Gearbox/diff Failure?

[GLPoomobile 958]

This follows on from this topic about my Mi which wouldn't start, and then couldn't be pushed more than 6 inches in gear before something locked up.

 

I've had the starter off today, and no change. I assumed my 2nd suspicion, that the belt had slipped causing valve to piston contact. But I had the inlet off to get to the start, so I could see the valves and it looks like they are all in the closed position (or thereabouts), but more importantly, I tried rocking the car in gear from the front and I could see that the valves were not moving, nor was the fly wheel.

 

So what happens is that when I try and rock the car with it in gear, I get a few inches of back and forth movement before I get a squishy resistance. At this point I can hear some movement towards the back of the gearbox, so probably in the diff.

 

I don't know what the failure is, but can't think why it would have failed. Before this, it drove fine. I parked up and left it. The following day I turned it over 3 or 4 times in quick succession before the starter failed and the problem became apparent. So I can't see why such circumstances could lead to a gearbox problem, but that is what seems the most likely thing at the moment.

 

Circumstances dictate that I cannot whip the gearbox off. I might be able to tackle the diff though.

 

Can anyone hazard a guess at what has happened and give me some pointers on where to start with this?

[Anthony 1,003]

Does it still not turn over with the clutch depressed, and with the clutch depressed, can the car be rolled? If so, it's nothing to do with the gearbox/diff

 

I've seen this problem twice in the past couple of years - once was a rod through the block (which seems very unlikely if it stopped whilst cranking it over) and the other was a bolt that had worked its way loose behind the crank pulley and jammed everything up. A bolt that had fallen down into the cambelt could cause this as well, although chances are if that was the case then you'd be able to turn the engine over backwards.

 

Stick a 22mm socket/spanner on the crank pulley bolt and see if it'll turn either way.

[Tom Fenton 1,542]

Bloody hell GLP, you don't have much luck do you?

 

Hopefully this isn't it, but when the head gasket let go big time on my old 306 diesel turbo, it would let water into one (or more possibly?) of the bores and hydraulic itself, so it would not turn over.

 

To rule this out, whip out your spark plugs and then try and push it/crank it.

[GLPoomobile 958]

OK, so just to confirm a few things...

 

I haven't actually tried doing anything with it in gear and the clutch depressed, but I can do that if it's worth checking. It will move freely if in neutral, and there doesn't seem to be any problem moving it through the gears.

 

I haven't tried testing the starter yet. I literally just pulled it off and went straight to seeing if I could get the car to move with the starter out of the way (since I assumed this was jamming and causing the problem).

 

I haven't tried turning the engine on the crank pulley bolt yet, for the simple reason that I've not wanted to lug my jack and stuff up the road. Obviously that time will no come, but for now I've avoided it if not necessary.

 

Correct me if I'm wrong, but I can't see how it could be anything to do with the engine. With the car in gear, moving it a good 12 inches (6 inches forward and 6 inches back), surely I would be seeing some movement in the flywheel if all was well? Or are you specultaing that the engine is jammed solid, hence why the flywheel does not move, but the gearboc still allows a small amount of movement?

 

Hmmm. Thinking about that last bit it's starting to make sense now! Maybe I should get up there and try turning it by hand

 

P.S. I've got all 4 spark plugs out.

[Masekwm 2]

Should the valves open and close just by rocking the car? It sounds just like a knackered starter. Is it like my knackered starter here

Edited June 12, 2010 by Masekwm

[GLPoomobile 958]

Should the valves open and close just by rocking the car? It sounds just like a knackered starter. Is it like my knackered starter here

 

You haven't read the topic, have you? The starter is off the engine, yet it still cannot be moved with it in gear. And yes the valves should move by rocking the car, IF everything is OK. Think about it. With the car in gear, any movement of the wheels will translate to movement of the crank, which turns the belt, which turns the cam pulleys, which turns the cams, and et voila the valves move.

 

I've just read a topic by Eob about a problem he had with his Mi16. Sounds identical to mine, and his turned out to be a slipped belt. I'm going back the road in a minute to get the car in the air and try turning it by hand. Look forward to an angry post by me a little later today.

[Masekwm 2]

Doh, of course the engine moves overwise you'd not be able to push start cars.

[GLPoomobile 958]

I owe Masekwm an apology, and I'm rather embarrassed as I think I may have made a mountain out of a mole hill. I think I've done what I always do, which is jump to the worst possible conclusion and skip past the obvious and most likely

 

Let me take a step back and explain things logically before I get to what has just happened.

 

Due to the many problems with my car, I have had to push it on a great many occassions, and it's not the easiest thing to get moving. Now on those occassions it's always been done in neutral, obviously. Prior to this problem, I think I've only ever tried to move a 205 GTI in gear on about 2 occassions, both due to a sticky starter motor. On those occassions I did the same as I have been doing recently, which is to rock the car back and forth in gear. Looking back, I recall that when I've done this in the past I've always had resistance, and just assumed that was down to the stuck starter.

 

What I failed to take in to consideration, is that when trying to push a car whilst in gear, you not only have to overcome the weight of the car, but also the resistance of the transmission and engine parts, and the compression of the engine.

 

So in hindsight, it looks like I've been totally sidelined by the many assumptions I made based on the fact I couldn't move the car in gear. What a twat!

 

This afternoon I took the belt cover off and gave everything a good check over to see if I could see any loose bolts causing an obstruction, and all looked OK. I then turned the engine by hand numerous times, and it moves freely. More importantly the timing holes look like they line up (checked by eye rather than using pins. I think this is good enough as there's no reason why it would have skipped a tooth).

 

Confident that there was nothing wrong with the engine, I put it back on it's wheels again and was met with the same resistance. But this time I got a bit more persisant and really put my back in to it. In 5th gear it moved much more easily than in 1st. But even in 1st if I really shove the bastard I can get it to move. Whilst doing this I can hear it puffing through the plug holes, as the plugs are just sitting loosely at the moment. Hearing the puff was what made it dawn on me that it was the engine compression that was making the car harder to move The clunking that I can hear in the gearbox is I think perfactly normal, as I guess there is a certain amount of free play before the gears mesh together and take up drive.

 

Finally, I put the starter motor back on and it kicks over no problem at all, even with the plugs back in and tightened. So I reckon all this drama was all down to a simple stuck starter motor. I think I'll probably replace it with a later slim motor now, as I can't be arsed going through this again if it happens again.

 

I still need to put everything properly back together, so won't know for sure until tomorrow that it's all OK, but it's looking promising

[Anthony 1,003]

You bloody plank!

 

I've got a couple of good slimline Valeo starters here if you need one.

[GLPoomobile 958]

Yeah I swear I'll never learn! No matter how logically I try to look at things, I always seem to somehow circumnavigate the obvious, then eventually end up at the less dramatic finale, feeling like a pillock But at least these things often turn out good (or not so bad, at least), so that's a relief.

 

Will PM you about a starter motor

[Masekwm 2]

You are the opposite of me. I always think "It can't be that bad, I'll tackle the easy option first". I then ignore everyone who say it's much worse, see my starter thread, and hopefully end up with a car that is fixed.

 

Glad it's hopefully a nice and easy fix of a new starter.

 

Keith