Manifold bolts

[Langdog]

First off, I'm working on a 1996 4.0 V6. What's the best way to loosen the bolts connecting the y-pipe flange to the exhaust manifold? I'm assuming a good penetrating lubricant like PB blaster will help, then a socket with some long extensions. What have you guys found to work best? Also, I plan on replacing these bolts when I'm done with the project...anybody have the specs on these?

 

[LEVE]

If you have a torch... heat them up to red hot, and let them cool to stone cold. This will crush the rust bond and free the bolt. PBblaster is great stuff, but you've to let it work. Spray it on the bolt over a two or three day period (keeping the engine cold) and then try to loosen.

Another good penetrate that I've used is a gun lube called "Break-Free.' I've seen it work apart force-fit parts.

When you do start the removal process, if the bolt starts to become hard to loosen... STOP. Reverse the direction and see if that will help.

Breaker bars and extensions help, but just be aware that you increase the chance of not breaking the bolt loose, but of twisting off the head. Then you get to drill out the remains of the bolt and restore threads. That's not fun.

 

[rurouni20xx]

oil of wintergreen from walgreens or someplace. i did my exhaust flange gaskets one time and i couldnt break them free w/ my 500ft lb 1/2 in drive impact. a friend of mine said try this, sprayed a lil on there and tapped on it w/ a hammer, went inside had a dp and came back out. took a 3/8 drive ratchet and socket and loosened them right off, i asked what it was and he told me oil of wintergreen. give it a shot worked for me. its cheap too. the army uses break free clp that leve speaks of to clean guns, thats good stuff too.

 

[Langdog]

Thanks, I'll have to try that. Will a propane torch be sufficient for this? Also, I'm still looking for the specs on these bolts...makes sense to replace a part that takes so much heat.

 

[rurouni20xx]

not sure off hand on specs trusty haynes manual should have it listed. a propane torch will not reach 1200 degrees last time i checked, which is basically how much heat you need to cherry metal. try the lubes first if no avail id opt for the torch, oxy acetalyene is the only way i know to get that temp.

 

[LEVE]

oxy acetalyene is the only way i know to get that temp.

Actually, you can do many of these jobs with MAPP gas. It's hotter than propane. At least, it has worked for me!

 

[rurouni20xx]

like i said, only way i know how, you may know otherwise. if all else fails...sawzall!

 

[jmcarthy]

I don't know about your '96 but the spec's on my bolts for a '97 4.0 were m12 x 150 2 inch. They should be tapered bolts too. I could not get them at local auto parts stores so I dropped by a Ford dealer. They were $7.50 a piece and they had to be ordered. $30 for exhaust bolts and I had to wait ... imagine that. Someone had been at the drivers side before me as the manifold was slightly deformed from someone overheating and the 2 bolts on that same side were bent. I broke one of the bolts off in the manifold and I have a torch set. I'm not sure if I had it heated thoroughly enough or not though but as I say it was already bent. I doubt mapp gas will work getting the manifold heated cherry red but go for it. Not wanting to spend $30 for manifold bolts I dropped four 3/8 X 2 1/2 inch bolts in and just double nutted them. You can probably use a 7/16 bolt but that broken stud I had drilled out at only 3/8 and I wanted all to match. Also another little benefit is next time I have to take them out I can just cut them with the torch or snap the bolts. I couldn't get an angle with the oxy acetylene to actually blow through that broken stud, hence the drilling. With a torch you have to be very careful as you can do more damage if you happen to burn wires or a sensor or something. I usually bend up an old tin can to protect anything remotely close. Also remember that the heat from the torch will only rise so look above where you are heating to make sure your not going to catch anything sensitive to heat.

 

[RangerFabWorks]

pb blaster spray it on heavy, let it soak overnight. spray a little more on in the morning, about 1 hour later you can break em free with a ratchet. works everytime if you dont have a torch

 

[Gary Alford]

12mm bolts

pb blaster spray it on heavy, let it soak overnight. spray a little more on in the morning, about 1 hour later you can break em free with a ratchet. works everytime if you dont have a torch

I dont mean to be a smart ass but HA! is my experience with these bolts. Useing a can of Kroil penetrateing oil and heating them up red hot and one still broke on each side. I was lucky to get te 8mm manifold bolts out without them breaking. This was on a 92 ranger in the snow belt with over 140,000 miles on it. What a lousy desighn,and getting replacement bolts is proveing to also be a pain in the ass, who would of thought with all the millions of 4.0's around.

 

[NEVERDONE86]

I snapped 4 bolts on each side, ground them flush and re drilled and tapped them. Replacement bolts for the 2.9l were outragous so I just used grade 8's. Ya just got to keep an eye on them to make shure they don't stretch or get worn.
Good luck!

 

[nathan ollila]

broken bolts

im in the process of grinding my exsaust manifold bolts down to drill out,,the all snapped but one..i took my fender well out still wondering if i will have the space to drill..stubby drill bits?

 

[veefer800canuck]

my originals came out fine, I replaced them with new hardware, and plenty of copper cote, don't know if that will help for next time, but it couldn't hurt.