[F06msportmia]

Hello Forum!

So I will try to sum this up as best as possible.

I was doing a front brake job (rotors, pads, sensors) and noticed some oil in places where there is not suppose to be. Like the rack and pinion boot and the undercarriage plastic cover. Automatically sirens went off and I thought of the worst case scenario.

Is it the rack and pinion seals, is it the tie rods that go into the R&P, is it the gasket????? Well I finally took into the dealer for a software update and the tech a friend of mine looked at the engine and valve cover. He told me that I had 3 bolts that were loose at the touch and 1 bolt was completely missing. That was a relief I was able to buy the set of bolts for $33. I was looking forward to plugging up this leak and cleaning up the bay. I get home and I start checking the bolts and I come to find that the 3 loose bolts were actually cracked in half.

So I go to Home Depot and get a screw extractor and drill bit so I can remove these screws and replace. A simple task just became a mission impossible considering that I am not mechanic.

So I start working on the screws and successfully with patience I remove 2 of them, but by this point I had bad feeling about the 3rd screw... Dont ask me why but I had that gut feeling that the 3rd would give me problems. Well I was right after 45 minutes the screw did not want to come out and by this point I screwed up the thread on the block.

So I rushed over to Ace Hardware with the OEM bolt and explained the situation to the guy in hardware department. Obviously if I wanted to go the OEM reconstruction route I would have to redrill the hole to make a new thread and then find the bolt that fits that thread. That AIN'T HAPPENING!

So we find a bolt that matches the diameter, 1 washer, 1 pressure washer & a nut. I also have to get a new drill bit that will drill out the cracked screw and give me a new finish on the block.

I get home and drill out the cracked screw, clean up the area and install the new bolt. I started off with something in mind of what the problem could possibly be and at the end it was completely different. Fast forward to today and there is ZERO leakage and the engine is nice and clean!

Pics are below!

[Denny347]

You replaced the factory star bolt with one from ACE Hardware?

[F06msportmia]

Originally Posted by Denny347

You replaced the factory star bolt with one from ACE Hardware?

Well its not like I had much choice. If the screw is stuck on the block & the thread has been completely destroyed, what do you do? Well you drill it out and find yourself a new screw. The function of the screw is to hold down the top of the valve cover in place, nice and tight.

I don't see where the issue could lie with a steel screw from ACE. As you see in the pics the shitty aluminum screws don't cut it.

Again I am no mechanic and I asked around and this was the best solution. If anyone on here can better advise I am all ears.

[GMWNashville]

You realize the broken pieces thread out with just a pick right? Takes no time at all..no drill or power tools required..

[F06msportmia]

Originally Posted by volkswackin

You realize the broken pieces thread out with just a pick right? Takes no time at all..no drill or power tools required..

Yes, 2 of them did with a little work, but I guess the 3rd screw the extractor must have destroyed the thread and just made it impossible to remove.

[Denny347]

Originally Posted by e90msportmia

Well its not like I had much choice. If the screw is stuck on the block & the thread has been completely destroyed, what do you do? Well you drill it out and find yourself a new screw. The function of the screw is to hold down the top of the valve cover in place, nice and tight.

I don't see where the issue could lie with a steel screw from ACE. As you see in the pics the shitty aluminum screws don't cut it.

Again I am no mechanic and I asked around and this was the best solution. If anyone on here can better advise I am all ears.

They are aluminum because the head is made from a magnesium alloy and there is a chemical reaction with steel bolts. This is a temp fix, go buy the appropriate torque to yield bolts and throw them in there. I understand what you had to do. No problem there. Just don't consider this a permanent fix.

[nate5ks]

Originally Posted by Denny347

They are aluminum because the head is made from a magnesium alloy and there is a chemical reaction with steel bolts. This is a temp fix, go buy the appropriate torque to yield bolts and throw them in there. I understand what you had to do. No problem there. Just don't consider this a permanent fix.

What reaction? I would've changed the gasket though for all that trouble.

[GMWNashville]

Originally Posted by e90msportmia

Yes, 2 of them did with a little work, but I guess the 3rd screw the extractor must have destroyed the thread and just made it impossible to remove.

What I'm saying is there's no need to use an extractor..I simple pick and spin it out works on the probably 100 I've had to do..

[AWD Addict]

Originally Posted by nate5ks

What reaction? I would've changed the gasket though for all that trouble.

a chemical reaction that will degrade the block / bolts.

Get the right part from BMW, and swap those out.

[Denny347]

Originally Posted by nate5ks

What reaction? I would've changed the gasket though for all that trouble.

In addition, magnesium – when bolted
together with steel bolts – suffers high corrosive attack
due to the high negative standard electrode potential
of magnesium

https://online.unileoben.ac.at/mu_on...&pCurrPk=20211

[F06msportmia]

Originally Posted by Denny347

They are aluminum because the head is made from a magnesium alloy and there is a chemical reaction with steel bolts. This is a temp fix, go buy the appropriate torque to yield bolts and throw them in there. I understand what you had to do. No problem there. Just don't consider this a permanent fix.

I guess the question is what type nut and bolt would work? Considering there is no more thread so forget the OEM bolts.
Titanium?
Stainless?
Steel?
Brass?
Galvanized?
Chrome plated?

I guess I can go back to aluminum just a nut and bolt to fit?

[F06msportmia]

Originally Posted by nate5ks

What reaction? I would've changed the gasket though for all that trouble.

I don't think you fully get what happened, changing the gasket would have taken 3 more hours. What happened was the bolts were loose because they had broken in the block.

No need to change the gasket if its perfectly fine...

[F06msportmia]

Originally Posted by Denny347

They are aluminum because the head is made from a magnesium alloy and there is a chemical reaction with steel bolts. This is a temp fix, go buy the appropriate torque to yield bolts and throw them in there. I understand what you had to do. No problem there. Just don't consider this a permanent fix.

Considering everything you said what would be a permanent fix given everything I have explained?

I appreciate any help!

[Denny347]

Originally Posted by e90msportmia

I guess the question is what type nut and bolt would work? Considering there is no more thread so forget the OEM bolts.
Titanium?
Stainless?
Steel?
Brass?
Galvanized?
Chrome plated?

I guess I can go back to aluminum just a nut and bolt to fit?

Ugh, no more thread? I honestly do not know, that is a new one on me.

[AdamN52]

I think you need to stick to the material of the stock bolt. Dissimilar metals don't get along and cause corrosion. Can you get an aluminum bolt of a larger diameter and tap the cylinder head to accept it?

I'm not sure if this is a viable solution, but maybe you could coat the steel bolt with something? Not sure what - just brainstorming.

[F06msportmia]

Originally Posted by AdamN52

I think you need to stick to the material of the stock bolt. Dissimilar metals don't get along and cause corrosion. Can you get an aluminum bolt of a larger diameter and tap the cylinder head to accept it?

I'm not sure if this is a viable solution, but maybe you could coat the steel bolt with something? Not sure what - just brainstorming.

Hello AdamN52,

Thanks for the recommendation, I think that is what I am going with. I am just going to get the same bolt that I already bought in aluminum and call it day. I did this about a week ago so I don't think I will have to much of an issue.

[AdamN52]

Sounds like a good plan, given what you're dealing with. Just keep checking for leaks on occasion.

I just did my valve cover gasket last week and I have no idea how you would have managed to extract screws if they were in certain locations...you must have more patience than I do!

[Meeni]

You cannot use a metal bolt in an aluminium block. It will damage the engine block. Have it swapped for a proper aluminium bolt.