Misfire, no compression on cylinder No.2

jjjh2n · Post by **jjjh2n** » 18 Oct 2010, 18:52

Hello all. I am just wanting to know if I am screwed on this one. I have a 98 S70 GLT Turbo with 153,000 miles on it. A couple of days ago I was driving on the highway doing about 82mph and the car started jerking(like a misfire) a little and then my CEL started flashing. I drove it home and pulled the codes... P0300, P0302,P0303.

So, I tested the resistance on the wires and they were within specs. Next, I pulled the plugs, left them connected to the wires and then grounded each one to see if there was any fire while the wife was cranking it. They all lit up fine and consistent. Then I pulled the injector rail out and cranked it up to see if they were pulsing ok. As far as I could tell they were normal. So, I reset the CEL. Drove it around, and it came on again. This time it only said misfire on Cyl. no. 2. I then did a compression test... ahhh man!
Cylinder No.1,3,4,5= 170-178psi. Cylinder No.2=8psi.
I did the leakdown test on no.2 and it did not improve.

My British haynes manual says that it is either a burnt or leaky valve, or a blown head gasket. I checked the oil and antifreeze and they look and smell normal, as much as I can tell. The temperature on the dash never got above halfway during driving, either.

Is there anything else that can cause no compression on a cylinder? It would be sweet if someone says that I just need a bottle of Restore or something, but I know that's just wishful thinking.

So, does this probably mean a burnt valve? I didn't understand that it could do it during normal driving. I wasn't driving it hard or anything.

I am trying to decide whether to take it to a garage and have them fix it or do it myself. The only problem is that I am back in school and have very limited time to work on it. Also, I have never done any valve work before, so I am kind of leery.

How big of a monster is replacing a valve on this volvo, if that ends up being my problem? Also, what else do you normally replace when replacing a valve, since you are already in there.

Sorry for the rambling.
Thanks, Josh

jjjh2n · Post by **jjjh2n** » 18 Oct 2010, 18:57

One more thing. Will it make it any worse to drive the car around town? Thanks

Post by **jblackburn** » 18 Oct 2010, 19:07

Burnt/stuck valve

Try holding the RPMs above 4000 in 'L' on a run down the highway for 2 minutes or so. People will look at you weird, but if the valve is just stuck, it'll come loose again with that.

Some questions for you to answer YOUR question as to what may have caused it:
-Does this car normally get revved over 3000? Spirited driving is good every now and then for these engines - the valves don't spin around until over 2800 RPM.
-Do you use premium fuel or 87 octane? 87 will burn valves in a turbo engine.
-Does your car burn oil? As the valve stem seals get old, they'll leak oil on the valves which can lead to them being burned.

As for replacing a valve...it's lengthy and a bit involved, but do-able by a mortal. Check out this write-up: https://www.matthewsvolvosite.com/2010/0 ... placement/

jjjh2n · Post by **jjjh2n** » 18 Oct 2010, 19:14

It is driven 5 days a week on 50 mile trips each day at about 78 to 83 mph. So, it gets revved. Also, I always use 93 octane. Yes, the car burns a little oil. It lightly smokes a bit when it is first started. Thanks for the help.

jjjh2n · Post by **jjjh2n** » 18 Oct 2010, 20:55

Would it be worth it just to put a reman or new head on, or a used engine in, instead of fool with the valve? If so, does anyone know of any good places to look for used engines or reman heads? Thanks for the replies.

Post by **jblackburn** » 18 Oct 2010, 21:27

The decision on which path to go is up to you - if I were in the same situation I'd honestly rather take my current & healthy engine that I know the history of and put a new head on it than put in a used one. That probably is easier than fooling with all the valves yourself, plus you get a fresh top end.

Clearwater Heads is a great source of rebuilt heads for Volvos. Just google the name.

Shipping is going to be expensive on an entire engine, so look for scrapped cars or in junkyards around you. Erie Vovo or http://www.vandsautodismantlers.com/ are two good sources of used parts.

jjjh2n · Post by **jjjh2n** » 19 Oct 2010, 12:49

Do you or does anyone else know where the casting # is for the head? Do I have to pull the cover off to see it? Thanks.

jjjh2n · Post by **jjjh2n** » 24 Oct 2010, 11:23

Hello, just wondering if anybody happens to know where the casting numbers on the cylinder head are on a 98 S70 GLT. Thanks for any help.

jjjh2n · Post by **jjjh2n** » 21 Nov 2010, 20:11

A few more questions...I am taking the car apart this week and I have done a few more compression tests(cylnder 2 is still reading 6~8 psi), leakdown test(sounds and feels like air is coming out tailpipe), paper at the tail pipe test(paper is being sucked in), vacuum gauge test(reads steady at 17mmHg or so). The two tests that throw me off are the compression test and vacuum test. I thought that if a valve is burned you would not get any compression built up in the cylinder. Does anyone know if I am wrong in thinking this? Also, I understood that the vacuum should not read steady and normal if there is a burned valve. So, could a bad lifter or something on this cylinder cause this? I have never taken a head off to look for this stuff. So, it will be all new to me, but it will be a fun project( with some cold beer and hopefully low repair $$) Thanks for any info or suggestions.

Post by **Ozark Lee** » 22 Nov 2010, 17:57

Everything you posted says a burned exhaust valve. If you can get someone to scope it you might be able to see it without removing the head but I think that (removing the head) is where you are going.

...Lee