Burned Valve Database DATA ONLY or a P0455 code will be set

[mecheng]

Having pulled several heads and valves for overheated or burnt valves, I think it it is a good idea to pull the head and the values. I don't think I have ever pulled valves and not seen some pitting on at least 3 of every 10 valves. Burnt valve just waiting for the time to happen. Usually under load when they are hottest.

The valves need to be cut and lapped or at least lapped so they can make a good seal.

Would it be easier/cheaper to buy new exhaust valves given labour rates? Also no worry about metal fatigue

[rspi]

Having pulled several heads and valves for overheated or burnt valves, I think it it is a good idea to pull the head and the values. I don't think I have ever pulled valves and not seen some pitting on at least 3 of every 10 valves. Burnt valve just waiting for the time to happen. Usually under load when they are hottest.

The valves need to be cut and lapped or at least lapped so they can make a good seal.

Would it be easier/cheaper to buy new exhaust valves given labour rates? Also no worry about metal fatigue

No. New valves have to be cut and lapped as well. Also, not sure how good I would feel about after market values, Volvo valves are expensive.

A reconditioned head usually cost about $500 done professionally. With new valves, that will add $300 to $800.

[101]

Supporting what rspi said above - I just paid $673 to recondition my head. Since I knew the history of my motor I didn't want to venture off and buy a reconditioned core that might have been seriously overheated or contained non-Volvo parts. Two of my exhaust valves had holes. The third exhibited some pitting and my shop made the call to not take a chance with it.

$406 Machine shop - 3 angle valve job, milling of the head surface, pressure test.
$197 3 Volvo exhaust valves. (catalog price is $86 each!)
$ 70 Volvo valve stem seal kit (catalog price is $92)


I do believe there is a vendor or two that make inconel exhaust valves for something like $50 or $60 each. If I had to replace a full set or exhaust valves I might consider that option, but I thought that was overkill for a LPT motor. As rspi said, new valves have to be cut and lapped as well, so there's minimal savings on labor.

And now a public service announcement - HAVE YOUR EXHAUST MANIFOLD MILLED! It's no fun to pay for a second set of exhaust manifold gaskets and remove the exhaust manifold from under the car once the engine is fully reassembled.

[rspi]

And now a public service announcement - HAVE YOUR EXHAUST MANIFOLD MILLED! It's no fun to pay for a second set of exhaust manifold gaskets and remove the exhaust manifold from under the car once the engine is fully reassembled.

Huh? Manifold milled? The shop that helped me rebuild the head over the past few days made sure I cleaned off the back of the head where the manifold mates. I'll do the same for the manifold this time. I have not had any issues with a manifold leaking using new gaskets. The shop did tell me that a manifold leak could cause valve issues.

[101]

When I pulled my engine down my exhaust manifold had loose bolts at #4 and #5 ... and it was pretty badly warped. Was it a contributing factor to my burned valves? Quite possibly.

[erikv11]

We're getting off topic but ... if you ever need replacement exhaust valves, try first to just get them from a used head. You can save a lot of $$.

[mecheng]

I've presented the data in a Pareto Chart to make it easier to read. Thanks to all those that added meaningful data; while not enough to make strong conclusions, it is a start and there are some trends.
98s that drive in hilly terrain, be warned, keep an eye out for cylinder 3 !

[songzunhuang]

Just jumping onto this thread. After a few months of trying to track down a P0305 (and replacing just about every ignition part), I took it to a shop this morning. The first inclination was a burnt valve. They are doing a leak down test to be sure. I may be adding to this database soon.

[rspi]

Recently purchased V70 NA with 202,300. Misfiring on #3. After driving several miles with the injector unplugged, decided to pull the head.

After getting the intake manifold off I found a nice size hole in the block right next to the oil trap box with a rod sticking out. Lol Surprise!

[j-dawg]

on the bright side, you don't have to worry about the PCV