Borked gearbox 2...

N

ndndndnd

Hello, apologies for the thread duplication - I realised that perhaps this was a better place for this thread than general discussion!

Diving home from work on Thursday, I smoothly double-de-clutched into third to overtake a slow-moving truck on a country lane when I heard a sudden, brief hiss...

Thought nothing of it until a mile further down the road when I noticed I was leaving a trail of thin, white smoke behind me. Driving gently, I kept an eye on the instruments (no sign of excess heat and no oil light), and nursed the car to my village. Pulling away from a junction, the clutch slipped noticeably and I assumed the clutch had failed, however that wouldn't explain the continuous plume of oily-smelling smoke I was leaving everywhere.

Pulling up at home, I hoiked up the bonnet and could hear a faint rattling from down by the gearbox at idle. Walking around the back of the car, I noticed the back was covered in droplets of oil. Kneeling down, the underside was covered in dripping gear oil and a pool was forming at the front...

So, what's happened? My girlfriend's father guessed the seal between the gearbox and the clutch bellhousing has failed. The Haynes manual suggests this requires a gearbox rebuild. Does this sound correct? What bits would I need to effect a repair? I'm guessing a s/h box and a new clutch. I've not done this before, but I think it's probably something I can tackle myself. I'm not going to drive the car until it's sorted.

Many thanks for any advice or help!

Neil
 
Hello,

I really could do with a bit of help on this one! Can anyone confirm if you need to disassemble the gearbox to replace the laygear bearing? (I think that's the one between the 'box and the clutch!)

If so, I'll probably stick on a s/h gearbox… any offers on that in the Kent area would be gratefully received too. I'd rather get a box off a member on here from a known car, than run the gauntlet of the local scrappy!

Many thanks,

Neil
 
Hi Neil, check if its lost any engine oil (engine dipstick) or gearbox oil (remove speedo pinion gear at the back of gearbox & pop the engine dipstick down the hole).

did the gearbox whine? the rattle only during idle could be loose clutch plate springs.

if the dripping oil is kinda golden clear and it's losing gear oil, sounds like the input shaft seal has failed badly somehow, leaked oil all over the bellhousing towards the clutch making it slip and spraying backwards towards the hot exhaust to burn.

requires disassembly to replace the seals or bearings.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-11#post-419711

2010-09-339-jpg.26831


replacing the whole gearbox would be cheaper & faster.

if it's leaking a dark brown oil, maybe rear crank seal or oil gallery plug seal or sump gasket is leaking into the bellhousing & exhaust?

need to take out the gearbox and closely diagnose the source of the leak.
 
Hello Pollyp, that's great advice - we're pretty sure it's gearbox oil, but it does make sense to actually check! I've not had a chance to look at the car since parking it last week, so I'll check all the levels when I get the chance. Like you say, I really need to get the box off to check where the oil's coming from.

The gearbox shifted fine as I drove home, with no whines, rattles or baulking. Actually, if it wasn't for the plume of smoke I'd have said the car drove as well as ever! Well, until the clutch started slipping...

I'll check more carefully to identify the fluid at the weekend. If it is the gearbox oil, I'll assume I'd be better off sourcing another gearbox.

Thanks for the help, much appreciated!

Neil
 
Well, the engine's still full of clean oil... so I guess the oil can only have come from the gearbox. I didn't have the time at the weekend to pull out the speedo drive and check, but I guess I'm in the market for a s/h gearbox... Anyone know any available in Kent?

Many thanks,

Neil
 
Hi Neil, what engine size & year is your car? I'm near Tunbridge Wells if my spare box is the right one for you.
Mike
 
Hello Mike,

My car's a '98 (coil in dizzy) 1.0l (manual gearbox, just to be sure!) What mileage is your car?

Tunbridge Wells would be very convenient if possible!

Cheers,

Neil
 
Pity, that would've been perfect! Thanks for the offer though. I probably ought to stick something up in the buy/sell section.

Does anyone have any recommendations about what to with the flywheel during a clutch change? I don't have runout tools or anything to measure deflection. Should I take it to someone to be resurfaced or is it likely to be ok? It won't have seen fresh air in 17 years and 152,000 miles...
 
Obviously though if there's oil all over the place and on the flywheel, I'd recommend cleaning it all off with some brake cleaner. Otherwise your new clutch could slip. If it has glazed the face you can always very lightly go over it with a fine wet and dry to deglaze the face. You don't need to as it does it itself over a couple of hundred miles. Just speeds it up a bit.
 
Thanks for the tip, I'll keep some brake cleaner handy when doing the job!

I've been wondering about the possibility of rebuilding the gearbox. As far as I know, the 'box is in good nick, with no whirring or crunching, so it's more of a known quantity than a s/h or breaker gearbox...

Rebuild kits containing bearings and seals are about £70 on eBay, so how tricky is it to crack one of these boxes open and rebuild them? Note that I've never removed a gearbox before, let alone tried to take one apart and then put it back together...
 
