Fix or Replace 4.0 (Donor Vehicles?)

[holyford86]

if the rust is just light surface rust and there is no pitting or scoring at all (if you can catch a fingernail on it, it is too deep) and you can verify that you have either a cylinder head or head gasket failure, I'd clean up the surface rust, a fine scotchbrite hand pad and some wd40 should make quick work of it.

I never recommend using a scotchbrite cookie on anything cylinder head related, you can take off a couple thousandths of material in the blink of an eye and really ruin your day. Scraping with a razor blade held in your hand and following up with a wipe down with brake parts cleaner on a rag should be sufficient, discoloration on the sealing surface of the cylinder head and block won't be an issue as long as you have removed all remaining gasket traces and debris.

 

[backporch]

Lifter Gasket?

Thanks for that response. I will go ahead and clean it up and make a determination.

It appears that the lifter is missing a "cup" in the picture. Anything special about that one? I found something close by that may have been jarred loose in the disassembly that is a hard rubber cone shape but it does not fit like the others appear to. That is the top of cylinder 6 closest to the driver.

 

[holyford86]

as far as I am aware you can run the lifter without it, I have had a couple missing on a couple 4.0s I have repaired before and there seemed to be no ill effects from leaving them off. Just make sure that you fully seat the push rod when you reinstall it and you should be fine.

 

[backporch]

Cracked Heads BOTH!!

After a closer visual inspection, visible cracks can be seen in 4 of the 6 cylinders between the valves. Both heads are junk.

My options at this point are an engine replacement or picking up good heads. I plan on hitting the scrap yard tomorrow to look into either of those.

For heads I understand that I need to find a donor vehicle with good compression 98-2000 to take advantage of the change in head design that my 99 had.

For replacement engines, I will search for a 90s Explorer or Ranger with engine code X, prefer 97 or later to get a compatible crank for my flywheel.

My truck is a 99 with California emissions and no EGR. Just wanted to double check that any of the engine code X engines will work with this if I swap my intake manifold and possibly exhaust manifold. Or at least move the EGR plug to the new manifold.

Thanks to everyone for getting me this far.