Rusted bolts/Elbow replacement

Vinny · Aug 4, 2010

EpicAdventure said:
My plan has been to replace the elbow and exhaust manifold in the attached picture all the way back to the engine.

The more I look at this picture, the more I wonder if I'll ever be able to get those bolts off the engine. They look pretty well rusted in place.

Anyone have any sage words of advice?

First off get the engine warmed up. Then spray each of the nuts (and that is what they should be nuts on a stud. If they are bolts someone has changed this before you) with a quality rust penetrant. I like CorrosionX but any good one will do. Now wait, respray and wait, respray and wait. You can restart the engine each time to heat up the nuts. The heat helps the penetrant do it's job.

Next use a six sided thin wall flex - socket (sorry I do not remember the size) not an eight point and not a twelve. Six is the one because it has the exact number of sides that the nut (or bolt) has. Make sure you are fully on the nut. The idea here is to not round off the corners of the nut. An electric impact gun (wrench) can be a help set on a low number. The impact will help loosen the nuts. But they are hard to come by so just a ratchet and a short extension and the flex - socket will do.

I the event that you find that someone has already tried this and rounded the nuts already (or you do) there is a tool kit that you can get at the NAPA store called a "Stuck Bolt, Nut and Stud Remover". The one I have is made by Lisle and the part number is 19250. This is handy to have on a boat anyway. I have used it several times on rounded nuts and bolts.

Replace the nuts with new ones and use anti seize on each one for future removal if needed.

If you break off a stud the world has not come to an end. Once you get the rest of the nuts off (but usually it is the last one that breaks, no real reason it just is) there may be enough material to get a vise grip on it and remove it from the heat exchanger. If it breaks up inside the exchanger then (you wanted to change the anti freeze any way didn't you) remove the exchanger and take it to a machine shop and they can remove the old stud and replace it with a new one. At that point I would have them replace all of them.

You may get to the point that removing the heat exchanger (replace all of the gaskets) is the way you need to go. That is not that bad of a job on your engine due to the access from the head that you have.

Have fun.

Bill Roosa · Aug 4, 2010

Technique and judicious use of lubricants

WD40 or any of the other "rust busters" need to get to work as soon as possible. This can take a few days to get into the cracks to do you any good.
The technique I've used to remove rusted nuts and studs is as follows:
Get as good an access to the nut as possible by removing whatever you need to to get at it.
Using a 6 sided socket twist counter-clock-wise just a little. If it moves great but don't keep twisting. Stop and go CW till it is tight again. Not working tight but move it back to where it was at the start. This will break up the rust on the threads and keep it from getting between the nut and stud. Repeat the above going a little further each time. Use more WD-40 to wash the rust away. IMPORTANT!!! If at any time you feel the stud start to twist off STOP and go the other way. The stud may be rusted along its length and weak in places that you can't see because the manifold hides it. This is really a touchy-feely thing that the first time you twist one off you know what it feels like. Prior to that you just have to try and "feel" it in the ratchet handle. It feels completely different from the nut turning. There is not a gritty feel and the amount of torque is constant. You only get about 1/8 turn before the stud snaps so take it SLOW. You can use a 6 sided wrench if you have enough clearance. This gives you a direct indication of if the stud or the nut is turning as you can see both. Don’t use the 12 sided sockets or wrenches as they will round off the nut which will mean using vice grips.
If the nut does not move then continue to twist in both directions. It may not feel like you are making any progress but slow is much better than snapping the stud off inside the engine block.
As a last resort, you can try a metal chisel to bash the nut into submission by splitting it. I never seem to be able to get a good hammer swing so don’t feel like you are one of Jerry’s kids, it happens to us all.
Don’t forget to pray and good luck.

Steve Dion · Aug 4, 2010

You will not know until you try. I would start with a properly sized wrench, socket and extension. If you can get the manifold off, that is all you care about. The rest of the stuff is going to be replaced.

If a stand sized wrench does not work, you may need to move up to a longer handle or use a breaker bar. I do not know if using PB Blaster or WD is going to help much, but it is worth trying too.