Has anyone replaced the bearings and seals themselves? I've followed pollyp's link (thanks!) so at least I have some idea what's inside the case, but he doesn't go as far as picking out the seals or replacing the bearings (although I may not have to...) Once the case is open, is replacing the seals kinda obvious? I've heard you'll need a press to get the bearings off the shaft...
 
the driveshaft seals can be easily pryed off from the outside then the new one punched in flat with a socket.
the input shaft seal replaced from the inside.

the input shaft bearing can be replaced at home with a puller & snap ring pliers

imag1526-jpg.38028


https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-120#post-706665

then punched back in with a long pipe

dsc09885-jpg.38143


the other tapered bearings are abit more specialised, requires a press or local garage/gearbox shop
 
More great advice! Thanks Pollyp!

Hmmm....

Had a quote for £500+ vat to rebuild and install the gearbox today - they refused to give me a quote without installation as they'd had too many people try to make a warranty claim after installing the gearbox badly themselves.

Looks like I'll be fixing this myself!

Does anyone have a part number for just the input shaft seal itself? I can't find anywhere that sells the seal separately from the whole rebuild kit. If I can get just that seal it'll be worth me just cracking open the gearbox to replace that seal. I'm pretty sure the rest of the 'box is fine. I moved it a couple of hundred metres into a shed yesterday and it changes gear easily with no whining or anything... You really wouldn't know there was anything wrong with it at all...
 
Gearbox input seal: £6 from Nissan. Part number 32113-M8000. At that price, I'm happy to order speculatively!
I'll still have to take the gearbox out to properly diagnose, but we'll see. If I can get the 'box back together and the car on the road for £6 plus a ball-joint splitter and a clutch I'll be a happy fella.
 
frank said:
white smoke from a g/box ?? sounds more like an engine issue to me
Click to expand...

What do you think might have happened?

The smoke was more grey than white. I'll admit I've not checked the coolant tank, but there was no evidence of overheating so I don't think the HG's gone through... Plus the car is stinks of gear oil and it's all over the underside and exhaust! The smoke was probably from the oil burning on the exhaust, not directly from the engine. ;)
 
have you checked the level neil ? there should,nt be any actual pressure in a g/box, unless it was seriously overfilled
 
frank said:
have you checked the level neil ? there should,nt be any actual pressure in a g/box, unless it was seriously overfilled
Click to expand...

Sorry Frank! I had noticed your post, and it is an obvious thing I should check. I was hoping to take a look last weekend but I have another car I'm trying to get back on the road too...

Does anyone have an opinion on cleaning up the clutch plate using clutch cleaner and reusing it? The clutch wasn't slipping too badly, and not at all under load so it might be saveable. I know the sensible thing is a new clutch, but...
 
Only had a couple of hours to work on the car on Sunday afternoon, so just starting pulling off ancillaries.

I pulled out the starter motor and found this:



The plot thickens! I've not got the gearbox off, but I'm kinda guessing something's wild and loose in the bellhousing and has probably got wrapped around the input shaft, tearing the seal...

I just can't believe I never heard a thing - car always started instantly and quietly! Must have been happening very slowly over a long period of time...

At least it means the gearbox itself is probably still good to go.
 
Thanks for the suggestion Frank - apologies for my ignorance, I've never changed a clutch before, but would the pressure plate strap be something included in a clutch kit?

Hoping to get the gearbox off this weekend, see if I can find an answer...
 
@ndndndnd This is pic of a regular pressure plate.

a60f00f582d6c0f24bd64d7f87925bd3.jpg


I'm guessing @frank means one of the metal spring straps. (Pictured), which is probably a good guess.

Ideally you need to get the box off and inspect everything. Catch any bits that fall out when you split the box from the engine. Also what were the symptoms? Ideally you need to at least identify what caused that damage to the starter, but you will probably be looking at a replacement Clutch at the least, and if you can't find good reason not to suspect the gearbox, you're going to need another one of those too.

Chris.

Edit: just read some of the earlier posts, and I'm guessing that you've also got a damaged seal. That would probably make smoke and cause the Clutch to slip.
 
Thanks for the advice Chris - I guess cleaning up the clutch really isn't going to be an option!

I already have the seal purchased from Nissan parts, waiting to go on.

Can anyone recommend a good budget clutch? I've seen Transmech, but I wonder if they're a little too 'budget'... I need the 180mm according to Nissan part Nos.

Can anyone give me any advice on changing the seal? I've followed Pollyp's very useful posts on getting the casing open and what's inside, but I'm going to be figuring things out for myself when it comes to the seal itself - or is it simply a matter of pulling out the shafts and prising out the seal, then using a socket to push it back in nice and evenly?

Cheers everyone!
 
Luk clutches, German tech, really good quality. I use them on the 3.0 V6 swaps and they are pretty damn good.

