Cleaning cylinder head and oil pan from sludge

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I am thinking of putting my cylinder head and oil pan in a strong solvent bath overnight to dissolve the pretty bad sludge I have in there. My questions are: 1) What is the best solvent to use for this? 2) What parts need to be re-lubricated with assembly grease before I reinstall it? Do valves and guides need any special treatment? Any suggestions/tips/advice would be appreciated. Edit: I have a BMW M52TUB25 from a 00 323i Before I get flamed for the sludge, I would like to explain that I recently bought the car 13K ago at 100K miles and the previous owner sadly followed the 15,500 mile OCI on [censored] oil
 
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 Originally Posted By: djlinux64
the previous owner sadly followed the 15,500 mile OCI on [censored] oil
\:\( Are you capable of doing this job? This isn't exactly a walk in the park job..:) Except the oil pan, that isn't too hard. How bad is the sludge? Maybe Auto-Rx would work..
 

Kestas

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 Originally Posted By: djlinux64
1) What is the best solvent to use for this?
What solvent do you have? Just about any solvent will attack the sludge. I'd be more concerned over the fact that you seem to be cleaning the head without undressing it. The seals can be adversely affected by certain solvents. If you have the head off, I'd probably have the head professionally reconditioned at a machine shop.
 

djlinux64

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Come on! What is hard is the stuff that requires heavy lifting because I don't have the strength to lift the bottom end out of the chassis! I have done two head jobs already on my friend's 535i and 528e, not to mention innumerable valve jobs on my motorcycle. I also dropped that engine once when I had to shake it upside down with a friend after I dropped a 10mm socket into the cam chain follower and the magnetic pick up tool failed to get in far enough. That was not very pleasant! Ironically, I never removed the oil pan before. I have only owned bikes for the last 6 years so this is my first personal car but the list of things I have not done are quickly shrinking. How hard is it to rebuild the manual transmission? I changed the oil to some RL MTL but that thing is still pretty sketchy. I may move up a thickness grade and try MT-90 next transmission oil change. Still, any recommendations on the original question? When I save up enough for a new head gasket from BMW then I will go through with this.
 

djlinux64

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 Originally Posted By: Kestas
 Originally Posted By: djlinux64
1) What is the best solvent to use for this?
What solvent do you have? Just about any solvent will attack the sludge. I'd be more concerned over the fact that you seem to be cleaning the head without undressing it. The seals can be adversely affected by certain solvents. If you have the head off, I'd probably have the head professionally reconditioned at a machine shop.
Having it professionally reconditioned sounds like a very very wise choice. Do you know anybody around the Washington D.C. area that can cut a college student a deal? ;-)
 

djlinux64

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 Originally Posted By: BimmerMan
 Originally Posted By: djlinux64
the previous owner sadly followed the 15,500 mile OCI on [censored] oil
\:\( Are you capable of doing this job? This isn't exactly a walk in the park job..:) Except the oil pan, that isn't too hard. How bad is the sludge? Maybe Auto-Rx would work..
I bought two bottles of Auto RX and I am halfway through the first rinse cycle. At the end of the first rinse I bombed the oil with 1 liter of kerosene to nuke the rest of the sludge that was left in there and a LOT of stuff came out after only 3000 miles. I will try one more run of ARX and then open up the valve cover and do another assessment.
 

Kestas

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If you want to save some money, you can strip down the head yourself. You could probably check the deck surface for flatness, lap the valve seats, and change the seals yourself. I'd still have the shop clean the head (it's cheap). I don't know about the valve guides. You may check them yourself, but the machine shop may have to do any replacing.
 
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 Originally Posted By: djlinux64
I have done two head jobs already on my friend's 535i and 528e, not to mention innumerable valve jobs on my motorcycle.
I was just checking...
 

djlinux64

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My concern is that solvent will get into somewhere it shouldn't and solvate the lubricant. I know that when you insert valves into the guides you should have them lubricated with moly grease. I am not sure if the same applies in this situation. I'd rather NOT remove the valves ... those are a real pain in the [censored] to deal with.
 

djlinux64

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 Originally Posted By: Kestas
If you want to save some money, you can strip down the head yourself. You could probably check the deck surface for flatness, lap the valve seats, and change the seals yourself. I'd still have the shop clean the head (it's cheap). I don't know about the valve guides. You may check them yourself, but the machine shop may have to do any replacing.
My buddy ground the valve seats on his BMW L6 head down to spec last week so that is something within my reach but I am not sure how to go about checking "the deck surface for flatness?" Where can I get a clue about which seals to replace or should I just replace all the flexible stuff on the head?
 

Kestas

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Checking the deck surface should be easy if you can find yourself an expensive, finely crafted ruler. Those edges are about as straight as you can get. Check with your buddies who have drafting supplies. The straight edge is layed on the deck surface and you look for gapping at the surface that would indicate waviness. Slipping a feeler gauge in the gaps will measure how much waviness you have. Just replace all the flexible parts in the head.
 
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I would use LOCTITE PRO VARNISH REMOVER for the first step then LAQUER THINNER as the 2nd step as most on this forum have recommended me the laquer thinner over others. Kestas right about the head distortion test. It's called a MACHINISTS STRAIGHT EDGE - it has no graduations on them, they come bevelled or un-bevelled. Starrett makes them and some others too.
 
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