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Big-Block Chevy....No oil pressure in top of motor? !!! UPDATE !!!

Discussion in 'The Garage' started by Greg72, Jul 31, 2002.

  1. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    OK folks I'm seriously depressed right now...

    Had a little noise in the engine after the 4th of July holiday that was traced to a bad rocker and pushrod (they were kinda welded to each other!) hoped it was a one-off failure and ordered a new set of 1.72 roller rockers and pushrods just to be safe.

    So tonight, we're unbolting the old rockers and notice that quite a few of the rockers are welding themselves to the pushrods....on a freshly built motor with maybe 3000 miles on it!!!

    Install all the new pushrods, rockers, guideplates...and start the motor with covers off and those little oil deflectors cliped to the rockers......and the oil is barely dribbling out the pushrods onto the rockers! Not good. I am told that the oil should be squirting like crazy from those areas....like all the way across the garage with those clips removed!!!!

    Oil pressure indicates about 75 psi cold, and around 65 psi when warmed up. For some reason, the oil isn't getting to the top of the motor.

    Theory #1: Oil restrictors screwed in to the rear of the block? Shouldn't have been used with a hydraulic cam, but maybe someone didn't know any better. We pulled the tranny inspection cover and looked for signs of them. The plugs look normal and "stock"....the recessed allen-type screws.

    Theory #2: Expensive internal stuff...


    The engine is a 396 block #3969854 (rear casting number) and #T0317TKB (front stamping behind alternator) Heads are the common #820-style Oval port iron ones.

    Looking for some hopeful answers.....I have a sinking feeling we're gonna be pulling the whole motor out to tear it down looking for the problem, and THAT does not sound like the kind of thing that's gonna let me drive to Moab in 21 days!!! /forums/images/icons/mad.gif

    Any ideas from the list? I really need a miracle on this one.....a simple, cheap and easy fix would be nice! /forums/images/icons/tongue.gif

    Thanks.
    __________________________________________________________

    Here are a few pics from last night (7/31):

    Scott (4x4HIGH) and Bruce (70~K5) came over and convinced me that there is nothing to fear....

    So we took this off...

    And the dog thought it made a GREAT doghouse!

    ...as you can see!

    Then Scott says: Don't just stand there let's go

    And Bruce says: Get that piece of crap outta here

    The Greg looks at what used to be a truck and says: Oh My GOD

    And here we are by 10PM

    Here is the aftermath this morning:

    Can you believe this was a truck yesterday?





    AMAZING!! I owe a BIG thanks to Scott and Bruce for their help....I can't believe we pulled the whole clip and the whole motor in about 4 hours! That's something I never believed would happen.....now we can really dig into the mystery of what's going on with this motor.

    Thought you'd all like to see the updates, I'm feeling MUCH more confident now about getting to Moab although clearly there is still MUCH to do!!! /forums/images/icons/cool.gif
     
  2. UseYourBlinker

    UseYourBlinker 1 ton status

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    I have no answeres for you Greg but hope you figure it out. I'm in kinda the same house. Haven't drove the K5 in about 3 weeks now. /forums/images/icons/frown.gif
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    More strippers......less truck problems!

    That's all I'm asking! LOL /forums/images/icons/grin.gif
     
  4. Chaz88K5

    Chaz88K5 1/2 ton status

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    ya know that roll over could have screwed it up for ya..hehe..no really i am not much help here..but i really hope you get it figured out in time /forums/images/icons/grin.gif
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    I don't think so....

    All 16 pushrods are low on pressure....something is blocking the oil from getting up top. With ~70 lbs on the bottom end, it sure doesn't sound like an oil pump problem.....somethings blocked, or assembled WRONG!

    I knew I shoulda bought a Samurai!
    /forums/images/icons/grin.gif LOL j/k ROTFLMAO /forums/images/icons/grin.gif
     
  6. Redfrog

    Redfrog 1/2 ton status

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    that sounds like what my 350 did right before it went bad
    very little oil to the top of the engine, toasted 2 rocker arms(blew the bottom out of them BIG BANG) the engine was rebuilt when I got it. sounded good so I did not really do any checking in to it just put on some 1.6 rockers. and hoped it would last until warm weater and it did, finally it started fouling plugs like crazy. to the tune of 1 every other day. So I parked it tore out the 350 and after it was all said and done the only thing that I am reuseing is the block.... everything else is new... with that said if I had it to do over agin I would have pulled it when it happened
    to fix the problems that it had.. I can't offer any other advise just telling my story /forums/images/icons/grin.gif
     
  7. Don

    Don 1/2 ton status

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Pull the Pan, Pull the Oil pump, Check the pressure releif Valve. If It is sticking open, =low oil pressure. if it is sticking closed,= high oil pressure.

    On Mine a recently Rebuilt 454, It runs, about 80lbs. cold, 60 hot at road speed. about 35 at Idle.

    Hope this Helps You out, all it takes is one tiny piece of crap to hold the releif Valve open, or closed. /forums/images/icons/confused.gif
     
  8. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    I read on here a couple of weeks ago about big blocks having a problem with oil up top.. I looked but couldn't find the post.. But I thought I remember Ryan posting about it...Dan
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Shawn Spickler did and article on his 454 rebuild over on www.offroad.com but I can't seem to find it anymore. It sent extra oil to the top (actually mid) of the motor in the lifter valleys where they (BBC) tend to starve. Although yours seems like it's a little higher up. The only thing I can think of is with oil pressures up to 65-75 you should be getting plenty of oil to the top, and since you are not, you may have plugged push rod centers (although not likely). Hopefully you figure it out shortly. Good Luck and let us know what you find.
     
