308 Head fused to block

I ran into the same on my 84 qv. I sprayed Kroil on the head studs ever day...beat it with a mallet...and it took weeks. But the head did finally come off. It gets exciting when it starts to move and the Kroil starts to leak through. They say patience is a virtue. ( I remember there is a place on the side where you can gently pry, but it is only on one side of the block)

 

Sounds like you've brought the car home from the mechanic?
Got the engine out yet?

Kroil is going to penetrate better at room temp than a chilly garage.
Guess the question there is what temp does your garage get down to?

 

The entire engine can be hot, it really doesn't matter. The whole thing in aluminum represents such a big heat sink though it would be hard to do. I usually surround the thing with some sort of space heaters set very close and let it sit for an hour or two until it is pretty warm to the touch all over then get a big rose bud and moving constantly, heat the heads. Again with the thermal inertia involved it is going to take some time to heat through and through. It needs to get HOT. I use an IR thermometer in several places and as many as possible in areas where the heat was not directly applied to try and get an accurate idea of the overall material temp. If a large oven was available that would be a real time and patience saver. The problem with that is to be small enough you would probably need to strip it down as much as possible to fit it in. When the time comes to actually get to work pulling the heads you want as big and heavy and immobile piece as you can get. I leave the block on the trans for just that reason.

It ain't easy, it never has been on big old aluminum, studded motors but in the case of the 4 valve motors with their shrouded studs there is no easy way. I have fought a couple of these things very hard and every time I find myself on the phone to everyone I know for suggestions and so far anyway what I have already said is the best that I have been able to come up with.

The old Ferrari business reminds me of the Navy SEALS BUDS creedo "The only easy day was yesterday".

 

BBBBbbbrrrrrr, ,
Welcome,
,
,
,
,
, to the Great White North,

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I had a car project in Idaho once,,, bbbbrrrrrr.

OK so,
Use Kroil and patience,
Once a corner is lifted, sprey kroil in the crack,
hammer back down.
hammer back up,
insert a popscicle stick, half way in between,
hammer down, this will lift the opposite side.
Good luck,
Edwardo

 

If the head is really stuck (there are many degrees) doing that will just bend the head.


Bad Idea.

 

Once you finally get the engine apart, mask off the studs & give them 3 coats of POR15. The POR15 will keep any moisture that seeps in away from the steel studs, & the studs away from the aluminum, should keep the main stud bodies from corroding. Be sure to follow the POR15 instructions. You can't coat the threads, but I'd give them a coating of Hylomar to help seal out moisture.

I just did this to my replacement waterpump bolts as the old ones were only a few years old & were badly corroded. The picture shows one of the old bolts after it had been wire brushed!!! & a coated new one. If I were doing them again, I'd have extended the POR15 down to cover the 1st 1-2 threads below the bolt body & the head's bottom.
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Could a puller work with some kind of rockers that would extend into the areas where the top of the studs are or is it just impossible? I would think if you can get one of those crazy spanners in there someone could come up with a sophisticated puller.

I spent a day getting my first 308 2V heads off then spent a day making a puller ... that's how my brain works. Anytime I hit something that's major labor intensive I spend some time to come up with a tool to make life easier. It would probably take a couple days to make something up for the 4V and sounds like it would be valuable tool if it could be done.

So any thought on a sophisticated puller? I'll make it for free and loan it out.


cheers

 

Rifledriver

Do you think using stainless head bolts would help this situation?

 

Stainless bolts aren't as strong as steel ones and would probably strip out.

 

I remeber an instance when the liners corroded to the head, is this what has happened?

 

Not only that but they would make the corrosion problem worse. The corrosion is on the aluminum head due to the contact with the steel bolt not with the bolt itself and a SS bolt will accelerate the process.

 

You could probably come up with a shape that bridged each pair of studs and screwed down from the top. Problem will be getting enough strength in it to stop the splaying effect. Really need one in front of you to see if there's enough room.
Imho the vertical offset is too much to get away with pressing down on each individually. I vote pairing them up with a shape cut out of pretty thick plate. Maybe 5/8"

 

I'm going over to a guys shop who usually has some 4V heads kicking around. I'll take a look.

cheers.

 

My idea is a dumb one.

Just looked and there's no way a bridged piece will ever get in there unless its installed in halves and bolted together.

Back to the drawing board...

 

So you are saying it's electrolysis cause by dissimilar materials?

 

Yes, galvanic corrosion between the steel and aluminum once a little water leaks past the head gasket to get the ball rolling.

 

Same thing with the WP bolts, galvanic corrosion. POR15 bonds tightly to the metal surface, excluding both moisture & O2. 3 coats will build up a thick enough film so that it's unlikely there are any pinholes where corrosion can begin take place. With some careful measurements, you could even coat the unused threads up to within a couple of threads of where the nut engages.

 

I've used POR15 before and it works great. The only problem is getting it off your hands. You have to out grow it.

 

I'm going to have to address this issue in the not too distant future on my 2V. If things don't go well, I'll fabricate and employ a puller.

Use of heat:

I couldn't find my Materials Selector publication from years ago so I'll just use some text book values.

The coefficient of thermal expansion for steel (for the bolts) is about 6.5 x 10-6 (inches/inch*F). For the aluminum head it's about 13 x 10-6 inches/inch*F). You need to be careful you don't heat the head too much as you may destroy it's hardness, a common porblem on Lotus heads. So, lets assume you start at room temperature (70 F) and heat to 250 F. I don't know the od diameter of the stud or the id of the head bore but let's assume the od of the stud is 0.55 inches and the id of the stud bore is 0.6 inches.

((13E-6) (0.60)-(6.5E-6) (0.55))*(250-70) = 0.00076 inch, the clearance gained. This assumes the corrosion build up hasn't progressed to the point where the it begins to put the hole in head into tension (elastic deformation).

mmmmm..... this doesn't seem to offer a lot of help. The clearance obtained from heating the head is not a lot but it should be helpful. Idealy, there would be enough clearance to allow the penetrating oil a crack to do it's work without evaporating due to the heat. This appears to be a crap shoot. At the very least, the bond between the head and stud will be compromised or made weaker.

The head is made of an aluminum alloy. Aluminum is a very good heat conductor. Because of this, heat gradients throughout the head when heating it will be relatively small. This means that as long as the heat source (torche) is keep moving, the head temperature will be relatively uniform (isothermal). This property is helpful. Still, a couple of torches heating the perimeter would be desireable.

Once the head has been removed and upon reinstalling, I plan to coat the id of the stud bore and od of the bolt with anti sieze compound. I have an old can of Permatex antisieze that is almost gone but it is greasy in consistancy and silver in color. It sticks tenaciously to anything it touches and prevents corroision very well.

POR-15 and similar products are good too, but they build up thickness. If the clearance between the head bore and stud od is close, I'd be hesitant to reduce it further still with a ridgid coating.

Bill

 

seems an aircraft sealant designed for galvanic corrosion would be really helpful in this situation.