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528i-FAN

Eeek, gearbox problems? HELP please.

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Took the bmw out this morning, not used it for 3 weeks or so. Seemed fine at first but after a mile or two started getting a grinding/scraping noise at certain revs, about 2300/2400 on acceleration. Also seems to do it in neutral when the ending is revved.

If revved higher there is a sort of tinkling noise also.

I've checked the fluid level and its exactly halfway between the low and high marks.

It's a 1980 E12 525 with Autobox.

Any ideas/suggestions would be gratefully received.

Lewis.

Update; topped it up a bit with ATF, still the same but notice while revving it standing over the engine that when the noise occurs there is also a blast of air coming from the engine, could this be something to do with viscous coupling etc???

I am not a mechanic :)

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Edited by 528i-FAN

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The air is from the fan so nothing to worry about that. You need to find out if the level should be checked from cold or warm first

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Thanks for the reply.

Yeh I checked the gearbox level with it warmed up and running as per the manual.

The blast of air seems to be much stronger when the noise occurs, made me wonder if its something to do with the coupling.

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Have you tried stopping the fan from moving and then running the engine ? Just hold it still and get someone to start and rev the engine. Could it be a water pump bearing making the noise ?

Another thing to check for as a collapsed or broken engine mount allowing a pulley to rub on something.

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No, as long as it can be turned relatively freely with the engine stopped, you should be alright. On a warmed up engine, once the revs have dropped to 650, you could probably get away with just stopping the fan with your hand, although I won't suggest you try it. You could stop it with a rolled up newspaper. I think I read that hint on here once. At least if it doesn't stop, it's only the newspaper and the fan blades that get hurt and not you.

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Auto or manual? From experience going manual with the big motor is a nice upgrade for an e12, however your biggest problem now is getting hold of the correct manual g/box suitable for your cable driven speedo, very difficult to find now and with prices to match.

Then your next problem would be which 3.5ltr unit to use. If you go for the early 3453cc M90 type with the dizzy on the front of the head then its a straight swap. Bear in mind though that these motors are the best part of 30+ years old and most have been ragged to death. So unless its very low mileage and you can hear it running,I'd be looking at at least a set of rings and shells at the bare minimum imo, pretty much a full rebuild.

If its a later 3430cc unit, then it'll require some wiring modifications to run the motronic management, or you'd have to swap the cam and front top timing cover if you wanted to avoid chopping your loom. Whichever route you take is fraught with expense and a little bit of your time. It can be done but is it worth it? Only you can decide that.

If your auto box does turn out to be faulty, consider a full rebuild. Old school auto boxes should pose no problems for a decent auto transmission specialist if they can get the parts....

Love the colour of your car btw. My own car was finished in cypress green, slightly darker in shade but not quite as nice as yours.

Good luck

Edited by FIVE-OH

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Thanks for that Five-oh, appreciate the advice. To be honest it would be a shame to take the engine out of the car as its a particularly sweet running M30, no noisy tappets etc.

I've been there before with auto to manual box conversions with my 2002 and wouldn't want to go down that road as it ends up being a lot more bother than first thought.

Saying that, if the gearbox is knackered I think I'd rather spend the same money putting a 3.5 in it even it it were with an auto.

Lewis.

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Fairly straightforward conversion, two choices, either an early e12 based e24, cheap and readily available, especially rusty ones, this will supply all the parts you would require, or an e12 m535i not cheap and not readily available, but more likely to have a manual box and an LSD, and you would require a mechanic, as you confess to not being one.

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Hi,

Sounds like the fan clutch bearing has failed. The old 'clunker' ZF 3HP20 and 22 are long lasting 'boxes.

With engine off, hold the fan blades firmly and try to 'rock' it sideways, I think you'll find plenty of movement.

My E12 525 4 speed manual has begun to make the tinkling noise now, after 30 years in use I think it's done well.

HTH.

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