oil pressure issues

[Blazin40s]

Gotta plastigauge it when u put it together.

[Bowtie972]

Plastigage is cheap and easy.  you can get it at most part stores. Costs a few bucks for a strip about 12" or so.   it looks like dental floss, you lay a small piece across the crank and put the cap back on and torque it.  Then remove the cap and the plastigage will be flattened out, on the package it came in there will be a chart, match the width of the flattened piece to the chart and it will tell you your bearing clearance.  If your within the specs called for your engine should be good.  I always do this with no oil on crank, check all the rods and mains, if all looks good clean off the plastigage and coat w/ oil or breakin lube.

Plastigage is a quick check just to make sure there were no mistakes at mach shop, or a wrong /mismarked bearing. 

[Hammerlane]

Plastigage is cheap and easy.  you can get it at most part stores. Costs a few bucks for a strip about 12" or so.   it looks like dental floss, you lay a small piece across the crank and put the cap back on and torque it.  Then remove the cap and the plastigage will be flattened out, on the package it came in there will be a chart, match the width of the flattened piece to the chart and it will tell you your bearing clearance.  If your within the specs called for your engine should be good.  I always do this with no oil on crank, check all the rods and mains, if all looks good clean off the plastigage and coat w/ oil or breakin lube.

Plastigage is a quick check just to make sure there were no mistakes at mach shop, or a wrong /mismarked bearing. 

x2  if your crank was turned you need oversize bearings, if your crank was turned and stock bearinings went in you
will show low pressure, it's whats called an "internal leak".
that's what the plastiguage will tell you.

you've had oil changes.. was the viscosity of the oil changed.. ie.. 40W down to 30W
possible "minor" loss there

[Kyle]

Plastigage is cheap and easy.  you can get it at most part stores. Costs a few bucks for a strip about 12" or so.   it looks like dental floss, you lay a small piece across the crank and put the cap back on and torque it.  Then remove the cap and the plastigage will be flattened out, on the package it came in there will be a chart, match the width of the flattened piece to the chart and it will tell you your bearing clearance.  If your within the specs called for your engine should be good.  I always do this with no oil on crank, check all the rods and mains, if all looks good clean off the plastigage and coat w/ oil or breakin lube.

Plastigage is a quick check just to make sure there were no mistakes at mach shop, or a wrong /mismarked bearing. 

x2  if your crank was turned you need oversize bearings, if your crank was turned and stock bearinings went in you
will show low pressure, it's whats called an "internal leak".
that's what the plastiguage will tell you.

you've had oil changes.. was the viscosity of the oil changed.. ie.. 40W down to 30W
possible "minor" loss there

it was turned and i did buy oversize rings like im supposed to lol .020 is quite a bit of slop for them things to not notice. actually when i put it all together with the assembly lube the crank was nice and snug when trying to turn it over by hand, but moved very smoothly when using the crank turning tool. and no i didnt switch weights at all

[betterbeaters]

I am betting its a bearing... better to be safe I would pull the motor and check everything out!

[Bryank]

if you couldn't turn the crank by hand freely without using a tool your main's were off. either due to a piece of something under main cap or bearing or crank or torque. You should ALWAYS be able to spin the crank freely by hand!
When the rods and pistons are hooked up its a different story

[7d9_z28]

threadjack, but KYLE! BryanK^^^^^ is the owner of Bad Obsession

[ToughBowtieTruck]

No, that's probably rod/main bearings.


I'm suspicious of that engine, head gaskets going bad during break-in? If any coolant found its way to the oil that could have set the bearings up for failure.

[Bryank]

threadjack, but KYLE! BryanK^^^^^ is the owner of Bad Obsession

small world! if ya guys need anything let me know ive built 3 high performance engines, i ain't no pro but i do know a bit
    And nice pic of my truck!

[old school truck dude]

I suspect something wrong on this motor too, Im thinkin internal. They wont run good on low oil pressure so somethins goin on and yup Id pull the pan. Seems like it never did run quite right either. We ARE talkin about the same motor as in the other thread, right? If the bearings are showin a copper colored spot, put the pan back on it with a couple bolts and pull it out. If it was me, I would be figurin out the cause of the premature failure or I would not put THAT motor back together, ever. No guessin, gotta KNOW, cuz its too much $$$ to waste.

When building an engine, Plastigage everything and check a couple different spots on each journal. Its cheap, and it dont lie. Gotta be gentle when you put the parts together and dont let them turn. Dry, no oil. Always use it when building. Checkin the crank might take all day, but how many days did you spend at work to buy that motor? 

[7d9_z28]

yeah its the same motor... its been naggin him since the start...

