, 249k

Long story short, I have 0 compression in cyl 5, and the only reading I could get on the guage was about 30psi at 3000+rpm. My hope is stuck valve, but my guess is burnt valve. I have fuel, spark, but apparently no air, or at least not usable air. I replaced the headgasket last July, the PCV system the previous year, and generally keep up with maintenance, and the car has rewarded me with good service. If there is some way to avoid removing the head just to check the valves I would like to know it! BTW, I have run 2 cans of seafoam: through the intake manifold via the vacuum tree, into the cylinder directly, and through the throttle body in an effort to free up a stuck valve. Also I have some other questions:

Is it viable to drive on 4 cylinders for the short while waiting for the repairs to happen? Is it better to disconnect the injector or not, in the hope that a stuck valve will become unstuck?

What would be considered "normal" for running on 4 cylinders? After I cleaned the PTC last night I noticed that the CEL flashes much sooner under load, and I suspect that the turbo is working better and the ECU parameters are exceeded much sooner as well, but nothing worse is happening to the motor than before.

What, if any, is the relationship between a misfire code thrown because of the bad coil wire, and a compression problem? With no compression I would still get a P0305 but for a different reason. Just wondering how one followed the other so fast, unless the compression was going already, and the coil wire was causing all of the other random ones until I replaced, leaving the consistent P0305 for bad compression.

If I had a choice I would park it until the repair happens but money is tight and I need a car! I'm working with 3 scenarios: 1. Most money-complete engine swap (possibly the easiest). Then I will have the opportunity to do a full upper rebuild on the bad head and swap it back in sometime in the future. 2. Less money, but close after machine shop-Find a used head, swap it in. I still have to plane it right? Almost the same amount of work but no valve work necessary. 3. Least money-Use existing head, get it cleaned and planed, replace only the bad valves.

Is there a definitive way to test the coil? There's no reason to think it's bad, I just wanted to know. No visible arcing, and it seems to be running OK on 4 cylinders.

Thanks in advance!

Lee

Post by **Ozark Lee** » 03 Apr 2014, 11:27

You can drive on 4 cylinders but given that you have no compression I would go ahead and unplug the fuel injector on #5. There is no reason to dump fuel into a cylinder that you know will never get burned. The catalytic converter gets unhappy when unburnt fuel flows through it.

If you can get a borescope you can often see a burnt valve but it is tough to maneuver the scope and know what you are actually seeing. A borescope isn't the kind of thing that you can "rent" from an auto parts store so you would really need to take it to a shop and have them check for you.

I wouldn't try to chase other possible ignition problems while you know from the compression test that #5 is dead. No compression on a cylinder will always trip misfire codes.

I think you have accurately described your options. You can often find a used engine for about the price of reworking your existing head but you don't have any history on the engine like you do with yours. Labor wise it isn't that much more work to just yank the engine and drop in a replacement than it is to pull the head. As far as cost goes, it is all over the place depending on local machine shop rates. Even with a used head that looks good I would never just bolt it on without a trip to the machine shop to check it for true and to pressure test it so that cost will need to be added to the head along with your head gasket and bolt set.

With a used engine you can just drop it in but I always take the opportunity to stage zero it on the engine stand. New timing belt, tensioner, and rollers. Replace the PCV system. Replace the sump O rings. Install all new camshaft seals and the rear main seal. You may also find other little things and they can add up but this is your chance to get it right and then you can pretty much forget about it beyond oil changes for another 70k miles. Changing the stage zero stuff never gets any easier than when the engine is on the engine stand.

The time factor is somewhat limiting for you as well. Most machine shops will take a couple of days at a minimum to service a head, a week is more of a typical time.

It is a tough decision and there is no pat answer. It all depends on availability of used engines, local machine shop rates, etc.

...Lee

shadetree_v70 · Post by **shadetree_v70** » 03 Apr 2014, 13:10

Well its nice to know my thinking isn't too warped. You're right about the engine swap option. Cost wise its the most out of range, but it sure would be nice to have the current one out for rebuild to put back in later! I think this time i will be going with taking out the head and having whats broken fixed. If i bring the head sans cams and lifters he's going to charge about 100 for planing, cleaning and testing, then 20 per cylinder for whatever valves it needs, including seals. Maybe just have him do them all and be done for another 200k.

Post by **cn90** » 03 Apr 2014, 13:21

You can also follow the current thread by "BigRed":

https://www.matthewsvolvosite.com/forums ... =1&t=62527

Post by **erikv11** » 03 Apr 2014, 13:54

If you pull the head, then best bet is to replace all of the valve stem seals at that time. They are probably the cause of the burnt valve. For replacing the bad valve(s) the best source is a junkyard or similarly someone with a pulled, worthless head. Be sure to get valves from a turbo car, they are different from the NA ones.

Post by **cn90** » 03 Apr 2014, 13:58

Interesting re turbo vs non-turbo.

If you enter PN 9471466 in the Volvo dealer website below, it is the same part for both turbo and non-turbo:

http://thevpstore.com/parts/index.cfm?a ... &maxRow=10

Post by **erikv11** » 03 Apr 2014, 14:13

Sure, the turbo valves will work just fine in an NA car, but there is no reason to spend the money on them for an NA.

shadetree_v70 · Post by **shadetree_v70** » 05 Apr 2014, 09:15

erikv11 wrote:If you pull the head, then best bet is to replace all of the valve stem seals at that time. They are probably the cause of the burnt valve. For replacing the bad valve(s) the best source is a junkyard or similarly someone with a pulled, worthless head. Be sure to get valves from a turbo car, they are different from the NA ones.

Yup new seals are going in. Is it advisable to do all the valves as opposed to just the damaged ones? I'm going to send out to be cleaned, planed and pressure tested, and if the damage is limited to the 1 or 2 that I suspect then I'll have them replaced, then install new seals. If the others hold pressure is there any reason to change them out or are they designed for the life of the car? I know this is elementary for most of you but this is new territory for me as far as the nature and limits of valve train stuff. I would rather fix it right, but replacing parts that can be cleaned and reused is silly to me.

Post by **rspi** » 05 Apr 2014, 09:49

When the shop gets the head, they will check all of the cylinders. There is NO reason to have other valves replaced, just the burnt one (or pair). If they rebuild the head, new stem seals, they will regrind all of the seats and valves to make sure they are in near new condition.

Have that cylinder injector tested and cleaned professionally.

Post by **erikv11** » 05 Apr 2014, 12:11

I agree completely with rspi.

I have used this outfit for fuel injector cleaning testing, was satisfied: http://www.cruzinperformance.com/