How to: 1994 Head gasket replacement / engine pull

[arco777]

1-2: Lower intake manifold before shots. It was filthy. Intake ports were solid black with burnt oily residue, likely from PCV oil vapor. Upper manifold had a pool of oil in it.

3. Pressure washing got most of the crud off the outside but did nothing for the oily reside in the ports. A portable steamer (purchased from Harbor Freight) worked great for removing the residue.

4-5. The lower intake manifold (LIM) gasket set I am using is a Fel-Pro set for a later 4.0 OHV. I had read that it was supposed to be an improvement. I don't recommend this one. The RTV machine at the plant left loose RTV on the gaskets that could have broke off and fallen into the valley, eventually clogging the oil pickup. The bigger problem is that the thickness of the gasket is causing issues with the intake sitting higher than normal, causing misalignment of the valve cover mating surfaces and bolts. I'm not happy with it, but it's what I have.

6-8. The gasket is installed dry, although the end seals are made with RTV which the kit includes. Pictures show the gap I have to deal with, which seems excessive and I think is due to the gasket thickness. Fortunately after install, I can easily verify I got enough RTV in and correct any weak spots. I also made sure to have good RTV coverage where the upper corners of the heads met the block.

9. Port alignment is good.

 

[arco777]

1-2. Heads and manifold get torqued at the same time, per Ford. Should make for the best alignment. Follow the sequence. When tightening the manifold bolts, you'll have to do each torque step multiple times (in sequence) before it will sit right. So for example, do bolts 1-8 in sequence to the required torque, then do them all over again in sequence, over and over until they stop turning at that torque value. Then go to the next step.

Abbreviated version of what I did:

1. RTV at block/head mating surface corners

2. Install manifold guide studs (6-7 ft-lb), nuts (7-9 ft-lbs) ADDED PER FORD MANUAL, BUT MY 94 DOES NOT HAVE THESE.

3. Install manifold bolts (in sequence), tighten to 3-6 ft-lb

4. Tighten head bolts in sequence to 52 ft-lb

5. Intake bolts to 6-11 ft-lb

6. Head bolts additional 80-85 degrees. Picture 3 shows how I used a dot of paint to mark the 12 o'clock point; then I used a long breaker bar to rotate the bolts to 80-85 degrees from that. You want to "sneak up" on the point, don't overshoot and back off!

7. Intake to 11-15 ft-lb, then 15-18 ft-lb final torque.

 

[arco777]

Valvetrain

1. I am re-using all my pushrods since they do not show wear at the tips. There was no abnormal valvetrain noise either and they check out at the same lengths. None are bent. I am re-installing them where they were because even though the rockers are new, the lifters are in the same spots and may have worn to the rods. Picture shows a good way of marking where your rods came from. I have them marked on the rod with a paint pen as a backup.

Rods simply drop into place. I used a dab of assembly lube on the ends - Be careful if you do this though because if you don't have the lifter phenolic guide cups on, and you lift the pushrod back up, the lifter hat/cup could pull out of the lifter. Bad things would happen. I triple checked at every point that this hadn't happened.

2-4: Comparison of the factory rockers and the Melling rockers. The Melling units have slightly larger internal oiling holes which should work well with the HV pump. Otherwise they're very similar at the contact points. The foot on the rockers is wider than stock, which is good because a couple are barely covering the valve tips and might not if they were stock width. Weight of the stock rockers is 89.2 grams, Melling rockers are 103.3. Definitely heavier but I can also see where the stock ones have shed a little weight from wear on the sides and contact surfaces. Internal diameter (for the shaft) is slightly tighter on the Melling though this may be due to wear on the stock ones. They fit perfectly on the shafts and feel smoother and less sloppy than stock.
Overall I'm so far pleased with the Melling units.

5. Stock assembly reference shot.

6. The ends each have a roll pin which easily knocks out, then a spring clip which holds tension on the end rocker. Rockers slide off without effort. Then the shaft pedestals come off. The pedestals are on tight but will move along with persuasion from a small hammer. They are aluminum so I'm not worried about them hurting the hardened steel shaft. I found it is easiest to leave a bolt in the center pedestal to help hold it, and knock both the end pedestals off. At the same time you can clean out the oil holes. Some had gunk in them. The shaft end plugs could be knocked out but I opted not to.

