2 of 3 bolts holding the black cover of distributor cap broken

[Jazz_89]

Guys,
I am trying to remove the distributor cap in order to make sure the crankshaft is at the correct position when doing valve adjustment.
But 2 of the 3 bolts holding the black cover of the distributor in place, where brittle and so the heads broke off with very little force. Now I can't remove the cover...and its weird, because only the bolt heads are broken.

Any help?

Thank you!

[632 Regal]

Sounds like there is some corrosion going on.

So you still have 1 bolt holding it on? That will have to be removed too.

With the heads broke off and the last bolt removed, the cover should come right off, the cap will most likely need to be pried off the bolts.

[Jazz_89]

There was only corrosion on the lower two bolts. Which I can't explain, because there are no other signs of rust in this compartment. The third bolt could be removed easily...
Apparently the threads did not brake clean off, so small bolt pieces prevent the cover to come off.
But thanks for the tip, I will try to clear the area with a sharp object and try to pull it off again.

[genphreak]

There was only corrosion on the lower two bolts. Which I can't explain, because there are no other signs of rust in this compartment. The third bolt could be removed easily...
Apparently the threads did not brake clean off, so small bolt pieces prevent the cover to come off.
But thanks for the tip, I will try to clear the area with a sharp object and try to pull it off again.Sounds like you need a bit os space and a rotary tool/Dremel.

They are always a bugger if left untouched for 10 years. The reason is the zinc plated bolts incur galvanic oxidation in the threads which over time and heat seizes the bolt good. Assuming you are talking about Hex bolts as there are some torx bolts inside the cap (3 on the rotor button) which may be as bad. Hell on M30 the rotor button can be seized to the camshaft sometimes. Key to success is to use the exact right angle, tool hardware (sockets/torx heads, etc) and give yourself room to work with (remove things in the way rather than break things because you can't get to them with ease)

Always worth exposing these nasty ones late in the day. Spray with penetrant before you go home and then attack them fresh in the morning... good luck- let us know how u go!

[Jazz_89]

Oh no...so these screes are also holding down the distributor cap? :/ I will not be able to reinstall the distributor cap with two of the bolt heads broken...
Is it possible to somehow replace them or must they be grinded out?

[genphreak]

Yes you will need to grind them out, don't worry though, a rotary tool will do it nicely- but you should remove the fan if you have not already. You need a 10mm spanner and a special fan removal tool, a must for all bmw owners.

You can make it yourself (search for it on this site) or buy one off ebay. You'll never get the fan off without it, it will also be stuck like a bastard. These are the bolts all M30 owners must overcome- as well as the crank nut should you ever need to do the head, make no mistake- that one requires a 3/4" 36mm socket, breaker bar and >1.5m long tube.

The bolts are designed to be captive to the cap- but they don't need to be. Be sure you re-fit them with washers like the original oneand just like everywhere else on your BMW where there is a fastener that can suffer form rust or galvanic corrosion, use a smudge of some copper grease over the thread, so it will never lock up and corrode again/always be easy to remove. Most cars have had these parts removed many times by now so their bolts may not be not seized but are often rounded, missing or incorrect.

Older BMWs with the incredibly reliable Motronic commonly can go for decades without them ever being touched!

[632 Regal]

Oh no...so these screes are also holding down the distributor cap? :/ I will not be able to reinstall the distributor cap with two of the bolt heads broken...
Is it possible to somehow replace them or must they be grinded out?

Okay man, you busted 2 of 3 heads off. remove the last and you should be able to get the cap and rotor off which I already mentioned.

To get the studs of the bolts out use a penetrating oil as also mentioned above and un-screw them. At this point you should be good as new and put stuff together.

[Jazz_89]

Alright
I will try to get the black cover off and see if there is any thread visible which can be turned off. If it is not possible, I will remove the whole upper timing cover and let new holes drilled in.

[Jazz_89]

Here are the two broken screw shafts on the upper timing cover. I think the best solution would be to weld them on a nut and then screw them off... But I do not have a welding machine^^
8438

[shogun]

vice grips will do https://en.wikipedia.org/wiki/Locking_pliers

[632 Regal]

Heat them with a torch and smack them with a hammer, like a nail then use vice grips. Rotor looks like its been a few weeks since it was new.

[Jazz_89]

vice grips will do https://en.wikipedia.org/wiki/Locking_pliers

I tried with vice grips, but not the original...the tip of the pliers got chewed.


Heat them with a torch and smack them with a hammer, like a nail then use vice grips.

Ok, but is an open fire in the engine compartment really a good idea? Anyway thanks, I might try this with a heated iron stick.



Rotor looks like its been a few weeks since it was new.
Seriously? XD I dont think anybody changed it since 1989^^


If everything fails I will remove the upper timing cover and let it machined. Even if this means, draining the coolant, removing the thermostat cover and replacibg all these little gaskets :/

[Javier]

Got once a similar issue with some M10 bolt at the back of the head with just about 4 mm to grab it with the vise-grip, 3 bolts in the water passage cap, one came loose easily, two of them broke the head, the last one came along with the vise-grip, the second one needed to be machined (still believe I damaged the evil one not locking the vise hard enough). If the vise gets loose and chew the bolt, it means they were not lock in place hard enough. Turn in the bolt in the tool and lock the vise in harder.

WD-40, Heating and hitting the bolt, and finally, Vice griping and twisting hard is the only way to go wile you have something to hold in. It does not mean it will come loose, but it is the best option. If the remaining portion of the bolt breaks again leaving you nothing to work, then you will have to machine. Last resource undoubtedly.

[632 Regal]

Ok, but is an open fire in the engine compartment really a good idea? Anyway thanks, I might try this with a heated iron stick.


Looking at the location in your pics your right, not a good idea. The heat/hammer idea is to crack it loose, no other reason and never try to loosen something like that while still very hot. Will be like twisting a wet noodle.

[genphreak]

The first thing to try is penetrating oil. Then grab two nuts. IIRC these threads are M4, but to screw them on first you need to clean up the top of the stud with a rotary tool so you can screw both nuts onto it one after the other.

Screw them on to a point where both are fully engaged with the thread. Now tighten the nuts against each other, (not the block the stud goes into). Now place a spanner on the nut closest to the block and turn anti-clockwise, it will either;

- undo the stud from the block, or
- break the stud, or
- turn the nearest nut to the top of the stud (in which case you need to tighten them against each other a little more than you did before, and try again...)

Vice grips and other forms of destructive removal should be undertaken last!