As a result of my low oil pressure situation (Connecting Rod Bolt Replacement?) I am putting a motor (about 145k miles on it) from a 1997 FZJ80 in to my 1994. Since there are some differences between the years I'm planning to strip the motor and basically only use the block and head from the 1997. Due to the head gasket issues some of these trucks have it seems like a good idea to swap that out and re-seal it while I've got it on the stand.
I'm trying to figure out how much work to do to the head though. I don't want to leave this motor in the truck long term (it's just a stop gap so I can leisurely rebuild the original motor) so I don't think it is worth it to rebuild the entire head. I did a leak down test and found all cylinders within about 5-10% of each other. While doing this I checked for air coming past the valves and found very little if any. The machinist recommended checking the valve clearances prior to pulling the cams. He said that if they are tight it can be an indication of the need for a valve job. I did this and all the valves were within the specifications and toward the middle to loose end of the range. Based on these two tests it seems like a valve grind is probably not necessary. However, when looking in to the exhaust ports I can see oily residue at the top of some of the valves. The center two exhaust ports also look different than the rest of them in that, to my uneducated eye, it looks like oily rather than just carbon build up. On the intake side I don't see the oily residue on the valves. I've attached a few pictures that hopefully show what I'm trying to describe. I can also snap a few more if it would be helpful.
So, my question is, would the oily residue be an indication of the valve stem seals leaking or perhaps something else entirely? If it is an indication that the valve stem seals are leaking, I was considering pulling the head, having the machine shop clean it, check it for cracks, and resurface it. Then I'll replace the valve stem seals myself and put it back on with a new head gasket. Any thoughts or advice about this plan?
I'm trying to figure out how much work to do to the head though. I don't want to leave this motor in the truck long term (it's just a stop gap so I can leisurely rebuild the original motor) so I don't think it is worth it to rebuild the entire head. I did a leak down test and found all cylinders within about 5-10% of each other. While doing this I checked for air coming past the valves and found very little if any. The machinist recommended checking the valve clearances prior to pulling the cams. He said that if they are tight it can be an indication of the need for a valve job. I did this and all the valves were within the specifications and toward the middle to loose end of the range. Based on these two tests it seems like a valve grind is probably not necessary. However, when looking in to the exhaust ports I can see oily residue at the top of some of the valves. The center two exhaust ports also look different than the rest of them in that, to my uneducated eye, it looks like oily rather than just carbon build up. On the intake side I don't see the oily residue on the valves. I've attached a few pictures that hopefully show what I'm trying to describe. I can also snap a few more if it would be helpful.
So, my question is, would the oily residue be an indication of the valve stem seals leaking or perhaps something else entirely? If it is an indication that the valve stem seals are leaking, I was considering pulling the head, having the machine shop clean it, check it for cracks, and resurface it. Then I'll replace the valve stem seals myself and put it back on with a new head gasket. Any thoughts or advice about this plan?
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