Drifter2090

Hey guys, just had a question regarding the one by one method headbolt change that I am about to do.

My car has 139k miles, a tech had suggested I spray the headbolts with penetrating oil (wd40, pb blaster) and let it sit overnight before trying to remove them. Is this necessary? will the penatrating oil even soak into the threads since the headbolts are usually sealed tight.

AMGSIXTHREE

Can't hurt. If the bolts are corroded it will soak into the corrosion and break it up.
But I think the issue with these is that the corrosion eats into the bolt itself and weakens it, not that the bolts get seized to the block or head. So if you have that issue the spray isn't going to resolve it.

Drifter2090

Hmm okay maybe I'll just do it then, I guess I need to do another oil change right after then to make sure all the fluid is gone. Thanks!

lo-fi

Watch this:

NZ-Merc

Hi I would recommend some form of grease/oil film to go on the shanks of the new bolts just to stop any corrosion from forming due perspiration and manual handling of the bolts, what I am thinking is dont put them in dry on the shanks.

Drifter2090

Hmm I thought the coolant would be protecting from corrosion in the future. I'm not too worried about the new bolts just scared of breaking an old one when removing

Drifter2090

Damn that's a lot of gunk, I wonder if that's from the engine sitting for so long without coolant/oil?

lo-fi

Probably but it definitely shows a worst case scenario (outside of one or more breaking off at the head) with respect to extracting head bolts.

NZ-Merc

Hi, I was meaning the acid from sweat on your hands at assembly can cause corrosion on metallic parts ie head bolts, this is why I was recommending assemble the head bolts lubed not dry would be best practice.
The bolt is surrounded by air in the bolt hole (head) and no the anti freeze does not and should not get in to the area around the head bolts, if it does you have the start of a bigger problem.

Drifter2090

Oh I see what you mean, I was going to wear new gloves when handling them but I also thought the new bolts came with that thin thin layer of white/grey coating that pushes out when tightening? What kind of lube should I use on the shank (assuming that's the non threaded area above the threaded?)?

Jasonoff

The head bolts go through the water jacket. They are exposed to coolant.

Drifter2090

This was my understanding too, hence why some say oem coolant changes are a must to keep headbolts corrosion free.

Jasonoff

Drain your coolant from the block (drain on each side) and make sure you suck all the coolant out of the threaded bolt hole in the block before threading in the new head bolt.

Drifter2090

Yeah I have a fluid extractor ready to go, do you think soaking the old bolt heads in penetrating oil will do anything?

Jasonoff

No, the head of the bolt is sealed on the mating surface. Even if it wasn't the threads are pretty far down. You'd need quite a bit of penetrating oil to get down to the threads.

Drifter2090

Okay that is what I figured as well. Thanks! I guess ill just take my chances and hope no bolts break when removing.

NZ-Merc

I would use engine oil on the shanks and if the workshop manual says lubed threads I would use engine oil on them too.

NZ-Merc

The thing is and I am 100% sure that the head bolts are not surrounded by water when in use.
The cavity surrounding the shanks where the bolt passes down head and will have air gap around it.

I am not sure if the holes at the bottom of the block through in to the water jacket but be very surprised if they did as that is an old technique and require special sealant to be applied to the threads on the bolts to stop water getting in to the engine.

So hence my statement no the the bolts are not surrounded by water.

Jasonoff

You may want to do a bit more research on the M156 platform.

BLKROKT

NZ-Merc

My apologies I am wrong I will have to do some study and eat some humble pie, please disregard any information I posted as not applicable to this engine type.
Yes new owner W204 C63.

All the best with your head bolt change out.

Drifter2090

No worries man, I know you were just trying to help.

Thank you, I appreciate it!

Jasonoff

@Drifter2090 Just follow the wis for removal/install of a cylinder head on details about the bolts. They're provided in a few HB threads already. You don't use any substances on the bolt shank OR threads and they will already have sealant on the head mating surface.

Drifter2090

Okay thanks, yeah that's what I figured, I saw the videos where grey/white grease pushes out around the heads when tightened to spec. Thanks man!

Drifter2090

@Jasonoff Just completed the passenger side with no issues! Just a question, even with the coolant drained and using a fluid extractor after removing the lower bolts, some coolant still got out. Should I do a first start then oil change? or oil change then do a first start? Also is there a break in period for the new lifters?