Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

'88 Suburban oil pressure question

Discussion in 'The Garage' started by bishopbiz, Oct 17, 2005.

  1. bishopbiz

    bishopbiz Newbie

    Joined:
    Oct 17, 2005
    Posts:
    4
    Likes Received:
    0
    Location:
    Missouri
    New to the site...
    I've got a 1988 Suburban, 350, 4x4... and a question about oil pressure. When the engine is cold, the oil pressure is fine. (have mechanical guage) When the engine gets up to temp, the oil pressure drops at idle... at a stop sign, for instance. There are no motor distress noises, and when I start rolling again, the rpm's bring the pressure right back up.
    I've gotten rid of most of the gremlins that have been plaguing me with this truck, and would like to keep it around for as long as possible. Any advice/input would be greatly appreciated. Thanks!
    I discovered the cure to the sagging front doors on this site today, so I can finally take care of that tomorrow.
     
  2. 4xcrazy

    4xcrazy 3/4 ton status

    Joined:
    Oct 31, 2003
    Posts:
    9,472
    Likes Received:
    5
    Location:
    Olympia/Lacey, Washington
    ya need to post up some readings for any real advise,,,
     
  3. ratchetgmc

    ratchetgmc Registered Member

    Joined:
    Mar 23, 2005
    Posts:
    11
    Likes Received:
    0
    Location:
    gloucester,va
    i also have the sagging front doors. please give me the answer that you have discovered. the answer to your problem that you may not want to hear. motor needs rebuilding. oil pressure is fine when cold because oil is thick. when comes up to temp oil thins out. no pressure because you have lost some of your motor clearences.
     
  4. 4xcrazy

    4xcrazy 3/4 ton status

    Joined:
    Oct 31, 2003
    Posts:
    9,472
    Likes Received:
    5
    Location:
    Olympia/Lacey, Washington
    try thicker oil too, i only run 20/50 because mine has 230k on it, oil pressure is still up around 30 psi though
     
  5. ratchetgmc

    ratchetgmc Registered Member

    Joined:
    Mar 23, 2005
    Posts:
    11
    Likes Received:
    0
    Location:
    gloucester,va
    some people will also add oil additives; stp;etc
     
  6. bishopbiz

    bishopbiz Newbie

    Joined:
    Oct 17, 2005
    Posts:
    4
    Likes Received:
    0
    Location:
    Missouri
    More Info - Readings...

    Okay... thanks. New to this.

    When the engine is cold, oil pressure is at 40-45. When the engine gets up to temp (195), oil pressure steadily drops to 10 when I have to stop. I have been putting it in neutral at stops to keep the rpm's up, which brings the oil pressure back up.
    I drive the truck about a mile and a half to work, so very little driving with the engine up to temp. Have been leery of any long drives because of my concerns about how it's running.
    Any suggestions?
    Thanks!
     
  7. bishopbiz

    bishopbiz Newbie

    Joined:
    Oct 17, 2005
    Posts:
    4
    Likes Received:
    0
    Location:
    Missouri
    More...

    I've got about 208K miles on the truck, though the motor was 'refreshed' 70K miles ago. Going to be switching from a Fram oil filter to Wix, and someone had suggested using CDMax2. Picked some up, but hesitant to use it. Is anyone familiar with the stuff? Would I have to drive it for awhile after putting it in? Let it sit and idle? Could it be oil pump itself?
    And thanks for the responses!
     
  8. bishopbiz

    bishopbiz Newbie

    Joined:
    Oct 17, 2005
    Posts:
    4
    Likes Received:
    0
    Location:
    Missouri
    sagging doors

    The problem is... the bushings and hinge pins are toast... will cost $7-15 for hinge refurbish kits at the parts store.
     
  9. diesel4me

    diesel4me 1 ton status Premium Member

    Joined:
    Jul 24, 2003
    Posts:
    17,568
    Likes Received:
    943
    Location:
    Massachussetts
    fairly normal...

    I had a 400 SB in my 74 K20 with the same symptoms for many years..oil pressure never went over 40 psi cold,after it warmed up it would drop to 10 psi at idle in drive..I tried adding Lucas oil treatment,STP,etc,20w-50 oil,it all helped slightly,but no real dramatic increase in oil pressure..

    I would not worry about it too much if there is no noisy lifters or knocking bearings..your motor probably has high mileage,and the bearings are showing their age(a bit on the loose side)..mine never had any noises,even upon cold start up,so I just lived with the low oil pressure--a new oil pump might have helped,but I never did anything about it--.

    I had a few other chevy V8's the same way..and drove them a long time..the only "real" fix is an overhaul..putting a new oil pump in a motor with loose bearings won't increase pressure much,but it could flood the cylinder walls with oil and make it smoke and burn oil.. :crazy:
     

Share This Page