Sounds like the engine of an old VW

[kap]

RgrF,
The pump was replaced almost three years ago when we got the used engine.

[decay]

small crack in the header/exhaust manifold?

just had that on our 1991 Geo Prizm.

[deckeda]

Exhaust leak? You said the sound wasn't under the hood, let it idle in the driveway and stick your ear under the car. Maybe with someone revving it a little.

[kap]

decay wrote:
small crack in the header/exhaust manifold?

What would be the signs? Water 'disappears'?

UPDATE: OMGosh, the question is stupid! I am googling for crack exhaust manifold. Sounds like my situation is it. Will have a friend help out with your suggestion this Sat A.M., deckeda.

[Dick Moore]

A bad misfire could cause that kind of sound, but I'm betting it's exhaust related.

[kap]

The more I read about it the more I am leaning toward the exhaust related issue.

[davester]

To pinpoint the location of the sound, get yourself about a four foot long piece of radiator hose and use it as a one-eared stethoscope. It's best to plug the other ear but not necessary.

[mrbigstuff]

I vote also for exhaust, also, but I am willing to wager it's a crack just before the muffler or silencer (depending on model).

[Harbourmaster]

Yeah Doc, My stomach has been bothering me lately, after a long hard run it sounds like an old steam radiator... can you tell me what's wrong with me?...

Your description is too vague for an accurate diagnosis so all you will get here is a bunch of WAG (Wild Ass Guesses).

This is exactly why mechanics (and doctors) don't try to do diagnostics over the phone...