HELP!! 1991 4.0 Ranger OHV. I need to replace head gaskets. I have it torn apart to the point I am ready to Loosen the head Bolts but....I cannot get
the exhaust pipes loose from the exhaust manifold. I have used penetrating oil and an electric impact gun with extension and socket from under the car.
They won't budge. I was thinking of trying heat..I have a MAP gas torch for soldering...what do you think?
Also the bolts from the exhaust manifold to the heads are impossible also (I was able to get 2 out)....so I decided to pull the heads with
the exhaust manifold still attached and deal with them off the engine...Do you see a problem doing it that way..and I can't try it until I get the exhaust pipes loose.

 

Heat works, but you've got to get it pretty dang hot (glowing red) unless they're not stuck really badly. Also, while the parts are still in the engine bay, you have to worry about where that heat will go. You don't want any collateral damage like a melted wire bundle, etc.

I did this job on my Aerostar and ran into the same problem as you're having. I tried penetrating oil, a long torque wrench for a lot of leverage (not enough room to rotate very much without being on a lift) and an air impact. I finally gave up on finesse and got out the Dremel to cut off the bolts. Once I did that, I was able to remove the heads with the manifolds attached. With the heads off the block, I was able to get the manifolds off the heads. Liberal use of penetrating oil and patience were key, but they were not stuck nearly as badly as the other bolts.

I had the machine shop who was going to rework the heads remove the frozen bolts and install helicoils. I also had the machine shop grind the manifolds flat so I could install them without gaskets like the factory does. In retrospect, it may have been cheaper to just replace the manifolds.

The Aerostar manifold design was such that I couldn't drill out the bolts and just use a bolt and a nut. Not sure if you could do that on your Ranger. If so, that's an option if you mess up the threads in the manifold. I wouldn't make this Plan A though.

Used manifolds change shape after getting hot, so the bolt holes might not line up where the manifold meets the head. The heads had already been off my Aerostar before I got it and someone had drilled the holes oversize. Without doing that, the manifolds wouldn't fit on the head. There are manifold spreaders but I wouldn't mess with that. It seems risky.

 

Thanks Mikeman, I can have access to the outer bolts for the exhaust header pipe to exhaust manifold...so I can use a dremmel. I am not sure I can reach the inner ones, I will see tomorrow. Also..when you installed the heads did you have the exhaust manifolds attached or did you install the manifolds after. There is AC in the truck and I can see it will be hard to manuver the heads and exhaust manifold passed the AC crossover pipe even to remove them.

 

Cutting the exhaust bolts was a last resort and certainly not my preference. I couldn't afford for my Aerostar to be down for long. If you can spare the downtime and are patient, try soaking the bolts frequently over several days then go at it with the impact.

I installed the manifold to the head and then installed the head/manifold assembly. The A/C lines in my Aerostar are routed differently than the Ranger so I can't really speak to your situation. I had a '91 Ranger, but never had to remove the heads, just the lower manifold. I would hope the heads could come off with the A/C still intact but moving the A/C compressor to the side. You only need to separate the head from the block enough to clear the alignment dowels (about a half inch). Maybe your Ranger is similar to the Bronco II layout. If so, Josh S was able to remove the engine without disconnecting the A/C system. Check here if for no other reason than to feast your eyes on a clean-looking Bronco II: https://www.ford-trucks.com/forums/1...9l-engine.html

 

Thanks for the info and great looking Bronco. The oil dipstick is on the drivers side and it goes through the gap in the exhaust manifold, sandwiched between the manifold and the head. There is a piece of metal welded to the dipstick tube which had a bolt attaching it to the manifold and that bolt is removed. Is there a way to pull the dipstick tube? If so then I think I can manuever around the ac line?

 

I finally got the exhaust pipes unscrewed from the heads. I tried a penetrating formula from BG and squirted it on and off for hours. Borrowed an air impact wrench that is stroner then my electric one and cranked the compressor to 135 LBS and using a few 1/2" extensions and a universal got them loose. Working on my back in the street is a bear, especially had knee surgery 2 weeks ago....but their out.

Now how to get the exhaust manifold unbolted from the head. There is no place for penetrating oil. Would you heat the heads of the bolts or just go for it with a breaker bar and a pipe?? any suggestions...?

I can see where the water was leaking into cylinder #1 ...the top of #1piston looks like it is brand new and shiny...But.. there is something strange. Looking at the 6 pair of valves of both heads where they seat. Some pairs have a blackish color where carbon has built up..but some of them have a tanish while color with no carbon. Any thoughts on that.....((#1 valves are fairly clean)

 

I recently did the same project on my 98 (3.0) and had the same trouble on both sides. I cut the bolts holding the manifolds to the exhaust pipes and took the heads off with the exhaust manifolds still attached. After the heads were off I could work on it much easier. I cut the heads off the stubborn ones with a torch and pulled the manifolds off leaving the studs in the head. (some were studs with nuts and some were bolts). I then heated the heads up and using a new pair of vice grips with square jaws and lots of PB Blaster the bolts/studs all unscrewed with no problems. I too had my manifolds machined to make sure that they were not warped and used all new studs. Don't forget to have your heads checked for cracks and resurfaced as well. The machine shop also re-seated the valves for me and used new valve seals. I've got about 5,000 miles on the new head gaskets. The truck has 258,500 miles and now has 170 pounds of compression (increased from 150 with the valves re-seated). It still runs like a champ.

 

A word of advice for those using impact wrenches: using extensions, or anything else except the socket will effectively reduce the power of the impact wrench. A lot of the hammering action will get lost in the slop between the socket & the wrench when an extension is added.

You can experiment on your own wheels to verify this. You'll notice that the wrench doesn't work nearly as well when an extension is added. Of course, if you can't get by without an extension, then you gotta do what you gotta do, but now you know why it might not work as well.

 

Thanks for the advice, I will try today. Did you install your heads with the exhaust manifolds bolted onto the heads or did you install them after the heads were torqued down?

 

I put the heads on first then the manifolds. The machine shop could not mount the heads in their milling machine with the manifolds on.

 

Good point, and there's something else at play, too. The spring rate of a torsion bar (or in this case, a long extension) is reduced with length. A 4 inch extension will be twice as stiff as an 8 inch extension. That means it takes twice as much rotation to develop the same torque. Impact wrenches provide a lot of torque over a small rotational displacement. With long extensions, you just end up winding up a softer spring and not developing as much torque. Couple that with the slop and the effectiveness is reduced.

Unlike Dan, I assembled the head and exhaust manifold after getting everything back from the machine shop and before putting the head on the block because it was much easier to do on the work bench. Access was much better especially when using a torque wrench. Again, that was on my Aerostar.

Good job whale15, you're whooping some butt. Be careful with that knee.

 

I finally got the exhaust manifolds unbolted from the heads. Only one bolt broke at the head of the bolt. I will try heating it cherry red and letting it cool a few times to break the rust. Problem is I can see a small crack in both heads between the intake and exhaust valve seats. I wonder if this can be superficial...but from what I have read it seems that is where the problem usually is. I started looking online for heads. I found kingcylinderheads.com that have NEW heads complete for 300 each, no cores. 2 year warranty. Ramscyl.com has 5 year warranty for remanufactured and cracked cores are ok, 295 each. Cylinderheads.com remanufactured is 185 each cracked cores ok 2 year warranty. Has anyone purchased from these company's or can suggest a reliable source.

 

If you can see the cracks without using the magnaflux process, it is probably not superficial. The new heads should come complete with new valves, springs etc. I would check to see if the re-man heads come with valves, springs, etc.