For easier disassembly you could probably heat the pedestals with a torch to expand them. For re-assembly you could chill the shaft and heat the pedestals, but they installed with gentle tapping for me.

7. Completed assemblies. Ensure you align the pedestals as accurately as possible before installation.

 

[arco777]

Ensure rocker arm shaft has oil holes pointing down; if you did not remove the center pedestals, it will be correct. Position can be recognized by notch on front face of the shaft.

1. Work the rocker assemblies into place, guiding the push rods into the rockers simultaneously. I added a dab of assembly lube to the tips of the valves and the top of the pushrods first.

When tightening down the pedestal bolts, turn each bolt 2 turns at a time to avoid bending the shaft. Once they start to tighten up, torque to 46-52 ft-lb.

2. The aftermarket heads (Pioneer) on my engine are very soft. Before I could reach the required torque value on the center pedestal bolt, the threads failed catastrophically. At the halfway point of the threads they split, with the upper half ripping up out of the head. The lower half jammed downwards and punched partially into the port, splitting the iron (think of a volcano).

For the port intrusion, the iron was still intact. I was able to insert a socket sideways into the port to act as a fulcrum and use a screwdriver to bend the iron back up into place, closing up the fracture. I mixed up JB-Weld and covered the fracture lines with a smooth, thin coat across the affected area. I'm confident this will hold.

3-5. The pedestal bolt threads are M10x1.50. For the stripped threads I used an OEM Tools #25632 thread repair kit. This is a heli-coil type insert kit and cost about $30 locally. It requires a 13/32 drill bit to prep the hole, which is not included. I performed the above repair first to prevent drill shavings from falling into the port. Also ensure the oil hole is plugged. Once the hole is drilled out, the hole is tapped using the kit-supplied tap. A proper tap wrench is recommended for "ferrous materials", but my heads are so soft that I was able to use the plastic tool to tap the hole. After tapping and cleaning the hole, the insert is threaded in. Finally, the drive tang is broken off from the bottom and retrieved from the hole. The new thread is supposed to be stronger than the original was.

Ford specifies 46-52 ft-lb of torque for the pedestal bolts, but clearly my heads are incapable of handling this. Perhaps on the outside bolts, but the inside ones are highly prone to the threads pulling out of the head due to the oiling recess. Therefore I am only able to take my bolts to around 40 ft-lb safely. I may add threadlock.

To be honest I am not happy with these heads. They only lasted 40k miles. I'm not sure exactly what caused the head gasket failure - it could have been a defective gasket, poor installation, defective radiator cap, or it might be these heads. They are overly soft, have rough finishes on gasket mating surfaces, and half the valves leaked since new (this has been corrected). The Morana heavy duty heads are looking really good right now.

 

[natenkiki2004]

That is horrible. If that was mine, I'd be tempted to get new heads. What about the dynamic stresses of running and the rocker arms providing stress on the shaft? I sincerely hope your fix holds but I don't see why that company should be trusted. Think about exhaust manifold bolts a few years down the road. If it's that soft, maybe valve seats and guides will rattle loose?

 

[jd4242]

Ensure rocker arm shaft has oil holes pointing down; if you did not remove the center pedestals, it will be correct. Position can be recognized by notch on front face of the shaft.

1. Work the rocker assemblies into place, guiding the push rods into the rockers simultaneously. I added a dab of assembly lube to the tips of the valves and the top of the pushrods first.

When tightening down the pedestal bolts, turn each bolt 2 turns at a time to avoid bending the shaft. Once they start to tighten up, torque to 46-52 ft-lb.

2. The aftermarket heads (Pioneer) on my engine are very soft. Before I could reach the required torque value on the center pedestal bolt, the threads failed catastrophically. At the halfway point of the threads they split, with the upper half ripping up out of the head. The lower half jammed downwards and punched partially into the port, splitting the iron (think of a volcano).

For the port intrusion, the iron was still intact. I was able to insert a socket sideways into the port to act as a fulcrum and use a screwdriver to bend the iron back up into place, closing up the fracture. I mixed up JB-Weld and covered the fracture lines with a smooth, thin coat across the affected area. I'm confident this will hold.

