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1988 Chevrolet Silverado 5.7L Intake Gasket Repl.

Home Forums Stay Dirty Lounge Service and Repair Questions Answered Here 1988 Chevrolet Silverado 5.7L Intake Gasket Repl.

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  • #589619
    RileyRiley
    Participant

      Good Evening Everyone,

      This promises to be a somewhat long post, but I will try to make it as concise as possible. A few months ago, I noticed a slight coolant leak on my ’88 5.7L V8. By slight, I mean once every couple of weeks, I was having to put about a pint to a quart of coolant in the radiator. I will go ahead and say this that I do not have any pressure testing tools, so I kind of had to wing this diagnosis, but I am 95% certain that what I have is a leak in the intake gasket.

      The evidence:
      1. No visible leaks of coolant on the ground anywhere
      2. No visible leaks on the radiator, hoses, passenger compartment, heater hoses, etc.
      3. There are small pools of coolant on the left-hand side of the intake manifold right behind the alternator and underneath the bracket that holds the throttle cable in place. I do not believe coolant moves through the Throttle Body and if it does, there are no “trails of coolant” to indicate that is where it is coming from
      *Note – this is a single piece “wet” intake manifold… GM did not put out 2 pc. manifolds on its trucks until ’96
      4. The oil has 3,000 miles on it and looks dark brown in color (not milky) and no noticeable compression issues based on the engines performance, so I do not believe coolant is going into the crankcase

      So based on this, I believe I can reasonably conclude coolant is seeping out through the intake gasket.

      Now, it would cost upwards of $250 to have a shop do this work for me, or I can spend $20 on an intake gasket set and $30 on a throttle body gasket set. I have never had any engine work done on this truck and I have zero experience in pulling engine components apart, even of this vintage.

      My questions are:
      1. My biggest concern… pulling the distributor out. This part scares me to death. I do not want to get myself in a position where I lose time of the engine. First, let me go through my plan… please let me know if this is sound or not: I’d start by putting masking tape and number the cylinders on the wires. Then reference where the housing goes (using a sharpie) and using a straight edge and a sharpie to mark on the firewall the direction the rotor is pointing prior to pulling it out. I know the rotor will rotate some as it’s pulled out and I will have to compensate for that slight rotation putting it back in.

      Is pulling a distributor hard? Is this plan sound? What are some things to keep in mind? Are there any gaskets/seals I need to account for?

      2. Is it worth it to “rebuild” the throttle body? (this is Twin Port Injection system… 2 large injectors spray fuel into the throttle body) Is this something I can do? Some research on youtube indicates it’s not that hard to do… but again… I don’t want my lack of experience to bite me…

      3. Upon researching this as best I can, My plan is to get 2 intake gaskets for either side of the engine and line the front and rear edges of the valley (between the two gaskets) with silicone. This seems to be the best at keeping oil from leaking.

      4. What is the best way to dispose of coolant? None of the auto parts stores take used coolant and I don’t want to ask a shop to take it since I’m not giving them business for this build?

      I will also be replacing the valve cover gaskets and the upper radiator hose… which shouldn’t be too hard.

      Before I undertake this project, I want to make sure that I can see it through to the end since this does involve engine components. Any advice would be much appreciated.

      Edit: The ECM also sits on the right-hand side of the intake manifold… is there anything I need to be concerned with here? Anything of note I need to take care of?

    Viewing 6 replies - 1 through 6 (of 6 total)
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    • #589626
      jasonjason
      Participant

        OK MY FRIEND IT SOUNDS LIKE A GOOD PLAN OF ACTION. I WOULD MAKE SURE THAT I SET THE ENGINE ON TOP DEAD CENTER BY LOOKING AT THE BALANCER ON THE MOTOR AND LINING UP THE POINTER WITH THE LINE ON THE BALANCER. ALSO YOU WILL NEED A GASKET FOR THE DISTRIBUTOR SHAFT AND I WOULD NOT MESS WITH THE THROTTLE BODY IF IT IS RUNNING FINE AND THERE IS NOT ANY SINE OF LEAKING GAS. I NO THAT AT MY SHOP WE HAVE SOMEONE PICK THE COOLANT AND OIL BUT I NO THAT ADVANCE AUTO PARTS DOES TAKE OLD OIL AND OIL WITH COOLANT IN IT SO MAYBE THAT WILL HELP. I WOULD MAKE SURE TO PUT GASKET MAKER ON THE CORNERS OF THE INTAKE ON ALL 4 TOP AND BOTTOM. BUT LONG AS YOU MARK THAT TIMING GOOD AND DO NOT TURN THE ENGINE AFTER THE DIS IS REMOVED U SHOULD BE GOOD. O YES WHEN LINING UP THE TIMING THE ROTOR WILL LINE UP WITH THE #1 TOWER ON THE DIS CAP AND THE POINTER WILL LINE UP WITH LINE ON THE BALANCER MAYBE THIS WILL HELP LET US NO HOW IT TURNS OUT.

