Hello,

I have an issue with my XJ8 (X308, 3.2 V8 from 2001)

Long story short; when the engine is at operating temperature (low RPM) and the car is in N or in P, something is rattling very hard. First I tought it was one of the catalytic converters but then I went under the car in a grease pit and I heard the sound coming from the bellhousing of the transmission. I just serviced my transmission with a new filter and fluid and the rattling was not gone. The car has no rough idle and perfoms good. The sound can be heard from outside the car. Anyone knows what this can be?

See the following image where the sound is coming from. Note that this sound only occurs when idling at 600-700 RPM. A cold start does not make this sound. Also when I press the gas pedal, the sound goes away.



I have a spare transmission (5HP24) and spare flexplate/torque converter, but I need some directions for what I should check before dropping my current (recently serviced) transmission.

Greetings.
- Terry

 

Are the Torque Converter drive plate bolts tight?

Could also be the TC itself?

One way to determine if it is the engine is to remove the TC bolts and start the engine. (no noise means TC or gearbox)

 

Apologies if I'm way off track with this, but are you sure it's a rattling sound and not cavitation type noise?
I had to top up my transmission fluid after changing the fluid and filter due to cavitation noises afterwards.
However that was only noticeable under moderately hard acceleration.

 

Thanks! I will check this, but sadly I don't have acces to the grease pit all the time, so it may take some weekends to get a hold of it .

The noise was present before the oil change and is at the right level. I've followed the instructions from ZF transmissions.Thanks for the response, but I don't think that is the issue I am having.

I have looked a bit more into this and it sounds a bit like this guy in the video is having at 0:25:


First I tought it was indeed a CAT but after going underneath the car, it looked like it was coming from the bellhousing. I have a spare CAT, so I can try that first.

 

Engineer's stethoscope is good for this kind of thing, especially if you have a pit to hand.

 

I managed to capture a video with the sound I am worried about.

 

Hello guys,

So I replaced the starter today, because some of the YouTube comments said it could be the return spring from the starter gear that might be broken. This is sadly not the case. I am going to replace the torque converter next I think. I will visit a tranmission shop soon for some advice. Maybe they know what the issue is.

The torque converter bolts are fine. I did not see any cracks in the flexplate, but I can't see much through that tiny little hole, sadly.

PS.
I purched a secondhand engine 3-4 months ago complete with alternator/powersteering pump/tranmission/etc. from a guy that won the same 3.2 V8 X308 on an action (engine ran 80.000 miles / 130.000 km), so I have almost every part to swap in and out.

 

if bolts are tight then its possable trans converter is on its way out .but i would think and hope its a bolt or tin shield issue

 

Very often clunking cat can be pinpointed by taping the cat by fist.

 

Thanks for all the responses . It is not a heat-shield or cat that is making the noise.

So I contacted the transmission shop last week and they told me I might have more than one problem going on with my transmission. Most likely some of the internal bearings are going bad.

They suggested I'd replace/swap my current transmission with the second one I have lying around first, because a complete rebuild will cost around €2500 euro's (around $3000)...

Next Thursday the transmission will be swapped. I'll keep you guys posted.

 

Since the noise you have is coming from the connection of the gearbox to the engine, it is quite likely that it is coming either from a faulty torque converter or, perhaps, cracked flex plate (not uncommon occurrence).

Are you going to also replace the torque converter? Ask the mechanic to carefully inspect the flex plate as sometimes cracks on it are not easy to spot.

 

Yes, I am going to replace the torque converter too. I can't really show the flex plate to a mechanic as I am replacing the transmission at a friends place, but I'll make sure there is no play in it and inspect it thoroughly. When it has play or is indeed cracked, I am going to replace the flex plate too.

 

Mine is making the same noise and from the same place.. bellhousing area. Look forward to hearing what your fix is.

 

Hey huntman40,

Last weekend I fitted another transmission & torque converter in the car, but it's not done yet. The exhaust is a massive pain in the (...), especially the left side since some cooling lines, wires, cables and heatshields are in the way big time. I will finish it the upcoming saturday and I will let you know the result.

 

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After topping off the fluid yesterday (didn't have enough so I had to order some), all my rattles and noises went away. My guess is that the torque converter was somewhat on it's way out, since the noise came from the bell housing. I tried to shake the torque converter to reproduce the sound, without success. Only after letting some fluid out of the old torque converter, there was a noise that sounded somewhat like the sound I had. Maybe the stator?

Anyways, just replacing everything helps a lot.. it always does .

If you are going to replace the transmission, let me know. I may have some good tips & tricks.

 

Whenever I remove a ZF 5HP24 gearbox I always renew the forward drum ('A'drum) 'just because'.

I usually find the end of the drum 'cracking' where the retaining ring sits.

The frictions/steels are usually serviceable so I just put them in the new drum.

 

I had same noise but much less than that . We couldn't figure out what was the cause until we lift car and engine was on then it was the transmission Mount it wasn't broke or cracked it was compressed I'm using cheap 20$ transmission mount so after more than a year the rubber of that Mount got compressed because of the transmission weight the mechanic said it looks fine I will add rubber washer it will fill the space now works fine . Also the mesh filter inside the cat converter may cause similar noise
hope this help

 

So yesterday I've disassembled my old transmission and did not see any broken drums or gears, so I am pretty sure it was either a bad torque converter or oil pump.

Sadly with my "new" transmission, I feel some kind of judder right before I come to a stop... but we'll see.

 

Tiny update:
After close inspection of my old valve body, I noticed a massive crack in the upper valve body, which I think caused my very uncommon but neckbreaking gear engagements.
I don't know if it is related to the tractor sound my transmission made, but I hope this helps somebody else.