Chevy S10 - GMC S15 and Sonoma Engine and Underhood Problems

scottzo6scottzo6 Member Posts: 1
i have a 99 sonoma 4.3 2wd recently my oil has sludged up three to for times within 2 weeks when i would start the truck in the morning it sounded like the motor was coming apart Any one know if the oil cooler can crack inside the radiator causing coolant to get in the oil????al the sludge seems to be around the filter and in the cooler lines


  • truckowner1truckowner1 Member Posts: 2
    In the process of selling my truck to future buyer when I decovered the oil leaks on the cooler hoses. Call dealer for recall possibility---no such luck with GMC. Dealers says $500 to FIX! When I checked Google I found suggestions on totally removal of Lines & Plugging openings. What shall I do?
  • truckowner1truckowner1 Member Posts: 2
    In the process of selling my truck to future buyer when I decovered the oil leaks on the cooler hoses. Call dealer for recall possibility---no such luck with GMC. Dealers says $500 to FIX! When I checked Google I found suggestions on totally removal of Lines & Plugging openings. What shall I do? ( Mileage 55K )
  • curtisacurtisa Member Posts: 2
    i have replaced fuel pump and filter even changed spark plugs bu it does not help can you help me has 2.8 liter 5 speed manual trans.
  • mrexfordmrexford Member Posts: 2
    i have a 95 s-10 that looses its antifreeze/water with no signs of leaking on the ground. i have been told it could be my freeze plugs. there is no water in the oil. oil changes are regular. so where is it going. no smoke from the tailpipe. it just smells hot all the time even when i maintain fluids. any answers?
  • donniem2donniem2 Member Posts: 2
    History: 4.3 v6, Check engine light on for about a week. Went off last time I drove it. Would not start, beat on tank and it started. Got it home, no sound from fuel pump. removed bed, removed fuel pump, connected 12v source to pump, pump ran fine. Using a test light I don't get power at the fuel pump connector, at least I don't think so. 3 sec. not alot of time to check.

    What should I check next? Which is f/pump relay? Where is ECM B fuse?
  • donniem2donniem2 Member Posts: 2
  • curtisacurtisa Member Posts: 2
  • curious_gearscurious_gears Member Posts: 60
    ok. so exactly what is it doing? dying while traveling up-hill, or just not going up the hill?
  • mrexfordmrexford Member Posts: 2
  • hoodlatchhoodlatch Member Posts: 255
    What size engine? Did you discover yet where the antifreeze is going?
  • stevenf20stevenf20 Member Posts: 3
    I recently purchased a 1999 GMC with the Vortek 4600, heaby duty suspension and locking rear axle. The truck is rated for 16-21 MPG, but I am only getting 13.5 and I do not do city driving.

    Is something wrong??
  • jpfjpf Member Posts: 496
    I have a 2000 S10 with the V6. I generally get 19 to 22 mpg on the highway. If your vehicle is 4WD, then you'll get less. If it's 2WD, then I would change the fuel filter and put some gas treatment into the tank the next time you fill up. Good luck.
  • stevenf20stevenf20 Member Posts: 3
    Do you have the heavy duty rear end?

    It is 4WD, but I would think that I should not get 6 MPG less beacuse of that. It is a small truck.
  • stevenf20stevenf20 Member Posts: 3
  • jpfjpf Member Posts: 496
    My truck is a base model with the work truck package. I consistently get about 20 mpg on the highway. You should get better than 13.5 mpg. I suggest you check all the basic stuff first, like tire pressure. Good luck.
  • gmcarfreakgmcarfreak Member Posts: 1
    :confuse: i have a 1991 GMC Jimmy 4x4 s-15 with the 4.3L engine and it was used for plowing for about 11 years and now i inherited it and it has no get up and go... the truck runs good. i replaced the fluids and thermostat. ehxaust. and lower radiator hose. my dad (former owner) told me that the person who had it before him did some underhood work and might have put the wires on wrong and that that might be why it doesnt have much go. so im just wondering if there is anywehre i can go to see some wiring diagrams... like the distributor to the spark plugs. just so i can see if they are in the right locations.
  • tjanzentjanzen Member Posts: 1
    Question: Can I replace my air injection exhaust manifold with a standard manifold (no air injection)?

