Driving with a burned exhaust valve

[rspi]

Interesting.

I believe the PCV system can last the life of the car if you use full synthetic oils and don't have to touch it. My car now has 305,000. I did the PCV when it had about 194,000 (shortly after I got it) and it is still pulling vacuum. Not sure if I used Volvo parts or not (yikes).

My valve stem seals have been leaking since I got the car. The PO used dino oil from what I could tell and did NOT service the PCV at all. It was 80% plugged when I did it. I use 91+ octane, a drop in K&N filter and drive pretty normal / passively. About once per day or every other day I will rev it up to about 4,000+ rpm's going off the line but not very often. When on the road, which is a lot, I will go WOT a few times a day, passing trucks, etc. I can go through 1 quart of oil every 800 miles while home, but on the road I can go about 3,000 miles without needing a quart. I change oil about every 8,000 miles on Mobile 1 HM, usually 10w-40.

[dosbricks]

I have about the same ownership, maintenance, and driving history as 101, with the exception of my changing to 91 octane a while back. Another difference being that the OP's car is a turbo.

This thread has about convinced me to keep on driving like an old lady because it's probably too late to blow out the cobs without taking a valve with it.

Now can I also worry like an old lady?

[mecheng]

The cleaning valve theory doesn't take much, they say anything above 3000rpm, sounds like OP did that on occasion. I've also heard the recommendation to sustain > 3000 rpm by driving on highway in 3rd gear, for a couple of minutes. I did with both of my cars with no ill affects.

The one common thread I read is a lot of ppl point out that when they were driving hard, the valve burned. Many like this OP report they were driving up hill. Some have also been honest enough to report 87 ocatane use. Rpsi results contradict those that say a leaky valve stem causes it.

OP: did you have leaky valve stems? (When you start the car cold, do you see a puff of blue smoke)?


Sadly, most ppl that burn valves quickly sell the car and never report why it occured so there is very little anecdotal evidence but I would say stick with 89 octane at the very minimum, but in the summer or with high loads/weight use 91+octane.

[101]

There were no leaky valve stem seals that I was aware of - at least not enough to ever show any trace of blue smoke.

I'll find out more once I take the head off in a few weeks.

[rspi]

I don't know why anyone would have an issue with buying 91+ with gas prices so low. When I ran the numbers, I got a little better mileage with 91+ which offset the cost.

[abscate]

It's a Constituitional right to gripe about gas costing more than it did when you first got your license...26 cents a gallon got me. I can't remember if that was high test. Get off my lawn Robert.

[rspi]

LOL, I probably would have gotten shot when I was pumping $4.38 in Cincinnati not long ago.

[mecheng]

I don't know why anyone would have an issue with buying 91+ with gas prices so low. When I ran the numbers, I got a little better mileage with 91+ which offset the cost.

We are not all youtube internet celebreties like you, in my neck of the woods there is a huge price difference between 87 and 91; thats where they get you. I use 91, but they screw you, costing 91 way more than 87.

[101]

It's generally 60 cents a gallon price difference here. I'm not sure if the fuel economy is that much better on 91.

I'll post some pictures of what I find once I get the head off.

[scot850]

I did run my 93 850 GLT (NA) on 87 octane fuel, but it wasn't driven hard and mostly town driving. However, when I did take it for longer runs on the highway, I always ran it on Premium (91 octane). My theory here was some of the brands here don't put cleaning detergents in the 87 octane gas, and by running at higher speeds there was a chance for some 'cleaning' to happen.

On our turbo Volvos, I only ever use 91 octane. I believe running turbos on low octane fuel causes them to burn the valves.

I have no evidence to back this up, but running regular gas at speed is running the car lean. The fact that it is often #3 cylinder that appears to fail it is the one that will get warmest.

Neil.