What did you do to your Volvo today? Topic is solved

[bmdubya1198]

I think that's how it goes, and it's aggravated by a hot lean mixture, which just torches the valve. I agree with the theory on oil reside retaining heat too, since that seems to be a common theme on these cars when they burn valves.

[RedBrickCollector]

From what I know watching too much of a certain kind of video youtube barely tolerates

Hot, high pressure gasses have an erosion effect, and any type of debris in the valve face would cause a break in the seal where combustion gasses would leak through. These gasses would slightly wear away at the metal as the combustion byproducts act like microscopic abrasives. The heat escaping into areas with significantly more oxygen than the cylinder would also make the metals much more reactive, not quite actual combustion, but scorching some off like the oxycetylene torch mentioned.

Now that could be barely a scratch the first time, but now it has an imperfect seal, and the next combustion finds that exact same spot over and over until you burn through the valve entirely.

I agree with the others that the valve stem seal is the root cause but I don't think it's the residue holding heat

I could very well be wrong haha

[volvolugnut]

Seems to me this is like the erosion of early rocket nozzles that were not of good enough material.
volvolugnut

[Sveedy]

So here's something else to chew on. My procedure for cleaning the head is copious amounts of throttle body cleaner (4 cans on this head), followed by a soak in hot water with detergent. Then another shot of throttle cleaner if needed, and finally WD40. When I lifted the head up to take it for its bath, I noticed this left behind. Yep. A valve seal just fell off of the guide. I don't think they're supposed to do that
So at least in this case, faulty seals were the culprit.

[scot850]

So is that where the expression, " My Volvo goes like a rocket!" comes from?



Neil

[Sveedy]

And, yes. That tray was clean when I started.

[DragosGD]

I installed and painted the reversing sensors on the rear bumper of my S70. The original VOLVO kit was bought many years ago, so it's a great achievement

[Sveedy]

Windows decided to stop working today. Took the master switch apart, and yuck...
Cleaned, reinstalled and windows work again, though one of the rears seems a little finicky.

[rspi]

Found the pieces to the cargo area shade so I can epoxy them back together in the days to come.

[jsrnsis]

I got the blue V70XC started after waffling on it for a year....and it's still making a horrific tapping sound, same as it was when I took the head off. I believed that was due to the RTV on the exhaust gaskets blowing out from a backfire, but maybe this car has a cracked exhaust manifold? Exhaust is separated in the middle behind the cat, but it seems to be coming from the engine bay and exhaust manifold area. Would have been nice to catch while the head was off, but I'm going to hook up the smoke machine when I get home.