1st generation engine compatibility

[94superXLT]

I have a 94 XLT 4.0L, auto 4x4. The original engine had 198k on it before BOTh heads cracked.
Since I just put a new $1800 tranny in it about a year ago, I figured I'd keep it and put a used engine in it.

My question is, will a 4.0 from an earlier year (91 - 93) go right in if the loom is still on the engine and I plug it into the 2 master plugs behind the alternator? Or would I be better off swapping the PCMs as well? I have all the salvage yards telling me they're the same engine, and I know that they basically are, but with the EGR differences and whatever else, will my 94 computer run an earlier engine OK?

I've searched the site and havent really found a direct answer to this.

Any help is GREATLY appreciated!

 

[Creager]

a 93 would probably be safer

i doubt there is much difference between the 91-92 OHV engines and the 93-94. It will probably swap interchangably. Doug904 would know for sure.

 

[410Fortune]

I would look for the latest model year OHV 4.0L you can find, up to 97 with the least miles on it.
You will re-use the intakes from your original.

There is alot of posts on this very same topic, try searching.
Doug904 posted a very detailed answer to this question.

 

[Creager]

Well, being that it is a OHV to OHV swap it's pretty straight foward like before mentioned but there are a few differences that can confuse a simple guy.

1) The intake studs in the fuel rail are longer because the plastic intake is thicker the the aluminum one, this really doesn't matter except for the front stud, you have to put the nut on the stud before you put the throttle cable bracket back on.

2) The CMP drive and/or sensor. All 95-00 will have this and use it,the 91-94 4.0's either won't have it OR you will have a different style. If you older truck doesn't have it then I wouldn't even take it off the block, it doesnt hurt anything sitting there.

3) All of the sensors, and don't forget the crank sensor in all of this. The temp sensors in the front of the intake must be swapped as well and finally all of the wiring harness from the vehicle it is going in must be used. Like before mentioned their won't be a low oil level sensor on a 98 and newer 4.0 so you'll either have to swap pans or not worry about it and let the wire hang, or tie it up out of the way. I think I would know before the oil level got low enough to trip this light anyway so I wouldn't worry with it.

4) The Exhaust manifolds must be used from the older Explorer but there too they bolt right up. On a 98 and newer there will be exhaust studs that must be removed from the heads, they won't work in the early model exhaust manifolds.

5) Upper intake and possibly fuel rail if your using a 98up returnless system. You can use the new injectors, don't remove them but the rail itself must be changed. Also the 96-up OHV's have a plastic spacer plate below the fuel rail and you must reuse this plate between the lower intake and fuel rail or the injectors will bind up and you'll get an vacuum leak because of the difference in height.

6) Finally the flywheel on a 98up are 8 bolts, you can use the new style flywheel on the old style transmissions no matter whether it's an auto or manual. Now if you have a C4 behind it that's a whole different ball game but I doubt anyone else has ran into this problem, if you do I have a special made flywheel lying around .

That's all I can think of right off hand but it's a very straight foward swap. It's the same basic long block just the heads are different. The exhaust ports on the 98up's will be smaller then your old ones but dont worry with that on a stock setup.

One important thing to remember is you can go late model to early model but you can't go early model to late. The reason being is the number of engine mount bolts on the side of the blocks. They used new castings for new bolt locations every couple of years and it's very specific on that. The way this goes is pretty much...

91-94 used one bolt setup
95-97 another
98-00 the final

You can use the 98-00 on any year model but the 95-97 can only go back, not foward.

Thanks, Doug904

i got an error message while trying to post this... and it said "The message you have entered is too short. Please lengthen your message to at least 1 characters." HUH? hahah

 

[94superXLT]

Thanks guys, I appreciate the help. I've had this thing since new but use it as a daily drive so I'm not really up on all this stuff for these.
So I'd need to swap intakes, sensors, and wiring loom if I used a newer engine than 94, but if I used a 92 or 93 I could leave all of that on the engine from the donor and put it right in? Reason I ask is I can get a 92 motor with only 58k on it, with the intakes and loom still intact, so I could just drop it right in and plug in the loom anf go right?

 

[410Fortune]

92-94 only difference, besides the heads being made stronger in 93, is the 91-92 uses a MAP sensor and a single 02 sensor.

Whatever engine you use (91-97 OHV 4.0L) you will retain your stock wiring and sensors, if you use a 95-97 engine you will put the 92 upper intake plenum on the later model engine.

after 93 they didnt really change a thing, except a plastic upper intake and some of the sensors, but the ports in the block are the same.

If you already have the 92 engine with 58K miles, it is a direct bolt in swap.

 

[jimbo74]

sure on that beign the only difference was the maf sensor? i beleive there is something about the egr system not being on a 91-92 but being on 93-94... this might pose an issue

 

[410Fortune]

Sorry MAP sensor.
91-92 has single 02 sensor and MAP
93 has dual 02 sensors, no MAP
94 has dual 02 sensors and EGR

They all have a MAF or MAS, but only the 91-92 had the manifold absolute pressure.

 

[94superXLT]

ok, so if I use a motor without the EGR (91 - 93) but retain my original loom, if I leave those unplgged (EGR plugs) wont my computer code up?

And how do I plug the MAP sensor in? My loom has no provisions for it since it's a 94 truck.......

 

[project92]

okay I'm confusied I bought a motor that had a 95+ head on a old 94 motor burnt a hole in the pistons... seem the 95+ motor the lowered the compresion (pistons) and raised it in the heads open chamber vrs closed chamber would this not throw you 93 in a tail spin or would it not matter?

 

[MrShorty]

'91 to '94 block is the same. So you strip the incompatible accessories off of the old engine, and put the accessories (EGR and other sensors and so forth and so on) from your '94 onto the replacement block. For example: A '91 only has 1 O2 sensor, so the driver's side exhaust manifold probably doesn't have a port for screwing in an O2 sensor. So, you take off the '91 exhaust manifold, and replace it with your '94 exhaust manifold.