When replacing the unit be sure that you coat all of the threads with never-seize. Do you know why you have so much rust?

Clark · Aug 4, 2010

Liquid Wrench or PB are much better choices than WD40. Good Luck!

Alan · Aug 4, 2010

An alternative

All really really good advice.
On really tight nuts there is another alternative to removing them if you want to avoid sheering the stud. If you have access a nut splitter will cut the nut allowing you to turn it off without breaking the stud. The nut is easily (and should be) replaced. Be sure to use anti seize compound when re-installing. This will make removal the next time a snap.

Shortly after I bought my boat I removed (one at a time) every bolt or nut before it had rusted in place on the engine and coated the threads with anti seize compound knowing full well that one day this would pay off. A new boat engine is the ideal time to do this.

Vinny · Aug 4, 2010

Re: An alternative

For me CorrosionX is the best but to each his own. WD40 is not a rust penetrant.

A nut splitter will not fit in there period. Neither will a hand wrench. The only thing that will fit is a flex socket on a short extension and a breaker bar or ratchet. Working it back and forth is a good technique sometime but usually if you get enough go juice on there the nut will be able to remove the rust as it comes off.

As to the question "why the rust?". The heat there is trapped and the rust comes from 20+ years of the exposure to the humid salt air.

Steve Dion · Aug 4, 2010

On the 2GM engine there we bolts in the head (not studs). I would guess it may be easier to remove with nuts. That is why I had to have 3 hands to put it back on the engine.

http://hunter.sailboatowners.com/index.php?option=com_kb&Itemid=267&cat_id=25&page=article&aid=6707

Vinny: Most of the time when they look like that the vented loop has dripped on it or there was some other leak. I guess I should be glad that we live in fresh water and have access to salt water to clean the crap off the bottom a few times a year.

Vinny · Aug 4, 2010

Steve Dion said:
On the 2GM engine there we bolts in the head (not studs). I would guess it may be easier to remove with nuts. That is why I had to have 3 hands to put it back on the engine.

Not doubting you but bolts are a bad idea. The reason is that as you said it takes several hands to put them together but even more important is that the threads are deep set under the flange and if you think getting penetrant to the threads on a nut is tough, on a bolt it is even worse. On most automotive exhausts studs with nuts are used. Intakes were a different story. But there is no where near the heat in an intake manifold as the 950 or so degrees that exist in the exhaust manifold.

The 2GM is an old engine so that might be an old design. But then again they don't put them together with the repair process in mind.

Rick Sylvester · Aug 5, 2010

You can't wait

to tackle that? Man, you're one sick puppy.

I just checked mine. Mine were (are) bolts. Lots of good suggestions here. I did mine two years ago and they looked just as bad as yours for exactly the reason Steve cites.

While you're at it I'd get rid of that PVC 'T' and all the single clamps. I'm assuming that it's for an added a/c unit. It qualifies as below-waterline and is a bad idea for a whole bunch of reasons. I'd at least put in a bronze unit and double clamp.

Have fun (?)

Vinny · Aug 5, 2010

Rick Sylvester said:
to tackle that? Man, you're one sick puppy.

I just checked mine. Mine were (are) bolts. Lots of good suggestions here. I did mine two years ago and they looked just as bad as yours for exactly the reason Steve cites.
(?)

I just went to several parts books and the repair manual on line for the 4JHE. All of them show studs and nuts at the mixing elbow.

But I also know that these engines were modified by Mack Boring for the H40 some 20+ years ago and for most of them they are on their 3rd or 4th mixing elbow so who knows what previous owners have done. I have seen them with three studs and one bolt. Now I am pretty certain that the factory or Boring wouldn't have done that. That looks a bit like shade tree to me. But I'm confused on how they grew the tree in that aft cabin.

Myself I prefer the studs and nuts as to bolts. Partly because that is the way the factory designed it and partly because as I have said before the bolt threads are buried so deep into the heat exchanger that getting any penetrant to them when the unit is assembled will be next to impossible.