    My cracked manifold has air injection system ports. Unfortunately this manifold is rather rare and expensive ($276). I can get a standard manifold for $130 in town. The standard manifold doesn't have air injection system. Is the computer expecting this input to the exhaust? There's an oxygen sensor(s) downstream. The dealership thinks it's a CA emissions thing. Does the standard engine and the air injection engine use the same computer?
  • 34theshow34theshow Member Posts: 1
    Donniem2, did you ever find the solution to your problem? I drive a 2001 GMC Sonoma, and it appears that I'm having the exact same problem. Please help if you can.
  • jnoltiejnoltie Member Posts: 1
    I recently bought a used 1998 S-10 pickup (didnt come with owners manual), and just spent an hour looking for the oil filter so I can change the oil but can't find the freakin' thing. Where is it? It is a 2.2 L engine.

    Also there's a nearly empty white plastic jug on the front right side, just behind the battery. What is supposed to go in there? My guess is coolant since its around where the coolant place was for my car, and I didnt see anything else around that held coolant.
  • ortonorton Member Posts: 2
  • ortonorton Member Posts: 2
    s the a easy way or method to getting to the wires and plug to change out? I seem to have a wire going bad on me. The shop changed the plugs after a service engine light can on, the wanted to change the wires, but I wasn't going to pay $200.00 for a set from them. The light went away and seemed to run fine for a couple days. Under a load the engine seems to knock a bit and a slight stall. So any ideas on how to get to the left side wire that you can't even see? lol
  • rthomp3rthomp3 Member Posts: 1
    hello I have a 2002 GMC ZR2 4.3 and i have the same problem. I seem to be going thru coolant but i can't seem to find where its going. I do also have this gurgling sound coming from my heater core area only on acceleration. All fluids are at recomended levels so i don't know what else to try. Ray
  • hoodlatchhoodlatch Member Posts: 255
    You might try removing the wheel and going in over the upper A-frame. It worked for me. :)
  • chuck1983chuck1983 Member Posts: 1
    hi i have an oil leak somewhere and i cant find it i changed my valve pan gasket and it still leaking on top of valve cover please help :(
  • texashippietexashippie Member Posts: 2
    Hi, Does anyone here know if I can put an older 4.3 in my 91 GMC Sonoma. I need to replace my motor. I found a 4.3 L out of an 85 that has been rebuilt, just not sure if it will work.

    It seems like any 4.3 L should work, if I just used the long block. With my intake and throttle body.

    I'm new to this truck so not sure what will work.

