Rattle noise in the transmission. Sounds like a loose heat shield

[katoranger]

Lately my 97 has a tinny rattle type sound that I believe is coming from the transmission.

It sounds like a loose heat shield, but I couldn't find any. I also sounds like a loose chain.

Some quick google searches point to the pump cavitating. It was alittle low on fluid. I added, but haven't driven it since.

Drives fine and no shifting issues. Just noisy. Goes away with a heavier throttle and barely noticable when cruising along at 50mph 1500 rpm. 2000rpm its there.

 

[1380Ken]

Are you sure that it isn't your exhaust. There is a cover on the flywheel that could be loose.

 

[katoranger]

I checked the exhaust. I was noticing alot of movement of the engine Then got my neighbor to look while I revved the engine. Discovered that the motor/trans mount with the little strut on it has broken. Doesn't look too bad to replace.

The description on the part says it absorbs vibration from the trans. I think the stress of trailer towing last week did it in.

Looks like I get to spend some money on a new one. At least that is an easy fix.

 

[katoranger]

I replaced the right transmission mount. The one with the strut on it. No change in noise, but the car is smoother.

I cannot tell where the noise is coming from. No CEL. It is loudest at about 2K rpms and is related to engine speed and load.

 

[Cadillac_AL]

cracked flex plate?

 

[maroonmetallic97]

Did you check the inspection plate? (I'm assuming this car has a little one)

I've never seen it on this car but, I had a 3800 firebird I drove to school. It did have one and the bolts were very tiny. Worked loose over time.

 

[katoranger]

I checked the inspection plate. It is missing. Took the serpentine belt off and started the car and the noise is still there so its not one of the accessories.

So other posts I read were pointed to the harmonic balancer. I pulled the front wheel off and the little plastic panel. I don't see any cracks or separation on the balancer.

A cracked flex plate is a maybe. Hopefully not though.

I am going to double check all the heat shields again. With the belt off I could hear alittle better and it sounds louder on the back of the engine. It may be above the exhaust in that area.

Thanks for the tips. It is not a grinding or a knock noise. Car performs fine otherwise too.

Much smoother with that new mount in space.

 

[maroonmetallic97]

How hard was that strut type mount to install? I have been holding off til it was warmer but, if it's easy I might as well do it.

 

[katoranger]

I think it took me about an hour. Getting it back in one the hard part.

I put the car on ramps and then used a smaller floor jack with a block of would to lift the engine.

Put all the bolts in place on the engine side first and then lower it back into place and put the 3 nuts on that hold it to the subframe.

I had to remove the clamp for the transmission lines to get the mount in and out.

 

[maroonmetallic97]

Thanks man!

By the way, I popped my head under my trans yesterday and there is definitely an inspection plate on the 97. I'd suggest you replace yours. Just a heads up.

 

[katoranger]

I will have to go did one out of the junkyard. Its gone.

 

[katoranger]

Here is my harmonic balancer. I don't think this is the problem.

It makes the noise in park, drive, neutral, reverse.

 

[GreenJip]

Did you ever find the problem? I am having the same noise coming from my 88 (with 67,000 miles) under similar conditions. Heavy throttle it goes away, cruising its not audible but 1500 to 2000 rpm I can hear this same rattle. Also, its not audible in park or nuetral.

 

[dcraig1000]

how about the heat shield for the catalytic converter? mine was driving me crazy until I put to sheet metal screws in where the rivets busted off.

 

[katoranger]

Now August. Still rattling. Can't be anything too serious. I am really thinking its the cat.

 

[DarkMaster]

Had a similar problem...turned out to be the harmonic balancer. it should not move free of the crank shaft. Mine did, the rubber separated from the outer metal piece. I also thought it could have been the lower crank bearings. they are easily accessible through the oil pan and cost about 50 bucks. Good luck

 

[katoranger]

December and still rattling. I think I may try replacing the balancer. It looks fine, but maybe its something I can see on the backside.

Still need the inpection cover too.

This car commands attention.🙂

 

[journeyforce]

Did you check the cat shield? What about the crossover pipe heat shield? That is above the trans and would put out a rattle like you describe

 

[katoranger]

I have checked all the heat shields that I can find. None seem to be loose and held them in place with a block of would to see if the noise would change. Nothing. I think it is worth at least looking closer at the harmonic balancer. I have two other vehicles so I am just going to take this apart and see if I can find anything.

 

[katoranger]

I checked the balancer again. It seems to be good. No wobble when running. Rubber looks nice. I can't spin the ring part. Everything moves together. Makes the noise with belt removed. Did notice that the tensioner pulley has alittle play.

I took some video then my phone froze and lost it. Will try again. The noise seems loudest on the back side of the engine toward the top.