How to check valves for leaks?

Question

I pulled the head on my '89 Toyota Cresidda and in a moment of ignorance, I laid the head on a wood dolly that had a towel on it valve-side down. Didn't realize at any given time a couple of the valves weren't going to be below the surface of the head. It was laid down gently but for a few minutes it sat that way until I realized this after examining it and started laying it on the side.

Yes, dumbass, ignorant amateur mistake but that's what I did. I advised the shop I took it to, they said they didn't see any obvious problems with any of the valves when they surfaced it, but is there a way to check the valves for leakage - i.e. bentness - myself? I thought about filling the individual chambers with oil and see how rapidly it oozed out, if there was any of them that displayed more obvious leakage than others .

Thoughts, advice?

Steve W. · Accepted Answer

There are a few ways. Level the head and pour a THIN liquid into the chamber and see if you have a leak. Use a vacuum pump and a rubber stopper over the port for each valve and see if you can pull a vacuum. Use a marker and coat the valves seating area, then rotate it gently and then look for an even area all the way around to be worn off.

Jeff · Answer

I think the machine shop is right: There is nothing to worry about. The valves are really hard and durable. It takes a lot to bend them, like dropping the head from a few feet high. I wouldn't recommend putting the head valve side down, but I wouldn't worry either.

The machine shop knows what it is talking about.

Jeff

user · Answer

Use a thin viscosity liquid such as a solvent(mineral spirits) as Steve W. mentioned. Turn the head with the combustion chambers facing up, fill with solvent, and observe for any leakage to the ports. It's difficult to bend a valve stem and you would notice it readily. I would doubt you damaged it by just laying it down.

How to check valves for leaks?

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