What else could clanking noise BE? (Page 1/3)
John W. Tilford APR 15, 05:32 PM
88GT with 3.4 push rod and 4T60 transmission.

Clue (?): Shortly AFTERI paid a local shop to replace the oil pan gasket and water pump (both leaks fixed) I noticed a mysterious noise from under the car. Will hear nothing unusual for several miles then little bangs which get bigger, go away, come back without getting bigger, etc. The worst are loud and actually vibrate the driver seat. Recently I've noticed they are worse when turning, especially turning left. Yet at other times I can cruise and turn with no unusual sounds.

The car has been up on lifts three times looking for the source/problem and I've crawled under a couple more. No, there are no branches caught in in the undercarriage and there's no other obvious cause.

First diagnosis: the connectors between the rear sway bar and the A arms had evidently never been changed. They looked like skeleton connectors, pads worn almost away, and could easily be flopped back and forth. So with the guidance of Forum members I bought some new connectors and had them installed. Felt great when I drove away . . right up until the noise came back.

Second diagnosis: Guy showed me. The exhaust was rusted through in a few spots anyway, but it was also rubbing against the outboard metal of the "frame" (cradle?). A spot had been rubbed clean of rust. So with the guidance of the Fiero Store, I bought an Ocelot exhaust system and had it installed. Felt great when I drove away. Sounded better. Then I heard the noise come back. Another Clue (/) - the exhaust installer re-used by cutting and welding the flat metal support "studs" from the old exhaust onto the new: "They are already grooved to fit the mounting springs".

Third diagnosis: When the exhaust installer guy had the car up the second time, he noticed the connectors from the front sway bar to the A arms was loose on one side. Clue (?): I had replaced those connectors my inexperienced self a few years ago WITH both inner and outer tie rods AND the brass replacement for the steering rack bushing. The installation shop obtained replacements and installed. Felt great when I drove away . . right up until the noise came back.

Related? Exhaust installer also said the motor mounts are worn down and the engine might have more than normal movement.

I have another appointment with shop which installed the front connectors, this time to drive a mechanic around so he can listen.

Can anyone think of what I'm missing in this click- click, pop -Pop, bang-BANG, then quiet for a while mystery?

John W. Tilford

theogre APR 15, 08:26 PM
Iffy engine/trans mounts is very bad. Noise is only a Warring.

Engine moves can have:
Pulleys and belt hitting
Alt and other parts can break
Exhaust will break
Intake parts can break too w/ some engine like Fiero L4.
Wires can make noise before shorts out or breaks.

If Trans moves Sideways etc, Inner CV(s) can have problems.
When you turn, One Inner CV is compressed hard, Other is pulled out.
Ether can made big binding and noise problems.
Out out too far will destroy the CV instantly. The axle then destroy other parts and/or lock the wheel depending just what loose end of axle hits.

Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 04-16-2021).]

John W. Tilford APR 16, 03:57 AM

Thank you!

I'm waiting now for the Fiero Store to open so I can order - and please check me on this -
front engine mount ("after market", much less expensive than "OEM")
rear engine mount
two transmission mounts (stock type OK for 4T60?)
"dog bone"

Fiero Store prices are reasonable. The Ocelot exhaust they sold me seems fine.

I'll suspend driving the 88GT until the slow and steady drive to the installing shop.

John W. Tilford

GKDINC APR 16, 08:32 AM
Look over the flex plate for cracks. Good luck, let us know what you find.
theogre APR 16, 05:48 PM
"Rubber" Engine/Trans mounts are ok. Many aftermarket are better then OEM but what TFS sells is any ones guess.

have no clue on engine mounts w/ Engine swap cars.
I think 4T60 should have same as any other Fiero V6 AT. Brackets on both types should use same 2 mounts from posted here.
John W. Tilford APR 16, 10:13 PM

You're scaring me now. Let's just see if the clinks and pops disappear after the new engine and transmission mounts are installed. OR, I have some ear plugs . .

