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Checking main cap installation
by
gnavs
on 14 Sep, 2011 11:20
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So my build has been on standby long enough and I'm really hoping to have time this weekend to drop the oilpan and investigate my sudden loss of oil pressure during one of my test runs. From talking with a couple guys it sounds like I may have spun a main bearing. I've checked the intermediate shaft and verified that it's spinning, which I can only assume means the oil pump is also spinning. I'll keep that in my list of possible causes though. Anything I should add or remove? I've got too much time and effort into this damn thing to see it grenade so covering all of my bases preemptively can only be a good thing, right?
Possible causes:- main bearing spun
- oil pump not working
- main caps not oriented properly (during the rebuild process I lost track of which one went where, they're all numbered but I don't know which side starts at 1)
- main bolts not torqued properly (I used theman53's 12.9 grade bolts torqued to factory specs)
TIA gurus....
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#1
by
monomer
on 14 Sep, 2011 13:59
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intermediate bushings new?
It's the usual cause of low oil pressure.
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#2
by
R.O.R-2.0
on 14 Sep, 2011 14:01
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sometimes the bottom of the vacuum pump (oil pump drive slot) gets super duper worn out, and then it cant drive the pump anymore..
are the brakes still working fine? or are they hard to push?
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#3
by
gnavs
on 14 Sep, 2011 14:20
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The intermediate bearings are new and the brakes seemed alright but I've really just been around the block with it.
Is there a way to check the vac pump clearances?
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#4
by
R.O.R-2.0
on 14 Sep, 2011 14:22
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pull the pump and eyeball the oil pump drive..
if its got nice, straight corners on everything, then its fine..
if its all wallowed out, and everything is nice and rounded over, then the drive slot is very worn..
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#5
by
gnavs
on 14 Sep, 2011 15:51
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I'll check that as well.
Any thoughts on the main cap orientation? I noticed when I was putting everything back together the crankshaft was near impossible to turn, later realized that I had the caps flipped the wrong way.
Another thing to keep in mind, I had my crank turned at the local machine shop to remove a small scratch on the bearing surface. It was the first oversize and I ended up getting the oversized bearings to match. I'm blindly trusting that the machine shop did it right but maybe that's something to check as well. HOpefully this is all stuff I can do from underneath without the oil pan installed, I'd hate to have to rip out the crankshaft again...
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#6
by
R.O.R-2.0
on 14 Sep, 2011 16:04
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I'll check that as well.
Any thoughts on the main cap orientation? I noticed when I was putting everything back together the crankshaft was near impossible to turn, later realized that I had the caps flipped the wrong way.
Another thing to keep in mind, I had my crank turned at the local machine shop to remove a small scratch on the bearing surface. It was the first oversize and I ended up getting the oversized bearings to match. I'm blindly trusting that the machine shop did it right but maybe that's something to check as well. HOpefully this is all stuff I can do from underneath without the oil pan installed, I'd hate to have to rip out the crankshaft again...
well, if the main caps were on wrong, it would definitely be near impossible to turn the crank.. you corrected that issue, right?
did you ever plasti-gauge the mains before buttoning up the bottom end?
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#7
by
Powered by Spearco
on 15 Sep, 2011 07:59
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The #'s on the main cap should be aligned the same way. Look in the book to confirm the proper a way.
Also, theres a small Vac. pump seal thats at the bottom of the pump inside the lower housing where the shaft extends. If thats worn/not sealing, it could be a problem with low oil pressure.
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#8
by
gnavs
on 15 Sep, 2011 08:11
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well, if the main caps were on wrong, it would definitely be near impossible to turn the crank.. you corrected that issue, right?
did you ever plasti-gauge the mains before buttoning up the bottom end?
I did correct the issue of the impossible to turn crankshaft, I do better with big fat issues that stare me in the face
I never did plastigauge the mains as I was working with a freshly turned crank with first oversized bearings. The assumption part may have been naive of me, you know what they say about assuming...
The #'s on the main cap should be aligned the same way. Look in the book to confirm the proper a way.
Also, theres a small Vac. pump seal thats at the bottom of the pump inside the lower housing where the shaft extends. If thats worn/not sealing, it could be a problem with low oil pressure.
The numbers were all on the same side, if that's what you mean, I just wasn't sure which end of the motor was #1, the pulley side or the output side...
This vac pump seal sounds interesting, I don't remember seeing a seal there. Does it go in between the block and the vac pump?
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#9
by
gnavs
on 15 Sep, 2011 08:12
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Thanks for the help so far guys
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#10
by
rabbitman
on 15 Sep, 2011 13:43
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Vac pump seal is in the bottom of the vac pump, you'd probably never notice it unless you looked for it........it's pretty small and hidden.
I would assume the #1 main cap goes on the same end as the #1 cylinder and so on and so forth.
For future reference, a camera used often during disassembly is very handy for reassembly especially if it's a while later
.
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#11
by
gldgti
on 15 Sep, 2011 22:52
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gnavs, the #1 end is the pulley end, the flywheel end is the #5 end.