Fixing a gaping hole in an 8ba guide bore!

[idiggett]

So i spent the past 3 years building this flathead. Doing all the homework and finding a choice block (or so i thought). This flathead ran a back-up generator in a hotel in PA until the 70s. Hours meter on the generator said 700 hours! (even had a maintenance ticket signed at 650 hours in 1969) When i brought it to the machine shop they said it did not even need to be bored, they could still see the hone marks from the factory.(i bored it .030 anyway) SCORE! So block in hand, the build started. Got her running about a month ago and things were great. (WERE great) Saturday i had her out when coolant started to POUR out the passenger side exhaust. I figured it was a head gasket...even though it was a pain it would be an easy fix. Removing the head i found the cylinder that was the culprit and put a new gasket on (even though i saw no damage to the original gasket). Started her back up and the same thing happened...coolant everywhere. So i tore into the engine deeper, fearing the worst....a crack that i over looked. Seeing nothing in the cylinder or valve area, i rolled the engine over by hand so i could see into the valve pocket. I found a pool of coolant (oh-shit) I removed the valve to get a better look....then i saw the horror that was looking back at me! a gaping hole in the valve guide bore! So after a tangent of some colorful language (that is still going on some 3 days later)...I thought.... i can fix this...or at least try.

So here are some questions

Does anyone have any experience fixing something like this?

I am making up a brass sleeve that i am planning on pressing in. i am going to ream the valve guide bore 1.035 to true things up and sleeve it with a .0005 press fit bushing. Obviously when i turn down the valve guide to fit, the spring will have to be installed from the bottom side. but a minor issue if it works....fingers crossed.

in the end...nothing may work....but i am gonna try. I am a machinist by trade and have access to some cool stuff. The guys at work are trying to help me with opinions....but i am looking for some real world experience fixing stuff like this.

Ron

[alanwoodieman]

worked in the paper making industry for 40 years and I saw some amazing repairs in the shop of these mills-I remember fixing a boiler control valve which had a blow hole in it similar to yours and a sleeve (steel) was made, coated with what I remember as being referred to as liquid glass was pressed in, 10 years later when I left that mill it was still there and steam pressure was around 250 lbs on that application-maybe some words of encouragement???

[51 MERC-CT]

My only question is why a brass sleeve? My preference would be a steel sleeve in the same manner as cylinders were sleeved.

[40 Deluxe]

Have you determeined the cause? Just a casting flaw manifesting itself after 60+ years? Or, could it be freeze damage (meaning a chance of more hidden cracks)? Or corrosion from extended sitting with the coolant slowly evaporating, allowing rust?

[bobH]

Deleted...

[Russ/40]

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Barring any other damage sounds like a doable plan. I'd lean to a stainless sleeve verses brass. Keep us in the loop, interesting project.

[nathanmac]

Hmmm, I'm just tearing into a 99 motor that has 124 hours on it, and cleaned up the intake manifold to find a hole in the water jacket under the carburettor. I'll be going over it with a fine tooth comb now to try and find any other areas that might have succumbed to corrosion (really hard to tell whether it was just a poor casting or not), and will be watching this thread with great interest.

Perhaps some of these motors that just didn't get much use and had water sitting in them for so long might have been prone to this sort of thing?

[v8nut]

I don't know where you live but near me in Turlock CA there is an outfit called Locknstich that can fix just about anything cast iron. Check out this link and the rest of the examples of repair on their web site. They fixed a Model T Cylinder Head for me.

http://www.locknstitch.com/Repair%20...der%20head.pdf

[38 coupe]

Cast iron has a fairly high carbon content that acts a bit like graphite lubricant. I would be wary of a steel sleeve with a steel lifter. You do not want similar hardness in two parts where one is moving next to the other. Maybe a high strength bronze bushing would work? Or make a cast iron sleeve?

[richard crow]

how about making a solid guide copy of orignal with a tight fit with grove for horse shoe clip put some lock tight sealent on it .this way you don,t have to reem the bore whitch must be stright or valve wount seat square & who nose what you could run into that hole bore may be paper thin.

[Walt Dupont--Me.]

Originally Posted by nathanmac

Hmmm, I'm just tearing into a 99 motor that has 124 hours on it, and cleaned up the intake manifold to find a hole in the water jacket under the carburettor. I'll be going over it with a fine tooth comb now to try and find any other areas that might have succumbed to corrosion (really hard to tell whether it was just a poor casting or not), and will be watching this thread with great interest.

Perhaps some of these motors that just didn't get much use and had water sitting in them for so long might have been prone to this sort of thing?