[Kyle]

threadjack, but KYLE! BryanK^^^^^ is the owner of Bad Obsession

small world! if ya guys need anything let me know ive built 3 high performance engines, i ain't no pro but i do know a bit
   And nice pic of my truck!

hell yea! thats awsome! and thanks man!

if you couldn't turn the crank by hand freely without using a tool your main's were off. either due to a piece of something under main cap or bearing or crank or torque. You should ALWAYS be able to spin the crank freely by hand!
When the rods and pistons are hooked up its a different story

it wasnt THAT hard to turn and i wasnt reefing on the tool to turn it. tool just made it smooth as butter



well what i managed to do today way changed out the sensor just to see whatd happen.... pulls bout 60 cold on start and slowly idles down to bout 20ish psi at idle(750rpms) and will drop down to 15-17ish under load idle(550rpms) and when i take it down the road itll climb up to bout 40 depending on the rpms

[old school truck dude]

threadjack, but KYLE! BryanK^^^^^ is the owner of Bad Obsession

small world! if ya guys need anything let me know ive built 3 high performance engines, i ain't no pro but i do know a bit
   And nice pic of my truck!

hell yea! thats awsome! and thanks man!

if you couldn't turn the crank by hand freely without using a tool your main's were off. either due to a piece of something under main cap or bearing or crank or torque. You should ALWAYS be able to spin the crank freely by hand!
When the rods and pistons are hooked up its a different story

it wasnt THAT hard to turn and i wasnt reefing on the tool to turn it. tool just made it smooth as butter



well what i managed to do today way changed out the sensor just to see whatd happen.... pulls bout 60 cold on start and slowly idles down to bout 20ish psi at idle(750rpms) and will drop down to 15-17ish under load idle(550rpms) and when i take it down the road itll climb up to bout 40 depending on the rpms

So now theres nothin wrong, sounds like. Well, it sounds like to me that we can type faster than you can fix your truck. we've already pulled the motor and tore it down, youll have to hurry to catch up with us on here!

[Kyle]

Well I ain't outta the woods yet... after puttin some extra miles on it and really lettin the oil warm up and get up to temp, the psi has dropped another 5psi. Somethin definately ain't right. I bought a gm performance high volume standard pressure pump and a new pickup screen and ill prolly be installing it this week/weekend. And ill pull a main cap off and see what it looks like, maybe a rod cap too, I really don't wanna take a bunch off cuz they're all sequenced

[Hammerlane]

Plastigage is cheap and easy.  you can get it at most part stores. Costs a few bucks for a strip about 12" or so.   it looks like dental floss, you lay a small piece across the crank and put the cap back on and torque it.  Then remove the cap and the plastigage will be flattened out, on the package it came in there will be a chart, match the width of the flattened piece to the chart and it will tell you your bearing clearance.  If your within the specs called for your engine should be good.  I always do this with no oil on crank, check all the rods and mains, if all looks good clean off the plastigage and coat w/ oil or breakin lube.

Plastigage is a quick check just to make sure there were no mistakes at mach shop, or a wrong /mismarked bearing. 

x2  if your crank was turned you need oversize bearings, if your crank was turned and stock bearinings went in you
will show low pressure, it's whats called an "internal leak".
that's what the plastiguage will tell you.

you've had oil changes.. was the viscosity of the oil changed.. ie.. 40W down to 30W
possible "minor" loss there

it was turned and i did buy oversize rings like im supposed to lol .020 is quite a bit of slop for them things to not notice. actually when i put it all together with the assembly lube the crank was nice and snug when trying to turn it over by hand, but moved very smoothly when using the crank turning tool. and no i didnt switch weights at all

eh.. as long as you've got the pan down.. take the oversize rings out of the crank.. they go on the pistons.

[Squirell]

Keep starting it, just a few more times and your almost guaranteed to ruin your crank

[betterbeaters]

Keep starting it, just a few more times and your almost guaranteed to ruin your crank

yep mine only ran a few 1-2 mins with lower than normal oil pressure and my crank needs polish amd my bearings are shot..

[ToughBowtieTruck]

Same here. Trashed a new crank and bearings because I didn't do the full break-in. Had to set it right to work to move. Bye bye lower end.

Got 4000 miles out of it though with 20w50 oil

[Kyle]

Well I've been still driving it around and seems to be holding up ok. Still holds bout 15 at idle..... but if it were a bearing, which ones would it be likely to be? Just the mains? Or rods and mains?

[betterbeaters]

if your still driving it and any bearing was going I bet they all are now..


oh and after I fixed my low oil pressure issue I had 75 psi and still had bad bearings..