Fix or Replace 4.0 (Donor Vehicles?)

I am looking to purchase a 99 Ranger 4WD manual transmission with a 4.0 engine. The truck will not start. The owner says that it had low compression in one cylinder way back and lost more and more power over time.

Seems like my options are to dig down and replace the head gaskets ( truck has over 200K miles). If I can bring it back to life for a few hundred dollars of parts, that would be a victory. Of course it could require much more and at a minimum I would probably have the heads looked at for cracks (can a home mechanic check that?) and checked for flatness.

Other option is to replace the engine. Anyone know which engines are directly or indirectly compatible? I guess what I am asking is which engines can be swapped complete and which would need to have a minimum number of parts swapped from the old engine. Would an auto trans engine be OK? Any issues about engines from 2wd without balance shaft?

Prices for used engines here are pretty pricey ( close to $1000 in scrap yards). I wouldn't mind picking up a used engine from somebody parting out a vehicle locally online.

Welcome to TRS

You have a 4.0l OHV engine in a 1999 Ranger, they were used in Rangers from 1990 to 2000 model years, very reliable engine, and 400k on bottom end would not be unusual, so if it is a valve or head issue then would be worth while repairing it.

2001 Rangers, and up, used the 4.0l SOHC engines, no relation to OHV so can not be swapped directly, but could be swapped if you change computer and engine wiring harness, it does bolt to trans and motor mounts

Check the oil for coolant, i.e. milkshake color, if that is seen then you may need to rebuild or replace the engine, if it has been sitting longer than 6 months.
Coolant in the oil will cause rusting in the bearings if it sits long enough, and they won't recover from that.

Changes in the OHV engine over the 10 years are here: http://www.therangerstation.com/how-to/engines-fuel-systems/rebuilding-the-ford-4-0l-pushrod-v6/

Because of crank shaft change from 6 to 8 bolts you would want a 1997-2000 engine
But you could use 1996 or earlier if you got 6 bolt Flywheel with it/for it
4.0l OHV was used in:
Ford Ranger/Mazda B-4000
Ford Explorer/Mazda Navajo
Ford Aerostar (1990–1997)


And you will use your current lower and upper intake with injectors on any replacement engine, this will allow plug and play for engine wiring harness and fuel system.


I would pull out all the spark plugs and look at each one, see what it tells you
Then with all spark plugs removed do compression test and write down results.
Then add teaspoon of oil to each cylinder and retest, write down results
Dry and Wet test
This will tell you if it is rings or valves or head gasket issues

4.0l OHV runs 9.0:1 compression ratio, so you would expect 150-160psi compression at sea level to 2,000ft elevation

A few years back I bought a Ranger roll-over. It had 220,000 Km on it. I've used that engine in my race truck and it currently is running in my 93 ranger. I've probably put 50,000 more Km on it. I paid $200.00.

Thanks for the details. Great Information.

I saw two trucks today. The 99 and an 01 with 4wd and auto trans. Both are 4.0 and have engine issues.

I was just passing by the 99 when the owner wasn't home so I couldn't see the oil, but that is great advice to check the oil for coolant. I did ask the owner if there were ever overheating issues, but didn't ask if that was avoided by adding coolant.

The 01 looked really clean, but it stalled shortly after running with some noise from the passenger side valve cover. I restarted it and saw the oil gauge drop to zero while the engine idled.

Seems like worst case both may need an engine replacement. Anyone have any thoughts about the 01 4.0 in terms of reliability/durability?

A home mechanic can perform basic checks on heads without too much trouble.

I'd recommend checking for warping and cracking. The bottom face of the head must be completely clean and free of burrs or raised metal "dings" for both checks; I've seen shops polish the test surface with scotch-brite buffs mounted on a die grinder for cleaning.

To check for warping: Get a good straightedge that's long enough to span the complete head, and an assortment of machinist's "shim foil" or "shim stock" that includes 0.001, 0.002, and 0.003" thicknesses. You may also be able to find a feeler gauge set with blades that thickness. Place the straightedge across the machined face of the head and try and slide the various shim material between the straightedge and the head. Repeat the test in several places with the straightedge running the along the head, across the head, and diagonally. If you can't fit the 0.001" shim between the straightedge and the head, then the head is beautiful. 0.001-0.005" is questionable, and anything 0.005" or over is probably something to have a shop check. Check the service manual for specific numbers, as they may differ from my estimates.

