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On clutches, gearboxes and the like


Gromit
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Evening one and all,

I've been busy of late putting in a new gearbox (and clutch & LesForkTM :i-m_so_happy: ) into the 110 after the old one started making noises.

Not having done such a big job before, I was rather chuffed that it all worked when I put it back together. :)

I was less chuffed the following day, on a run to the airport, when it all stopped working. :angry:

It went like this:

mile 15, noticed oil smell and stopped to find ATF all over the gearbox and rear diff. Needing to get to the airport I pressed on.

mile 40 got to the airport, where I noticed ATF all over the back door.

mile 60 noticed slight change in noise following by acrid plastic burning smell.

Stopped to find lots of smoke coming from the bell housing wading plug.

Sent my annoyed passengers off in search of a tow car :lol:

When it had cooled down, the clutch was initially seized. Once it moved, the clutch dragged, so no gears while the engine was running.

Got towed home 15 miles by the dad's 1.6 Laguna :lol:

Now, the questions!

I guess the most likely culprit is the release bearing has melted, but why?

The clutch was new, but was about 4 years old. Maybe the bearing had died on the shelf, but I checked and oiled it before it went in, and it seemed fine.

I haven't found the leak (I haven't looked to be honest), but if it had been the front seal of the 'box, would this have killed the bearing?

I haven't checked how much oil is left in the 'box. Could lack of oil and heat have melted bearing?

I'm looking a new NSK bearing here and the plastic housing is not in the centre of the bearing. I think I remember noticing this on the old one, but forgot when fitting it. Which way up should it be fitted? there's no mention in the manual.

Not looking forward to pulling the whole thing apart again, but maybe some of you can give me some clues and maybe some motivation :)

Cheers All,

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ATF oil is from the gearbox. If it's coming out of the wading plug hole, then the gearbox rear seal has gone. It may well get on the clutch - not sure about the thrust bearing though, as it would be above the flow of the leak. I can't imagine that the oil would be hot enough to damage the thrust bearing sleeve - I would have thought that the plastic would be pretty heat resistant. It would be interesting to see exactly what's happened though. Shame you have to take it all apart again Gromit :(

Les.

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So, an update. I'm mid job at the moment.

Just dropped the gearbox to find this:

_DSC0616.jpg

The bellhousing is full of engine oil and melted plastic.

The plastic is from the release bearing which has been cooked.

_DSC0617.jpg

Here's what the clutch looks like:

_DSC0618.jpg

Looks like the oil is coming from the crank oil seal, which is annoying as I'd just replaced it with a 'genuine' one from an online supplier.

We'll see what state it is in when I pull the flywheel.

:angry:

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It looks to me like you have a faulty thrust bearing Gromit. Bearmach had a bad batch of them some time ago - there was no grease in the bearing. They showed me one that had been returned and it melted like yours within a few miles. No grease in the bearing would generate a lot of heat pretty quickly and would melt the sleeve. Hot engine oil won't do it, and it can't get on the thrust bearing in sufficient quantity to affect it anyway. The fingers on your clutch cover - is it blue where the thrust bearing contacts it? It looks like it in your picture, so a lot of friction there in such a small space of time. If you spin the thrust bearing by hand and it's dry/crunchy/doesn't turn smoothly, then whoever sold you it has sold you a duff one. If that's the case, then I would suggest they replace the whole clutch kit.

Les.

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Thanks for the input Les.

The bearing actually still feels fine. It's the carrier that has melted from the inside out.

The fingers on the clutch cover aren't blue, but are marked from contact with the bearing.

The kit came from LR about 4/5 years ago (were Valeo LR OEM suppliers?), so my chances of getting a refund are slim.

Could the carrier have melted from the clutch slipping due to oil contamination? Either way, there was a lot of heat, as the flywheel is now cracked/crazed where it contacts the friction plate.

Can this be repaired? :(

Some more pics from this afternoon.

Friction plate gearbox side:

There's some blue between the centre section and the friction material that isn't present on the other side.

Might be normal, I'm not sure.

_DSC0627.jpg

and flywheel side:

_DSC0626.jpg

The clutch fingers:

_DSC0631.jpg

Release bearing:

_DSC0632.jpg

The flywheel. It's like this all the way round. :(

_DSC0625.jpg

Crank oil seal. Looks the same as it did when it went in a week ago. Not damaged or melted.

No brand markings on it, despite me asking and paying for a genuine one :angry:

It obviously does nothing toward keeping the oil on one side.

_DSC0629.jpg

_DSC0630.jpg

I have to wait a week for another oil seal and decide what to do about the flywheel.

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Couple of observations on this:

The melted carrier plastic. If the release bearing is pushing against the cover plate with 'some' pressure it will generate heat. This implies that there is/was NO free play in the system. This heat build up might be enough to melt the plastic. Heat has come from some source/cause.

Oil leak - either the seal was pushed in at a slight angle and not square to the shaft, pushed in too far, or not far enough. If none of the above then look for excessive crankcase pressure - done any other jobs on the engine recently?

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Depending on deep the cracking is - the flywheel can be skimmed. The pegs are a right swine to get out, so get the enginners to do it for you - they are only a few pence each. The blue steel between the friction material and the centre hub is normal - it's sprung steel. It looks like oil has been thrown from the centre outwards - are you sure gearbox oil wasn't coming up the thrust bearing guide/sleeve?, as this seems the only way it can get there. Heat on the clutch plate would have to pass right through the clutch cover, along the fingers, onto then onto the thrust bearing. I would expect the contact face of the clutch cover to be blue if it got that hot. The oil seal does look ok, but then it takes very little to allow the oil out and faults can't always be seen. Is the land on the end of the crank ok - pitted or rusty perhaps? This would 'sand away' the lip of the seal pretty quickly.

Your flywheel and clutch look bad Gromit. I would suggest you repair/replace the flywheel, fit a new clutch, clean the thrust bearing slide, check and/or replace the gearbox input seal, go to church and confess all your sins, then put it all back together - the Lord will forgive you and all will be fine :lol:

Les.

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again, thanks for the enlightenment. :)

I've drained the gearbox, well I haven't actually, cause it was empty. :blink:

I wonder how much heat an empty gear box creates. Looking at the release bearing again, it looks like it started to melt from the gearbox side.

I've separated the boxes and not found evidence of the source of the leak. So I've a new front and rear seals to go in. I don't think it was the front seal, as there is no ATF in the bellhousing. The radial oil marks on the friction plate are odd, but it doesn't look like 3 litres of ATF when through there. :huh:

There were a few bits in the gearbox drain filter, so I may have done some damage to the box. Well, I'll just have to try it and see.

I've also a new clutch and will have a crank seal, so just the flywheel to sort out somehow.

I believe I fitted the crank oil seal correctly. Knowing how much work it'd be to do it again, I was pretty careful. No work done to i recently and it breathes a normally as a moon mileage chip fryer should ;)

Live and learn, sort of; well, the living thing anyway.

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