[FOSOS]

Eyo! So I've had a knock in the front end of my 2002 GUIII TB48 since I got it. Always sounded like a bush or the spring. Had 2 mechanics suss it before I bought it and they said not to worry about the sound and that it was a good patrol and that I should get it.

But here we are 3 months later. The knock is still there and has gotten worse over the past couple of weeks. So I took her to my mechanic yesterday and they come back saying it's coming from the auto trans. Particularly from the bell housing. All bushes look fine.

The knock usually happened on take-off or coming to a stop. and was worse when switching to reverse. But it happens when I accelerate not ****ing. If I just idle in gear it's fine.

The knock consists of a few individual knocks (1 -4). Its more like a loading up/down sound. Sounds like metal crushing rubber (bush). It does not sound like grinding gears the knocks happen to slow.

The mechanic did find a way to reproduce the knock.

Switch to 'D'
Hold Brake
Rev it around 2000
Let the revs drop back down
Switch to Reverse
Then accelerate. (This is when the knock happens)

Does feel more like something in the trans after seeing this. Sounded like $$$

The trans does drive mostly fine. It's a little slow shifting up hills. But shifts are smooth.

I think I also might have some grounding issues so I hope this hasn't messed with the tcu.

She's booked in with trans specialist next week. Not driving it in the meantime.

If anyone has experienced something similar please post up. And how $$$ is it for getting it looked at?

Cheers

 

[FOSOS]

Cheers @klappers.

Bit of an update though. The transmission guy took it for a drive. says it is not the gearbox, and that the knock is frontend related.

So gonna replace radius bushes (ones got a split, but we kinda doubt a little split could make such a large knock). Reseat Springs (I'll add that if I take off slowly the knock sounds more like rubbing/loading up noise). And yeah we'll check that slip joint first.

Must say, the auto trans is getting a little slow so still don't think I'm out of the woods on this one. But it's going back soon for a service. let the saga continue.

 

[FOSOS]

The other thing that can make a big knock in the front is the "mushroom" bushes on the ends of the radius arms at the chassis end. Is this what you were checking or the differential end?

We're doing all of them.

 

[FOSOS]

Bit of an update on this and it's really not good. Starting to loose a bit of love for the old girl.

We replaced radius bushes all 6. It may have settled the loading-up noise. But the significant knock is still there. My mechanics are at a bit of a loss. But his next steps are.

@klappers My guy ruled out slip joints.

The transfer case has been replaced at some point in its life. So we'll drop and inspect the oil on that.
Suss the diff oils.

The engine/trans mounts look pretty good but we're not ruling them out. (It does knock every now and then when its first turned over).

BUT... Here's where it gets interesting and it is probably worth starting another thread.

As soon as I pulled out of the mechanics she started missing and was absolutely gutless. Great, we got engine problems.

Mechaninc rekons coils are gone. But what are the odds, the engine has had zero problems on a recent trip to Melbourne and the past three months? Seems that the list of things going wrong keeps growing.

I don't know when to cut my losses. So if anyone has words of wisdom. I'd be bloody keen to hear it. I just want to get on a track.

 

[FOSOS]

So after I left the car at the shop. The Mechanic did a scan and got the ignition primary code. Which he wants to replace harnesses and coils at once. I took it home and the missing was intermittent, went for a drive in yesterday and it was fine. But the day before was missing every time I hit the accelerator.

Cause it's so intermittent, would it be better if we just did the harness first? MAFs been cleaned. Mechanics are telling me to stay away from after-market coils. Even online seems to say stay away. But all comes down to $$$.

As for the slip joint. We have only diagnosed that because noise is coming from between the trans and the engine. But I might chase it up again.

As for the knock. After replacing the radius arms it seems that half the knock is gone. (The loading up part) But the big clunk is still present. I think the next thing is engine mounts (as you can hear the knock when you start up the engine. just once..). Then trans mounts.

 

[FOSOS]

Does your 1k estimate take labor into account? Mechanics quoted 1500.

 

[FOSOS]

So the missing is fixed. Coils and Plugs did the job. End up sourcing the parts myself. Got the mechanic to help me pop them in for 50$ and some beers. Parts were 900. So I'm stocked its come under the 1k mark. All her powers back now, which feels bloody good.

Still chasing the knock. Even with changing the radius bushes, there's still a knock or two under my feet when coming to a stop.

@Vanne Sussed the links and they look okay visually.

 

[FOSOS]

Ahh, more of an update. Pretty sure I've found the culprit of the knock. Feel a bit silly if it is. I'm missing the nut for the left transmission mount and the cross member. Tragic that two mechanics have completely overlooked it.

Gonna replace the whole set. Does anyone have any resources to swap them out? If I jack the box up will they come out?

 

[FOSOS]

@klappers Can you do it without removing the cross member?

 

[FOSOS]

Closing this out. The sound/knock was from the missing trans mount (left) nut under the cross member.

I did order new mounts, but I actually discovered that the threads on the original mount were fine. So just whacked a nut on it. Boom sound is gone. Driveline is a lot stiffer too.

I'll keep the mount for when the originals go.

After scouring this forum for the 10th time. I did find this. Which is what made me have a peek. Cheers @Yes.

Engine mounts and transmission mounts... if yours is a 4.8, check to see if the transmission mount bolts are still there.

Still got some more issues I need to tackle like the fuel pump, wobbles, and tuning to get this 4.8 dialed (as much as a series 3 can be). But I'll spin up a new thread for that when the time comes.

Cheers to everyone and especially @klappers.