124 230TE gearbox woes

[J532KTT]

Evening guys.

My 230 has started making a rattling sound when pulling away from standing, and when revving the engine in neutral.
It's a knocking that gets louder with revs at standing and a brief sound when pulling away.
If the gearbox is locked in 1st it doesn't happen but when it goes off in 2nd, it's whilst the torque convertor is taking the strain upon take off (if you know what I mean)
Is this a fluid issue or am I looking at a new box...? I was told these old 4 speed units were daily bomb proof so hopefully just fluid!

Cheers.

 

[jamesfuller]

Is it a knock or a rattle, you mention both above.

My 230 started making a metallic rattling noise in certain situations (slow and labouring in traffic up hill etc)
This was actually the exhaust, it sounded like when a heat shield drops on a modern car but it was actually a centre silencer falling to bits inside.

Might just be worth giving the exhausts a quick thump to see if they rattle!

 

[johnsco]

Check your fluid ... But also check your exhaust and engine mountings that could cause these symptoms.

 

[J532KTT]

The fluid is a nice golden colour and seems to be in good order.

Theres three rattles.

One is the backbox against the tow bar at 55mph.
One is the middle back box slightly collapsed internally.

The third one comes from the front.
This is the worrying one on pulling off and sounds like the transmission but it is possible that all boxes have issues. :/
If so, a whole exhaust replacement will cripple me. Haha

 

[grober]

Doesn't sound like the gearbox at all. More likely engine or gearbox mounts or the propshaft couplings or centre bearing mount. Engine movement may mean the exhaust is moving also. Time to get it up on a 4post lift and giving things a good wiggle from underneath

 

[J532KTT]

Had her in the air today.

Rear back box is fouling the towbar again (New rubbers on order from MB, Kwik Fit used cable ties!)
There's three clamps on the front/middle joint which are loose and bumbling about causing noise. These items are going to be sorted and then see how it goes.

I had a thought driving home, the rear suspension fluid is very low. Would this make a noise? There's fluid in the reservoir but the dip stick is dry.

 

[balge]

...
I had a thought driving home, the rear suspension fluid is very low. Would this make a noise? There's fluid in the reservoir but the dip stick is dry.

I would think it might make a noise if it runs dry, but probably not a rattle...

ECP have the fluid on offer atm - febi 02615

chuck a jug or two in to be on the safe side...

 

[1001ab]

I had a thought driving home, the rear suspension fluid is very low. Would this make a noise? There's fluid in the reservoir but the dip stick is dry.

I doubt it would make a noise if it was low on fluid but it wouldn't feel right. I think the rams would stop it actually bottoming out and clunking.
One of mine is super-bouncy, which I think is failed spheres.
I was cautioned about putting too much fluid in, the system doesn't seem to take much in total.

 

[kth286]

a couple of comments

1. gearbox fluid would normally be bright red when in good condition, not yellow.

2. broken spheres would cause hard/stiff rear suspension normally.

 

[hotrodder]

ATF is only bright red because it's usually dyed that colour, while not so common it is available undyed in which case it's natural colour is a golden/amber. Maybe not in the UK but you can even get dexron II, III etc that's dyed green! In any case the important bit is that it should be translucent and not murky/opaque or have 'bits' in it and obviously if you don't know what flavour it is/when it was last changed some fresh stuff and a new filter is a good idea

The SLS system has a total capacity of around 2 litres, dying spheres tend to make the suspension bouncy initially as the nitrogen gradually escapes and once it's all gone/the bladder that seperates the N2 from the oil ruptures you're left with rock hard suspension and zero damping as the spheres fill with oil. Obviously when this happens as the space the N2 occupied is filled with oil and the fluid level in the resevoir drops

 

[J532KTT]

The suspension is very supple all in all. Although the self levelling isn't all that effective.

I've got to somehow wrestle the lid off the reservoir to fill it. That'll be great fun.

I'll change the atf asap. Is it a diy job or a garage job...?

 

[1001ab]

I'll change the atf asap. Is it a diy job or a garage job...?

It's very straightforward if you're okay with leaving the TC fluid in place.

Get the car lifted, there's a drain bolt to release the fluid. Best done while the car is warm from running for a bit.

If you want to do the TC fluid too, you'll need to get a breaker bar on the engine at the front and get someone to crank it round manually while you spy through the access hole for the TC drain bolt.

I think it's 7 litres of ATF if you ignore the TC fluid.

 

[V8Darren]

I see you've already found the cause of your knocking, but just thought I'd add this in case someone else has a rattle and finds this post in the future.

It's well worth checking the bolts to the diff. On my old CLK, one of the rear bolts had come out at some point (I think even before I had the car) and stripped the tread in the diff casing. eventually it loosens the other bolt and starts knocking towards the back of the car. Mine got so bad that it snapped the front diff bolt and rendered the car undrivable (didn't take very long at all). Getting the new bolt in the front was no fun at all, so well worth sorting early.