Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Chevy S10 - GMC S15 and Sonoma Engine and Underhood Problems



  • gonogogonogo Posts: 869
    Are you using Dexcool coolant, or green stuff?
  • Not certain - the dealer simply states replaced coolant on its invoice. Can you help me understand the difference?
  • dave8697dave8697 Posts: 1,479
    Engines blocks have sand in the passageways sometimes when new. If the first person who changed your waterpump flushed the block during the installation it should all be gone. It is abrasive on seals and bearings and could be a contributor to early failure of the factory water pump.
    I have 3 GM 4.3's including one in a Sonoma. They all have their second water pump in them but after a minimum of 70k mi.
  • gonogogonogo Posts: 869
    Dexcool is orange, the dealer would use that. If it has orange I don't know what the problem would be. If it is green that could be the problem. You can see the color in the reservoir.
  • philipk65philipk65 Posts: 3
    I have a '91 S-10 4.3 L. I'm live in California and it won't pass the emissions test. The only category it fails is the "NO - 15 mph" test.

    Before I throw money at parts I don't need. What is the cause for the truck to fail the 15 mph NO test?

    O2 sensor, cat. converter, EGR. could all be a cause, but if try to test each one the best I could.

    What about the EGR vacuum soleniod?

    Any advice would be great! Thanks Kevin
  • poncho167poncho167 Posts: 1,178
    I am sure you probably did, but they always say to run it at freeway speeds to get it warmed up before testing. Is your air filter clean and your truck in good running order otherwise?
  • philipk65philipk65 Posts: 3
    Yes, Iran it 12 miles at highway speeds before the test, and it was a clean airfilter and in good running order.
  • wmccrearywmccreary Posts: 10
    I threw a rod in my truck with 279,000 miles its been the best truck i have had so I had a rebuilt engine put in. After installed The re builder said the is a miss in engine and they think it is the E CM and I should pick it up and take it to a garage and have in diagnosed(the did not have the disnoseic tools ) so I did and they said that #4 cylinder was getting to much fuel and they tried different things and they thought it was the ECM to so I purchased a Used ECM and had it programed to my Vin# and installed it. It did not change anything it still misses at Idle and on acceleration it seems to be ok and at high rpms until you let off the gas. I don't know what to do? can you please help. thanks
  • gonogogonogo Posts: 869
    I would first pull the vacuum hose off the fuel pressure regulator. It will be on the passenger side at the rear, you will see a diaphragm housing with a hose on it. If you smell fuel or see fuel replace the regulator. Don't start the engine with the hose off, fuel may spray everywhere.
  • skohanskskohansk Posts: 3
    Lets just say that the cat isn't plugged or for that matter, has anything in it. Whereabouts would I even start looking for a vacuum leak? Also, just want to say thanks for what you guys do.
  • hoodlatchhoodlatch Mid-westPosts: 255
    Not familiar with 91 S-10 four wheel drive. Last 4 by 4 I had was a Jeep Wagoneer. The front differential and X-fer case were controlled by vacuum. All the hoses and vacuum manifold fittings that were underneath the car were weather beaten rubber and required occasional doctoring. Actually all the rubber vacuum hoses and fittings needed replacing but the jalopy was so ate up from salt, the hoses was the least of its problem.

    On the S-10 that I drive now (92, 4.3Z) I had a problem similar to yours that was bugging me to no end. Finally I accidentally came across the problem. The vacuum line that runs from the PVC valve to the front of the throttle body had a bad vacuum leak. As it turned out the plastic elbow had a serious crack on the bottom of it that you wouldn’t normally see. After I replace that it ran like a champ.

    Suggest you go hand over hand tracing all your rubber vacuum hoses back to the intake manifold. It’s time consuming but on rigs that have a little age on it like yours and mine, there’s a good chance that the vacuum hoses could have an Aortic Aneurysm.

    Good luck and keep us updated on developments. :)
  • hepner1hepner1 Posts: 2
    My 94 s10 with 2.2 4cyl suddenly started running rough. I have replaced plugs and wires after I found the #1 wire broken. It is still running rough. Any ideas where to go next?
  • hoodlatchhoodlatch Mid-westPosts: 255
    You might try running a compression check. :)
  • I have a 2002 GMC Sonoma, Single Cab, SLS, Stepside, 4.3L, 5 Speed, 2WD, with the ZQ8 Suspension Package. We have had this truck since we drove it off of the showroom floor in 2003. This truck has been great to us however I change all of the fluids more often then they should be changed. Now when I drive the truck if makes awful noises. Its fine when you accelerate but it just sounds awful when you let off of the gas or push the clutch in. I think it might be the rear end, my brother thinks it the transmission, and my dad thinks its the clutch. Anyone have any ideas? I have already pulled the rear diff cover off and the rear end looks like it might be bad. Also does anyone know how many splines this truck has on the rear axle? Any help is appreciated.
  • gonogogonogo Posts: 869
    Coasting noise is usually rear end, tell by sound coming from rear. Most likely needs bearings, if gears not damaged.
  • hepner1hepner1 Posts: 2
    Compression within 5% of spec an all 4 holes, any other ideas?
  • Out of the Blue one morning My 1995 Chevy S 10 started Missing.i started my trouble shooting by seeing what Cylinder was not firing.It was number 2.I chnged Plugs ,Plug Wires,Got a new Battery.I made sure every Plug was getting fire by Taking the wire off each plug one at a time.When i took off # 2 off the motor did not Change.I also checked for any Vacum leaks.I bought some Fuel injector Cleener and Shot it down the throttlebody.Did not make a difference.I took it to a Auto repair shop.The first thing they did was a Compression check all cylinders checked out good 120.tehn they started doing test on the injectors they checked out good.Now they are telling me that The computer might not be sending good signals to the fuel injectors,Might have to buy new computer,They tell me my Model truck has the PCM cumputer.They are suppose to call me with the final results tomorrow,Just wondering if anybody else had this kind of problem.Not sure if the computer can be reprogramed?????If anybody has any ideals i would like to here from you.Frustrated in Georgia.
  • hoodlatchhoodlatch Mid-westPosts: 255
    Some of the GM engines have EGR problems clogging up also. They make and after market gasket/screen for GM, maybe there's one for Honda too.
  • hoodlatchhoodlatch Mid-westPosts: 255
    Did you check out the coil for #2? You might try switching the coils around and see if your miss moves around also. A coil doesn't normally go out all at once like you described, but it doesn't cost anything except a little time for the procedure above. :)
  • hoodlatchhoodlatch Mid-westPosts: 255
    Compression check sounds great. That eliminates questionable valves and other innards. Suggest you might check out your coils while your in the trouble shooting mode. :)
Sign In or Register to comment.