Distributor rotor destruction *** SOLVED

Specific conversations and info for the BMW E28 M5 and M535i.
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Stevenz
Posts: 15
Joined: Jul 12, 2017 5:19 AM
Location: Covina ca

Distributor rotor destruction *** SOLVED

Post by Stevenz »

Newbie so forgive if this has been discussed, have not been able to find anything.

1987 535i manual

Previous owner skipped timing replaced chain and said head and valves were good

Problem idles fine as soon as any throttle is applied stutters and back fires can not pass 2000 rpm

After a bunch of searching and checking everything i saw on previous posts.

I removed distributor cap and rotor
Found rotor was damaged like it had been hit with something.

Switched both working cap and rotor from my 528e to 535 and vice versa. 528e developed the issue with the 535 cap and rotor

535 ran good for a second then started doing the same thing

Removed cap and the rotor was broken almost exactly the same way.

So i think i Is narrowed it down to a problem with the rotor but
Before I put a new one on there and destroy it
Can anyone tell me what would cause the rotor to be damaged like that in a matter of seconds?

Thanks for any info. Sorry for any
Last edited by Stevenz on Sep 06, 2021 8:03 PM, edited 1 time in total.
RobertRO
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Joined: Feb 12, 2006 12:00 PM
Location: Romania
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Re: Distributor rotor destruction

Post by RobertRO »

Prerequisite: the camshaft timing must be correct. If it's not, or if there's any doubt about it, then do not start again the engine until you fix the timing.

Remove the distributor cap and rotor. Then remove the rotor adaptor; there's a bolt right in the middle. The rotor adaptor has a pin that keys it to the camshaft. Crefully check the pin: it must be intact.
Reinstall the rotor adaptor, making sure that its pin fits correctly in the camshaft hole. Snug the bolt in. Then grab the adaptor by hand (don't apply Godzilla force on it) and try to turn it left / right. It should not move in relation with the camshaft. Finally, torque the bolt at 23 Nm.
Then install a good rotor; it must be properly seated on the adaptor. Finally, install a good distributor cap. Make sure the spark plug wires are in the right order (do not assume it, check and double check).

Then test and see what happens.
gadget73
Posts: 1176
Joined: Nov 22, 2017 10:30 PM
Location: New Jersey

Re: Distributor rotor destruction

Post by gadget73 »

requisite mention of no BMW experience but i have seen this in distributors with worn out bushings. Usually you can wiggle the shaft around a lot if thats whats going on.
Stevenz
Posts: 15
Joined: Jul 12, 2017 5:19 AM
Location: Covina ca

Re: Distributor rotor destruction

Post by Stevenz »

RobertRO wrote: Aug 23, 2021 9:01 AM Prerequisite: the camshaft timing must be correct. If it's not, or if there's any doubt about it, then do not start again the engine until you fix the timing.

Remove the distributor cap and rotor. Then remove the rotor adaptor; there's a bolt right in the middle. The rotor adaptor has a pin that keys it to the camshaft. Crefully check the pin: it must be intact.
Reinstall the rotor adaptor, making sure that its pin fits correctly in the camshaft hole. Snug the bolt in. Then grab the adaptor by hand (don't apply Godzilla force on it) and try to turn it left / right. It should not move in relation with the camshaft. Finally, torque the bolt at 23 Nm.
Then install a good rotor; it must be properly seated on the adaptor. Finally, install a good distributor cap. Make sure the spark plug wires are in the right order (do not assume it, check and double check).

Then test and see what happens.
Thanks it was the adapter...pin was not positioned properly by whoever worked on it last.

Idles and revs again
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