95 OHV TO later model SOHC. Who can help, with details?

[tangoyankee]

I have a 95 b4000 4x4 5spd. that I have put a lot of maintenance into through the years. I love it and it has served me well. The engine has between 200k-300k on it; ( the speedo/odo did not work for 19 yrs)
Now I need to change head gaskets. I'm a little concerned with this much mileage what I may find when I pull the heads.
so I can
1. Pull the heads, change head gaskets and run with it.
2. Get new or reman heads (but then what about the bottom?)
3. Buy a used 4.0l ohv engine
4. Buy a used Sohc engine and computer.

I can do 1. thru 3. on my own but need details, real details about swapping to a Sohc.
has anyone done it??

 

[franklin2]

Can you have it down long enough to get YOUR engine rebuilt? You know the history and it was taken care of. That is what I would do. No messing with computers or wires either. The original engine will plug right back in place.

 

[RonD]

I would pull the heads have them cleaned and pressure tested, if they are not cracked then have machine shop install new valve stem seals(they come with Head Gasket Kit) and resurface the heads
If a head is cracked then get a replacement head

4.0l OHVs were not known for burnt exhaust valves, just cracked heads if overheated
If heads are not cracked you can ask machine how much for a valve job, thats the difference from rebuilt head and your uncracked head, the valve job
And price rebuilt heads to see the cost difference

Rebuilt heads are also plug and play, no real down time, which for some is worth the extra money
But regardless you need the head gasket kit and new head bolts, they can't be reused

I wouldn't worry about the bottom end until well past 400k
Its not like the bad old days with bearings lasting 100-150k, lol
400+k to over 500k is not unusual for bottom ends after 1985 or so
Vehicles failing under 500k is usually not because of the bottom end

Once its running sell it and buy a 2001-2011 with 4.0l SOHC engine

Swapping in a V8 is one thing, can't buy a stock V8 Ranger/B-series, so worth the effort
You can buy a factory 4.0l SOHC Ranger/B-series, and it's exactly the same effort as swapping in an Explorer V8

 

[JOLENE_THE_RANGER]

I’ve done the ohv to sohc swap in both a obd1 and obd2 truck. You can swap the engine without changing wire harness or computer.
I have a whole write up on it on a different site. I’ll pm you the link.

 

[tangoyankee]

I would pull the heads have them cleaned and pressure tested, if they are not cracked then have machine shop install new valve stem seals(they come with Head Gasket Kit) and resurface the heads
If a head is cracked then get a replacement head

4.0l OHVs were not known for burnt exhaust valves, just cracked heads if overheated
If heads are not cracked you can ask machine how much for a valve job, thats the difference from rebuilt head and your uncracked head, the valve job
And price rebuilt heads to see the cost difference

Rebuilt heads are also plug and play, no real down time, which for some is worth the extra money
But regardless you need the head gasket kit and new head bolts, they can't be reused

I wouldn't worry about the bottom end until well past 400k
Its not like the bad old days with bearings lasting 100-150k, lol
400+k to over 500k is not unusual for bottom ends after 1985 or so
Vehicles failing under 500k is usually not because of the bottom end

Once its running sell it and buy a 2001-2011 with 4.0l SOHC engine

Swapping in a V8 is one thing, can't buy a stock V8 Ranger/B-series, so worth the effort
You can buy a factory 4.0l SOHC Ranger/B-series, and it's exactly the same effort as swapping in an Explorer V8

Well RonD,
I took your advice and pulled the heads. (Getting exhaust manifold bolts out without breaking any was no joke)
Besides leaking coolant out of the head gasket above cylinder 4, the valves were leaky, and one of the heads was cracked between intake and exhaust valve. So ended up with reman heads.
Bought new exhaust manifolds because the y pipe bolts were rust-welded in them. Had to cut the bolts to get manifolds out.

Cleaned everything up (28 years of accumulation) put it all back together with new gaskets, and new injectorsetc.

When it started up the very first time it sounded great for about 10 seconds. Then ran terrible and kept stalling. As I was revving it to keep it running, it would slowly even out and then idle smoothly for about 10 min, then stall. Figured out that it was relearning all the "new" parts.
finally it evened out enough to test drive around the neighborhood to keep the learning process going.
Let it idle for 10-15 min and it didn't stall so with my son following me we took the 35 min expressway drive back home.

the only "problem" is that it is running hotter than before. Before the repair it ran pretty consistently at 197 deg. Now it's running at 206 over 45 mph. City driving it sometimes climbs into the 220s.
Any input you have is welcome. Thanks for your help.

 

[tangoyankee]

It has probably travelled about 50mi. But I think its still learning because although it starts right up and runs smooth, it doesn't seem to have as much power as before the repair. Which is the opposite of what I expected.

 

[RonD]

Good work

Did you pull the water pump when doing the head swap, not required but many do that to flush out the block while heads are off

Running warmer under load/driving is usually a circulation issue, either thru the engine or thru the radiator
Water pump provides that circulation but it can be limited by debris in the system

Running warmer at idle or lower speed driving is usually the fan clutch

After warm up and driving it for 15-20 min shut off engine and unbolt the fan shroud and move it back
Run your hand over the radiator feeling for cooler spots, block passages
Should be a nice even heat, warmer towards upper hose then getting less warmer towards lower hose
Should be about a 15-20deg difference from upper to lower hose

And no pinging/knocking so far?

 

[tangoyankee]

No pinging.
I did not remove the water pump.
and I have wondered about debris or gunk from lower end limiting circulation.

also I have what I think is a bleeder cap on my top heater hose. So now I'm wondering if I have an air lock or air in the system. I may try that next.

 

[RonD]

Yes, open the heater hose cap and top up radiator until coolant comes out the cap opening then put cap back on, all the air is out, for sure.

 

[rhekman]

It has probably travelled about 50mi. But I think its still learning because although it starts right up and runs smooth, it doesn't seem to have as much power as before the repair. Which is the opposite of what I expected.

Any check engine light? High idle on startup? Colors/smells from the exhaust?

When I replaced a cracked head on my '95, I found a bad O2 sensor that was causing it to run dead rich seemingly at random. I'd also be concerned about vacuum leaks after having everything off the top of the motor - intake gaskets, pcv, brake booster, egr, etc.

 

[tangoyankee]

Yes, open the heater hose cap and top up radiator until coolant comes out the cap opening then put cap back on, all the air is out, for sure.

I had not run the heater previously. So
I did that and then Bled the air out . It is running at 197-203deg all the time now.

 

[tangoyankee]

Any check engine light? High idle on startup? Colors/smells from the exhaust?

When I replaced a cracked head on my '95, I found a bad O2 sensor that was causing it to run dead rich seemingly at random. I'd also be concerned about vacuum leaks after having everything off the top of the motor - intake gaskets, pcv, brake booster, egr, etc.

vacuum is steady at idle and at 2000 rpm.
the only code I have is 1443 (evaporative system)
It seems to have gained some or all of its pep and power back as the learning continues. It is pretty much the same as it was before I tore it down. Although I was expecting a noticeable increase with new heads and new injectors. But hey it's running and running good so no complaints.

 

[smilinjack]

Hey Tango,
If you ever get to where you need to replace more parts on your 4.0 I've got a 4.0 out of my 95 Ranger with about 80K on it,
and it ran perfect when I removed it. Also have the 5 speed manual that operated perfectly upon removal.
I removed the entire drivetrain to install my 408 Cleveland and it's drivetrain. Just sayin', and I'd give ya a great deal on it!