Clunk after coming off the throttle

[raptoranderson]

Hey everyone, I'm back again I've been throwing money at my '98 GST Eclipse over the past few weeks with replacing the spark plugs, changing the oil, compression testing the cylinders, pressure testing the cooling system, replacing the spark plug wires, rebuilding my blow-off valve, changing my thermostat, etc .... and I just got the car to a point where I could drive it and came upon another odd problem.

I was doing short pulls with the car to make sure the blow-off valve was working since the tuning screw ontop of it had stripped-out and so I re-tapped it and fitted a new screw when I noticed a noise coming from the passenger's side of the car. Every time I came off the gas after reaching 2,000 or 3,000 rpm there was a clunk. I could feel it in the pedals and it wasn't anything earth shattering, but it was a noticeable noise almost like someone taking a toolbox and bumping it into the engine bay. So a fairly sizeable sensation

My buddy who has a Jeep said he had exactly the same sensation when his differential mounts were worn-out and I can attest to having driven with him in his car to try to investigate the noise when he had that exact issue. I had the driver's side motor mount replaced last year after it completely shore-off the car and it has been no problem ever since. Could it be the passenger's side mount is now on its last legs?

I haven't done anything strenuous or arduous to the car and have only driven it a total of 30 or 40 miles whilst testing and repairing it. Anyone have any ideas?

 

[dexterholland04]

Could be a handful of things. Motor mounts could definitely be one of them. If they're cracked, replace them. Get the car on jack stands and pull the front wheels off. Make sure everything is tight in the front suspension. Make sure that the transmission bell housing bolts are all there and are tight. Make sure that the rear transmission bolt is in; the one that goes through the rear ear of the engine block in to the transmission.

 

[VistaAWD]

"I had the driver's side motor mount replaced last year after it completely shore-off the car and it has been no problem ever since. Could it be the passenger's side mount is now on its last legs?"

Yes this seems logical to me. The other mounts should have the same amount of wear and tear on them as the one you replaced or close to it. If they were not bad at the time you replaced the drivers side mount theres a good chance they are now. I believe its good practice to change things out that relate at the same time. Just like when replacing a slave cylinder it's a good time to replace the master cylinder because they should have the same amount of wear on them.

Still a good idea to check sway bar links ect... in the suspension like dexterholland04 suggested.

Post back when you figure it out. Would love to know what the problem actually turned out to be.

 

[ThunderChild]

Start looking at control arm bushings too. mine was doing a similar clunk after I took the t-case put and was running fwd, without the extra support the control arm started making noise due to some play.

 

[Teezy]

Check both lower control arm balljoints on both the driver and passenger sides as well as your motor mounts. Jack up the car, grab your control arms and just feel for play in the balljoint. Also check for ripped or torn ball joint boots.

 

[raptoranderson]

Check both lower control arm balljoints on both the driver and passenger sides as well as your motor mounts. Jack up the car, grab your control arms and just feel for play in the balljoint. Also check for ripped or torn ball joint boots.

With the mounts should I be looking for bushings that are torn/ cracking or is it less obvious than that when it comes to having worn bushings?

 

[Geeb]

It could be something a bit heavier too like the trans itself. But rule out the smaller things first for sure.

 

[PlanZero]

I've had torn mounts that were not visible until removal. Have someone shift gears while you look at the motor, if its bouncing around replace all your mounts. Its fairly easy, just make sure you get the right ones. Poly front and rear are good if you don't want the full vibration of all 4 poly mounts, and I found in my fwd made a huge difference in clunk and wheel hop. I just filled my old front and rear mounts with deck urethane, and new rubber side and trans mount were like $10 each from rockauto.com

 

[AlmightySo]

Check and make sure all tranny bolts are tightened, when I bought my gsx the po had all the tranny bolts loose & I took it for a test drive without knowing and it was also loud clunks, whenever I let off throttle & when I started on the throttle

 

[dieselgenset]

did you figure it out?

 

[raptoranderson]

Sorry, I've been away since the beginning of December so I haven't driven the car since then I head back home Friday and it needs a new set of tires so when I get it up on a hoist I'll inspect all of the bushings and mounts on both of the front wheels and also the transmission and engine and let you know what I find!

This car isn't going to be around for much longer as I'm buying a much cleaner and less rusted-out GSX in a couple weeks so if anyone needs any spare parts