Stuck Lower Unit Bolts

[tvd]

Well, I am helping a friend replace his water pump in a 1980 115 V-4 crossflow.
The problem is that of the 7 bolts holding the lower unit on, 5 are stuck solid.
I know we are going to break them if we force them.
All four on the sides of the gearcase, and the 9/16 head bolt way up under the trim tab are the five that are stuck. The trim tab is off, and the one 5/8" bolt under the trim tab is out.

I have searched here, and find many many posts on removing broken bolts, but nothing on how to free up stuck bolts holding the L/U on, and avoid breaking them in the first place.

Using a torch, can I heat the heads up hot enough to have the heat penetrate at least 1.5 inches down the bolt and into the midsection to effectively free it up?
I don't see how to even get the torch in to the bolt up under the trim tab.

Should I heat the crap out of the heads, and then deliberately try to shear the heads off? When the lower is down, then I would have at least an inch of bolt sticking out to work with.

Or will simply heating the heads, allowing cooling, then a strong socket and breaker bar do the whole task?

Also, would a hand impact driver on the bolts help by transmitting the shock of a hammer blow, without shearing the heads of the bolts off?

Two of the bolts are not "gettable" with a socket due to cav plate interference.

Help please!!! Ideas welcome!!!

 

[rolmops]

Re: Stuck Lower Unit Bolts

Before giving any advice,is this engine in a salt or fresh water environment?
If it is salt water you may have an electrolysis problem.
If it is fresh you have a good chance that heating the bolts will be your ticket,because these bolts are often put in with loctite.It should be the blue version but people often use red.
Once you can loosen one,screw it out ,oil it up a bit and put it right back in tight.That way there will be no undue pressure on the bolt next to it,which would make it harder to loosen it up.Do the entire set that way and then loosen 'm up and take them out

 

[boobie]

Re: Stuck Lower Unit Bolts

I've always heated the area around the bolt and then worked it back and forth and they will usually break loose. By heating the bolt head you are expanding it more which you don't want. You'll have to use a long wrench or a shallow socket and breaker bar for the bolts in the cav plate area.

 

[tvd]

Re: Stuck Lower Unit Bolts

Thanks for the responses...
This engine is 30 yrs old...it could have been used in both salt and fresh water. I think the L/U has been replaced because it is a different color than the leg.

Regarding heat.....I guess I can torch the sides of the midsection where the four stuck side bolts are and hope the heat penetrates to the bolt threads. But I cannot get to that bolt way up under the trim tab. The only place I can heat it is directly from the top of the head.

I am going to try today with the help of the oxy torch. I hope I don't melt a hole in the side of the midsection. At any rate, I am looking at burned paint...and probably broken bolts to remove from the midsection. This will not be a very fun day.

 

[Chris1956]

Re: Stuck Lower Unit Bolts

Use propane and penetrating oil. Heat the bolt head, and remove the torch and spray with the oil. Now use a hand or air-driven impact wrench to impart some vibration and torque. Repeat heat-oil-impact.

Do not crack the casting by hitting the impact wrench too hard.

 

[ONERCBOATER]

Re: Stuck Lower Unit Bolts

i know on my LU (and rest of engine for that matter) i had issues with a few bolts, i did the heat and cool routine, and sprayed with penetrating oil, no joy still stuck attempted to loosen and attempted to tighten, tightended all surrounding/supporting bolts to relieve stress.... waited a day, sprayed again heated again.......waited a day, after several days of this (about a week) they came loose as if by magic, i was completely shocked by how easily they freed at that point. I think the heat and chill helps the penetrating oil creep in there. I also noted that when released it wasn't the threaded portion that was sticking it was the smooth portion that corroded to the housing. Not sure that this will help you but perhaps it will give you insight.

also this sight provides valuable advice for removing stuck bolts.... the man is incredibly helpful, even though most of the stuff is on smaller motors like mine, the how to remove stuck bolts and how to address broken ones is very good and works. the link is below it may be of use to you.

http://www.sschapterpsa.com/ramblings/Ramblings.html

Sean

 

[wilde1j]

Re: Stuck Lower Unit Bolts

When you put the bolts back, coat with gasket cement or non-hardening Permatex and you won't have a struggle getting them out again.

 

[tvd]

Re: Stuck Lower Unit Bolts

Well, that was FUN....not. So here is waht happened.

Of the five stuck L/U bolts descrobed above, I got four out successfully.
One bolt on the starboard side that is blocked by the cav plate (no clear socket access) broke on me.

But that was not the end of the problems.
Once the L/U was off, I proceeded to attempt to remove the shift shaft cover, the water pump, and the upper driveshaft bearing housing.
Two broken bolts on the shift shaft cover, and two broken screws on the water pump housing outlet..those flat head screws that hold the water tube guide.

So, I been drilling out broken bolts all day. I cannot get the broken bolt out of the midsection. It is drilled all the way through the center, and retapped with a 5/16-18 tap.
We tried every easy out I had in the tool box (you know "easy out" is a BS term, nothingeasy about them). We used propane, then oxy and it still would not budge.
I wlll have to put a smaller bolt in there. The owner agrees it is all we can do.

All the other broken ones are out, the upper seals on the L/U are replaced, and it held 15 lbs of pressure for over 4 hours. Waiting on a waterpump kit.

ONERC, yes I found that on four of the five big bolts, the threads were not really the stuck part, but the shank of the bolt. You are right about that.

Jim Wilde...yes I always use OMC Gasket sealer on bolts...but the biggest help of all would be regular service by the owner. I am sure this thing has not been touched for years. Black gooey L/U oil, broken impeller blades...what a mess. I am not even going to try to pull the propshaft carrier. Those four bolts in the back will surely snap.

Thank you all for your suggestions. Very much!