    Any help will be appreciated. :sick:
  • jrockojrocko Member Posts: 2
    I am having the same issue. I thought the fuel pump was going bad. Sometimes it would pump and sometimes not, so I replaced the pump, sending unit, and filter. It started up immediately after replacing the parts, but died about 5 miles later. Now it runs for a minute or two, then dies, and will start again if I let it sit (15-30mins). My only idea, is that maybe its not getting a signal from the ECM or maybe a bad relay. Any ideas?
  • 5speedfiend5speedfiend Member Posts: 5
  • 5speedfiend5speedfiend Member Posts: 5
    I know I'm not the only one with this problem, but still haven't seen a definite solution to this problem in this forum yet! Here's my story: Truck was running great, then it suddenly died. Motor would crank over, but not fire up. Had towed to shop, hooked up to computer and told crank sensor was bad. Changed crank sensor and truck fired up with a bad miss on all cylinders. Checked computer again and said IAC was bad. Replaced that, no difference. Then proceeded to change cap, rotor, plugs, coil, ignition module, cam sensor, cleaned,but not replaced, EGR valve(VERY little carbon build-up plus no trouble code for it). Gave up and took to dealer who said injector's might be clogged and ran a cleaner through it that uses nitrogen to "pop" them clear. NO change. They said #2 and #4 were open, but all others were clogged. Said it be $1,000 to replace injectors. Took truck home and found a place that sent me a complete reconditioned assembly w/new pressure regulator for $219. Then put that one in and still no change. Took back to shop and checked fuel pressure, it was on low end of specs so I replaced that and still no difference. Oxygen sensors appear to work correctly as they are changing readings constantly. I'm at my wits end and do not wish to give up on it as the truck is in excellent shape w/240,000 miles(but only 40,000 on new GM long block that I had installed 2 years ago). Now keep in mind, after I changed the Crank sensor and IAC motor, the only code that shows up is random/multiple cylinder misfire. Anyone Have another idea?
  • jpfjpf Member Posts: 496
    Back in 1999 I bought an 86 Lebaron convertible with the Chrysler 2.2 engine. The owner that I bought the car from replaced the engine with a 2.2 out of an 88 Dodge Shadow. He said the most important thing is to make sure the engine bolt patterns match. Although it's the same 4.3 engine, the bolt patterns may differ between an 85 and a 91. Good luck.
  • jbikulciusjbikulcius Member Posts: 1
    I have a 92 S-10 with a 2.8 in it.saturday i pulled it in the garage for a basic tune-up and oil change. changed the oil,distributor cap,rotor,spark plugs,spark plug wires,air filter,fuel filter. went to start it up nothing happened rolled over like crazy but never fired.sunday re-installed all the old stuff that it started with when i pulled it in and nothing, rolls over no fire. so i replaced the coil and now only get yellow spark,any ideas i'm about out of them and the wife wants her car back. :mad:
  • hoodlatchhoodlatch Member Posts: 255
    had the same problem once with a 350 (similar engine). we finally had to pull distributor and replace pick-up coil.
  • 5speedfiend5speedfiend Member Posts: 5
    **Update** I haven't totally fixed problem yet but I started checking for wiring problems. Found that both battery cables were severly corroded inside their plastic housings. So I've replaced the cables and the motor is now running much stronger but still has the misfire. Now a new code has come up, crank sensor intermittant.
  • sonoma4muddersonoma4mudder Member Posts: 1
    I had the exact same problem with my 91 sonoma, 4cyl - 2.5. I had just tuned it and everything.

    It ended up being a distributor problem - which became a bigger problem with the limited production run of these engines.

    I ended up installing a Multiple Spark Discharge - distributorless spark delivery system.

    Now the truck runs like a dream...a little 4 banger pounding along like a v6 - I recommend the MSD for ANYONE with spark issues in the the older s series trucks.
  • 5speedfiend5speedfiend Member Posts: 5
    *** Final update *** The problem is now solved. It appears that the crank positon sensor that was replaced directly after problem arose was either the wrong one or was bad. Replaced sensor with new one and truck runs perfectly. This was rather annoying as the no codes alluding to this were seen until EVERY sensor on top of engine was replaced.
  • mikeythekatmikeythekat Member Posts: 3
    I have a 1997 Sonoma with 4.3 V-6. I'm getting the SES light and Autozone says there are 2 codes and both say that #3 clyinder is misfiring. My truck worked fine until it sat in my garage for almost a week when it was in the 20's and 30's out every day. I then went to leave for work an now it idles rough, sounds like a hole in my muffler an the SES light is always on. I have replaced the plugs and wires and rest the computer buy still giving same SES codes. One thing I noticed when changing the #3 plu was there was a little oil on it. Has anyone else had this problem? I have read somepeople have had similar problems but not this issue. Can anyone please help? I love my truck and don't want to have major engine problems.
  • jnealjneal Member Posts: 247
    What are the codes??
  • mikeythekatmikeythekat Member Posts: 3
    I think they are 302? I'm not 100% though.
  • chukchuk Member Posts: 10
    I am trying to replace the heater core in my 2000 S-Blazer. I got the dash out and the heater/ventilation unit loose except for what appear to be 2 bolts coming through from the engine side of the firewall at the bottom. I am working from a Haynes manual, but there is no mention of these bolts. If I am right, the only recourse is to depressurize the A/C system & remove the evaporator to get to these 2 bolts. Seems ridiculous to have to do this to replace a heater core.

    Looking for any help or advice that might be out there.

