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Head resurfacing
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=92910		 Page 1 of 1
Author:  NH3tech91 [ Wed Apr 10, 2024 11:16 am ]
Post subject:  Head resurfacing
I'm new to the CRD and first experience is a engine rebuild. I've got the bottom end squared away but the head needs resurfaced. Oem ceramic tips broke off. Reading the manual it says it isn't resurfacable but a minimum head thickness of 3.541 inch. My head is roughly a 1/4 inch thicker than the minimum thickness. I could see the piston hitting the valves when they're closed if you take to much off. I tried looking on here to see if I could find a post but no luck. Has anyone resurfaced the head with any luck? Or just order a new/used one?
Author:  WWDiesel [ Wed Apr 10, 2024 12:41 pm ]
Post subject:  Re: Head resurfacing
Keep in mind, it is reported that the cylinder head comes new from the factory with a super thin nickel coating to protect the aluminum head surface from *galvanic corrosion due to it being in contact with the steel head gasket. So if you mill/machine the head to ensure flatness, you are removing the protective nickel coating. This may be why the FSM says the head is not machineable?
Also, as you described; if you machine the head, you are bringing the valves, when at full open, closer to the top of the piston. This is an "interference" engine, so valve to piston clearance is critical.
If you do machine the head, be sure and use the thickest head gasket available to compensate for material removed.

Quote:
*Galvanic Corrosion
"When aluminum and steel are placed in direct contact, galvanic corrosion can occur. This is because aluminum and steel have different electrochemical properties. When aluminum and stainless steel are used in an assembly together, the electrons from the aluminum will begin to transfer into the stainless steel. This can result in aluminum weakening! This weakened aluminum can cause it to deteriorate at a faster rate."


:ALONE:
Author:  turblediesel [ Wed Apr 10, 2024 12:44 pm ]
Post subject:  Re: Head resurfacing
There are three different head gasket thicknesses. This may be more for the amount of liner protrusion from the block. The left side of the block near the front has some numbers and (I think) some dots to indicate which gasket was used at the factory. The gaskets have 1, 2, or 3 small holes which tell what thickness the gasket is and the dots correlate to the gasket holes.

I only know this stuff from reading here, no personal experience with the head off on this engine, yet.
Author:  DieselJeepLuvr [ Wed Apr 10, 2024 1:00 pm ]
Post subject:  Re: Head resurfacing
I've resurfaced heads (that were not cracked) and used the 2 hole gasket with no issues. I've compared a brand new head from ID parts with one I've had resurfaced and found absolutely no difference in the surface material. I 've also compared factory head surfaces with 100k miles to a resurfaced head with 70k miles and found no difference in wear or deterioration. The resurfaced head was cracked but it also had 240k miles on it with lots of hard towing. These heads have a shelf life and will eventually crack and need replaced. Though expensive, a new head will have new valves, springs and seals.
Author:  NH3tech91 [ Wed Apr 10, 2024 1:30 pm ]
Post subject:  Re: Head resurfacing
I'm leaning towards getting a good used one and cleaning it up and having a valve job done. I also have seen on Alibaba heads for 425 plus 50 for shipping im kinda instead in buying just to see at that price what you get.
Author:  DieselJeepLuvr [ Thu Apr 11, 2024 12:15 am ]
Post subject:  Re: Head resurfacing
Those Chinese heads are probably fine bare as their aluminum casting process is first rate the only thing I'd be concerned with would be whether the valves and springs are of OEM quality as that's usually the best way to keep the costs down. I've considered picking up a batch of them and doing some testing but just not sure if there'd be an adequate market on an untested product of questionable durability. Remember if the valves break because of poor quality your motor is toast. If the springs break or float causing piston to valve contact, your motor is toast.

But hey! Get one, install it and let us know how it holds up after 100K.
Author:  NH3tech91 [ Fri Apr 12, 2024 10:37 am ]
Post subject:  Re: Head resurfacing
I'll probably order the Alibaba one next bonus so I can order valves and springs with it. Have a shop look it over and see how it compares. If the casting is decent and just need to do valve job beats id parts price significantly.
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