Frozen Bolts on Exhaust Manifold

[Joker757]

1999 7.4L MPI. I was taking the port exhaust apart and the bolt heads on number 5 and 7 cylinder at the manifold were rusted so bad that I could not get my socket to bite. I had to grind the heads of the bolts off. I got the manifold off (needs replacing) but the 4 bolts on 5 and 7 are frozen solid in the block. I tried PB Blaster and heat with no success. My next step tomorrow was to cut the bolts off flush, drill and re-thread. I'm going to put the manifold back on to use as a guide. I don't know how to weld nor do I have ready access to someone who does so welding a nut to the bolt is out. Any suggestions or tips? Anything I should look out for? Thanks.

 

[Bondo]

Re: Frozen Bolts on Exhaust Manifold

but the 4 bolts on 5 and 7 are frozen solid in the block. I tried PB Blaster and heat with no success. My next step tomorrow was to cut the bolts off flush, drill and re-thread.

Ayuh,.... DON'T do That...

You need some Heat,+ Vice-grips to remove them....

 

[Joker757]

Re: Frozen Bolts on Exhaust Manifold

tried that. The grips just spin and the bolt doesn't budge. Trust me, I put those things on as tight as humanly possible. I can't think of any other way.

 

[Bondo]

Re: Frozen Bolts on Exhaust Manifold

Ayuh,... If you're not up to the task,... Pull the heads,+ bring them to a Machine Shop....
If you do as you're planning,... You'll be buying New Heads....

The grips just spin and the bolt doesn't budge. Trust me, I put those things on as tight as humanly possible.

You need BIG Heat,... Oxy/ Ace kinda Heat....
Bend a 90? into the remaining bolt to stop the vise-grips fromSlipping...
Heat the bolt Cherry Red down right next to the head,+ Quench it with cold water,... Lube it,+ turn it out....

Btw,... WHY did you Over-tighten them,..??
Not that it matters,.. The load is gone,+ the threads are relieved...

 

[Bt Doctur]

Re: Frozen Bolts on Exhaust Manifold

At least you got yours off, I just spent 5 hrs cutting a 7.4 manifold off, 1 piece at a time. And a BIG hammer.

 

[MikDee]

Re: Frozen Bolts on Exhaust Manifold

Soak them with PB blaster, then tap on the top of them with a light hammer to try & break the rust seal, Then use a good 8" pipe wrench, with good jaws (preferably new), with a small piece of 3/4" pipe on it as a lever if you need it, it works better then a vice grips, because once it bites, it will not slip in the right direction, (as long as you're pushing down on the handle, not up), but the bolts may snap. Take it from an old pipefitter

 

[Joker757]

Re: Frozen Bolts on Exhaust Manifold

Ayuh,... If you're not up to the task,... Pull the heads,+ bring them to a Machine Shop....
If you do as you're planning,... You'll be buying New Heads....


You need BIG Heat,... Oxy/ Ace kinda Heat....
Bend a 90? into the remaining bolt to stop the vise-grips fromSlipping...
Heat the bolt Cherry Red down right next to the head,+ Quench it with cold water,... Lube it,+ turn it out....

Btw,... WHY did you Over-tighten them,..??
Not that it matters,.. The load is gone,+ the threads are relieved...

I had a Mecury mechanic replace the last set of manifolds. I think its rust and not from overtightening them. the other came out very easy. There was a lot of rust. I'll try your suggestions tomorrow. If that doesn't work looks like I'll be pulling the heads.

 

[AZSenza]

Re: Frozen Bolts on Exhaust Manifold

The Penentrant needs to soak in good. It will work best with a few good taps from a hammer (like your trying to nail it back into the block) after each spray. Go to an auto parts store and look at bolt removers, the best ones are shaped like a nut and cut into the bolt as you wrench it off. You shouldn't need heat, yet. This process has never let me down since I've learned it (like 20 years) The heat method works well to and its almost instant.

 

[bigskiohio]

Re: Frozen Bolts on Exhaust Manifold

if heat doesn't work a machine shop can remove it or install helicoil.

 

[Joker757]

Re: Frozen Bolts on Exhaust Manifold

well I've been at it since 6am EDT. I still can't get those bolts to budge. At some point the time/effort to remove the bolts will yeild a diminishing return. therefore I've decided to pull the heads. This will also give me a chance to clean the engine (remove rust and paint) as well. Can someone tell me if the heads for the port and starboard are seperate or is it all one piece? I'm hoping that I only have to remove the side with the stuck bolts. I already have the intake manifold cover off and most of the cables/wires out of the way. I do have the SELOC shop manaual. Any advice?

 

[45Auto]

Re: Frozen Bolts on Exhaust Manifold

Never understood why people don't fill out the info so others know about where you're located. Could easily be an Iboater willing to help out close by with all the welding equipment you need to get them out.

Good Luck!

 

[Bondo]

Re: Frozen Bolts on Exhaust Manifold

I do have the SELOC shop manaual. Any advice?

Ayuh,... Go up to the Adults Only section,+ download the Merc manual for your motor....

Are you using Extreme Heat,..??
Heating the old bolts Cherry Red,+ Quenching them will usually break 'em Free...

 

[Polar_Bus]

Re: Frozen Bolts on Exhaust Manifold

Are you using Extreme Heat,..??
Heating the old bolts Cherry Red,+ Quenching them will usually break 'em Free...

+1, excellent tip. I have a small oxy/actylene plumbers tank setup, and this method gets the bolt(s) out every time !

 

[Joker757]

Re: Frozen Bolts on Exhaust Manifold

I live in West Palm Beach, FL

I started the process of pulling the head. I got all of the bolts free however one of them the head is realy rusted and started breaking apart. I'm now hesitant to use heat as I've disconnected the fuel lines and the entire engine compartment smells of gas. I'm going to take it to the marina this week, have them pull the engine out for me. I will bring it home and work on the engine while on a stand. This will be much easier and safer I think. Also there's a ton of rust. This way I can knock it all of and paint the engine and give the bilge a good going over. Anyone have any suggestions how to pull the engine if I wanted to do it myself? I have a radar arch and I would have to clear the stern of the boat which is approx 9ft off the ground. The marina uses a small crane with a telescoping boom on it.

 

[45Auto]

Re: Frozen Bolts on Exhaust Manifold

People that have access to them typically use backhoes or forklifts (or cranes) to raise the engine. Lots of people build an A-frame out of 6x6 lumber.

 

[littlebookworm]

Re: Frozen Bolts on Exhaust Manifold

Like many jobs on a boat, this one seems to be escalating. With that much rust-related problems, don't be surprised at what you find when you pull the heads. As to pulling the engine itself, I've been able to pull a 350 from a 25' cruiser using a rented automotive engine hoist. Make sure it goes high enough to pull the engine over the transom. You may have to use some chain to pull the engine out of the bilge area, then set it down on some 2" x 8" boards laid across the rear deck, then reset the hoist to lift it clear. If you don't feel confident doing it yourself, the money you pay the marina to do it is money well spent. Be careful and good luck. Hy

 

[Joker757]

Re: Frozen Bolts on Exhaust Manifold

With the intake manifold off I can see quite well inside and all looks shiny. The rust appears to be mainly isolated to the exterior of the engine. I'm going to pay someone to pull the engine and I can do the restoration myself while on a stand then pay them to put it back in.