I have a 1998 S90 volvo, I have a cylinder number not firing, I have changed the plugs, I check the coil on another cylinder and it works fine. I now know that the wiring to number 5 is bad or something is wrong, one mechanic told off the top of his head it would be around $440 to $500 to fix. 2 months ago I had a complete head gasket done and the car was running great. Now it's running very rough on the 5 remaining cylinders

I need a better answer or solution, I can't believe after almost a complete tune up that it takes another $600 buck to get a cylinder firing and the car back to normal?? Can you please give me some answers?

 

Hi Kim,

My guess would be that your head gasket job has failed. A head gasket job would have to done near perfect, if not, it will leak again. Have someone check compression.

These cars are known for having burnt valves. If someone had the head off, they should have had the head checked and cleaned up. A proper head gasket job should cost no less than $1,800 at a reputable shop. If someone did it in their back yard, it should have cost no less than $1,500. A Volvo shop would likely charge $2,500 and the dealer would likely charge about $4,000. So, you can gauge by those cost as to what kind of service you likely received. If someone just pulled the head and slapped another gasket in there without cleaning up the head (having the valves lapped and checked for flatness), they 1/2 did the job which is likely why you are here posting your issue.

When someone has a blown head gasket or blown motor, the lower part of the motor (block) does not have it's proper seal with the upper part (head) of the motor. There is oil and coolant going through passages of the motor and when the seal is lost those fluids often mix. There is also intake air and exhaust air that goes through the head. Sometimes when the head gasket is breached, the air is mixed with the fluids. At any rate, if someone doesn't do the job perfect, there can be a super small leak in the gasket that will grow over time to a larger leak. This leak will cause the fluids or air to mix and be a blown/leaking head gasket again.


I once had a misfire with my 960. It was missing because the wires that went in the back of the plug that connected the coil pack had loose wires in the back of it. So, when I made sure the wires were pushed all the way in the miss went away.

A car needs 4 things to fire; Air, Fuel, Spark and Compression.

Hope this info helps, have a compression test done.

 

A head gasket won't cause one coil not to fire.

 

I believe she was saying that the cylinder was not firing as in the car is missing. Code read from OBD.

 

I guess she didn't specify, but because she said the cylinder isn't firing but the coil fires on another cylinder, that leads me to believe she meant the coil is not firing.

Also, good video. But a head gasket can leak without overheating. As you said, the combustion chamber is under a lot of pressure and high temperatures. After time, a head gasket can leak just because of that. And a water pump isn't exactly common to fail, on a Volvo anyway. It's purely mechanical, as you know. So if the belt is turning, the water pump is turning. Unless somehow the shaft breaks but the toothed gear somehow stays in place.

 

Like this?

 

Wow, holy crap. Is that a Volvo pump or aftermarket?

 

That was a Volvo pump I pulled out of one of my S90's. I drove the car 20 miles like that without overheating it.

 

Also, the head gasket in the S70 was leaking for months before my daughter overheated it. It only overheated because the hose bursted.

 

A former coworker of mine had a car from an Indy shop who put an aftermarket timing kit on. The incorrectly set the tensioner and snapped the pump. That was the only time I had ever heard of that happening.

And yes, overheating is commonly a cause of a blown head gasket. That can be due to any coolant leak, bad thermostat, or the rare broken water pump.