Hello and good day:

This is my first post, so please bear with me!!!

My daughter bought a 1996 3.8 L Pontiac Bonneville SE two years ago to go to college. The care was is in great shape, and has run great during this time.

She has always been good to check the Fluids in her car...one day she noticed that the Coolant Reservoir was empty...she refilled the tank...2 days later she noticed it empty again.

She brought it home last week, and we took it to our local Repair shop...they stated it need a new Water Pump...We had it replaced.

Well she went back to school, and when she got there the tank was empty again. I went down there to check it myself...we put a gallon of antifreeze into the Tank, and the Radiator. Turn the car on...let it build up pressure...then discovered that there was still a leak coming from the under side of the care

The leak ...looks like it is coming from the back 3 cylinder head leaking above the water pump...I cant get a good visual on the location of the leak...it appears to be just above the two hoses the go to the Heater Core.

Dose any one have any ideas what may be causing this...and how can I check this, and possibly repair this less than spending Thousand of dollars for a Head Gasket.

Thanks in advance...any more info need please advise.

If the leak is above the hoses, that'* a little tough as that'* the hood. Take a closer look at the passenger end of the motor. There is a plastic coolant elbow located right above the water pump. There are also o-rings on the fittings that the heater hoses connect to.

And be thankful it'* an external leak. The usual leak here would be internal from the upper intake manifold. If you think the coolant is pumping out of the exhaust, pull the upper manifold, most likely it'* bad.

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Hello and good day Bill:

Thank you for the Info...I will follow your advice...I had forgotten to mention that there is no signs of Antifreeze/Oil mix in the Radiator. the Oil is clear and good.

When this Leak occurs it is clear green color leak. I will start pulling things to see if we can locate it.

Thanks again.

From the sounds of it, bill is spot on.

You will need this from a auto parts store like autozone or advance auto, they are under $10


If you look in this picture, your engine will be a bit different because you have a SE and some parts are missing in this picture. But look on the left side of the lower intake manifold, you will see the elbow go from the LIM to the bracket (alternator). Remove this bracket and you can change the elbow. Lube the O ring with a little oil or Vaseline.

Thank you guys sooooooo!!!!! much. This makes sense...because its just above the Water Pump.

How much tear down do I have to remove to get to this??? Can you guys give me some advice on what I need to do first, and what I need to take off in order???

Thanks again

Basically you will need to remove the alternator, so pull the neg battery cable. Then remove the bracket for the alt. The elbow goes in to that. You will need to drain some coolant to do all this.

Keep in mind the package has two elbows because there are two going into the bracket. The lower can be tough to spot. Wiggle wiggle wiggle, try not to pry if possible. On 96-9? years the bottom elbow was cast metal as part of the bracket. Prying can break the timing cover in those years.

I'll second the advice above on it being the elbow o-ring. I had the exact same leak happen, the new elbow and o-rings fixed it. I thought it was the water pump at first as well, assuming it was the typical GM bad water pump seal. The coolant elbow is a relatively cheap and simple repair.

That said, keep a close eye at the motor for the intake manifold coolant leak, if you haven't already been through that expensive nightmare. You'll also notice coolant level going down regularly, and if you do, look for coolant puddling up at the top of the motor/base of the intake manifold. You can also smell it burning off from the motor heat. Some mechanics are so aware of it that they can smell an undiagnosed bad intake manifold just by that smell from a GM car up on the lift! Friggin' GM recommended Dexcool...