VS Ecotec Thumps & Rattles

[nathanVY]

Hey everyone, have been having these problems for a while now and can't figure it out.

Ecotec 3.8L, 1996 with 180kms on it. Still young.

Problem #1

Thumps somewhere in the rear (unsure if it's auto or diff or what) when given hard acceleration or if you're going DOWN a hill, take your foot off the pedal and put it back on, thump!!!


Problem #2

Recently I've been hearing a rattling sound (definitely on the left hand side), only when IN DRIVE AND STATIONARY. Can't hear it when moving. I can hear it inside the cabin, but have struggled to find where it's coming from outside the car. Since the car doesn't do it all the time, just sometimes (getting more frequent and annoying) I usually have to put it in drive and if it starts rattling put the handbrake on and have a listen.

To no avail, still no idea where it's coming from. I have a small hunch it could be the air con unit - when I first bought the car I noticed a distinct scratchy noise that was clearly coming from the a/c unit. Back then it only made that noise when first started the car or around 3krpm. Now (5000kms later) I can't hear it at all just this rattle.

What do you think? A/C unit? or just the pulley bearings?
Is my engine buggered?

Just changed the oil today (10W50 i think) in my mates workshop and the filter too. Going to run it for a week or so until it's black again and flush it out and put new oil in.

Any thoughts would be much appreciated!!!
Cheers


EDIT: Also since the rear main seal was done (power steering rack and gearbox dropped) it's shuddering around 70 - 100kmh. Just out of alignment?

[VR_Acclaim]

yeah def be out of allignmet ate or ur tailshaft is unbalance the thump could 1 of 4 mjor things,,,gear box mount, unis, diff or control arm bush(mine done this) as for the rattle cuod be ur exhaust or sumin stuck in ur ac vent

[nathanVY]

yeah def be out of allignmet ate or ur tailshaft is unbalance the thump could 1 of 4 mjor things,,,gear box mount, unis, diff or control arm bush(mine done this) as for the rattle cuod be ur exhaust or sumin stuck in ur ac vent

ok thats cool, ill get a wheel alignment after I fit my pacemakers

gearbox mounts seem ok.
how do I check the unis & diff/control arm bushes??? (I have access to a hoist which makes things easier)

my car is IRS btw.

pretty sure the exhaust doesn't rattle.. getting it replaced with twin 2 1/4 soon anyways so that will eliminate that problem if thats it lol.

[nathanVY]

bump, any ideas on the thumping? what bushes are common to cause this in the rear?

[nathanVY]

No one knows???

[IBLOWN]

The thump will be slop in the diff. Needs to be re-shimmed or new diff. Jack the car up in park and turn the tailshaft back and forth and you'll see about half a turn slack.

The rattle is most likely the idler tensioner pulley arm. The spring loses tension and needs to be replaced. To test it, squirt some wd40 in the hole where the spring is, put a 15mm socket on the pulley bolt and push it up and down all the way about 20 times. If the rattle stops then you need to change the tensioner. The wd40 will only temporarily help the problem. The tensioners only really rattle when in drive at idle or lower revs.

[VT-565]

Tailshaft centrebearing or mount?
Rear K frame bushes?

[nathanVY]

The thump will be slop in the diff. Needs to be re-shimmed or new diff. Jack the car up in park and turn the tailshaft back and forth and you'll see about half a turn slack.

The rattle is most likely the idler tensioner pulley arm. The spring loses tension and needs to be replaced. To test it, squirt some wd40 in the hole where the spring is, put a 15mm socket on the pulley bolt and push it up and down all the way about 20 times. If the rattle stops then you need to change the tensioner. The wd40 will only temporarily help the problem. The tensioners only really rattle when in drive at idle or lower revs.

Fantastic thankyou, might look at getting an LSD instead Will give that tensioner a spray and see how we go

[VR_Acclaim]

arent all irs lsd? both of mine have been..so is the 5l wreck in the shed

[IBLOWN]

arent all irs lsd? both of mine have been..so is the 5l wreck in the shed

No only a factory option. LSD will have a tag on the housing.

[nathanVY]

maybe in the v8s but definitely not v6s

[rombouts91]

i also have a similar problem with my vs when i accelerate hard i get a thumping and gurgling type noise from the exhaust and get piss all torque any ideas would be helpfull