3-5. The pedestal bolt threads are M10x1.50. For the stripped threads I used an OEM Tools #25632 thread repair kit. This is a heli-coil type insert kit and cost about $30 locally. It requires a 13/32 drill bit to prep the hole, which is not included. I performed the above repair first to prevent drill shavings from falling into the port. Also ensure the oil hole is plugged. Once the hole is drilled out, the hole is tapped using the kit-supplied tap. A proper tap wrench is recommended for "ferrous materials", but my heads are so soft that I was able to use the plastic tool to tap the hole. After tapping and cleaning the hole, the insert is threaded in. Finally, the drive tang is broken off from the bottom and retrieved from the hole. The new thread is supposed to be stronger than the original was.

Ford specifies 46-52 ft-lb of torque for the pedestal bolts, but clearly my heads are incapable of handling this. Perhaps on the outside bolts, but the inside ones are highly prone to the threads pulling out of the head due to the oiling recess. Therefore I am only able to take my bolts to around 40 ft-lb safely. I may add threadlock.

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Your pictures didnt load..if it was the middle pedestal make sure you didnt block the oil hole,thats where the rockers get there oil from..i always check this hole because ive gotten head that its been drilled and tapped to deep..ive had minor pin holes going into the port,this lets oil get sucked in and would smoke BAD..i put a flashlight over the threaded hole and look for light inside the ports , simple check.i also check the exhaust ports..

I to have used JB type material called "high temp liquid metal" to rebuild ports,it has worked well..i actually port the exhaust ports to the point where all three of the top bolts extruded into the ports..i put that liquid metal down in the hole and cut bolts to squeeze the excess out into the port..once dry i grind and polish it..never had issues

 

[arco777]

I am very tempted to spend the money on a set of new heads from Morana. I bought these in 2007 or so from NAPA, and while Pioneer is still in business I don't think they sell heads any more. I didn't know any better at the time; I was told "just buy new, any aftermarket set is better than stock". The guy who rebuilt these heads told me he was surprised at how heavy they were, yet how porous the casting was.

I don't even know if I can trust them with boost.

 

[arco777]

Your pictures didnt load..if it was the middle pedestal make sure you didnt block the oil hole,thats where the rockers get there oil from..i always check this hole because ive gotten head that its been drilled and tapped to deep..ive had minor pin holes going into the port,this lets oil get sucked in and would smoke BAD..i put a flashlight over the threaded hole and look for light inside the ports , simple check.i also check the exhaust ports..

I to have used JB type material called "high temp liquid metal" to rebuild ports,it has worked well..i actually port the exhaust ports to the point where all three of the top bolts extruded into the ports..i put that liquid metal down in the hole and cut bolts to squeeze the excess out into the port..once dry i grind and polish it..never had issues

I will double check on the pictures; I had to delete and re-add them as I missed one.

I was careful on the oil hole. I actually did use a flashlight down the bolt hole while looking in the port to check for light.

 

[natenkiki2004]

Well, they're together. It's not the end of the world to replace heads with the engine in the vehicle. The bottom end will be rock solid. If the engine runs well but the heads blow out in 2,000 miles, then you know everything else is great and it's worth it to put the money into a set of quality heads. If you swap them out now, a lot of money and time will be pissed away. I'm sure you will but keep an eye on oil and coolant as that's the only thing a head failure will affect the rest of the engine with.

 

[arco777]

I need a way to pre-oil the engine. Just before I re-install the motor, I'd like to verify proper oil flow and pre-oil everything so it doesn't start totally dry.The cam position sensor is driven off the cam, and drives the oil pump driveshaft. This shaft end is down in a hole and there isn't much clearance around it.

I'm not saying this is the easiest way, there's probably a tool, but I'm cheap. This is what I did.

EDIT: This tool worked great.

