'97 del Sol noise at 2500 rpm under load

Last summer had the Timing Belt and Water Pump replaced in my '97 del Sol Si
(95000 miles at that time). While in the shop for this preventive
maintenance also had the shop adjust the valves and other tune-up items).
Since that time we have noticed a noise at about 2500 rpm coming from the
engine compartment. At first it wasn't too bad but it seems to be getting
louder (colder weather a factor?). The noise only seems to occur at about
2500 rpm when the car is under load (pushing down on the accelerator).

Any thoughts? Is the maintenance done last summer a clue or is that just a
coincidence?

Scott

 

Could be a total coincidence - hard to say.

Perhaps buy a cheap automotive stethoscope and probe around. It could
be a bearing in the AC or steering pump (possibly water pump - I
wouldn't exclude it just because it is new). Maybe the timing belt
idler has a bad bearing.

If it is an automatic, also probe around where the transmission and
engine meet up (drive plate and torque converter). Sometimes the bolts
that hold these things together slowly walk themselves out and can
cause resonance at certain speeds.

There are many other things that could cause resonant noise like this -
others here will have more suggestions, I am sure.

Remco

 

It has a manual transmission.

Yes, noises are difficult. [GG]

I was hoping that perhaps the specific rpm and the fact that it occurs at
that rpm only while there is a "demand" on the engine (pushing the
accelerator) might point to a known historical possibility.

Thanks!

Best regards,

Scott

 

dude, you have to be much more specific about the noise, conditions
under which it occurs, and what you've done to identify it. saying that
you "noticed a noise at about 2500 rpm coming from the engine
compartment" only rules out about 20% of the automotive systems.

if my grandmother drove her car to your house and said "there's
something wrong with my car", could you help her without doing your own
diagnostics? 'cos her description of the problem isn't helping. you
want to drive your del sol to my house? i'll tell you the problem. but
until you do, you gotta help us help you by being /way/ more specific.

 

Jim,

I know you are trying to be helpful.

As I have already mentioned, it is very difficult to communicate to others
what a noise sounds like via the written word. I was refraining from
attempting that to avoid mis-communicating a symptom. The noise probably
would be best described as a reasonablly low frequency buzzing or rattling
noise - somewhat metalic sounding.

Since the noise occurs at the rpm and conditions that I previously reported
after valve maintenance and the timing belt & the water pump were replaced,
I thought that might be little more information than "there's something
wrong with my car".

I stand corrected.

All I was trying to do in the original post was to plumb the corporate
knowledge of this group to see if, after the maintenance I have described,
anyone else had experienced a similar situation. I take it you have not.

Best regards,

Scott

 

Also have a close look at the heat shields. They usually bolt on, but
some of the bolting lips tend to rot out, causing them to rattle at
some RPMs.

Not sure on a delSol, but some hondas/acuras have a double (as in pipe
within a pipe) going from the exhaust header to the cat. They are
welded together in spots and these connections tend to break after a
while. That can cause weird resonances and, since the sound travels,
can be pretty hard to find.

Remco