John W. Tilford

John W. Tilford APR 24, 08:36 PM
Add to the ever longer list of parts bought and installed in the pursuit of fixing the still mysterious clanking sounds under the 1988 GT (with 3.4 push rod and 4T60 trans):
Motor and transmission mounts (including "dog bone").

Shop test drove car after new Fiero Store mounts installed. No clanks. Shop said the old mounts were really worn down. I drove the car home. More "dramatic" engine sound and nice vibration, as expected. No clanks! Great! Then at about seven miles the first little clink. Then more. Then the louder clanks, just as before. Clinks and clanks when driving level and straight but more when going through "dips" in the road. This time not such an evident increase in clanks when turning from our shared lane into our driveway.

Although the "best exhaust shop in Bloomington, IN" guy who noticed the motor mounts being worn down while installing the new (Ocelot, from Fiero Store - only source I could find) exhaust system obviously thought he'd done a great job hanging the new exhaust, I'm still suspicious of the exhaust system as a cause for the clanks for these reasons:
1) Clink/clank noises (and clank associated vibration which can be felt through the driver seat) ONLY START AFTER SEVERAL MILES, i.e., after everything is fully warmed up and fully expanded. The "best exhaust shop" guy showed me a rubbing point on the old exhaust before installing the new.
2) Exhaust installer re-used the same pieces (flat rectangular steel with notches to match the hanging springs) used by the old exhaust system by cutting them off the old and welding to the new.
3) More than a month ago while I was on my back under the car with a rubber hammer banging on everything I could reach, the sound which most resembled the while driving clanks was when I hit the exhaust near the engine.

Other information: the car has not had a catalytic converter since at least as far back as 2005. The new Ocelot exhaust only extended "from cat to back of car" so a new straight length of exhaust pipe tubing was welded in where the cat would have been located, just as was done for the former filler piece in the exhaust system which was just replaced. I don't know if the length of the old or new filler pipe was exact. A too-long piece mistake could have been repeated. Loose/worn motor mounts and resulting engine movement started the clinks/clanks by pushing/pulling against the exhaust system and compounding the mistake???

What do you think about arranging to pick up the exhaust guy and taking him for a ride AFTER the car is fully warmed up and clanking? He hears it, then we return and immediately put the car on a lift and look?

John W. Tilford

[This message has been edited by John W. Tilford (edited 04-25-2021).]

fieroguru APR 25, 10:28 AM
It sounds like one of your axles shafts is a little too long or too short. As the suspension cycles going over large bumps or turns, the inter tripot starts to angle and bind on the tripot housing.
theogre APR 25, 11:08 AM

Originally posted by fieroguru:
It sounds like one of your axles shafts is a little too long or too short. As the suspension cycles going over large bumps or turns, the inter tripot starts to angle and bind on the tripot housing.

Or Trans have moved sideways doing same thing. As that can/will stretch one and compress other axle even rest not running.

Look at all pulleys too. If even 1 pulley is close to frame that should, brand engine/trans mounting allow a little sideways play and pulleys other things hit.
Exhaust and some other parts grow when hot too and may hit somewhere.

Brake and suspension parts can do same when hot and noise is problem w/ them not engine problem.
John W. Tilford APR 25, 11:14 AM

The Meineke shop which just installed the motor/trans mounts said they "checked the CV joints" as I had requested and could find nothing wrong. Of course, I'm not sure how they checked or how much they know about Fiero short and longer axles. Probably more than I do. How could I or a professional check what you describe?

Also, I wonder how I could hear no clink/clank at all for the tens of thousands of miles since the 3.4 and 4T60 were installed until earlier this year? (Although, the extensive labor for changing the oil pan gasket and water pump and belt cover did suspiciously precede the noises.) And what would explain the several miles delay each time I drive it before the noises start?

John W. Tilford