Heating up a bolt

rcknecht

rcknecht

Well-Known Member
Mar 23, 2009
3,861
toms river,nj
Boat Info
340 Sundancer 2001
Engines
T 454 MPI
Would it be really stupid if I used propane torch on my manifold bolts to heat them up?

Would an electric heat gun be ok? :huh:

If not what do you recommend?

I am have a heck of a time getting my bolts loose...
 
Last edited:
Re: Heating up a boat

I've used a good heat gun to heat stubborn bolts before... done know if I would trust propane...
 
Re: Heating up a boat

Neither approach is going to provide enough heat to break the corrosion.

Before I learned about the Mercruiser riser/manifold dance, I had the same problem on a pair of 7.4's in a 340EC project boat. I used penetrating oil then a socket and a cheater. When the head rounded off enough to give up. I used an air pencil grinder with a cut off wheel and ground the bolt heads off. That allowed me to remove the cylinder heads over the bolts. The remaining bolt looks like a stud threaded into the head. You can then get serious with penetrating oil and the protruding bolt shank is a lot easier to grab onto than a rounded off bolt head. Just don't break it off. If you are still unsuccessful, the protruding bolt is easier and safer to get to with an acetylene torch and should heat up easily.

Good luck with it.
 
Re: Heating up a boat

fwebster said:
Neither approach is going to provide enough heat to break the corrosion.

Before I learned about the Mercruiser riser/manifold dance, I had the same problem on a pair of 7.4's in a 340EC project boat. I used penetrating oil then a socket and a cheater. When the head rounded off enough to give up. I used an air pencil grinder with a cut off wheel and ground the bolt heads off. That allowed me to remove the cylinder heads over the bolts. The remaining bolt looks like a stud threaded into the head. You can then get serious with penetrating oil and the protruding bolt shank is a lot easier to grab onto than a rounded off bolt head. Just don't break it off. If you are still unsuccessful, the protruding bolt is easier and safer to get to with an acetylene torch and should heat up easily.

Good luck with it.
Click to expand...

^^^^^^^
Frank is the man...:thumbsup:
We are lucky to have him at CSR
 
Re: Heating up a boat

warm up engine to 125 or drain down some coolant and heat head . Use map gas yellow tank a lot hotter the bolt is imersed in cold coolant and wont get warm.
 
I've never tried this method personally, but it sounds like it might work:

Heat one side of the bolt using the propane torch for 30 seconds to a minute.
Press a candle against the other side of the exposed end of the bolt, getting it as close to the threads as possible. Do this while still applying heat from the propane torch. The difference in temperature on the two sides of the bolt will cause the melting wax to flow down the threads, lubricating them.





​
 
dicor said:
I've never tried this method personally, but it sounds like it might work:

Heat one side of the bolt using the propane torch for 30 seconds to a minute.
Press a candle against the other side of the exposed end of the bolt, getting it as close to the threads as possible. Do this while still applying heat from the propane torch. The difference in temperature on the two sides of the bolt will cause the melting wax to flow down the threads, lubricating them.





​
Click to expand...

X2
This method works very well. Tried it successfully a few times.
Key is to have some patience.
Don't expect to get it all apart the same session.
 
When I did my manifolds last winter I used a propane torch with great success on a couple of the bolts. Heated them up for a few minutes and they broke free easy.
 
Thanks guys... It did not want to do something stupid and be in one the Darwin e-mail chains... Many dies using a blow torch on this engine...

I don't have rust problem, the bolts are stainless steel on a stainless manifold... I have an access problem... I can't get a socket on the the bolt.. It is half cut off now... I went out and bought better tools... My boat is my excuse for purchasing odd tools... I found at Harbor Freight, 60 deg offset open ends and crow feet...

Thanks again for the advice... I like the candle wax idea. It reminds me of how soldering cooper pipe works...
 
I couldn't get 4 of my bolts out, tried the PB Blaster route, socket with a breaker bar, a few other things............ no dice. Borrowed a set of Craftsman bolt extractors and they popped the bolts right off. Just put a socket over the hex end of the bolt extrator and use a breaker bar, couldn't have been any easier.

SHC-952061.jpg


John
 
I have a set of these, but I can't get them on, not enough clearance...


xravenx said:
I couldn't get 4 of my bolts out, tried the PB Blaster route, socket with a breaker bar, a few other things............ no dice. Borrowed a set of Craftsman bolt extractors and they popped the bolts right off. Just put a socket over the hex end of the bolt extrator and use a breaker bar, couldn't have been any easier.

SHC-952061.jpg


John
Click to expand...
 
What's the mechanism at work with heating the bolt? If it's corroded in place, what does the heat do to the corrosion that loosens it. If it's not corroded how can heat loosen it unless the bolt is in a dissimilar metal that expands more than the bolt? I have heard of heating the whole area around a bolt and then spraying coolant from a can onto the bolt to chill it quicker than the surrounding material.

I bet Frank knows...
 
In my case, it is cast iron and SS... I have used heat to extract bolts, I have also used freon to cool bolts... It has worked for me in the past... The suggest of the candle wax was new to me but, I think it could work... I will tell every next how I made out.. Thanks again...
 
Frank's on the money on this one, Rod. If you can finally work the bolt free, great. If not, grind/cut off the head, pull the manifold, and then work the remaining stud. Apply heat to the head, grab the stud with vice-grips, and gently, slowly, work it loose. Have patience - you don't want to break the remaining stud off flush with the head surface. If you do, you'll be drilling and re-tapping the head itself. If you can't get it loose by Friday, let me know - I'll take a ride down there and help you with it.

Dale
 
Thanks Dale... I bought a new Dremel and grinding wheels and plan on finishing cutting the head off. Then I will use the vice grip to unscrew it...

MasterFab said:
Frank's on the money on this one, Rod. If you can finally work the bolt free, great. If not, grind/cut off the head, pull the manifold, and then work the remaining stud. Apply heat to the head, grab the stud with vice-grips, and gently, slowly, work it loose. Have patience - you don't want to break the remaining stud off flush with the head surface. If you do, you'll be drilling and re-tapping the head itself. If you can't get it loose by Friday, let me know - I'll take a ride down there and help you with it.

Dale
Click to expand...
 
Henry Boyd said:
I'm sorry, am I the only one who thinks using an open flame torch in the engine compartment of a gas boat is a really dumb idea?


Henry
Click to expand...
No - the OP seemed to think there may be a problem with it - but everyone here seemed to give him "permission" to do it - just remember advice you get on an internet forum is sometimes worth exactly what you pay for it
 
I would expect that anyone using an open flame in the engine room, when required, would follow accepted safety practices. The engine room should be opened, fuel solenoids closed, and blowers operated for a few minutes. Then verify that the engine room is dry, and sniff around a bit. Operate the torch carefully, and maintain a secure position. Light the torch, heat a confined area, and then extinguish it. An individual who knows how to properly operate a torch, and has the proper knowledge to perform this job in the first place, can operate in a safe manner.

Dale
 
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