Technical 'Welded' intake valve?!!!

You over come that by removing the ground cable from the battery. It normally happens to the inserts I suppose it could happen to the valve but it would be less noticeable. The inserts are soft and thin. I have seen what you describe but never to a valve.

 

No,,,,I’m certain the valve shown here was not damaged from welding .

And you are right,,,,,,it was the bearings that were damaged in heavy equipment,,,,not valves .

Tommy

 

I was heavy maintenance manager for a paving company for a while.
It is also a problem with race cars, welding improperly will make ya pay.

Your logic is good by the way and perhaps will help someone not trash their engine of other driveline components.

 

I’m not pushing the weld damage theory but here’s what makes sense to me:

The valve train is under spring pressure. All the parts are touching, providing electrical continuity and less likely to arc.

Crank & bearings may be isolated by a thin film of oil, creating a gap, which could theoretically be arced. Slim chance but still a chance IMO

 

Actually, the question now is how to rectify the problem. The shop who did work probably made a mistake. It happens........
even in the best shops. I would not try to save that valve. I would get a new valve (maybe an oversize stem if available) and hone the guide till it fits correctly. Then clean it well and oil it before installation. You will never get the stem on that valve right without getting it undersize.

As for the "welding" idea, I don't think electrical welding would have produced the longitudinal marks on the stem. Too much heat from friction could produce those marks as well as some balls. Just my best guess.....

 

I also remember in the late 80s early 90s Ford had a bulletin for the rear thrust bearing failure in an AOD/AODE Trans. Installing a ground strap on the tail housing was the fix.