Made a stupid mistake..

Hi all,

I've just bought a Range Rover p38 DSE and possibly done something very daft and broken it!
I was attempting to remove the fan clutch from the water pump on the 2.5 BMW engine. It is stuck on good and i've realised i've turned the engine backwards about 2 or 3 turns. I thought when the nut was turning, it was the pulley slipping on the belt, then I realised I was actually turning the engine backwards.

I know i've been a complete idiot, but does anyone know if I will have or could have damaged the engine? Caused the chain to jump a tooth, put the timing out, etc?

Only had the car a week and possibly broken it already :-( Hope someone can put my mind at rest or tell me how to test if the chain has jumped.

Cheers Jim

Its fooked now for sure.

Only kidding, Its fine. You haven't done anything wrong.

Rasher said:

Its fooked now for sure.

Only kidding, Its fine. You haven't done anything wrong.

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Hi Rasher,

Cheers for reply. I have been looking on the net and it seems some engines the chain can jump if turned in reverse. So you reckon I can start the engine safely, without checking the timing etc? Many thanks, Jim

It should be fine if all you have done is turn it by the fan belt. If you want to double check then turn the engine a full turn by hand. if anything had jumped it would lock up if it turns freely it should be ok to start it up.

Turning the engine with the viscous fan nut i would think is virtually impossible. If you are trying to undo the fan in the correct direction (clockwise) you cannot turn the engine backwards in any case. You will never undo it anticlockwise it is a left hand thread. .

Rasher said:

It should be fine if all you have done is turn it by the fan belt. If you want to double check then turn the engine a full turn by hand. if anything had jumped it would lock up if it turns freely it should be ok to start it up.

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Yeah, it was turning via the fan belt, but it was turning the same as if I had a socket on the crank pulley I guess?
I was turning the fan clutch and thought it was slipping on the belt, but then I looked down at the crank pulley and saw it was turning anti-clockwise. It maybe turned the crank pulley over 2-3 times... Just started to panic cos I know it's an interference engine and it sounds difficult to set up the timing, if I made it jump a tooth..
Will try turning the crank pulley a few complete revolutions by hand tomorrow and see what happens.
Thanks for advice, glad I joined the forum. I love the car and was gutted that I could have b*ggerd up the timing in my first week of ownership! I enjoy working on my cars, but often seem to create 2 problems for every 1 I fix..

Cheers Jim

wammers said:

Turning the engine with the viscous fan nut i would think is virtually impossible. If you are trying to undo the fan in the correct direction (clockwise) you cannot turn the engine backwards in any case. You will never undo it anticlockwise it is a left hand thread. .

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Hi Wammers,

Ok, well i've been turning the fan clutch nut the wrong way then, Doh!
But, what its weird cos I def saw the crank pulley turn anti-clockwise, which can only mean the engine is turning backwards, surely? I can understand now why the fan clutch wasn't coming off, but seeing as I did manage to turn engine the wrong way, do you think I could have upset the timing or damaged it? What would her be to stop it from turning the wrong way? Cheers Jim

you wont have hurt the engine , i turn them backwards often

As above, if you messed up the timing enough to cause conflict you would feel it when turning by hand the correct way. I guess there is always a borderline, but if it were that close to the edge, I cant think.it would get anywhere near to starting.

It's not a problem. The engine will be fine. It's one of those myths that Haynes manual jockeys spew all the time.

Ok, so general opinion is turn it over a few times by hand and if all ok, then it's safe to try to start it? Just to confirm it's the BMW 2.5 Diesel engine i've got, not the v8.. Cheers Jim

I'd start it without worry.

4x4Dog said:

It's not a problem. The engine will be fine. It's one of those myths that Haynes manual jockeys spew all the time.

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Depends how good your chains are and how good the crank sprocket is. It is entirely possible to jump the crank sprocket on the M51 by turning the engine backwards.

wammers said:

Depends how good your chains are and how good the crank sprocket is. It is entirely possible to jump the crank sprocket on the M51 by turning the engine backwards.