1. Acquire a junk cam position sensor. I'd put a new cam sensor in my truck and cut up the old one, but a new one is $150. Late 93 through 95 Explorers use the cam sensor I need. I fought with a 95 Limited for a while to try to get the cam sensor out, but I didn't bring the right weapons. If you remove the hood and upper intake (takes 5-10 minutes) you can get at the sensor, but there's little room. Unbolting the AC lines, trans dipstick bracket, ripping the wiring harness out of the way, and removing the fuel rail will get you more room, but you still aren't getting that sensor hold-down bolt out without a crow-foot wrench or a tiny 10mm box end. A much easier donor is an Aerostar! Find an Aerostar and remove the access panel under the dash. Pull one 13mm bolt to get some lines out of the way and you have easy access to the sensor hold-down bolt.

Note: You might think you can cut up an old oil pump rotor to make an adapter from, since it has the same shape and drive as the end of the cam sensor. Unfortunately the outer diameter is slightly too large for the hole in the block.

2-3. This was a 96 Aerostar (just my luck) so the sensor has changed and is incompatible as a spare. But, it still fits in the earlier hole just fine!

3. Remove the two bolts holding the sensor hat and pull it off. It's a simple hall effect unit. This gets you past the junkyard's cashier more cheaply. I quote "oh, that's from an old points-style distributor, right? $4.00". It isn't technically lying to not correct someone's error...

4. Knock out the roll pin. It was pretty easy, no special tools required. I may have used a Chinese screwdriver and abused my 1/2 drive ratchet as a hammer.

5. Knock the shaft backwards, through the gear and the housing, out. Heating the gear first helps. Try not to mash up the end of the shaft as the hole tolerance in the block is tight and you'll have to file the shaft tip back down if you do.

6. Chop the sensor end off. I used an angle grinder with a cutoff wheel. Get the cut end as flat as possible and perpendicular to the shaft. Beveling the edge helps.

7. The shaft is just over 1/2" diameter so my 3/8 drill won't cut it. I used a chunk of rubber hose to join it to a 1/4 drive 3/8" socket which is about 1/2" diameter as well. This is where you want the end of the shaft to be cut flat, so it sits straight as possible.

The socket is attached to a wobble drive. Why? I tested this setup with and without a wobble drive to 1500 RPM. With the wobble drive, it's more forgiving of being used at a slight angle. You still want to run the unit as straight as possible, but this lets you fudge the angle slightly and the wobble drive will handle it. The drill has a 1/4" socket adapter chucked into it.

Keep in mind there are oiling provisions for the stock cam sensor shaft in operation, and you won't have this angled perfectly, so I don't recommend using this at high speeds or for any longer than necessary. Oil the shaft before use or use assembly lube. Ensure the tool is free of any metal filings or burrs sticking out, to avoid contamination. Rotation direction is clockwise.

I will be using this to operate the oil pump and push oil through the block. Might refine the design some. Comments welcome.

 

[jd4242]

I use a E11 torks bit(pretty sure on size,ill double check) on a 1/4" extension with a wobble bit in my drill..my bit i had to sand down some to fit but my buddy has one that fits down in there i use now

 

[arco777]

Lessons learned I wish I'd known earlier - Oil level sensor.

If your oil level sensor has a plastic piece rattling around in it, and there's no continuity across it, it's probably just fine. You didn't break it...

1. During engine removal, I couldn't find a disconnect plug for the oil level sensor. Turns out the plug was right on it. The single-pin cylindrical plug slides into the body of the sensor and is retained by a spring clip.

2. View of the connector.

3-4. If you managed to kill your stock oil sender, good luck finding a replacement for an Explorer. Turns out a unit made for a '87 or so Mustang 5.0 (pictured) fits fine and is widely available. The sealing surface is slightly larger and it does not include a gasket, so you'd need to buy or make a seal for it (easy). But, the length and thread and function are identical. Not cheap for some reason. Part number on the box was E4AZ-6C624-A, number on the sensor is slightly different.

The way the sensor works is there's a caged float in the sensor body with contacts on both ends. The inner end contacts the connection pin. The outer end has small teeth sticking out that contact the inside of the "cage". The cage of course is part of the body of the sensor and grounds through the oil pan.

 

[arco777]

So I mentioned the heads and intake aren't lining up at the valve cover mating surfaces. Pictures attached. I don't like it. Fits slightly better on one side, but I'm not sure if I want to take it off and put a thinner manifold gasket on or what.

