What's In A Tune-Up?

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by mrcaddy, Apr 16, 2010.

  1. mrcaddy

    mrcaddy Rockstar

    I have a 1995 Chevy Suburban C1500 2wd with 350 and 205,000 miles. I think it's really going through the gas af of late and I know it's been awhile since it's been serviced. What all should I look at? Is there a list? I was going to go through the Chilton's list, but how accurate is that? I know it needs new plugs as they have been in there since 50,000 miles. This vehicle runs like a top and never shows the Check Engine Light. The fuel injectors are rattling/tapping like crazy.
    What do you think? Thanks,Scott
  2. ejohnson03

    ejohnson03 Epic Member 5+ Years 1000 Posts

    Well... since you are asking us for our opinions...

    With that many miles on her, I would consider a rebuild. But before just jumping into it, have a compression check done on all the cylinders.

    The taping that you are hearing may not be the injectors, but rather the Valves rattling in the cylinder head.

    If you know a very reputable mechanic, it wouldn't hurt to have them give it a look.

    Depending on your type of usage for the truck, transportation or hauling stuff, and on the size of your budget, you may want to just leave it alone.

    If it ain't broke, don't fix it, as the saying goes...
  3. mrcaddy

    mrcaddy Rockstar

    I might do the compression check. It runs real smoth, but I guess it would be good to know. The tapping is coming from the fuel injectors. No one around here will believe me and my favorite mechanic's hearing is failing so he can't hear it. It is more of a fast whirring noise. I've asked about it before, but it seems to stump everyone. It can be heard much better while sitting in the driver's seat with the radio off, but one day I took the air cleaner off and heard the noise clearer. Also, I can feel it when I put a finger on one of them.
    Anyway, no heavy hauling, just back and forth to work. I really don't use it to the full potential and probably should get rid of it.
    Hey, I had the tranny rebuilt at 156,000 (I think). Is it time to change the filter? Scott
  4. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    Things I would probably change/check as part of a tune-up:

    1) Replace spark plugs
    2) Check spark plug wires
    3) fuel filter
    4) air filter
    5) distributor cap/rotor
    6) ignition timing

    That would be a good start.
  5. j-schmizzle

    j-schmizzle Rockstar 4 Years 1000 Posts

    X² + check out the AT fluid & gasket & cooling fluids + check u're brakes
  6. Z71_guy

    Z71_guy Epic Member 5+ Years 1000 Posts

    dont forget the PCV valve
  7. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    This is what I do:

    Start with a warm engine. Pull the Throttle Body off. Remove IAC and TPS. Do NOT remove the throttle plate. TB cleaner and toothbrush, go to town. I disengage the return spring, make it easier to clean the plate and bore. It should look just like new when you are done. Put the IAC and TPS back on the TB, and put it back on the manifold. If it's a TBI, you will need a new gasket, Vortec reuse the old one. Start the engine.

    Next comes the fun part, Seafoam. Get the engine up to temp. Pull the air cleaner/snorkel off the TB. Start the engine, and slowly pour the Seafoam in. Pour it in just fast enough so the engine doesn't stall. Shut it off as soon as you are done. The longer you let the SF sit, the better. A couple hours is good. While you are waiting, it's a good time to change your fuel and air filters.

    Pull your ECM fuses to clear any codes from putting the Seafoam in and running without the MAF.

    If you have a Vortec, clean your Mass Airflow Sensor. Use CRC MAF Cleaner only. I take the MAF all apart, so I can clean the wires really well on both sides. Be very careful with the sensor. Only use the spray on the wires. Do not touch the wires with anything. No brushes, Q-Tips, fingers, nothing. Don't let the plastic tube hit the wires, or use compressed air. Put it all back together.

    After the Seafoam has set for an hour or two, put the ECM fuses back in and start it up. Take it for a ride. You will have quite a smoke show coming out the tailpipe. Open her up a few times to really clear it out.

    After this, regular stuff. Plugs, wires, cap, rotor.

    AC Delco plugs. Platinum or Iridium for Vortec engines, gapped at a loose.040". Regular ACDs for TBI engines, gapped at .035". ACD Cap & Rotor. Napa Premium wires, Blue MAx by Belden.

    It's best to change plugs on a cold engine, so I do them the next morning. When you do your wires, clean the coil tower with a scotch brite pad. Also, when doing plugs, wires, cap & rotor; I like to do one step at a time, and run the engine for a moment between steps to make sure everything is OK.

    Don't forget a new PCV valve, and a can of Seafoam in the gas tank.

    You should be pleased with the improvement.
  8. bigdaddy77084

    bigdaddy77084 Epic Member 5+ Years 500 Posts

    X2 That old engine should run another 100k. Dont forget to check your belts,hoses and vacuum lines.
  9. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Absolutely. I have a friend with a 96 Sub. 338K on the clock, never worked on the engine. They use it to transport students every day.

    I've got 150K on my 97. Those are hard miles too. 182K on my 95 Hoe. Frame is bad, runs perfect. 186K on the 96 Hoe, that's her daily driver.
  10. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    I should have added O2 sensors. After 60K or so they can get a little lazy reporting mixture changes. Robs power and economy. TBIs have one sensor, Vortecs you only need to change the pre-cat sensors. The post cat sensors just verify the cats are working. They don't affect engine operation at all.

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