jaygray
New Member
Are you replacing the rear main with the engine still in the car? Pull it. The job will be cleaner and you'll be able to see what you're doing.
I think i broke rear main bearing
- Thread starter illrad91
- Start date
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Take the cap to a Machine shop and have it filled with spray weld. Then have it drilled, threaded and reface the pump surface. I would bolt and torque it to an old block we have when welding it. Spray weld is the correct way . You won't even see where it was welded. And leave the engine in the car.
Newbomb Turk
Well-Known Member
Probably the BEST fix right here^^^.
Newbomb Turk
Well-Known Member
Well then, we will see how I do. I’ve got a BBC on the dyno that has a helicoil in a head stud hole.
I’m betting it won’t fail.
The chances of fitting a main cap and cleaning it up with a line hone is slim. You have to line bore them.
Dan the man
Well-Known Member
It might not fail with a stud, I've seen them fail with the use of bolts. I do wish you the best of luck.
illrad91
Well-Known Member
If I take the cap off do I still need to hone the block?
illrad91
Well-Known Member
I'm not gonna lie to you guys I half assed it threaded it and put a longer bolt. It has less than 10k on the motor from what he told me but I'm gonna put a bigger motor down the line regardless but for now I think I should be fine I hope? That's a tomorrow problem lol I know I shouldn't half *** it but it is what it is thanks everyone for your guys help seriously I thought I was done for lol
It looks like there is already a heli coil in the other hole. Someone probably used bolts that were too long and cracked it. A thread sert would be more than sufficient to repair that. Yeah, heli-coils are awesome but on something like that I would use a solid thread sert.
That's gotta be fixed correctly, with another rear main cap and to have the block align honed so that it fits properly. JB Weld? Nut Sert? No way. That's where the oil pump mounts. Need I say more?
You half assed it so far and look at what it got you.
I cannot agree. There's no way in hades that cracked in two places bolt hole will hold a thread sert or a heli coil. Ain't happenin. At least not for long.
illrad91
Well-Known Member
What do you mean? It was my first time opening the oil pump.
If you use the original cap it is already sized to your block. Take it off , Fix it and put it back on, If the bearing looks good reuse it.
Just quoting you, buddy. You said it yourself. Anything other than another main cap and align honing it to mate with the block is half assin it. You've already see the results from you half assin it the first time, just like you said in that quote up there ^^^^^^. Do it right and it'll turn out fine.
mopowers
Well-Known Member
How about a brazed stud, then use a nut to secure the pump? Could that work?
refacing the pump surface would be an issue.
Any welding done on that cap to repair it and you risk heating it until it's out of shape. Think about it. There's really only one correct way to do it. Fix it with bubble gum. My car runs great!
Newbomb Turk
Well-Known Member
You don’t think that was my first repair like that do you?
I’ve been doing this a LONG time and I’ve never EVER had one fail. So if you or your buddy is failing them, take a look in the mirror.
It’s essentially the same repair for spark plug holes. Zero failures there too.
I don’t need luck.
illrad91
Well-Known Member
I think it happened when I tried to torque it. This time I just did it by hand. It looks like it was machined both sides before it was put together.
That too. Whatever it takes.
Dan the man
Well-Known Member
I've never heard of a heli coils hold in a cylinder head bolt hole not to say that they don't work. We wasn't the one's who installed it it was the machine shop, after the heli coil failure the block was junk. Are you using something other than a heli coil ?
Dave999
Well-Known Member
years ago in Australia
small country garages were issued with a main cap repair set by Chrysler Australia
and a special set of bearings that covered the normal oversizes plus a range with a couple of thou variation that came from the production line that "fixed up" bad tolerances, in problem engines
these caps were all slightly too tall
all had been honed with a precise offset one way or the other
in a situation like this a country garage would
spend some time with the kit and either the bore gauge or plastiguage
find the cap that fitted best
find a combination of upper and lower bearings that fit best which may or may not be a matched set. the one of "best fit" in the cap i think...might have that wrong..!
