Hey Spook...

Thanks for the good advice...

But I'm wondering, could this be caused by a valve problem?

This car was purchased in January by my friend, and I am suspicious of how it was maintained. It only has 120,000 on the clock, but my gut tells me the PO's idea of good PM was "jiffy Lube twice a year, whether it needs it or not."

I'm supicious the car was overheated. It has a brand new water pump on it, and the POs (just from what I've seen of other PM stuff) did not seem like the type of owners to replace something like that prophelactically... After I've driven the car for a week, I notice it's going through lots of oil... about a quart every 500 Miles...

So, My overactive imagination has visions of an overheat in the recent past, valve train damage, and replacing the water pump and selling it off to my friend over at the college. (he didn't know me then, it was in fact our mutual Volvo ownership that made us friends)

I'm gonna do a compression test on wednesday -- I'll let you know what I find. I told my friend to be prepared for a new head, and have already put out feelers on getting a rebuilt head or a one pulled off a known good engine. I hope I'm wrong...

Thanks again,
Fred

Dear Fred,

Good a.m. and may this find you well. What is the mileage on this vehicle?

Here are some possibilities:

(a) There is a metal shield over the catalytic converter. These sometimes come loose, and vibrate at certain frequencies.

(b) If this car is a wagon, check the center column support for the driveshaft. This is a large rubber grommet. If it is worn, the drive shaft will vibrate. Grasp the drive shaft and push it from side to side. If you can move it much more than 1/8", the grommet is worn. This could allow part of the driveshaft to contact underbody sheet.

(c) Is the exhaust system properly mounted? If the work was done by a general exhaust shop, they might not have mounted the system properly, allowing a pipe to strike underbody sheet metal. The rubber hangers allow the system to flex, as the engine shifts during acceleration and braking. If the hangers are missing and/or damaged, metal-to-metal contact could produce noise.

(d) Check the harmonic balancer (crank pulley). If this has failed, it could generate all sorts of noise. Check it as follows. Using white out, put a line from the inner surface (next to the bolt) across the pulley's face (in which there are several round depressions). If, after a short drive, the line has separated, the balancer has failed, and needs to be replaced.

(e) Check the shield over the exhaust manifold. Usually these are very tight. If it is loose, it might vibrate/resonate under acceleration.

(f) There was a recent post about noises coming from inside the transmission, due to a loose bolt. There won't be anything externally visible, but an inspection will show this.

(g) Are the engine mounts - and the transmission mount - in good condition? If they are worn, the engine might - under acceleration - shift such that a part, e.g., an exhaust pipe, contacts a body panel, and resonates.

Hope this helps. Let us know what you find.

Yours faithfully,

spook

P.S: Noise seems like it might be coming from the area around the catalytic converter, but it's hard to tell exactly since it can only be replicated at speed, in gear.

P.S.S: Exhaust was recently replaced from the cat back, but not including the cat itself... the cat forward is very old, but the exhaust systems seems to be fairly sound overall. Just wondering id the Cat element is ruined and causing this (seen it before)

THanks again.

Fred