Main bearing cap broken how to repair

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Dusterguy

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I torqued my oil pump to my block and it wasnt fully seated to the cap/block what happen was pump snapped in half and broked the bearing cap. Great! Look at these pics and tell if I need to repair this part or is it necessary? And if yes how to do it? First I thought that I solder it back with silver, but I dont know would it be strong enough. Sure I need new oilpump too.

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In last pic you see part that broked off.
 
That is where the intermediate shaft goes, it should not be a problem. I would not worry about it.
 
I sometimes take mild chances with engine abnormalities if I can see it will not effect things, but I would be hesitant to run without that repaired. There is a fair amount of torque that is transmitted to the pump at higher RPM's especially, and the recess there indexes the pump in place. If it shifts even a small amount, it will put abnormal side force on the pump shaft, the through-block bushing, the pump shaft gear and the cam gear.

If you do run with it as is, the good thing is that the pump portion that fits in that recess will be trying to shift to the right in the bottom picture, towards the rear crank throw as it reacts to the pump shaft torque and the 2 bolts. At least there is some material left there, but it is not very well supported with the side broken out. Any repair of that area will mainly be under tension.

Silver solder does not seem adequate, IMHO. Ideal, you'd braze it, or use some other low or no pre-heat process; IMHO brazing should be adequate for the forces involved. Then have the main block bore with cap torqued in place rechecked for true roundness.

There looks to be too little material around the cap casting to put a bronze bushing in that area. Any epoxy on the surface of the break will be under tension with the way the forces work out, so would have to be pretty thickly laid over the surface to have any chance to work.

This thread has an interesting video with nickel 99 rods...."No-PreHeat" Cast Iron Repair Technique - Miller Welding Discussion Forums
 
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Ok I might just try it without repair. Not going to tear down everyhthing again otherwise this engine will never be complete.
 
My feelings I would not run it the way it is. Simply it is broken and needs repaired or replaced. If it was mine, I would replaced the cap with a new one OR a used one, and take the necessary steps to insure a proper fit. I would braze it, if I could no longer get the part, or if the car is going down the road for good. The oil pump nipple and shaft must be inline with the bushing and distributor shaft or you may have early failure. The opening has been created now, you have a hole, oil pools in this area to help lubricate the lower part of the distributor shaft and upper part of the oil pimp it self. I would not sleep at night knowing this broke, take the extra...and fix it.
 
The aliglement of oil pump shaft and pump would not be different. That hole still centers it properly. And what comes to distributor shaft end oiling I believe there is so much oil spilling going on that it would not be problem either. I cant sleep at night if I cant finish this damn car.

That proken piece is very thin and I dont believe it was designet to take any kind of force. Maybe the hole is just for alligment for oil pump shaft and pump. Or at least I hope so.
 
I would
A) "run the piss out of it" to quote a well-known member., and
B) forget I ever saw that. and
C) um , um, oh yeah; run the piss out out of it.

It's like your wife when she's not in the mood. Do you really care.
Let me rephrase that; how much do you really care?
 
You're correct that the hole is for alignment of the shaft, the pump driven impeller, the shaft bushing, and the gear mesh on the cam. And while the broken area is indeed thin, the direction in which it is stressed is horizontally to the right in the last picture, not outward from the axis of the pump shaft. This recess is what prevents the pump from wanting to move around the hold-down bolts in a CCW fashion (when viewed from the bottom); these bolts by themselves can't necessarily be counted on the keep the pump perfectly aligned over the long term; there is no other indexing in the setup other than the recess.

The right side of the recess in the bottom pix, towards the crank throw, takes move of the side force of the pump trying to move. The loss of the broken piece removes some of the material helping to hold that side in place. I don't think any of us can tell for sure if that right side of the recess will eventually crack out too and perhaps allow the pump to move out of alignment, or if it will stay solid for ever.

I assume you are seeking opinions. Understanding the above, I would personally want to do something to restore the integrity of the recess.

If you choose to not do anything, then I would suggest using Permatex #1 in place of a pump gasket, after cleaning both surfaces thoroughly and making sure three are no burrs on the surfaces, and letting it set up overnight. Permatex #1 is designed to oil seal 2 metal to metal surfaces, and provide a gluing action between them; it was developed to join the 2 crankcase halves of small aircraft opposed cylinder engines with an oil-tight seal, and I would think would provide some 'glue strength' to assist in keeping the pump from moving.
 
LMAO
That sounds easy today,wait til you're sixtyish and a kidney-stone gets in the way.
Don't be in a rush to find a wife, lol. It seems young ones today can't cook, and they will feed you into an early grave. And they all just wanna have fun. Wait until they are older and get some sense.Life is not all fun.
 