Bill Roosa · Aug 5, 2010

The reason they have bolts

They ALL start out with studs and nuts. The owner then breaks the stud off below the block surface trying to replace the part and has to drill-EZout-tap the hole to get it back together and does not bother to go find studs (they are harder to find) and just goes with bolts.

FTR, if you do break off the stud and it is above the block surface they can be screwed out just like a bolt. If you are not so lucky then drilling and EZouting the stud is not that difficult. Just be sure to get the right size drill bit, the right size EZout and most importantly center punch the stud in the EXACT CENTER before drilling with a very small drill. Then use the correct size drill bit to get the EZout to bite.

Vinny · Aug 5, 2010

Bill Roosa said:
They ALL start out with studs and nuts. The owner then breaks the stud off below the block surface trying to replace the part and has to drill-EZout-tap the hole to get it back together and does not bother to go find studs (they are harder to find) and just goes with bolts.

FTR, if you do break off the stud and it is above the block surface they can be screwed out just like a bolt. If you are not so lucky then drilling and EZouting the stud is not that difficult. Just be sure to get the right size drill bit, the right size EZout and most importantly center punch the stud in the EXACT CENTER before drilling with a very small drill. Then use the correct size drill bit to get the EZout to bite.

All true Bill,

There is not a lot of room to work in the area we are talking about on the 40 so for most folks it will be safer, if they can not get a good grip with the stud removal tool I suggested, to just bite the bullet, remove the heat exchanger and take it to a machine shop that is experienced in that sort of thing. Besides with the heat exchanger off it can then be disassembled and all of the scale of 20+ years can be removed at the same time.:dance:

Alacrity · Aug 19, 2010

I replaced the mixing elbow last week. My engine had bolts and I couldn't believe how easy it was to remove them. Unfortunately, it was difficult to keep the gasket lined up while I reinstalled it. Studs would have made the installation much more pleasant. Although slightly frustrating, the overall job was simple. The attached picture shows how much buildup the old elbow had.

Vinny · Aug 19, 2010

Alacrity said:
I replaced the mixing elbow last week. My engine had bolts and I couldn't believe how easy it was to remove them. Unfortunately, it was difficult to keep the gasket lined up while I reinstalled it. Studs would have made the installation much more pleasant. Although slightly frustrating, the overall job was simple. The attached picture shows how much buildup the old elbow had.

Now that you have it on why not get four studs, four lock washers and four nuts. Remove the bolts one at a time and then install the studs one at a time.

Steve Dion · Aug 19, 2010

Vinny:

That would be a good idea to replace the bolts with studs. They can be put into the head with loctite that will permanently glue them in place. Depending on the engine configuration one could use a combination of bolts & studs depending on the access.

Vinny · Aug 21, 2010

EpicAdventure said:
What's the advantage of a stud vs. a bolt? Is it that once they do corrode somewhat, it is easier to get a nut off a stud than it is to get an entire bolt out?

As I have said in this post before, "Myself I prefer the studs and nuts as to bolts. Partly because that is the way the factory designed it and partly because as I have said before the bolt threads are buried so deep into the heat exchanger that getting any penetrant to them when the unit is assembled will be next to impossible."

The ease of putting it back together with studs is one more reason. Hang the gasket, set the elbow then hold it in place with one hand and put on a nut, any nut and it stays where it is. Try that with bolts. Put one bolt in, if you can and then let go of the elbow, depending on which bolt you got in it (elbow and gasket) will swing off to one side or the other, then you have to realign the gasket and the elbow and try to find the hole with the second bolt. Why make it more difficult than it needs to be. Working on while standing on your head or cramped into a small place is difficult enough, you don't need to add to the challenge.

Besides why reinvent the wheel. I really don't ever remember an exhaust system that the manifold was attached to the engine with bolts. Even in very old engines, before cross flow induction, that used the same side of the head for intake and exhaust they used studs. There was a reason for it.

Rusted bolts/Elbow replacement

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