And if its just the driveshaft seal you're talking about, dig out the old one with a big screwdriver, and fit new one with a socket of the same size.

Chris.
 
I'm hoping to get the gearbox off this weekend - if my girlfriend lets me (she can understand working on the MX5 or the Chevy, but she remains puzzled by my affection for my Micra!). I'll get a clutch kit on the way home from work and crack on from there.

Chris: it's the input shaft seal, not one of the driveshaft seals - hence I'll need to crack open the gearbox.

Does anyone know if the LUK clutches come with an alignment tool? I hear some kits do...
 
Thanks for the advice guys - an alignment tool was only £8 at eurocarparts, so I got one. If it makes the job a bit more idiot proof, then I'm all for that!
 
Right!

Having never taken the 'box off before, it was a complete bear of a job! Didn't get as far as changing the clutch or opening the case, but here's what fell out of the bellhousing:



Any idea what they are? Is not obvious (yet!) where they've come from...

The bellhousing itself had taken a beating, scored around the circumference:



And holed here:



Is this above the selector mechanism?

The clutch itself seemed fine, albeit with a cursory inspection and without removing it - it also shows signs of a few hits around the edges of the pressure plate cover.



So, sadly, no answers but more questions!

Who's got any theories?!
 
Car isn't parked at home, so it's tricky to go and check.

I just googled what a pressure plate strap is and I'll know what to look for, although the fragments do look like one of the straps. Whatever it is has shattered to pieces inside the housing, and there's gritty, oily debris around the seal, bearing and input shaft - so that probably explains where the oil came from...
 
That debris does look like it could be one of the straps, meaning the Clutch is also buggered.

If the strap came loose it would have spun round and hit the bell housing.

You need to get the Clutch off and inspect it really.

Chris.
 
I know what you mean about it looking like engine oil. It does look quite black, but then wouldn't transmission oil go black when exposed to that much dirt? It does smell like gear oil, and the gearbox seems to have little oil in it. I'm starting to wonder if both crank output and gearbox input seals are shot and I'm looking at a mixture of both oils. Come to think of it, I think the car was using slightly more engine oil - but not very much. I put it down to the age of the engine - 150,000+ miles. Perhaps this is where it's been slowly going...

I meant to take a photo of the input shaft seal.

I'll take the clutch off when I get a chance - I did pick up a new one based on your advice, and it seems you're correct! It'll probably be next weekend before I get another chance to have a look at it...

What would cause a pressure strap to fail? Just age? I'm guessing the strap atomising inside the bellhousing precipitated the seal/s failing, rather than the other way round.
 
It was @frank that called it, the strap I mean. They shouldn't come apart unless it's a sh#te Clutch or you've been dropping it like a phat beat at a Skrillex concert. But yes, strap caused the damage to the seals.

I've never seen dirty gearbox oil, its just cogs in a box so the worst you would see is metal swarf in the oil. Engine oil goes black because its subjected to heat and the combustion chambers / cylinders.

You may find that the loose strap has done damage behind the flywheel, allowing it to get into the bell housing.

Chris.
 
ndndndnd said:
How big an issue is that hole in the bellhousing? Am I going to have to seal that up (jb weld?) before using the box again?
Click to expand...
Erm, if its smashed a hole in the bell housing then you probably have metal inside.

For me that would be a gearbox swap, unless you want to pay to get someone to dismantle And inspect? But I know which will cost less.

Chris.
 
Lol. Cheese gearbox. Is that so you can play a tune on it?

And just had a look at the gearbox hole again, its close to a bolt thread so maybe it didn't get into the gearbox. But if it didn't, where did the oil get out? And was there any metal / contamination in the gearbox oil when you drained it?

Chris.
 
Had a quick chance to look at the car tonight. I can confirm it was one of the pressure plate straps that caused the damage.

Here's the input seal:


Looking at again (whilst not knackered!) and I'm starting to doubt my version of events. I'm not convinced that input seal's actually leaking. Am I actually looking at a pressure plate strap that's broken free and whipped a hole in the bellhousing, releasing all the gearbox oil?

I'll admit were didn't drain the gearbox before removing. The drain plug put up a fight and we were so convinced it was empty we just pulled it anyway. No oil came out when I pulled the driveshafts...

If my version of events is correct, can I just weld up the hole in the gearbox (perhaps flush the box with oil to remove any small metal particles?) and replace the clutch? At least that way I can avoid opening the gearbox...

Oh, and maybe check/replace the crankshaft seal, too!
 
I'd get it welded up and a new clutch assembly. Should be fine then. Might as well check the crank seal while its accessible. Glad you've almost sorted it. Just flush the box with some cheap £2.99 engine oil from asda. By the way, I use 75/80 gl-4 gbox oil in mine as I found the 80/90 one that was recommended, too thick when cold. It was a pain till it had been driven a few hundred yards.
 

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