        #589629
        JamesonJameson
        Participant

          You are in luck that that is one of the easiest and most straight forward intakes to remove. Being inexperienced, you should definitely label all the wires and mark the distributor cap/rotor etc.

          Mark the cap in relationship to the distributor. Mark the distrib in relationship to the firewall, and mark the rotor in relationship to the intake. This is the easiest way.

          I wouldnt worry about the throttle body unless you have other issues you didnt mention. Coolant does not run through that throttle body. You actually shouldnt have to even remove the throttle body from the intake, just remove all as an assembly.

          Remove the intake bolts in sequence if there is one and torque/tighten them in sequence upon reinstall.

          Other than that, put RTV in the proper places, usually shown in the gasket kit, but you can look it up too. Make sure you toque to spec and use the correct sequence. Then fill and bleed the system.

          Even for your first time, is should not be hard, just time consuming labeling everything and taking your time.

          Any jiffy lube will take used fluids.

          #589630
          Rob megeeRob megee
          Participant

            Before you pull the distributor I would get the engine to top dead center number one cyl. on the compression cycle. Eric has a great video on how to do that with a vacuum/pressure gauge. Also look at the timing mark on the crankshaft pulley align that to zero. That just makes sure you are at tdc. Then the rotor should be pointing to the number one plug wire on the cap. You don’t have to do it that way, it just would give you a known reference point in case you had issues and needed help. The distributor will rotate when you pull it out pay attention about how far the rotor changes. Start in that position when reinstalling it. It may take a couple of try’s. Be carful when reinstalling that the base of the distributor is flush with the manifold before tightening the bolt. Maybe someone that knows that engine could chime in, at one time the distributor drove the oil pump. I don’t know if this engine has that. If so, there will be a slot in the bottom of the shaft of the distributor that the oil pump shaft will fit into. It usually goes in pretty easy. Again, this isn’t the only way to do it, I just think if you needed help it would be a known starting point. Then align the distributor case to the marks you made before pulling it out. You will need to time the engine when done.

            #589635
            jasonjason
            Participant

              O YES THIS ENGINES DIS DOES TURN THE OIL PUMP SO MAKE SURE THAT DIS IS ALL THE WAY DOWN. THE WAY I DO THIS IS WIN I PUT THE DIS IN ONCE I AM SURE THAT IT IS GOING TO FALL IN RIGHT. IF THE DIS IS NOT ALL THE WAY DOWN YOU MAY NEED TO TURN THE MOTOR CLOCK WISE WHILE HOLDING DOWN ON THE DIS AND IT WILL FALL IN. THIN YOU CAN BACK IT UP TILL THE LINE ON THE CRANK PULLEY IS LINED BACK UP IF THE ROTOR IS BACK WERE IT SHOULD BE ON YOUR MARK POINTING BACK AT THE #1 POST ON THE CAP U ARE GOOD.

              #589637
              Rob megeeRob megee
              Participant

                In the olden days we would try to install the distributor and see if it drops into the oil pump shaft. If not remove the distributor and turn the shaft with a flat blade screwdriver so it would line up. It should just drop in, maybe 1 in 7 I would need to turn the oil pump shaft.

                #589862
                EricTheCarGuy 1EricTheCarGuy
                Keymaster

                  Some great suggestions have been made here and I have little to add. I think the most difficult thing will be getting the distributor in and out but if you mark it as suggested, I don’t think that will be an issue for you. Outside of that, work clean and keep your parts and fasteners organized and I think you’ll do fine.

                  Good luck and keep us updated on your progress.

                Viewing 6 replies - 1 through 6 (of 6 total)
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