Engine: Major Problem

[Skybolt]

Just came back from the machine shop after having the block bored and pulled the block out of my truck to find a hole in one of the bores. It appears that they went through an oil gallery at the bottom of bore #5. Could have been an air pocket in the casting as no other bores were affected. What now? Can this be fixed? Should I even bother? Len.

[Dick Steinkamp]

And they didn't notice it? I might be tempted to change machine shops.

How much did you have them bore it?

Can it be sleeved?

[RadioRoy]

I had a Champion engine fail because the cylinder wall was bored into a casting bubble and into the water jacket. It did not show up until the engine had about 30 miles on it. When it stopped running, I removed the spark plugs and had a friend crank the engine while I peered into the cylinder. the spout of water that shot out hit me in the face and knocked me off the fender and onto the ground. It was a real three stooges moment.

[DieselJim]

I had one bored big oversize that went into the water jacket. They put a sleeve in. Worked ok on the water. May not where there is oil pressure.

[Skybolt]

And they didn't notice it? I might be tempted to change machine shops.

How much did you have them bore it?

Can it be sleeved?

My thoughts exactly.

I will be calling them tomorrow. I have a few questions myself.

It was a special project I was working on so it was a 0.100" over in a 259 full flow. I have had this done before but not had this problem. Depending on what they say will determine if I get them to fix it or grab my crank and rotating assembly and run. The block was sonically checked, magnafluxed, decked to be square, alignment of main caps checked, and cam bearings installed. So, you can see where I'm at.

[jclary]

Your post sent me to checking a shop manual. The particular manual does not show a huge picture of the oil gallery system, but it does show it. I wish it gave a transparent depiction of the cylinder bores as well, but it does not. Therefore I have a little difficulty visualizing the relationship of the oil passages to the cylinder bores. The puzzle to me is how you have broken through an oil passage at the bottom of the bore. Unless there is a severe taper, looks like the break through would be all the way from the main front to back galley all way down.

Wonder if it is a water jacket instead of oil galley. Also, if it is a casting "air" bubble, perhaps a little exploring with a dental pick would confirm that. If it was a casting bubble, and at the bottom of the bore...is it possible that it is below the "ring wipe contact" area? Just curious. I have not given this situation much thought until now. Hope everything works out.

[Corley]

Many years ago, my cousin had a cylinder wall fall through into the water jacket on a '49 Olds that he'd bored 1/4" over, and installed in his Model A. This was in about 1955, and any overhead valve V-8 engine was pretty expensive, and not plentiful, so for a farm kid on very limited funds, the thought of replacing it was not a happy option. The cylinder wall fell through while he was at the drag races in Bakersfield CA, and he had driven the car from Washington, so it was his transportation back home.

The hole was only about 1/4" in size, and was fairly close to the top of the cylinder. He did a track side repair by pulling the head, positioned the piston to the bottom, and brazed the hole up. He then filed/sanded the braze to just below the bore so the rings could not touch it, buttoned it back up, and went back to racing. He later put that same engine in a '34 Ford that was his daily driver for several years, and never had any trouble with the repair at all. Lucky? Yes, but also gutsy to even try it. Of course we did lot's of stuff back then that we'd never attempt today.

I'm not saying you should attempt the above repair, but it probably could be sleeved if it were worth saving. Probably best to just get a different block and start over. I'm betting that when you told them to bore it .100" over, they told you it would be on a best effort basis, with no guarantees, right? Most shops won't take responsibility for that much overbore, what with all the thin wall castings, shifted cores, etc. that they run into.

[Skybolt]

Because all the oil gallery plugs are out I can shine a flashlight through one and it shines through the hole. It is a front to back gallery. I will take some photos and post them so you can all get an idea. It is far below any ring contact area. At first I thought if it was just a hole to the cam or somewhere like that I wouldn't care too much but after seeing it in the gallery it was another matter. Sleeving or welding/brazing it closed could be an option but I will have to talk to the owner of the shop and see what happens.

