94 Explorer 4.0 Head/Gasket

[USS RIGHTEOUS]

94 4.0 Head gasket - Replaced 94 engine with 99 engine

Hi there! New guy on the block here. Just got my wife a 94. Bought the truck for 400 bucks. Needs head work. Did a cyllinder drop test. It is running on the passenger side only. Cranks real funky like no compression. Lot's of coolant spewing in drivers side bank. So what are the odds of the head being any good? Oil pressure is real good and there is no banging or tapping. Either way it's coming apart. This is my first Explorer. (cherry popper) Are the head bolts torque to yield? Also should I just go ahead and pull the other head even if the compression is up? Any words of advice? Thanks, Jon:exporange

 

[quicklook2]

do compression check, head is probably bad but who knows until it is apart, you need new head bolts.

 

[Maniak]

Yes, the head bolts are TTY.. You will need to replace them.

The heads are prone to cracking.. If ones bad, take the other off and get them both pressure tested/fluxed. If you get new (rebuilt) ones, try to get the 93tm castings (you should already have them).. 91-92 explorers had older castings (90tm) which are not as good.

When its time for gaskets, think about using the actual ford lower intake gasket (metal/rubber) and the real ford valve cover gaskets (metal/rubber). The felpro head gasket set uses cork/paper for those gasekts..

Torrie at fastpartsnetwork.com (explorerforum sponsor) has them.

~Mark

 

[USS RIGHTEOUS]

Hey cool, this is good info thanks! If the heads are bad, I'm considering on finding a complete running engine in the yard. By the time I put in the money and effort, I might be better off with a lower mileage engine. This one has 150k on it and I fear that if I tighten up the top end, I may start blowing past rings. Wouldn't mind droppin in a 5.0L , but that could be too involving and I want to get this on the road soon. Well only way for me to know is to start tearing it down and see what's goin on inside. Thanks guys. By the way, how tough is it to break loose those silly torx head bolts?

 

[Maniak]

I had no problems pulling the torx (t-55) head bolts. They all came out easy (I use my impact wrench to take them off)..

Putting them on is interesting.. I think its 60lbs then 85 degrees (thats the fun part).

Changing the heads isn't too bad.. (assuming the exhaust comes off easily).. It takes me < 12 hours for the total job, and I'm taking my time.


~Mark

 

[USS RIGHTEOUS]

I started on it last night. Have a feeling I'm gonna be looking for at least one head. There are a lot of 95-97 heads on Ebay. Will they work?

 

[Maniak]

the 95tm heads have don't have a deep cutout for the valves.. they would give you higher compression.. I believe there are people who have done that conversion, but if I remember correctly they used a comp 422 cam and different springs and pushrods.. and had to run on super unleaded.

I've seen "new" castings on the 'net (not ebay) for about $240 each.

The heads I have on now, and the heads I had on before were both rebuilds (with repairs).. If I were to do it again (and I had the money) I would buy "new" heads and use my old hardware on the new castings. Since I didn't have the money last time I got rebuilds.. cost me < $300 total for the pair.. New castings would have cost me $750 for bare castings and labor to put them completly together.

~Mark

 

[410Fortune]

for $400 I am picking up a 96 Ranger 4.0L with 87K miles on it and dropping it into our 97 explorer that has a leaking head gasket and or bad head...sometimes its just easier

New engine comes with warranty and lots of spare parts.....

 

[Maniak]

The "spare" motor I just built came from a '91 with somewhere in the low 100k range of miles (130k I think he said).. Both heads were cracked.. For first Gens it seems to be rare to find heads that don't have some cracks.. (had one in a water jacket, not sure where the others were)..

~Mark

 

[USS RIGHTEOUS]

Hmmm. I think I'll check the yards first. Either for a head or an engine if one presents itself. Still won't know 'till i get it apart. It's only banging on one bank, so it's likely that the one head is toast. I figure I'll blow air in the other 3 cylinders and see what happens.

 

[USS RIGHTEOUS]

Okay, I hit the yard this morning. Found what may be gold if it'll work. It is a 99 Explorer. The front end was hit so that's probably why it's in the yard. The trans and exhaust are out, so that makes pulling the engine easy. Also I found a tag stuck to the engine that says it's a Ford rebuilt unit with an April 01 date on it. PN starts with F8... Big question, will a 99 work in a 94? Also it was missing and exhaust manifold. Will mine work?

 

[Maniak]

the 99 heads are different than the '91-94. I believe they are the 98TM heads (similar to 95TM but with smaller ports).. You will increase the compression by a lot if you use those heads.

There is a good article by I think Doug Andersen about rebuilding the 4.0. He talks about the different blocks, cranks, cams, heads etc between all the 4.0 motors. There is someone on here recently that built or is building a 4.0 OHV and is using a 95TM head with 90TM block/pistons (what your asking to do). He is using a different cam and push rods etc and is taking into account the higher compression that the mixing of the new heads with old pistons

Here's a pic of the difference between 95TM (left) and 90/93TM (right)

The above pic is from TennTechMan who did that mod..
I belive Creager also did it (or was going to.. been a while since I looked at the thread)

~Mark

 

[USS RIGHTEOUS]

Hey, I really appreciate you taking the time to explain and give pics on these heads. Wow, what a difference! What I was really getting at was can I use the whole engine from a 99? Sorry about the confusion.

 

[Maniak]

ahh.. yea.. thats different..

Here is a snipit of 410Fortunes message (http://www.explorerforum.com/forums/showthread.php?t=195427&highlight=99+engine) to someone doing a 99 engine into a 94..

Basically all you wanted from the 99 engine was the block and heads, the intakes, sensors, everything else would stay from your 92 block.

As I understand it.. yes you can.. BUT the piece I'm not sure about is how the computer will handle the different heads/piston combo.. or if it even matters since they were changed together which didn't change the compression.

 

[USS RIGHTEOUS]

Yea, I figured that much. I have no problem with delving into the world of automotive electronics. I'll grab the computer with it to be on the safe side. Maybe even the harness. Oh yea, I forgot to mention the engine only costs $95 with a $10 core. It's just not cost effective to fool around with heads that may or may not be any good. Thanks for getting back.

 

[USS RIGHTEOUS]

Well I'm off to the yard tomorrow. Not much holding that engine in. If it takes me an hour to get it out, then it'll take too long. easy pickins

 

[USS RIGHTEOUS]

Okay, I've almost got the engine out of my truck except the exhaust. I gotta borrow a torch for that. The engine at the yard is ready to come out, but I ran out of time yesterday. I should be getting it tomorrow. Boy am I sore from all that wrenching! One thing I noticed is that the 99 engine uses a single fuel line and the 94 uses a two fuel line setup. I'd rather stick with the original 94 fuel delivery setup if possible just to keep it simple. Will I have to change the whole intake manifold to the 94 setup? I see that maconneck changed his. I also see that he was doing a 92 which I believe does not have DIS. That probably gave him bigger problems than I would have.

 

[Maniak]

the '92 is also DIS just not SFI..

As I understand it, you will need to use your own fuel rail, not the one from the '99

~Mark

 

[USS RIGHTEOUS]

Aaah. Thanks, I see. Now I'm learning. Knowledge is power...I like power!

 

[mikeinri]

DUDE!!! $95 for the engine! Wow, that's like free almost!

Mike