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You're correct that the hole is for alignment of the shaft, the pump driven impeller, the shaft bushing, and the gear mesh on the cam. And while the broken area is indeed thin, the direction in which it is stressed is horizontally to the right in the last picture, not outward from the axis of the pump shaft. This recess is what prevents the pump from wanting to move around the hold-down bolts in a CCW fashion (when viewed from the bottom); these bolts by themselves can't necessarily be counted on the keep the pump perfectly aligned over the long term; there is no other indexing in the setup other than the recess.

The right side of the recess in the bottom pix, towards the crank throw, takes move of the side force of the pump trying to move. The loss of the broken piece removes some of the material helping to hold that side in place. I don't think any of us can tell for sure if that right side of the recess will eventually crack out too and perhaps allow the pump to move out of alignment, or if it will stay solid for ever.

I assume you are seeking opinions. Understanding the above, I would personally want to do something to restore the integrity of the recess.

If you choose to not do anything, then I would suggest using Permatex #1 in place of a pump gasket, after cleaning both surfaces thoroughly and making sure three are no burrs on the surfaces, and letting it set up overnight. Permatex #1 is designed to oil seal 2 metal to metal surfaces, and provide a gluing action between them; it was developed to join the 2 crankcase halves of small aircraft opposed cylinder engines with an oil-tight seal, and I would think would provide some 'glue strength' to assist in keeping the pump from moving.

What permatex glue are you referring? I like to take a look what it is. It would not hurt to glue it back, if the glue is strong enough to hold it in place.

edit: Permatex #1 yes I found it.
 
Mmmmm, you're not seeing what I am suggesting. Re-read my post to understand the reasoning... the Permatex #1 would in place of the pump gasket, between the pump and cap. It would not be of any use to reglue the broken piece in place.

I'm making not any guarantees; it is just that you sound determined to proceed as-is, and this is one suggestion to possibly reinforce the pump alignment.
 
Run it. Leave the broken piece off.
It's mainly an index-hole. Once the pump bolts are torqued down the pump doesn't go anywhere.
I would perhaps smooth the area where it broke so no additional material will come off.
 
It would not hurt to file the sharp edges off, but I agree. Install the pump carefully and run piss out of it.
 
yes run it like it is.... forget permatex.. IRON must be welded...which is a very difficuled story....

Greetings Juergen
 
Short of replacement take it off and run a grinder over the sharp edges to prevent it from getting hairline fractures. Then cross your fingers that it won't give you a problem down the road.
 
That area doesn't do one damn thing cept make sure the oil pump drive shaft is where it belongs when you put it together.
Nothing is supported by that material, and nothing ever touches the inside of it around the edges when the pump spins.

Pull it, grind off the sharp edges to make sure no other little piece is going to come off later and run the hell out of it.
NO WAY would I try to glue or weld that piece back on because it'll probably just end up it the pan when it really makes ZERO difference after the oil pump is bolted down anyway.
 
Once the pump bolts are torqued down the pump doesn't go anywhere.
This is the part that I am not wholly convinced is true, over the long term with heat cycles and vibration, pump torque, and a paper gasket between. It only has to creep a few thousandths to start sideloading the pump shaft, etc. Buuuuut, I can't prove it; perhaps too much imagination.
 
Imagination is a good thing, not many people have it ;) but if one is really concerned here, perhaps you could drill a short 1/4" hole in both cap and pumpbase and install a dowelpin.
About the only thing I could see would 'notice' if the pump has moved a thou or two, is the intermediate shaft bearing.
I believe there's enough 'joint' play at the intermediate shaft at the pump end that a very slight misalignment wouls pose not much problems.
 
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That area doesn't do one damn thing cept make sure the oil pump drive shaft is where it belongs when you put it together.
Nothing is supported by that material, and nothing ever touches the inside of it around the edges when the pump spins.

Pull it, grind off the sharp edges to make sure no other little piece is going to come off later and run the hell out of it.
NO WAY would I try to glue or weld that piece back on because it'll probably just end up it the pan when it really makes ZERO difference after the oil pump is bolted down anyway.

WHY THE HELL doesn't multiquote work?

This is what I'd do
 
This is the part that I am not wholly convinced is true, over the long term with heat cycles and vibration, pump torque, and a paper gasket between. It only has to creep a few thousandths to start sideloading the pump shaft, etc. Buuuuut, I can't prove it; perhaps too much imagination.

The problem with that theory is that there is no provision either in the pump input drive or the inside of the locating hole it the cap for surface to surface contact.
Surfaces don't match or anything, and if it was made to contact there it wouldn't be a cast surface but a bushing in the hole.
Also I have never seen contact marks of any kind inside there on any pump ever.
 
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