To check for cracks: Get a "Dye-Penetrant" test kit. Clean the test surface thoroughly with a clean-evaporating solvent like acetone. Generally, you use the kit by wiping a bold red dye solution across the entire bottom surface of the head, especially including the area surrounding the valves. If there are cracks or surface irregularities, the dye will get drawn into them, although you can't see that yet. Let the dye sit on the surface for several minutes, then wipe the dye off as well as possible, paying close attention to cleaning rough spots well. Then you spray a powdery white Developer onto the test surface. Any dye that remains in/below the surface will bleed up into the developer and show that red color. A rough spot that couldn't be cleaned completely of dye will show a mild response that's spread out a little, and you probably noticed those spots while cleaning the dye. Rough spots themselves are not a problem. Any crack will show a bold response along the length of the crack, because there was lots of dye absorbed into the depth of the crack. Carefully inspect around the valve openings and between the passages in the head, because the thinner material in those places are more likely to crack than in other, thicker places.

Questions from the scrap yard

I called a scrap yard and they asked about California emissions and whether or not there is an EGR valve.

I don't have the car to do a visual check for an EGR valve, but I do have a picture of every sticker in the engine compartment and door jamb. Asking the owner to search for the EGR valve.

Looks like the car was equipped with emissions conforming "to California regulations applicable to 1999 model year"... I don't know about the EGR.

Wondering if anyone knows the importance of matching these to how the car was equipped? If my choices are only federal emissions is there a way to swap certain parts?

Thanks for the help.

No EGR.

Looks like the truck does not have an EGR valve and is California emissions. One yard said all engines are compatible within a few years (probably the crank pin setup mentioned before) So according to him it doesn't matter low emission, EGR, automatic trans or 4wd. He said only a swap of the intake manifold is expected. Not sure if that is related to EGR or if other models(explorer) have different manifolds.

If anyone has experience with this and guidance would be appreciated.

1990 to 2000 Rangers used the 4.0l OHV engines
2001 and up Rangers got the 4.0l SOHC engines

Engines are not related at all, only thing they have in common is displacement, 4liter, and transmission bolt pattern, so no interchangeable parts
Different computers and wiring as well

The 4.0l SOHC engines from 1997(explorer option) to 2003 had timing chain issues, and engine needed to be pulled out to replace rear timing chain, so not an easy fix.
If older engine was repaired with the new tensioners(2004) the problem was gone, as was seen on 2004 to 2012 Rangers
So heads up if you hear rattling noises from a 4.0l SOHC engine, at that point it is too late to just change the tensioners, chains and guides also need to be changed, so engine must come out.

2000 and earlier 4.0l OHV engines just had the "DO NOT OVERHEAT THIS ENGINE" warning, which is good advice for any engine, lol, and in the worst case just the heads needed to be tested or swapped which can be done with engine in the vehicle.

1999 vehicle should have an EGR Valve, regardless of engine size, but when swapping engines the EGR is not an issue, as you will be swapping the 1999 upper and lower intake over to the "new/used" engine so EGR or no EGR will be swapped over with that.
The computer that runs the engine will be EGR or No EGR and thats what you have to stay with

Thanks RonD.

Most of what you said makes sense. Just wanted to clarify the use of the SOHC engines, specifically in the Explorer. Starting with 97, was a 4.0 in an explorer SOHC, OHV, or was that an option for 97-2000?

If I find a donor engine, I can use my flywheel on a 97-2000 Ranger
If I get an early 6 bolt flywheel, I can use a 90-96 Ranger and 90-97 Aerostar/Explorer.

You were pretty clear in your posts. I am only asking because one yard quoted me a price on a 98 Explorer if I remember correctly. Doesn't sound like it will swap without the harness and ECU/PCM, but the guy in the yard didn't mention any of that.

Thanks again

4.0l SOHC engine was an Option starting in 1997 for Explorers, standard engine was the 4.0l OHV, so could be either until 2001 model year

4.0l OHV was last used in 2000 Model year for Explorers or Rangers
in 2001 4.0l SOHC was only 4.0l engine used

8th digit in VIN can also tell you what engine
X = 4.0l OHV
E or K = 4.0l SOHC
K was flex fuel model

Used engines are often listed that way, i.e. Ford 4.0l VIN X, OR 4.0l VIN E, that tells you if it is a OHV or SOHC

OK, so my option to replace the engine with same basic setup, swap flywheel and possibly intake manifolds and fuel injection is:
97-2000 Ranger with 4.0
97-2000 Explorer with engine code X
and maybe a 97 Aerostar assume same engine code X

Any pre-97 4.0 works with a flywheel change. I assume that the pressure plate from the 99 can transfer over? and there are no clutch mechanism/throw out bearing issues.

