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Need some HELP!!

Discussion in 'Chevy Trucks' started by B&E snowplowing, Nov 26, 2006.

  1. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    I have a 1990 GMC 2500 with about 200,000km with a 8' Western....Here's my problem. When the engine is cold I have excellent oil pressure, as the engine heats up my oil pressure goes down. It actually goes down to the point that when I am sitting at a red light, in gear the gauge goes straight to zero. When the light turns green, and I step on the gas the oil pressure goes back up to 125 to 150 kpl.

    I started to hear a knocking noise about a week ago only when the engine was cold, or was under pressure. (going up a large hill with a heavy load) Took it into the shop, and was told I had a cracked flywheel. $1000.00 later the noise is gone but I am concerned about the oil pressure.

    Thought I had a faulty sending unit, so I replaced it. Didn't work. Thought that maybe the gauge was on it's way out, so I replaced it. Didn't work. The only thing that happened when I replaced the dash cluster is that the speedometer stopped working, so I put the old cluster back in and still low oil pressure and guess what? STILL NO SPEEDOMETER.

    Took the truck to the shop once again thinking I was about to replace a motor and found out that there is a "little" play in the thrust berings. Mechanic said No need to change it, it could last 1 month or 10 years.

    HELP someone, cause now I don't know what to do.

    Question 1 Could the thrust berings cause low oil pressure.
    Question 2 Any idea as to why the speedometer stopped working.
    Question 3 Should I just replace the engine.

    With the way my luck has been going, I will get out the first night of plowing and have NO oil pressure, NO speedometer, and most likely NO engine left.

    Sorry this was so long winded, but I'm really looking for some help.
  2. Joe D

    Joe D Senior Member
    Messages: 605

    Get a mechanical guage and check pressure with that before doing anything. It sounds like worn main bearings but check the pressure 1st.
  3. midnightsun13

    midnightsun13 Junior Member
    Messages: 25

    your speedometer/cluster is electric i agree with getting a mechanical guage and checking the oil pressure....if the mechanical guage gives a good reading.....your problem is electrical....theres a warning on the back of the cluster to avoid static electricity.....its possible something may have gotten fried in the cluster or wiring to the cluster when the new one was intstalled that made the speedo stop working
  4. Rcgm

    Rcgm Senior Member
    Messages: 613

    I had a 1996 chevy 2500 did the same thing.I took it in it leaked some oil and a little antifreeze towards the back of the engine.It was some kind of seal the mechanic told me that seal can cause your oil pressure gauge to run low.I can't recall what seal it was.Does it leak oil or antifreeze?Let me guess your gas guage doesn't work either does it?Mine went out.
    I ended up selling that truck and miss it so much now I loved that truck.I would never mind I just miss old betsy:D

  5. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    Need HELP!

    Yes, I have an oil leak at the back of the engine, but no coolant leaks. I use no coolant at all. My gas gauge does work. I don't know what to think because the truck runs great. No noises, knocks or rattles coming from the engine just low oil pressure.

    I don't really want to put an engine in it....What if I run thicker oil in it. I currently use 10W30 ?

    So far the winter has been extremely poor. No snow means no money....No money means I really can't afford $3000.00 for an engine. See I really need some HELP.
  6. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Your motor is likely just tired. Worn bearings cause larger clearances and lowers oil pressure. I agree that checking with a known mechanical guage should be your first move. I would find it unlikely that the oil pump is worn, and the changes from cold to warm tend to support the theory of excess clearance.

    The solution is a new set of bearings in the engine, but that is probably more work than you are prepared to do. A high pressure relief valve spring in the pump would also work but obviously that means dropping the pan.

    What would I do? Do an oil change and install 20W50. Keep in mind though, that especially in the colder monthes (ie: now) you will need a starter and battery in tip-top shape to crank that sucker in the middle of the night. Consider having a block heater plugged in then if so equipped. This will definately raise the oil pressure!
  7. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    Thanks for all the help

    I really want to thank everyone for all there help. Looks like I'm going with the 20W50, cause I can't see me spending $3000.00 for a truck that is 16 years old.

    Good thing I have a block heater, Even though I have the block heater plugged in, is it still going to be a son-of-a-gun to turn over in the middle of the night when we need it the most.

    Here's an idea, I get up every hour and go outside and start the truck... LOL LOL

    Once again thanks for all your help..Gotta admit I love this site.
  8. Rcgm

    Rcgm Senior Member
    Messages: 613

    LOL the idea sounds great :nono: I got a better idea see if you can get your wife to go out every hour and start it up to keep it warm:redbounce Let us know what she says when you run that one by her.LOL

  9. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    ok I ran that idea by my wife. Here was her response..... @^%$##%^ @$%&& @#$%^*&&& #$#$%^% need I say anymore LOL LOL