99 Grand Prix Coolant Leak


Old 07-14-05, 06:06 AM
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99 Grand Prix Coolant Leak

Hi All,

I just pruchased a 99 Pontiac Grand Prix 3.8L (No Super charger). I was told when I bought it that the intake and upper plentium gaskets were replaced which I do beleive is true. I did notice that there is coolant leaking from a little 90 degree elbow pipe coming out of the front (Front of engine) part of the intake/plentium ***embly and goes into it appears to be going into the belt tensioner ***embley. If I explained it well enough for anyone to understand, can this be easily replaced? Could it just be an o-ring and how would I go about replacing it?

Thanks so much,

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Old 07-14-05, 06:32 AM
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Very Common problem with just about everyone of those 3800 V6's. You could count on the leaks from the gaskets sometime after 50K. Dealers I think charge $800 and up for the repair.
But that is the only problem the 3800 has and otherwise a great engine.
Old 07-14-05, 06:45 AM
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Self Repair

Thank you for your response. I have noticed that these engines have a history of coolant leaks.I am curious if I can just replace that 90 degree pipe coming out of the intake? I dont see how it sheld in there other than a press fit
Old 07-14-05, 07:28 PM
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You can replace just the elbow. You will need to remove the belt and unbolt the alternator, set it aside, and drain the coolant. Next, remove the bolt that holds each of the heater hoses to the tensioner assembly and carfully remove the hoses/fittings. Unbolt the tensioner assembly (2 more bolts) and remove tensioner carefully, there is an o-ring on the back side. Now, be careful upon reassembly, as not to damage the new elbow. I always put a little Vaseline on the o-rings, along with the o-rings for the heater hoses and on the back of the tensioner assembly, to aid in reinstalling.
Be sure to disconnect the battery first though, so you don't ground out the battery positive on the alternator. Add new coolant and make sure you get all the air out of the system. Pretty straight forward repair, but take your time.
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