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Ok, now im worried, cos I have absolutely no idea how to check the timing on the m51 engine.
Is it tricky, is there a guide on here somewhere? The Car has done about 120,000 miles, so chain and crank sprocket maybe quite worn.. :-( FDSH upto about 100,000 though, so appears to have been well looked after..
I guess if I turn it over a few times by hand and it seems ok, then I start it and it runs bad, then i've messed up the timing. Does resetting the timing chain involve the resetting the fip that I keep reading about? Cos that sounds like a nightmare..

Jim_UK said:

Ok, so general opinion is turn it over a few times by hand and if all ok, then it's safe to try to start it? Just to confirm it's the BMW 2.5 Diesel engine i've got, not the v8.. Cheers Jim

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Turn it over in the correct direction (clockwise) a few times to check for fouls. Unless you have no compression i would think it highly unlikely you turned it backwards two or three times with the viscous fan nut. Viscous fans ALWAYS undo in the direction of their rotation.

Jim_UK said:

Ok, now im worried, cos I have absolutely no idea how to check the timing on the m51 engine.
Is it tricky, is there a guide on here somewhere? The Car has done about 120,000 miles, so chain and crank sprocket maybe quite worn.. :-( FDSH upto about 100,000 though, so appears to have been well looked after..
I guess if I turn it over a few times by hand and it seems ok, then I start it and it runs bad, then i've messed up the timing. Does resetting the timing chain involve the resetting the fip that I keep reading about? Cos that sounds like a nightmare..

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To check timing you need special tooling. If the chain has jumped you will need to remove the front cover and reset it. Again special tooling. Just turn and check for fouls, if non try to start it up and see how it runs.

wammers said:

Depends how good your chains are and how good the crank sprocket is. It is entirely possible to jump the crank sprocket on the M51 by turning the engine backwards.

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True, but if it's hoopa-jooped then it's hoopa-jooped. If I'd spun the crank 720 and didn't feel any lockups then I'd go for it. If it lights, it lights, and everything is OK and I get on with life. If it doesn't then that's the time to worry about timing.

4x4Dog said:

True, but if it's hoopa-jooped then it's hoopa-jooped. If I'd spun the crank 720 and didn't feel any lockups then I'd go for it. If it lights, it lights, and everything is OK and I get on with life. If it doesn't then that's the time to worry about timing.

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Yeah i know that, it is why i said turn it over to check for fouls then try to start it.

wammers said:

Turn it over in the correct direction (clockwise) a few times to check for fouls. Unless you have no compression i would think it highly unlikely you turned it backwards two or three times with the viscous fan nut. Viscous fans ALWAYS undo in the direction of their rotation.


To check timing you need special tooling. If the chain has jumped you will need to remove the front cover and reset it. Again special tooling. Just turn and check for fouls, if non try to start it up and see how it runs.

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Cheers Wammers, thats helpful information. When I say i turned it backward 2 or 3 times, what I mean is, you know when you start to turn a crank pulley, then it hits a spot where it sort or suddenly jumps forward? Well that happened probably 2 times, so not 2 or 3 complete revolutions, but crank pulley certainly rotated backwards more than 360degrees. I dunno if that means my compression is a little bit low, but the car was driving and starting well hot and cold before. I was using a big 32mm wrench on the fan clutch nut, so not that difficult to turn 6 pistons over. I have removed fan clutches before so should have remebered about the left hand thread, just rushing to get the job done before the rain came and wasn't thinkin clearly.

Thanks to everyone for replying, all advice appreciated. I will try turning it over in the right direction tomorrow by hand and report back. Wish me luck! Jim

Have you started it up?

Rasher said:

Have you started it up?

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No mate, it's been ****ing down all day here. Tomorrow is suposed to be dry, so im intending to finish replacing the water pump, then try turning it by hand and if ok then will start it up. Then if all is well, i've only got to do new brake lines (totally rotten), oil service, replace headlining, power steering fluid, re-dye drivers seat bolster, ATF change, fix passenger electric window, waxoil chassis and then hopefully drive and enjoy it! Jim