Gary Gaukler

Hi all,

So yesterday I spent 5 bucks on a mechanic's stethoscope. Now I am wondering how to interpret the various noises that the stethoscope picks up on our cars.

Holding the stethoscope to the cam cover, I can hear distinct 'clacking' noises that seem to get louder the closer one gets to the fuel injectors. So I am assuming that this is the noise of the fuel injectors firing.

Going further down to the exhaust side of the head, those clacking noises are pretty much gone, and there is just some random background noise.

Does that sound like everythinng is okay? How would I check for wrist pin noises, rod bearing noises etc.? Does anyone have a list of what you need to listen for?

Thanks!

Gary.

DanR 1201

Gary this is a hard one. I've been using a stethoscope for a few years and still can't trust my ears. Use it often and on different items. Eventually you'll get a feel "ear" for what sounds right and wrong. I recently suspected worn bearings in my alternator in my 951. After I removed it, I wasn't certain because the bearings felt ok when spun by hand. Changed them anyway and the noise was gone.

Gary Gaukler

Thanks Dan for your reply.

It's hard to know though when something sounds "right"... I only have this one 951, so I have really no baseline for comparison...

Anybody else have experience in using a mechanic's stethoscope?

Thanks,

Gary.

turbite

Gary,

You're welcome to try it on my 951, though it doesnt make too many noises
Where'd you get the stethoscope for $5?

Gary Gaukler

Hehe, yeah, damn, your valvetrain is REALLY quiet!

I got it at Harbor Freight in Newark. Cool place. So many tools to choose from, and very cheap! I also got a nice set of metric wrenches 8 - 19mm for 7.99, and a set of 4 prybars for 6.99. Quality? Well, it's certainly not Snap-on or Hazett, but it seems plenty good for my purposes.

Gary.

Laust Pedersen

A mechanics stethoscope has its own acoustic transfer function, which unfortunately changes depending on how hard you push. According to my ears it amplifies only the midrange spectrum.
Despair not, it is easily worth a $5 investment and can among other things be used to detect if injectors are working or not (apply it in the axial direction on top of the injector body) and determine if bearings are worn or dry.

Laust

Danno

And you can also use the stethoscope to verify your heartrate when you get the bill from some of those mechanics out there...

Tom M'Guinn

I did not know there was a Harbor Frieght in Newark. Cool. I use a stethescope every now and then. Not sure I've ever actually found anything with it, other than to confirm that the stock injectors click really loud.

Matt H

What the hell are you guys talking about? A mechanics scope is not flat and does not look like one at the doctors office. It has a long metal end (looks like a giant needle of sorts).
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote

seb928s

It's common that the 944 cars have loud injectors.

Peckster

You'll make yourself crazy listening with that thing. I just use one when I can hear a noise and want to find out where it's coming from. A long screwdriver held to your ear works pretty well too.

Gary Gaukler

Yes, that's the one that I am talking about. I have the one in your picture.

Well, I was hoping that there are some 'rules of thumb', you know...

Like, "if you hear a clacking noise at the camtower near the injectors, but no noises further down on the side of the head, then your wrist pins, rod bearings, etc. are A-Okay"

All right, so it appears to be more complicated than that. That's fine. It's still a fascinating tool to play around with.

Thanks,

Gary.

Matt H

Yep, neat to mess around with. I kind of agree with Peckster, you can drive yourself nuts. The other real issue is trying to figure out whether a noise is normal or not.
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote