L-Body Knock Sound/Feel When Transition from Accel to Decel

[jmgtp]

I have this slight knock (you can feel and hear it - not an engine knock, but rather because it feels like the engine is moving too much in the bay and there is contact somewhere) inbetween accel and decel or if I jab the gas real quick. This is in regards to a 1990 Beretta 3.1 (manual trans). I've replaced the lower torque strut and the front mount (the one by the water pump area). While replacing these two mounts helped significantly there is still a knock evident. The upper mount on the transmission appears to be ok, I cannot see any tears in the rubber and it does not seem to be degraded. I havent looked yet, but I'm assuming there is one more mount under the engine somewhere. But, the car has a bad axle, the lower boot is ripped (drivers side - and drivers side is where the knock seems like its coming from) and it clicks a tiny bit on sharp turns. Could this be the source of the knock? Could there be that much play in the CV or would it have self destructed by then?

[v6h.o.]

there is a mount on the rear of the engine as well. on the pass side of the car.

yes that cv joint could be making some noise as well.

[Canada]

Check your control arm bushings.....that was the problem with 2/3 of my noises.

[bszopi]

Might also be a wheel bearing going out. I can't remember what the sound was when my wheel bearing died, but I know it was only when turning. I first thought it was the half-shaft, so I replaced that. Then I was quite pissed to find out the sound was still there after the fun time I had replacing the shaft...

[Canada]

Reason #3,829 why you should repack them once a year.

[Anonymous]

Uh, you realize they have a sealed hub assembly, right? No way to repack them.

[jmgtp]

thanks for the responses. When I get some time I'm gonna get under the car again and see whats going on. I'd imagine if it was control arm bushings that it would make similar noise/knocks when hitting the brakes (even if in neutral) as that would load them up. The problem only exists on sudden harsh clutch engagement or if I hammer it real fast, the engine literally feels like its clunking around. The upper trans mount looks good, so that leaves the lower engine mount and then axles and hubs, etc.

Now that my 3.1 is finally running I love it! 3.1 + 5 speed = fun. Its pretty torquey down low and I'm craving more but can't afford to piss money away on my winter beater. I gotta say being used to shifting the dohc at 7k and now hitting a wall at 4500 feels very weird to me :P

[Anonymous]

I gotta say being used to shifting the dohc at 7k and now hitting a wall at 4500 feels very weird to me :P

4500? Mine always felt like it would readily rev to 6k, and make power to mid-low 5000's before I put the big TB on it... now it feels like it's shifted even higher.

[jmgtp]

well i'm very used to the dohc powerband where its just really starting to open up at 3500 and then slaps over to 7k. My 3.1 in first gear seems to pull to near 6k, but 2nd gear and above i find myself shifting at 5k at most. I free revd it in neutral on an explatory rev to see where the rev limiter would be and it appears to have none as it kissed 7k without a problem. 4500 may have been a bit of an understatement, but with the exception of first gear 6k is pointless 5k-5.5k is about the last reaches of the powerband. I do very much enjoy the torque down low though. In a porky w-body with an auto I dont think it would be as peppy but in a light L body with a stick it moves pretty darn good, it still doesnt compare to the dohc but I don't expect it to especially in stock form. I'm already craving more torque (and I'm dying for top end power!) but UD pullies and top end swaps cost a bit too much for my winter stand in car.

If someone has an UD pulley they wanna let go cheap lemme know!

[montecarlols(z31)96]

prolly one of the motor mounts or the control arm bushings, my old beretta had the same problem

[Scott_68B]

Now that my 3.1 is finally running I love it! 3.1 + 5 speed = fun.

Glad you got it running, what ended up being the problem?

Scott

[Anonymous]

You know the anti-seize that every place tells you to put on the threads of the spark plugs? Well, he used that and the plugs weren't grounding properly! Easy enough fix.

[jmgtp]

Ya that was pretty much it. There wasnt even that much on there but sure enough when I removed the plugs and cleaned the threads with some carb cleaner and reinstalled all was well again.