  • elfeoelfeo Member Posts: 1
    Dear thebigal,
    Sounds like you might have a 99 cent problem. Remove your distributor cap and peek behind at the base of the distributor to see if oil is seeping from there. You might have to use a small mirror and flashlight to look back there. If so remove your distributor (make sure and turn crank to TDC and mark direction of rotor before removing) and replace the rubber O-ring on the distributor housing. This O-ring will cost about 99 cents at your local auto parts shop. Bring the distributor with you to the parts shop so they can match up the right O-ring. They usually carry an assortment of different sizes. I had a similar problem recently on my '93 Sonoma (2.8 V6) and was relieved to find out it wasn't the rear main seal. Hope this helps you out.
  • lakelivenlakeliven Member Posts: 4
    I have a 1996 Chevy s10 and the number 3 cylinder misfires constantly. I have had to replace the spark plug 3 times because it is causing the porcelain part of the spark plug to crack. Any ideas why this is happening? I have replace plug wire, and spark plugs.
  • hoodlatchhoodlatch Member Posts: 255
    This is the first time I ever heard of a cylinder misfiring caused the porcelain to go bad. That's a new one for me. One time I got a plug that had faulty porcelain. Also on occasion I have cracked the porcelain installing the plug. Is it possible that the socket isn't properly aligned when tightening and causing the plug to crack? I know some of the plugs on my S-10 are a bare to get to, especially on the driver’s side. What I do now when its time to change out the plugs is remove the front wheels and go in above the A-frame with long extensions on 3/8 in drive. As for the miss on #3 cyl., have you ran a compression check?
    Good luck :)
  • lakelivenlakeliven Member Posts: 4
    The compression has been checked and everything appears to be fine. It's weird because I will be driving down the road, then the service engine light comes on and then there is a big pop sound and that's when I know the porcelain on the spark plug has cracked. I just keep an extra spark plug handy.
  • jnealjneal Member Posts: 247
    When you say "the porcelain is cracked" are you talking about the top part of the plug or the part that is actually inside the cylinder??
  • lakelivenlakeliven Member Posts: 4
    It has cracked once where the porcelain goes into the plug and then again about mid-way down the porcelain.
  • mikeythekatmikeythekat Member Posts: 3
  • lakelivenlakeliven Member Posts: 4
  • jnealjneal Member Posts: 247
    As hoodlatch said, some plugs can be a bear to get to....are you sure you aren't cracking them when you install them?

    I'm still not sure from your answer whether the plug is cracking inside the cylinder or outside. I'm not aware of anything that can be wrong with the engine that would cause the plug to crack on the outside of the cylinder. Inside is a different story...detonation, backfiring etc......several things can crack a plug internally.
  • s10frustrations10frustration Member Posts: 3
    I have a 2001 Chevy S10, automatic with a 2.2 engine code 5.

    It was running great when one very cold morning on the way to work it died and blew oil out of the dip stick and all over the motor.

    When I restarted the truck, it was very hard to get started. It was missing terribly and the crank case pressure was so high that it blows the dip stick out. A pressure test was good except one cylinder was getting so much fuel that it was making my compression gage shoot up to 300 psi.

    I was told o change the fuel regulator, which is in the fuel filter. I should mention that this truck has California Emmissions. After that the truck still ran like one cylinder was missing. I cahnged the plugs, coils, ignition module and catalytic converter with no success.

    If the truck is setting idling in park and you rev it up, it begins cutting out and will begin to puffing smoke out of the dip stick. At one point it was so bad that it blew the dipstick out so hard that it knocked a chunk out of my wall.

    Does anyone have any ideas? I am stumped, frustrated and about broke! The truck ran beautiful until that morning. I did have one code present P0410 "secondary air injection malfunction" after I replaced the fuel regulator this code went away and I have no codes present.

    I did read that you can get this code if you are getting excessive fuel.

    I need help!!!!!!!
  • hoodlatchhoodlatch Member Posts: 255
    It sounds like your getting compression in the crank case. If that's the case my guess would be something like a hole in a piston or broken rings or both. Is it possible you dropped a valve and knocked a hole in the top of a piston?
  • s10frustrations10frustration Member Posts: 3
    Thanks for the response. Last night I removed the valve cover and the rocker arms and then using compressed air, I pressurized each cylinder, every one had some sort of leak into the crankcase, #1 and #4 were really bad. #4 dumped the air right back out of the dip stick. I believe your right, the rings are probably shot. It was running great until that one minute.

    I am in the process of taking the head off. I'll let you know what I find.
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