Tough decision...replacing head gaskets. Rings? Bearings? Oil Pump? Where do I stop?

[sattech2000]

Need advice. I’m struggling with a tough decision.

Just picked up a 99 explorer with a 4.0 Body’s in good shape but has a blown head gasket with 147k on it. Paid $750 and it fit the budget well….it’ll be a nice upgrade to my ranger extended cab 2.9. My daughters are loving me right now.

The short version:
Replacing head gaskets and cant decide if I should replace the rings and possibly bearings, oil pump, etc....or slap the heads back on and forget about it.

The long version:
The guy I bought it from cracked a head two years ago and did a head job on it. He said it overheated on him this time and didn’t want to mess with fixing it, wasn’t sure of the cause of the failure the first time.

I’ve got the heads off and they checked good for cracks (Thankfully, those are expensive!) Have the heads back together with new valve seals and lapped them in. The guides felt a little loose to me but I could see the stamp marks on the inside of the replacement valve guides on the head that was replaced two years ago. I’m starting to question this and really kicking myself for forgetting to have them checked when it was at the machine shop.

I gave it a little thought and contacted the guy I bought it from about oil consumption. He said about a quart every oil change and never noticed any smoke on a cold startup…not unreasonable with that mileage…. But I started thinking. I’ve got about $200 in a set of head gaskets and bolts.

I’ve got another couple hundred in the budget for repairs but suspect ball joints and some drive train issues will need to be addressed in the near future. I don’t have enough to do a basic rebuild. Parts for the engine are $$$  I really need to get this truck on the road but hate doing things half a$$’ed. Unfortunately that also gets me in trouble a lot of times.

I can’t afford rod/mains/oil pump/timing set. My thinking was to do the rings, plasi-gauge the rods/mains and maybe a new oil pump unless the bearings end up needing replacement also. Or do I just slap the heads back on and stop making things so damn complicated? Ughh I need a beer just from thinking about it all. Guess I’m wondering if there’s any common problem on these motors that I should pay close attention to while it’s apart or if it’s typically reliable.

 

[Big Jim M]

147k!!

That isn't enough miles to warrant taking the engine out and redoing it. It's about 1/2 worn out! I'd be looking at the heads and seeing if the guides were worn. They should be pretty tight at that milage.
Just put the heads back on it and leave well enough alone. A warning though! If it did overheat there is a reason! Most likely from a coolant leak somewhere. So be careful to get ALL the coolant in there.. Then check it daily for a while to make sure the coolant stays FULL..
Big JIm

 

[sattech2000]

I (and my wallet) are liking the sound of that!

And i'm with ya on the overheat problem. I flushed the system before disassembly and have a new thermostat for reassembly. Will be watching it closely.

One of my own self taught tricks on the valve guides...and I could be totally off base with this, if I held my finger over the stem on the head, and pulled the valve out, if I heard a pop sound from the vacuum I knew it would be tight and good(of course this test would be after seals removed and everything cleaned with no oil). If I didn't then I usually knew they needed to be serviced. is that any type of indicator or whats the best way to check the clearance on them besides running back to the machine shop.

 

[Big Jim M]

hmmm

I (and my wallet) are liking the sound of that!

And i'm with ya on the overheat problem. I flushed the system before disassembly and have a new thermostat for reassembly. Will be watching it closely.

One of my own self taught tricks on the valve guides...and I could be totally off base with this, if I held my finger over the stem on the head, and pulled the valve out, if I heard a pop sound from the vacuum I knew it would be tight and good(of course this test would be after seals removed and everything cleaned with no oil). If I didn't then I usually knew they needed to be serviced. is that any type of indicator or whats the best way to check the clearance on them besides running back to the machine shop.

What I do is free up a few valves and rock them back and forth to see how loose they are in the guides. The looser they are the more vac they will have to pull oil past the seals. With only 147K on them they should be Ok. The oil used by the previous owner could have been from overheated seals and not bad guides..
Big JIm

 

[odley2001]

Good used 4.0 engines are really cheap, I'd find one and change it out, it a lot cheaper than buying parts or doing a full rebuild and concentrating on the other issues

 

[sattech2000]

It's kind of a long story but in a nutshell i have about a $500 credit to use at a local parts store. Not enough to do a full rebuild but more then enough for the head gaskets. Are there any other prone failures on these I should think about while it's apart? How well are the timing chain tensioner and guides holding up? Looks like i'll leave the bottom end alone and plan on reassembly this weekend
Thank you!