A few questions regarding parts replacement when rebuilding this engine:
1. Do I have to remove the timing chain to clean the engine well? Engine is also getting new oil pump since I had bought one when thinking about just fixing the original engine. If yes, then what parts there have to be replaced on reinstall?
2. Water pump has severe corrosion and the smaller pipe has broken slightly when removing the hose so I'm replacing it. Considering the upgrades to cooling system (larger rad & efan) do I need a premium pump or just a standard?
3. Engine has cam synchronizer. If the gears have no visible damage, does it need replaced.
4. The heads have some pretty nasty gunk buildup inside. Unfortunately I can't find anywhere around here that still dips engines so how do I clean the heads? Harbor Freight has a brush set for cleaning engines and I have a degreaser that works on tractor engines. Can I just use the degreaser with the brush set? I found a place to test the heads but they require you to bring them in clean.
5. The engine also has both the temperature sender and sensor. I got both out yesterday and had them set down, unfortunately I had a dizzy spell and ended up knowing my tray off the table so now I don't know which goes on which side. Any help?

 

4.0l OHV has a timing chain tensioner, that should be replace but the chain and gears are OK with visual inspection, no they don't need to be removed

4.0l OHV was never an over heating engine so stock pump and rad are fine
But you never want to allow it to over heat by running low on coolant or you WILL crack a head

Heads should go to machine shop to be pressure tested and surfaced, no way around that

CAM synchro is fine to reuse

Placement holes for the temp units doesn't matter, but they have different plugs or should have
Cone shape tip is ECT Sensor, 5volt used by computer only, green/red wire
Cylinder shape tip is Sender, 12volt used by dash gauge only, red/white wire

 

Thanks, my stock tank was cracked and I scored a 3 row aluminum one for less than a stock one. I'm still looking for a place to test the heads, no one does it in my county anymore.

 

Found a place that will test and resurface both heads for $170 if I bring them in stripped down and cleaned.

Got passenger side head off. Photos below of each cylinder on block & head. Looks like someone sleeved the block in the past unless they came sleeved. Any opinions?

Cylinder 3 block


Cylinder 2 block

Cylinder 2 head

Cylinder 1 block

Cylinder 1 head

 

For sure have a cracked head, cylinder 3, so that head needs to be replaced

Crack is between valve seats, easily seen
It was a known thin spot in the casting so will crack if engine is over heated too far, the metal expands and cracks
Need to replace it with another 98TM head

the 4.0l had 3 head models, 90TM, 95TM/97TM(were the same), and the 98TM used in 1998-2000 Rangers, they have a different exhaust port design

Yes, those are stock "sleeves" for the cylinders, factory

 

I started cleaning up the passenger head, figured since it was cracked I could use it to try different cleaners. Turns out that crack between the valves on cylinder 3 was just heavy carbon buildup with a crack in it. Dodged a bullet there. Got driver's side off and no visible damage, just a lot of carbon buildup.

 

Yes, big bullet, sweet dodge, lol

 

Cam - The camshaft has uneven wear so I'm replacing it. The only hard use my truck will get is towing so is a stock cam fine or do I need an upgrade of some kind?

Cam bearings - I see some listed with additional oil grooves/wider passages and a wider #4 bearing. These sound more reliable than stock to me but want to make sure.

Lifters - also have uneven wear so I'm replacing. Are stock hydraulics fine or should I get ones with wider oil passages if there is a significant price difference?

Pushrods - already purchased due to flat spots but am I missing anything I should replace around the valves?

Cam synchronizer - unknown condition so should I replace if I find one at a decent price?

Anything else I may need to replace? I have a long list of stuff already purchased and waiting for the rebuild. And I found someone with Ford experience whose offered to put it together for me for free. Asked around and he knows Fords and has rebuilts lots of engines ( mostlyV8), doing it free cause of how my family has done me on it and I work with his wife.