Results 1 to 11 of 11

Thread: 2000 4.3 questions with internal/external a/f leak

  1. #1
    Registered User
    Join Date
    Apr 2013
    Posts
    1

    2000 4.3 questions with internal/external a/f leak

    hey every one. i havent been on here in ages and its also been a while since ive fooled with a 4.3.

    i just got a 00 blazer handed to me. ran it a little bit and it overheats.

    i have coolant gushing out above the bell housing for the trans and its made its way into the oil as well.
    its not the heater core and i cannot catch it flowing actively seems like it builds pressure then releases.

    question: cant remember if the 4.3 has freeze out plugs on the rear of the block or not?

  2. #2
    I'm BATMAN! Harley's Avatar
    Join Date
    Jun 2003
    Location
    Warren, MI
    Posts
    2,420
    I'm pretty sure there are freeze plugs in the back of the block behind the flywheel/flexplate (inside the bellhousing), but if coolant is in the oil I'd suspect intake gaskets first and headgaskets second.
    Black 'n Tanazer, Long Bed, Coupe Quattro, Old Caddy, Old Rice

    Member of the SCUDS Task Force
    Spike Clean Up & Disposal Service

  3. #3
    Senior Member u_aint_REDie's Avatar
    Join Date
    Nov 2001
    Location
    South NJ
    Posts
    2,356
    That's where I'm starting but the rate the a/f is coming out seems alarming and makes me lean toward a freeze out plug it's certainly no drip but more like a 1/2" hole back there with an open faucet I can't remember for the life of me and I'm getting mixed answers everywhere. It's dead 50/50 if there are freeze plugs back there or not.
    1985 Chevy s-10 Blazer 4x4
    2000 Chevy s-10 LS Standard Cab

  4. #4
    I'm BATMAN! Harley's Avatar
    Join Date
    Jun 2003
    Location
    Warren, MI
    Posts
    2,420
    If they are there I can guarantee they aren't above the bellhousing, but inside of it.
    Black 'n Tanazer, Long Bed, Coupe Quattro, Old Caddy, Old Rice

    Member of the SCUDS Task Force
    Spike Clean Up & Disposal Service

  5. #5
    Administrator Blazin Low's Avatar
    Join Date
    Oct 2001
    Location
    In Front of You
    Posts
    4,704
    hey dude, whats up!
    this is a test of the sig

  6. #6
    Senior Member u_aint_REDie's Avatar
    Join Date
    Nov 2001
    Location
    South NJ
    Posts
    2,356
    got laid off of work and bored. so im gathering mini trucks and scratching my head on what to do with them. after i get my old lady's blazer running agian so i can have my truck back though i think its a lost cause she fell in love with the 383 so i may be beat lol.
    1985 Chevy s-10 Blazer 4x4
    2000 Chevy s-10 LS Standard Cab

  7. #7
    Senior Member u_aint_REDie's Avatar
    Join Date
    Nov 2001
    Location
    South NJ
    Posts
    2,356
    also. back to my original problem. i cant replicate the external a/f leak and it will not over heat again. however. my radiator is building a lot of pressure but not over heating.
    shouldnt the pressure release through the over flow reservoir? why would it continue to build pressure on the cap? i just got started on this thing. the previous owner was an idiot and had no idea what he was doing when he swapped the engine.

    there are to many variables and im unsure of maybe some one could share there thoughts.

    the trucks a 98 blazer 4x4

    the new engine im told is a 00 and dont know what it came from.

    i believe its an 02 personally.

    question: if the new engine is either year would the stock 98 computer work?
    reasons i ask is EVERY code the engine could throw comes up on the scanner. i erased them and ran it to check to see if anywhere old and every one came back.
    o2 sensor, maf, iac, running rich bank 1 and 2, theres something like 13 codes

    it really cant be possible they all went bad at once.

    it runs rich as ive ever seen anything run and has a horrible hesitation i drove it 20 miles and burned a half tank of fuel. and im not exaggerating.

    thoughts?
    1985 Chevy s-10 Blazer 4x4
    2000 Chevy s-10 LS Standard Cab

  8. #8
    I'm BATMAN! Harley's Avatar
    Join Date
    Jun 2003
    Location
    Warren, MI
    Posts
    2,420
    The radiator cap should release pressure to the overflow at 16psi. I believe you can rent/borrow a coolant pressure test kit from the parts store that will have an attachment to test the cap. There are also combustion leak testers you can purchase like this one from Lisle:

    http://www.amazon.com/Lisle-75500-Co.../dp/B0007ZDRUI

    Excessive pressure could be from cumbustion gasses getting into the coolant from a blown head gasket, which could also cause overheating. When I first swapped a used 4.3 into my Blazer I had some overheating problems too, but the coolant was also disappearing. I eventually pulled the heads, had them decked, and replaced the gaskets, but there wasn't any obvious damage to the gasket. Engine didn't overheat after that, but can't say for sure what step in the process fixed the problem. When the heads were decked he cleaned and cleared out several oil and coolant passages too. At the same time as the head gaskets I also replaced the factory intake gaskets since those are prone to failure as well.

    Block and heads are quite similar if not the same throughout 98+. There were some changes in the intake system, sensors, and PCM (computer) during that time from what I know. The biggest was the removal of EGR sometime around 02-03.

    Should be able to run any block/heads and just swap over the sensors, intake, and PCM from the original vehicle without trouble. Knowing more one could easily interchange those parts too, but may need to make changes to the PCM depending on what was swapped.
    Black 'n Tanazer, Long Bed, Coupe Quattro, Old Caddy, Old Rice

    Member of the SCUDS Task Force
    Spike Clean Up & Disposal Service

  9. #9
    Senior Member u_aint_REDie's Avatar
    Join Date
    Nov 2001
    Location
    South NJ
    Posts
    2,356
    Any one have a clue where this plug goes? Ive been feeling around but I cant find its home.

    1985 Chevy s-10 Blazer 4x4
    2000 Chevy s-10 LS Standard Cab

  10. #10
    I'm BATMAN! Harley's Avatar
    Join Date
    Jun 2003
    Location
    Warren, MI
    Posts
    2,420
    It is most likely the knock sensor connector. Wire for that sensor is dark blue.

    The knock sensor should be below the oil pressure sender on that engine. Service document says to pull the dizzy to get to it, but you might be able to without.
    Black 'n Tanazer, Long Bed, Coupe Quattro, Old Caddy, Old Rice

    Member of the SCUDS Task Force
    Spike Clean Up & Disposal Service

  11. #11
    Senior Member u_aint_REDie's Avatar
    Join Date
    Nov 2001
    Location
    South NJ
    Posts
    2,356
    that makes sense i really need a better manual for this thing. I miss my carbs lol computers suck. thank you harley
    1985 Chevy s-10 Blazer 4x4
    2000 Chevy s-10 LS Standard Cab

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •