Block Deck Repair

[More Power]

I received the following email and image today asking about how to repair a block deck.

9/30/2008
Hi Jim,
I've got an interesting problem. I should probably post this to the forum but as the situation is quite acute, I decided to drop you email. Perhaps you or someone in the community can help.

My ´95 suburban blew the head gasket. I have the heads removed now and in addition to damaged gasket we found a severe corrosion damage (or whatever you might call that) in the block in between the front / 1st cylinder on the passenger side. See picture.

Now, I'm curious if anyone knows how to repair this without removing the engine and having the block welded and machined. (or a new motor) The hole is pretty deep, I did not measure it yet but I think just milling it would not be possible. You would end up having problems with the intake as the head would be at least 2mm lower than the other. If milling both sides you'd then have to machine the intake too. Also, compression ratio might be a problem if taking 2mm or so off the block.

Although these vehicles are not so common here, my mechanic told me that almost all 6.5TDs that have blown the head gasket have shown the same corrosion problem. We do not know if the corrosion is due to the head gasket failure or the other way round, the gasket failure due the corrosion.
Thanks,
Ari






Here's my reply:

Hi Ari,
What you're seeing is the corrosive result of combustion gases forcing their way past the fire-ring in the head gasket and into the cooling system over a fairly long period of time. The corrosive action is mostly due to water molecules finding their way into pores of the cast iron, which then turn to steam as a result of high temperature combustion. This process slowly erodes away the cast iron over time, and is similar to the cavitation erosion problem the early Ford diesel engine experienced in their cylinder walls.

The best repair would include machining the block deck surface and using a thicker head gasket. Or, the eroded area could be cleaned and filled with cast iron weld, then machined flat. This would allow for less being taken off the block deck. I'm afraid a proper repair will require you to pull the engine.
Jim

If anyone has a better idea, please let us know.

[JoeyD]

Jim, I have repaired holes like that with JB weld with great results. Same areas around the cylinder bore. Keep it smooth is important though and will need to be sanded or ground smooth as can be.

[bluuzman]

Hi,

The method JoeyD described was considered also in my case as the primary option as it would save me a significant amount of money. Some kind of expert who have actually done block repairs several times with JB-Weld or similar said that the corroded area is so large and deep that he would not consider trying.

The hole goes in principle under the flame ring. This means the epoxy material would be in contact with hot combustion gases or at least very close to that.
I think temperature might exceed 500F there and it would probably start eating the epoxy.

Do you think it would really work?

BR, Ari

[TAG]

Funny story here. Back in the seventies we had a truck that came into our shop regularly that belonged to oliver machinery (now of oliver rods fame). It was an early seventies chevy with a 350 in it. The rh exhaust manifold was cracked nearly in half on the passenger side. Someone in their maintenace department decides to just bondo the crap out of it, right on the manifold next to the head. Had a big gob of it. I laughed like hell the first time i saw it, but about 4 years later they got rid of the truck with the bondo still sealing the cracked manifold. I mention this because im pretty sure jb weld is gray colored bondo. I think heat is not an issue.

[JoeyD]

Hi,

The method JoeyD described was considered also in my case as the primary option as it would save me a significant amount of money. Some kind of expert who have actually done block repairs several times with JB-Weld or similar said that the corroded area is so large and deep that he would not consider trying.

The hole goes in principle under the flame ring. This means the epoxy material would be in contact with hot combustion gases or at least very close to that.
I think temperature might exceed 500F there and it would probably start eating the epoxy.

Do you think it would really work?

BR, Ari

Seeing how I have acualy done it with JB weld and it worked, what does your expert say about that?

[bluuzman]

Well, I just decided to go for a replacement engine. Probably JB Weld might have worked as it did for JoeyD..

Thanks for replies!

-ari

[Robyn]

The decks on the 6.5 can be cut .010" and the thicker gasket used.

Any other repair in this area is most likely an exercise in futility.

Welding on these thin castings is not something that should be considered.
The high temperature and pressures in the area are going to destroy any epoxy fix in short order.

When this sort of situation is encountered the only real answer if machining is not feasable is a different block.

Best

Robyn

[mstockton]

I had a similar problem on my 6.2 build. Mine had corrosion around a coolant passage, but the cylinder next to the passage had an intact fire ring. I'm not sure if the head gasket was blown, the injection system was on its last legs when I bought the truck, but the truck seemed to run fine (all 8 cylinders firing correctly), and I found that nasty suprise once I tore the engine apart. I cleaned the area and had to slap the the new heads on the engine. I was forced by time and monetary constraints to do this. I would never recommend doing this as a stable repair as a professional diesel technician (for Caterpillar), but in my case, it was a matter of "gettin' 'er done". So far it has held fine and the engine runs like a top. The coolant leak that existed before (external where the corrosion was located) has stopped, and I am crossing my fingers for the future. The only reason I did this at all was because my fire ring surface was still in perfect condition which would allow the head gasket to seal the combustion gasses. I still might have a coolant leak around that coolant passage, which will only compound the problem. In the poster's case, I could only see replacing the block or machining the surface if it was salvagable. Although it looks from the pictures to be very deep.Sorry for the length of this post, just giving my $.02


-Martin

[bluuzman]

Thanks folks, the new engine is in now and we'll fire it up any day.
Damn expensive but what helps when a man loves his machine!

-ari

[bluuzman]

Got the rig back some weeks ago. It has now a used HMMVV whatever (Hummer) engine from US army. It should have some 10..40kmiles on it and the mechanic told it looked like new inside when they checked the engine.

Who knows but it runs very nicely (as the old one did). I got the injectors rebuilt at the same time. A new water pump and some necessary gaskets but all the other accessories are from the old engine.

I probably paid 3 times more than a price of a similar vehicle in US
(55hours of labour + the motor and other parts + injector service) but I'm glad they had these motors available here. Otherwise I'd still have a piece of
junk with no value at all. Now I have a piece of junk but it runs..

Thanks for advice and comments.

BR, Ari

[6.2Frank]

Might help someone:

Once upon a x I pulled the water pump on my 6.2 thinking the pump had failed and was leaking from the back letting water out of a machined hole behind it. NOT. The 'machined hole' was from the water passage corroded all the way through. I fixed that w/JB. Cleaning gasket surface to install {premature} new water pump had another area crumble away - fixed it w/JB, too. Only about 10.000 miles so far - but not as hot as current discussion.

Haven't owned the truck for but 30.000 or so miles. Don't know if previous owner had corrosion problems and what he put in for coolant.
\
Since JB experience I use only Prestone, I think it is, and distilled water.
If anyone happens by this and knows better, please send a message to me:
'83 6.2 Frank; lexrexus@fastmail.fm


Tnx!!!