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  1. #1

    Default Coolant leaking by starter


    I just signed up to the forum as I have a little problem with my S10 and was hoping someone could give me some advice as to what the problem is as I sure can't see it.

    I have a 2002 S10 (automatic) with about 145K on it. Last Saturday when I pulled into the gas station to fill it, I noticed steam. Looking under the truck, there was coolant dripping on the exhaust pipe.

    After I got back home, I jacked the front end up and looking from above and below (engine running), I couldn't see where the coolant was coming from. I wiped off the starter as that was where the coolant was dripping from and sure enough it started flowing down the side of the starter again.

    From this far back on the engine, does anyone has a guess as to where the leak is coming from? Heater hose, freeze plug? I guess it could be like a leaking roof - where the water is dripping may not necessarily be where the hole is......

    It seems to only leak 'under pressure'. I put a pan under it to catch the fluid but the dripping eventually stops.

    I do some of my own work on the truck (transmission fluid change, oil change, brakes, shocks, etc) but I kind of wanted to ask about this so I have an idea where to start. Haven't done a pressure test, that is probably the first thing I should do, but any ideas of what is "probably" the source of the leak?

    Thanks in advance.


  2. #2

    mfleetwood's Avatar
    Join Date
    Jul 2010
    Denver, CO
    Blog Entries


    Moved thread to correct section as this should help in getting more responses, faster.

    Welcome to the Club and I hope your problem has an easy and/or inexpensive answer.

    Mike (Denver, CO) - 2008 Sierra 1500 Z71 SLE 5.3L 4WD

    SUSPENSION: Rancho 4" Suspension Lift; Rancho RS9000XL Shocks; Rancho Skid Plates; Rancho MyRide Wireless Shock Controller;
    BFG All Terrain KO 315/70/17
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    PERFORMANCE: DiableSport Predator Tuner; Custom Tuned by Diablew; Magnaflow Exhaust; AFE Cold Air Intake
    ELECTRONICS: Kenwood DNX6180 Touchscreen; Subthump box w/10" Kicker; Driver Information Center (DIC); Rear View Camera
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  3. #3
    Jr. Engineer Jamm3r's Avatar
    Join Date
    Dec 2012
    Minneapolis area


    I'd be guessing, but maybe a frost plug.

    Pressure testers are worth their weight in gold for this sort of thing because you can pressurize the water jacket while the truck is cold and engine stopped and poke around without hurting yourself on hot or moving parts. I have one and use it all the time for this sort of stuff.
    Minneapolis area - 1997 K2500 regular cab long bed + 8.5' Western Unimount plow + modified transmission + 2nd battery + modified camper charge circuit + 1971 Cayo camper -and- 2004 4x4 Suburban 2500 8.1 + Maxbrake controller + 2nd battery + modified trailer charge circuit + Reese receiver, pulls 30' Airstream trailer

  4. #4


    I think your freeze plug towards the back of the engine has rusted out. ( not that uncommon on an engine that old) You most like need to disconnect the batter, remover the starter and get some shop towels and wipe down the side of the engine where the starter, Passengers side, and see what condition all of the freeze out plugs are in. most likely if one has rotted away, the others aren't far behind. Use a big screw driver and knock it through the bad plug and gently pry it out, get new ones as in what ever size the other ae, just gently tap the new plug in and if it's not too hard to see, push it in till the rim of the freeze-out plug is flush with the engine block. Good luck, not all that tough a job, but time consuming.

    Oh, welcome to this forum.
    Last edited by JTward1; 01-04-2013 at 10:22 AM.

  5. #5


    Thanks for the advice; guess I know what I'll be doing this weekend....... Too bad GM put the exhaust pipe in the way of dropping out the starter. Hope those nuts cooperate........

  6. #6

    Join Date
    Feb 2008
    Red Wing, Minnesota, United States


    I believe the coolant temp sensor may back there too, I know it's back that way on the vortec 5.7,
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual

  7. #7


    Be sure the lower intake is dry before you take things apart. The 4.3's are well known for lower intakes leaking pretty steady when hot.
    01' 1500 LT Z71 ECSB 5.3L
    line-x'd front brush guard with KC Daylighters, 6000k HID lows and highs, rewired highbeams, Trans-go mild shift kit, custom stainless duals, 3500 dually OEM taillights, K&N CAI. Still have OEM fender flairs and leveling kit in boxes waiting for time.

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