  10. Blazer1970

    Blazer1970 1/2 ton status

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Are you sure that the lifters are correct for the motor? It would be easy to end up with a set that are the correct diameter, but the oil holes in the sides are in the wrong location for the block that you have. I think all BB lifters are the same, but maybe you got small block lifters or something?
     
  11. Scorpion

    Scorpion Registered Member

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    I hate to tell you this but I had this same experience with my '69 chevelle. After putting the second cam, lifters, etc. in the motor, I decided that I should get some better answers as I didn't want to repeat this every 3k. I went and talked to a friend at the Chevy dealership. We talked to a couple of the old-timer heavy duty guys (25 years they've been working on GMs) and they said that some of the 396 (and 402) blocks were prone to upper end oiling problems. They couldn't remember if it was a casting issue with the block or what the deal was but it had actually been addressed by GM many years ago. The only other thing I remember from my problem is that the damage was much worse on the back end of the block because the front was getting just a little more oil. I hope this isn't the case for you as it will get much more expensive before you'll get any exact answers.

    Best of luck.
     
  12. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Where is pressure sender located for the gage? There are multiple ports on most engines. The port above the oil filter is going to show more main pressure. Pressure up at the fitting by the distributor is going to me more of a mix. Some engines have a fitting at the front of the block.
    What I would do is see if this motor has the front fitting. If it does check pressure there. That's going to be at the end of the jounal that feeds the cam. If you have good pressure there then it may not be the block at all. What may have happend is the plugs in the end of the block under the timming cover are not installed. another possiblility is bad lifters. The push rods get the oil through the lifter.
    THe fact that your showing so good of pressure where the sender is leads me to think those plugs are out on the lifter runs or a problem with the lifters. Or the restrictor screws. I think your going to get out of this without a block issue. Might have to pull the front of the engine down.
     
  13. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Grimmy,

    The current pressure gauge uses the rear mounted one above the oil filter.....that's where the mechanical stock gauge went, so when I swapped out my gauges I re-used that location and put the electrical sender there.

    The problem with this whole issue, is that it's gonna take a LOT of time to figure out and with 21 days to Moab, time is not one of the things I've got a lot of....especially with as much OTHER stuff as I still need to get done. If I spend all this time tearing the motor down and can't find anything obvious, I probably won't have enough time left to acquire and install a new motor...... /forums/images/icons/frown.gif
     
  14. Burt4x4

    Burt4x4 3/4 ton status

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    I can't help but I can CRY FOR YOU!!!!!!!!!!!!
    WWWWWWWWWWAAAAAAAAAAAAAAAAAA!!!!
    I hope hope hope you get that fixed!!
     
  15. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Hay the pressure is on! Put my truck together for a year (floors were gone only time I had driven the truck was 5.5 miles from the guy I bought it froms drive to my driveway). Drive it for emmisions inspection and it's shifting funny. 1st feels fine then it would shift and feel funny and no 2-3 shift. Pulled the tranny open it up and it sounded like broken glass. Sprag was blown. I had never rebuilt a tranny before in my life. Ordered the parts. They arived on Friday. Get inspecting it and the stator shaft splines are toast. Foward drive drum is screwed up from the sprag blowing. Run to my local tranny shop and he sells me some good used parts. Proceed to rebuild my first transmission. Finish putting it together and get it back in the truck Sunday Evening. Drive it around the block. Seems ok. Drive it a few times durring the week after work. Thursday Afternoon I drive it 2 hours to the trailride/ Convention I had helped plan for over a year and wheeled all weekend. /forums/images/icons/smile.gif You can do it.
     
  16. Swanson52

    Swanson52 1/2 ton status

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    This is probably a stretch, even if I am right...I *THINK* early 396 engines used a grooved rear cam bearing, with the later using a standard...could someone have installed the earlier grooved type, causing oil to not lube the cam and top end? /forums/images/icons/confused.gif Wish I could help ya more.
     
  17. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    The cam bearing is probably the next "simple" thing we are going to check...hopefully the wrong style is in there, and it's somehow locking oil from getting up to the rocker area.....
     
  18. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Gokartergo...
    I posted a little while ago about my 454 getting a lot of oil to the top end... to the point where oil comes out of the breathers past 2 baffles!

    I'm sure greg wishes he had this problem right about now.

    Good Luck Greg!!!
     
  19. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Ryan,

    YES I do!!!!

    Looks like Scott and I are going to pull the motor to check the cam bearing...maybe it's the wrong style for the block and doesn't have the groove cut in it?

    Any chance you have a cherry picker or engine stand I could borrow for a week or so? I am probably going to pull the front clip off the truck starting Friday night (it's supposed to be easy) and then maybe get the engine up-and out on Saturday if possible.

    I'm really gonna push to get this motor out, fixed, and back in before Moab. This is a HUGE setback on an already tight schedule for me, so I'm hoping for a little good fortune here...... /forums/images/icons/smile.gif
     
  20. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

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    Re: Big-Block Chevy....No oil pressure in top of motor?

    Did you pull the timing cover and check the front galley plugs? There just like small freeze plugs and 1, 2, or all 3 may have popped out or werent installed in the first place...
     

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