use a manual (flat plate glass and abrasive paper) method or a machining method to take off a few thou from the mounting face of the cap to get top/bottom clearance
if you could achieve 0.0005 to 0.0015 thou clearance at 3 places across the top surface of the journal put it back together and off you go 500 miles on break in oil. job done using chrysler parts when your nearest main dealer is 100s of miles away.
these kits have not existed since the 70s
you don't have to align bore...... its just a sensible way to do the job if you don't have the special kit...! (or access to the incremental oversize bearings)
i used a front cap from a 318 in my hemi 6 its a big fat thing compared with standard, cap 1 fitted nice in cap 2 position, (cap 2 was sprung, loose in the register) so i could fit the 318 cap in cap 1 position which accommodated its excessive thickness.
i had 4 318 caps to choose from
i chose the "best-fit" one and we got away with a hone i had the time i didn't have the money and i didn't have access to any hemi 6 main caps. there were only 4 of the motors in the country 1 in a museum and 2 in cars + my near scrap rebuilder, which, with much head scratching and swearing, I successfully tuned into a decent motor
needs must....and occasionally you get lucky
Dave
small country garages were issued with a main cap repair set by Chrysler Australia
and a special set of bearings that covered the normal oversizes plus a range with a couple of thou variation that came from the production line that "fixed up" bad tolerances, in problem engines
these caps were all slightly too tall
all had been honed with a precise offset one way or the other
in a situation like this a country garage would
spend some time with the kit and either the bore gauge or plastiguage
find the cap that fitted best
find a combination of upper and lower bearings that fit best which may or may not be a matched set. the one of "best fit" in the cap i think...might have that wrong..!
use a manual (flat plate glass and abrasive paper) method or a machining method to take off a few thou from the mounting face of the cap to get top/bottom clearance
if you could achieve 0.0005 to 0.0015 thou clearance at 3 places across the top surface of the journal put it back together and off you go 500 miles on break in oil. job done using chrysler parts when your nearest main dealer is 100s of miles away.
these kits have not existed since the 70s
you don't have to align bore...... its just a sensible way to do the job if you don't have the special kit...! (or access to the incremental oversize bearings)
i used a front cap from a 318 in my hemi 6 its a big fat thing compared with standard, cap 1 fitted nice in cap 2 position, (cap 2 was sprung, loose in the register) so i could fit the 318 cap in cap 1 position which accommodated its excessive thickness.
i had 4 318 caps to choose from
i chose the "best-fit" one and we got away with a hone i had the time i didn't have the money and i didn't have access to any hemi 6 main caps. there were only 4 of the motors in the country 1 in a museum and 2 in cars + my near scrap rebuilder, which, with much head scratching and swearing, I successfully tuned into a decent motor
needs must....and occasionally you get lucky
Dave
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To do it right, YES!!
Newbomb Turk
Well-Known Member
Dave999
Well-Known Member
yes
Unless you have access to stuff to do the job differently which is nigh on impossible today without unobtainable or maybe custom bearings, a pile of main caps and a dogged determination to find the right one
i was just illustrating that there are other ways
cap off a different block, then all caps ground at the mounting face to make them too short.
in bad cases they may do the block faces as well. but that moves the crank up....
Then bolted up and bored to align the lot at a slight undersize
then honed to size within tolerances listed in the manual.
the set up of the boring bar and hone is the expensive bit. the kit costs a lot also
the longer the engine and the bigger the bore the fewer choices of shop you have (only 1 place in the UK that i know of with kit do do a straight 8 for example)
find someone who is getting one done and share the cost
the actual machining job doesn't take long
Dave
Unless you have access to stuff to do the job differently which is nigh on impossible today without unobtainable or maybe custom bearings, a pile of main caps and a dogged determination to find the right one
i was just illustrating that there are other ways
cap off a different block, then all caps ground at the mounting face to make them too short.
in bad cases they may do the block faces as well. but that moves the crank up....
Then bolted up and bored to align the lot at a slight undersize
then honed to size within tolerances listed in the manual.
the set up of the boring bar and hone is the expensive bit. the kit costs a lot also
the longer the engine and the bigger the bore the fewer choices of shop you have (only 1 place in the UK that i know of with kit do do a straight 8 for example)
find someone who is getting one done and share the cost
the actual machining job doesn't take long
Dave
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