I have a set of Permadry style valve cover gaskets and a set of cork. There's no way the Permadry ones would seal like this, which tells me this is not normal. A while ago I had a set of Permadry units on and both seeped, one badly. Permadry gaskets work great if the mounting surface is perfect but I think not only is the surface of the heads a really rough machining, but they may have misaligned in this same spot. Either way, cork gaskets solved the seepage and worked fine. I'm also adding Morana valve cover support rails with studs which will greatly improve clamping spread and force.

Opinions please. I could probably make these seal as is but it would take more RTV than I'm comfortable with. Is the LIM gasket thickess the problem? Thinking of ditching the later style design for an earlier one if it is thinner. Why is this not lining up???

EDIT: Just ordered one of the earlier style gasket sets (one piece). Also an extra pair of head gaskets.

 

[natenkiki2004]

I don't think mine were like that, it may be a head issue. I used the two-piece metal & silicone LIM gasket from Magnum as well as the valve cover gaskets from Magnum. I really like them, they're silicone-in-plastic. I did put a bit of Permatex Black on that mating surface though, just to ensure it was leak free. Attached is the only picture I have of those mating surfaces.

 

[arco777]

I guess when the new gasket set arrives I will compare its thickness to the one-piece style. Most likely going to tear it apart and switch styles either way. I'm pretty sure it was never this bad before, they lined up pretty well. I ran cork gaskets without any RTV (except for the required dab at the two corner edges) and had no leaks.

 

[arco777]

Found a picture of the LIM gasket type I had before. Not sure what it is.

 

[2stroke]

Did you use RTV when you installed the lower intake gasket? I always advise against RTV on any gasket except in corners like the valley where the gasket cannot seal. If you used RTV around the intake and cooling ports, I wonder if you didn't create an uneven seal. I only replaced the lower intake gasket once on a 4.0 and I used the felpro one piece gasket. It sealed up great, and has lasted 2 years so far.

 

[arco777]

Did you use RTV when you installed the lower intake gasket? I always advise against RTV on any gasket except in corners like the valley where the gasket cannot seal. If you used RTV around the intake and cooling ports, I wonder if you didn't create an uneven seal. I only replaced the lower intake gasket once on a 4.0 and I used the felpro one piece gasket. It sealed up great, and has lasted 2 years so far.

I only used RTV for the end seals, per the Fel-Pro instructions. I checked end seal clearances on the gasket before running the RTV beads and even then it looked a little larger than I expected. The gasket is designed to be installed dry around the ports.

 

[natenkiki2004]

I know people generally never trust an armchair mechanic over an engineer but, I gotta say, I don't understand the method behind torquing heads and the LIM together. The fitment of the LIM means nothing if the heads aren't properly seated, sealed and torqued. I see no reason why the heads shouldn't be done first fully. Then clean surfaces, prep the LIM and put it in place. I say this because I wonder if maybe the heads and LIM are binding and giving this issue. Probably not, it's likely more of a shoddy cast since there's other evidence of that. I don't think the gaskets are an issue, the two-piece set works great and many people including myself are happy with it. Both sets work, otherwise Ford wouldn't have used them.

For what it's worth, I followed RTV instructions but also smeared a super thin layer around the water jacket ports just to give some sticktivity to them.

 

[arco777]

I know people generally never trust an armchair mechanic over an engineer but, I gotta say, I don't understand the method behind torquing heads and the LIM together. The fitment of the LIM means nothing if the heads aren't properly seated, sealed and torqued. I see no reason why the heads shouldn't be done first fully. Then clean surfaces, prep the LIM and put it in place. I say this because I wonder if maybe the heads and LIM are binding and giving this issue. Probably not, it's likely more of a shoddy cast since there's other evidence of that. I don't think the gaskets are an issue, the two-piece set works great and many people including myself are happy with it. Both sets work, otherwise Ford wouldn't have used them.

For what it's worth, I followed RTV instructions but also smeared a super thin layer around the water jacket ports just to give some sticktivity to them.

I don't know either. There are different procedures in the FSM depending on what all you're replacing, and the steps change slightly.

The heads shouldn't be able to move at all. I think they fit pretty snugly on the dowel pins.

I did the same on the water jacket ports. Posts to follow.