engine toast? or just head gasket R&R?

[UltrafanUK]

Zinc, Moly and Boron based additives included in many good major brand oils form a thin layer on exposed metals that will offer a high degree of protection when the oil film breaks down during cold starts and mayo incidents. Alas the Moly gets washed off by the coolant, but the Zinc and Boron Nitride (Ceratec has both Moly and BN) do not, so they should still be working even when the engine starts to rattle from low oil pressure. Moly is more effective if an engine runs out of oil.

Changing a HG is a much more expensive job than an oil cooler (They can also cause Mayo incidents) job and if it's easy to drop the sump I would be inclined to check the main bearings for wear before going to trouble of pulling the head off and checking the cylinder walls.

The overheating will not be an issue in head warping terms unless a steam train job was long enough to warp the head.

 

[jrobie79]

I am curious what happened or if it was just a coincidence...

This is the 2nd car I've owned with this engine, and I did a similar procedure on the previous one, hwoever I used oxalic acid (wood bleach) treatment to get rid of rust. And from what I've read on the BMW forums it can be harmful to aluminum - although I've read if its clean aluminum it doesn't react with it, just the corrosion. But I drove that for about 2 hours to make sure it cleaned everything, and the car ran fine for another 2 years until the body rusted out on me. Odd.

 

[mk378]

Ultrafan has a good point to check any oil coolers or other places where oil and coolant meet before concluding it must be the head gasket.

 

[jrobie79]

I got the head off.... No obvious failure, nor any failure of the profile gasket. I'll clean up the block and pressure wash the head tomorrow to see if I can see any cracks.

 

[RooflessVW]

Originally Posted By: mk378
Ultrafan has a good point to check any oil coolers or other places where oil and coolant meet before concluding it must be the head gasket.


There's a reason no one with BMW experience has suggested an oil cooler...

 

[kc8adu]

yes the ones i have seen are oil to air.
look at that profile gasket closer.one i helped with looked ok at first but had a crack in it.enough to let coolant into the oil.

 

[andyd]

I checked an I-4 head with a straight edge. Perfect, no need for planing.

 

[artificialist]

One major thing that sucks about overheating is that it can sometimes ruin the piston ring tension. Since the engine will not hold compression because the head or gasket failed, you don't know if your rings failed until the engine is reassembled.

Also, if you had a head gasket fail, have someone turn the engine a few times while the head is removed. Sometimes if the engine has too much water in a cylinder, the connecting rod bends because water can't be compressed. By having someone turn the engine, you can know if every piton rises properly to top dead center. Failure to do this may mean a cylinder with compression that is too low.

Good luck, hopefully neither problem happened to you.

 

[antonmnster]

I'd wager the flush ate an already weak spot in the HG. I'd make sure it's all true, throw a gasket set in it and drive it. Wasn't run long enough with coolant to do serious damage.

My first BMW was a 91 318is that I bought 19 years ago (!!). So much fun - much better to drive a slow car fast than the other way around!

 

[jrobie79]

Any tips on a piston soak? I have been reading good things about GM's Top End Cleaner, however I don't want to damage the cylinder walls as I obviously can't get every cylinder TDC at the same time for an overnight soak. Can I just put the Top End Cleaner in each overnight and vacuum up the [censored] left behind in the AM? Will this present any issues to the exposed cylinder walls?

Secondly, since I got the head off, I want to remove the valves to save some cost on getting it cleaned, pressure tested, and resurfaced. Any one know of any tricks to get the valves off? I've read you need a special tool to install, but if I can get them out myself, I'll do that.

 

[mk378]

Removing or installing valves is the same process, same tool. It's not a complicated or expensive tool.

You said the engine was "not worth a complete rebuild", so really why do much other than spend $50 on a gasket to put it back together and test drive to see what you have. If it has major problems you're wasting money doing anything to this one versus replacing the whole engine.

It was running OK before, right?

 

[jrobie79]

Originally Posted By: mk378


You said the engine was "not worth a complete rebuild", so really why do much other than spend $50 on a gasket to put it back together and test drive to see what you have. If it has major problems you're wasting money doing anything to this one versus replacing the whole engine.

It was running OK before, right?


It's not worth the time. Car is in my parents garage, 45 minutes from me. Going up there to do an engine swap is not feasible after work. The head took all of two hours to remove, and won't take much longer to put back on. If I had my own garage I'd be doing an s52 swap no question.

 

[DemoFly]

Originally Posted By: jrobie79
Any tips on a piston soak? I have been reading good things about GM's Top End Cleaner, however I don't want to damage the cylinder walls as I obviously can't get every cylinder TDC at the same time for an overnight soak. Can I just put the Top End Cleaner in each overnight and vacuum up the [censored] left behind in the AM? Will this present any issues to the exposed cylinder walls?

Secondly, since I got the head off, I want to remove the valves to save some cost on getting it cleaned, pressure tested, and resurfaced. Any one know of any tricks to get the valves off? I've read you need a special tool to install, but if I can get them out myself, I'll do that.

Since the head is out of the vehicle:

https://www.amazon.com/gp/product/B000F5...8KS7PCMVTN9MF9B

Otherwise, I have one of these and it's a bit unnerving to use but it works. I admit I only use it on small engines, but I know of people that use them on cars.

https://www.amazon.com/Lisle-36050-Keepe...le+valve+keeper