Nathanmac, there is no water in the intake manifold on a flathead, I think your looking exh. cross over. Walt

[Walt Dupont--Me.]

Originally Posted by 38 coupe

Cast iron has a fairly high carbon content that acts a bit like graphite lubricant. I would be wary of a steel sleeve with a steel lifter. You do not want similar hardness in two parts where one is moving next to the other. Maybe a high strength bronze bushing would work? Or make a cast iron sleeve?

His hole is not in the lifter bore, it's in the cast iron giude bore. Walt

[nathanmac]

Originally Posted by Walt Dupont--Me.

Nathanmac, there is no water in the intake manifold on a flathead, I think your looking exh. cross over. Walt

Hey thanks for clearing that up and setting my mind at ease - I'm a bit of a newbie as you can tell and didn't get to looking much closer at it late last night when I found it. There was a bit of pitting below it which I assumed was from water seeping down over it - perhaps it's just pitted from lack of paint in that area and extra heat.

[Karl Wolf]

Look at an old Ford wheel cylinder as repair material, it's 1" inside... Cast iron with cast iron... I was taught to use Irontite's ceramic motor seal as install lube/ sealer...
Karl

[JonC]

I like Karl's idea of using similar materials, no expansion rate differances to contend with.

[JWL]

The cast iron sleeve is a bad idea for a thin wall, press fit, repair. I would use steel with a slathering of "Permanent" Loc-tite.

There are some good questions asked above. Is this the single problem because of a poor fill as originally cast? Or, is there a serious core shift? A small, 90 degree probe, on the end of a sonic micrometer to view other guide bores might save some future headaches.

Good luck.
JWL

[Charlie ny]

idi,
I lived this same mess a few year ago. I shrunk fit a .060 wall steel sleeve into guide bore with locktite. If you freeze the sleeve it will shrink
at least .003 to .004 on the dia. For once I got smart ahead of time and
turned up a piloted driver to assist installing the sleeve...which must be
done quickly. I think I used about .0015 interference fit. The sleeve
went in and is still working just fine.
Do not attempt to open up the guide bore. Things get trickier
than you might think and you'll hate yourself.
Charlie ny

[Mike51Merc]

A wad of JB Weld smoothed out with a brake cylinder hone? How about gluing the guide in place with your sealant of choice? Just kidding, but you never know.

Seems to me all you need to do is keep about 15 lbs of coolant pressure out of there. What sucks is that you can't access the hole. I like the sleeve ideas. You could even sleeve it undersize and then cut the valve guide to fit. EDIT: Sorry, you already said that.

[idiggett]

I made a brass sleeve, but now that i have read all the postings... i am rethinking my thought process. I figured that a soft metal has a better chance of sealing up tight. I also considered the expansion rates of brass vs cast...but do not know enuff about that science to know if it is on the help or hinder side The maintenance guys where i worked told me that plugs in industrial boiler tubes are always made of a softer metal than the tube. I am hoping that the locktite is just to hold things in place and not for sealing purposes. In theory, a soft metal pressed into a harder metal will seal on its own...i hope

As far as why it happened...i have no idea. i think i might have ruled out freeze, if you look at hole it has a small crack that is shifted "IN". look at the end of the pick in the picture it is pointing at it. This small crack lines up to the edge of the seal on the guide. in the picture you can see the cross section of the wall thickness really well. It ls only about 1/16 of an inch thick! which i would think is way to thin. It looks like it was waiting to happen. I have no way to tell if all the other valve bores are like this...i hope not. I had another person tell me the sand casting of these blocks was not exactly cutting edge at the time. easy to believe. Another said, it probably was selected as an industrial block because of this defect. But i dont see how anyone could have known this was a defect before hand.

I will also add that this is a blown engine. the idea has been floated that this was caused from boost pressure. However i am running 6# of boost with a 7# radiator cap. In theory it sees less stress under boost, and i have NEVER herd it backfire out the intake, which has 15# pressure reliefs on it also. So i dont think it is a boost issue.

I am hesitant to move forward fixing this with out all points considered. It seems my choices are

1. sleeve it and turn the guide down
2. make an oversize guide and press it in.

a thin wall sleeve seems like a better choice as it may conform better to the wall when pressed in. given the fact that the cast bore is only 1/16 inch thick,
brass might be more forgiving than steel when it comes to putting pressure on the wall and cracking it further.

Whatta ya think?

[Mike51Merc]

A thin walled brass sleeve has a greater potential for deforming as it's pressed into place. Kingpin bushings come to mind--- the kingpin will fit the bushing until you press the bushing in place and then the kingpin won't fit it anymore until you ream the bushing.

You may have to do the same to fit your guide in after inserting the bushing.