[gordr]

A couple of questions come to mind. One, could the oil gallery be sleeved? Maybe bore it out one size oversize, and then press in a thick-walled tube of the right size, chilling the tube in liquid nitrogen first, maybe?

Two, if one cylinder in a given bank broke through to the oil gallery, how thin is the metal in the other three?

Three, have you miked the bores to see if it is in fact .100 over, or did they goof and bore it much larger?

[jackb]

how about a new block ?

[jclary]

Because all the oil gallery plugs are out I can shine a flashlight through one and it shines through the hole. It is a front to back gallery. I will take some photos and post them so you can all get an idea. It is far below any ring contact area. At first I thought if it was just a hole to the cam or somewhere like that I wouldn't care too much but after seeing it in the gallery it was another matter. Sleeving or welding/brazing it closed could be an option but I will have to talk to the owner of the shop and see what happens.

Well...you answered most of my question. Being it is a main galley, I would question the integrity of the entire block. Also, I question the size of the overbore. Someone with more knowledge of engine building and the maximum allowance will hopefully give guidance. However, if it were mine, I would look for another block and alter my overbore plans.

We know that these are rugged engines and pack a pretty big punch for their size. However, what good is beefing up the power potential if you compromise the toughness of the engine and lose your confidence and peace of mind about it staying together when you use the added horse power?

I have a spare engine that I have had stored under a cover on a dolly for decades. I'm sure others have some also. Checking another block for rebuild shouldn't be any more trouble or expensive than sleeving and adapting the damaged one you have. The bright side is that you have discovered this before putting it back together and having it fail later.

[Skybolt]

Well...you answered most of my question. Being it is a main galley, I would question the integrity of the entire block. Also, I question the size of the overbore. Someone with more knowledge of engine building and the maximum allowance will hopefully give guidance. However, if it were mine, I would look for another block and alter my overbore plans.

We know that these are rugged engines and pack a pretty big punch for their size. However, what good is beefing up the power potential if you compromise the toughness of the engine and lose your confidence and peace of mind about it staying together when you use the added horse power?

I have a spare engine that I have had stored under a cover on a dolly for decades. I'm sure others have some also. Checking another block for rebuild shouldn't be any more trouble or expensive than sleeving and adapting the damaged one you have. The bright side is that you have discovered this before putting it back together and having it fail later.

I have run this size over bore on full flow 259's before with no problems. An engine I had built up 24 years ago is in my brother's car as I write and it has 0.100" over, so not usually a problem. Sonic testing of all the known problem areas of the block for core shift did not show any problems. Casting flaws like this happen. I have 8 heads on the shelf and 2 of those have casting flaws. These odds are not good but it's what I have to work with. From the size of the hole the wall at that point must have been almost transparent. After all they only took 0.050" off that side and the hole looks like it was out at least that much. If it didn't break through now and was a little bit further in I might have had a very hard oil pressure problem to find.

I just got off the phone with the shop owner and he was aware of the hole but was told by his technician that it went into the crank case/oil pan area and would not be a problem. He now realizes he should have checked it himself. Sleeving will be the remedy after another sonic check of the other bores in the same location to be sure its a casting fault and not core shift. More money but cheaper than starting again with another unknown quantity.

[jclary]

Thanks for the lesson Mr. Skybolt. Now...I know more than I did. I am also confident that you know more than I do. That gives me another person to aggravate when I get in over my head!

[PackardV8]

This problem with full-flow blocks occasionally being thin in the area of the oil gallery is well-known and has been discussed here many times. That's why I personally choose an early block for performance builds. They're thicker in that area.

Some full flow blocks will not give problems at .100" over. Ted has raced supercharged blocks which were .117" and even .125" over with no problems.

Bottom line, a careful sonic test in the oil gallery area should have found the thin spot. However, the machine shop has to be told to test specifically that area and not just a few random areas.

jack vines

[JoeHall]

Soo, if bored out an extra .125" or so for sleeving, in addition to the desired .100" oversize, will that total .225" or so cause other problems with that oil gallery, i.e. restrict flow?