Perfect.

Thanks for all your help.. Now to continue shopping.

You got it

Engine Gasket Kit

I started to take apart the engine. Still a way to go to get the heads off, but at least the oil looked good, like oil change oil should. The coolant was very dark. Thin like water but dark brown.

I picked up a Head gasket set and bolts. Have a Haynes manual and will hopefully have the heads off this weekend to do a cleanup and evaluation. I may go ahead and reassemble if it looks reasonable. Not sure I will do a more formal machine shop repair. I am looking to keep this as a work truck with limited miles.

The kit is a Mahle/victor reintz from RockAuto HS5887B

Anyhow, I was wondering what some of these gaskets in the kit are?
Looks like:
2 head gaskets
2 exhaust gaskets
2 intake manifold to head gaskets
1 upper intake manifold gasket
2 valve cover gaskets
1 throttle body gasket ?
1 EGR gasket?

Then there are a bunch of smaller gaskets (based on picture, parts arriving soon)
12 small orings? fuel injector?
6 small orings? valve seals?
1 large oring and one medium - oring maybe thermostat?
12 copper washers? smaller than the smallest orings.
6 thin rubber gaskets that are the shape of upper intake manifold hole
2 other #8 shaped rubber gaskets, same material as 6 thin gaskets... a small and large.

RonD said:

Welcome to TRS

You have a 4.0l OHV engine in a 1999 Ranger, they were used in Rangers from 1990 to 2000 model years, very reliable engine, and 400k on bottom end would not be unusual, so if it is a valve or head issue then would be worth while repairing it.

2001 Rangers, and up, used the 4.0l SOHC engines, no relation to OHV so can not be swapped directly, but could be swapped if you change computer and engine wiring harness, it does bolt to trans and motor mounts

Check the oil for coolant, i.e. milkshake color, if that is seen then you may need to rebuild or replace the engine, if it has been sitting longer than 6 months.
Coolant in the oil will cause rusting in the bearings if it sits long enough, and they won't recover from that.

Changes in the OHV engine over the 10 years are here: http://www.therangerstation.com/how-to/engines-fuel-systems/rebuilding-the-ford-4-0l-pushrod-v6/

Because of crank shaft change from 6 to 8 bolts you would want a 1997-2000 engine
But you could use 1996 or earlier if you got 6 bolt Flywheel with it/for it
4.0l OHV was used in:
Ford Ranger/Mazda B-4000
Ford Explorer/Mazda Navajo
Ford Aerostar (1990–1997)


And you will use your current lower and upper intake with injectors on any replacement engine, this will allow plug and play for engine wiring harness and fuel system.


I would pull out all the spark plugs and look at each one, see what it tells you
Then with all spark plugs removed do compression test and write down results.
Then add teaspoon of oil to each cylinder and retest, write down results
Dry and Wet test
This will tell you if it is rings or valves or head gasket issues

4.0l OHV runs 9.0:1 compression ratio, so you would expect 150-160psi compression at sea level to 2,000ft elevation

Click to expand...

the 4.0 SOHC can run on a OHV ECM pretty easily...... there are a couple of guys running it them on the explorerforums, pretty easy swap.....


any 4.0 will work, 2000 has a different cam synchronizer than the earlier 91-94s , but i believe you can just swap the sensor and not have to pull the entire dist. gear out. the newer ones got plastic uppers, but i believe they are even interchangable.... mainly just the only difference in them is the flywheel and egr.

Could use opinion

I took the heads off the engine and i noticed two things.

One is that there was surface rust in one of the cylinders. Hard to say how bad, but any seems bad. The engine turns over and before buying I attempted to start it and it sputtered while it cranked. I guess I mention that because the cylinder that was showing rust may not be the worst since the engine was just cranked recently.

The other thing was what looked like a crack in once cylinder directly between the valves. Not sure it was a crack for sure, and I haven't cleaned up any or checked for flatness.


I wonder at this point if there are enough red flags that I should probably just look for a used engine.

Thanks