99 Suburban head gasket leak

Discussion in 'GM Powertrain' started by alanbmx, Mar 5, 2011.

  1. alanbmx

    alanbmx New Member

    I purchaced a 99 K1500 Suburban with 103,000 miles recently. It is leaking coolant from the block to head on both heads, started about a week after purchace. There is a slight amount of moisture on the inside of the oil cap and inside of valve cover. Checked a couple of head bolts seemed to be torqued to spec. Looks like head gasket was just replaced.

    Could this be from whoever did the work not using new head bolts? I paid $4750, It is clean inside and out. I have driven it on two 300 mile trips with no overheating issues at all. It was leaking coolant at the time of both trips, ran great now has a slight miss

    By alanbmx at 2011-03-04
  2. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Are you sure it is a head gasket leak? Intake manifold gasket leaks are more common?

    It is POSSIBLE that it was from using old bolts/studs/fasteners- but I would bet there is more to it than that- probably warped overheated or some such.
    Make sure you don't have
    COOLANT IN OIL- cloudy oil-
    OIL IN COOLANT- oily coolant -smells funny also-feels funny also-
    COOLANT OR OIL IN COMBUSTION CHAMBER- look for fouled plugs

    If BOTH HEAD GASKETS are actually leaking- and actually contaminated the oil , and the motor was overheated abused I would not pay someone to fix that motor- it would be well over $1000- probably $1500- for a 100,000 mile beat up motor with a very limited life expectancy.
    Buy a new crate GM Goodwrench motor- $2200 delivered- have it installed- maybe $3200 total or DIY maybe $2700 total with hoist rental gaskets, fluids etc

    If it is just the intake manifold gaskets- DIY for $100 and cross your fingers- change plugs if fouled.
    Don't throw $$ at a beat up motor- not when new Goodwrench motors are so cheap.You would then have a great vehicle-low miles for $8000- cost $45000 to buy a new one, so you will come out alright.
    Your Suburban has a great body- worth a spending money for a good motor.They get good mpg hy- great trip vehicles great do anything vehicles.
    PS Yes, the PO probably knew something was wrong.Many folks are thieves. You'll be ok $$ wise- a good body is the most important thing on an older vehicle.
  3. alanbmx

    alanbmx New Member

    I think at this point all I can do is take the heads off, and see what I find. What is the trick to removing the heater hose from the intake. The one on my 95 with a 7.4 litre crumbled into pieces causing me alot of greif getting the remains out and retapping the intake

    DAREDEVIL Rockstar 4 Years 1000 Posts

    dont take he heads off, like phoebeisis said....its more likeley your intake!!!!! very comon on the 350 vortec's ! and actually a little PITA to fix aswell.
  5. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Real easy, do a pressure test on the cooling system. See if you can get coolant to leak out between the block and heads.

    As for the heater hose connector, there is no easy fix. You can try heating it up, it may help loosen the adhesive they put on the threads. But you will probably end up breaking it and digging the old one out.
  6. alanbmx

    alanbmx New Member

    How do I release the hose from the fitting that screws into the intake? On my 95 I ended up putting a brass hose fitting into the intake and cutting the heater hose.

    ---------- Post added at 07:41 AM ---------- Previous post was at 07:39 AM ----------

    Where is the leak usually coming from on the intake?
  7. alanbmx

    alanbmx New Member

    Well I went and got a radiator pressure test set-up from my local parts house (loaner at no cost) pressurized the system and it leaks like crazy from the intake gasket at the back and leaks at the front too. Even a little coming out of the intake bolts. So thankfully it is not the headgasket. Do these intakes corode to the point where they have to be replaced or do the gaskets disintegrate.

    I guess my question is, are the intakes the problem on these or the gaskets failing because of the crappy dex antifreeze GM puts int them??
  8. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    If the truck DOES have new headgaskets, sounds like someone used the wrong intake gasket. The new gasket for the Vortecs from Felpro is virtually impossible to mess up. When I did my intake gaskets, there was some minor erosion around the coolant ports at the front of the intake. I just spread a little Permatex Ultra Black around the port and it has been fine.

    As for the quick disconnect, there is a plastic tab on either side of the fitting that you squeeze to remove it. But take the crappy pot metal fitting out and replace it with a steel one while the intake is on the bench.
  9. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Well, that is good luck.
    Like 2COR517 said the latest bestest FelPro set- with a number like 58000 or 98000 or some such is supposed to fix the problem.
    Put them on my 1998 Suburban about 1 year ago-alls well so far.
    Many folks do blame the Dexcool.
    Best to change it out every 3 years 30,000 miles- not the 100,000 miles GM suggests.
    Some folks go back to old antifreeze- ethylene glycol- green stuff- but Ive stuck with Dexcool- just don't try that 100,000 mile BS
    Average shade tree mechanic- hand tools no pneumatic or electric- takes 7-10 hours to do job- take your time- take digital pictures so you know what goes where etc.
    Post pictures so we can see how clean your bay is or isn't!!
    PS Don't run it much until you have it fixed-missing means coolant in CC on plugs-not good
    Last edited: Mar 7, 2011
  10. alanbmx

    alanbmx New Member

    Going to tackle it tommorow. the plastic tabs on the quikdisconnect are gone. I had to dig out and re tap the intake on my 95 2500 suburban years ago. The crappy pot metal fitting crumbled when I tried to remove it forcing me to have to remove the intake off the big block so I could remove the reminants. Thanks for the crappy design GM. Replaced it with a brass fitting. I found the Fel-Pro 98000 gasket set at Kragen-O'Reileys. Glad to see they still stock Fel-Pro. I never like to use anything else. I will try to take some pics to post. Thanks for the help

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