1998 v70xc Dead cylinder issue.

James1216 · Post by **James1216** » 26 Sep 2015, 08:27

Hello members, I am new here!

I got a 98 v70xc from a friend recently that I've always wanted. Here is the time I could use experienced advice. This car has 200k miles and has a dead #3cylinder. Compression test was done by a friend and said everything is good. He also tested cylinders 2 & 4 to check for head gasket leaking. Car has new cap, wires and plugs. I changed the #3 dead cylinder plug with a new plug and it started and ran like new for 40 miles then the same thing happen, Dead #3. When the car sits running for a little you start to hear a very soft pop, pop ,pop in the air box that I am not sure if its related or not. This will come and go, its not all of the time. Any advice on how do narrow this problem down will be greatly appreciated.

Thanks
-James1216

Post by **Clockboy** » 26 Sep 2015, 10:14

Fuel injector?

Post by **tryingbe** » 26 Sep 2015, 10:16

What compression number? What leak down test number? Was the plug foul with oil?

James1216 · Post by **James1216** » 26 Sep 2015, 10:22

Hi. I will look into the injector not working to see if that is the issue. Could it still be a valve issue if the compression test was good or most likley another issue?

Post by **Clockboy** » 26 Sep 2015, 11:24

I think a valve issue could cause the plug to foul with oil and then not fire. A leak down test and the condition of the spark plug would let you know if there was a problem.

Post by **abscate** » 26 Sep 2015, 11:27

If a valve is sticking closed you could get good compression and no firing once the plug fouls.

Good news is this is rare, and usually curable

If it isn't the valve, go back to Stage 0 and evaluate cap rotor plugs wires...yes...even if they are new.

James1216 · Post by **James1216** » 26 Sep 2015, 12:30

Thanks for the help. My friend did the compression test (he is a GM mechanic) and told me the compression was good on 2,3&4 but did not tell me the numbers.The plug is not bad looking. My friend does not have the time to investagate the problem for a few weeks. I was looking to see what other issues might cause this so I could look into it.

Post by **Ozark Lee** » 26 Sep 2015, 16:38

You said it has new spark plugs, wires, and a new cap but what brand are they? Volvos are very picky about ignition parts and pretty much anything except Bougicord plug wires are trouble and the spark plugs need to be a single electrode type gapped at 0.028" or slightly less. The multi-prong plugs are always trouble since you can't gap them.

...Lee