gaiusmarius

Hi all, i want to change the coolant on my 1991 pontiac grand prix 3.1

I've learned from this site that you need to bleed the air out of the system when doing this but i don't know where or even if there are any bleeder valves on the engine. If anyone knows where i might find it or them i'd realy appreciate it!!

inafogg

if there are any??take a look around thermostat housing good luck

gaiusmarius

Did have a look earlier, nothing recognizable as a valve, the schreider valve is obvious, but not what i need to find.

richtazz

there should be one brass knurled valve that has a flat head screwdriver slot in it on the t-stat housing, and there is possibly a second one on top of the coolant transfer tube that comes out of the timing cover just behind the water pump. I'll see if I can find my bleed proceedure I posted a while ago and post a link for you if I find it.

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richtazz

Here's the link. It's from the Chevy Lumina Forums, but it applies to your car as well if you have two bleeder valves.

http://www.automotiveforums.com/vbul...eed+proceedure

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gaiusmarius

Thanks guys for the help!

Looked at the locations indicated until my eyes bled, nothing even remotely resembling a place to put a screwdriver in, but there is something that kinda looks like a bleeder at both places except they require a very very small wrench to turn, which i didn't touch as i don't know enough to know if they are it.

Not even sure where the tsat housing is because there are 2 places that look nearly identical to what i know a tstat housing would look like (from pics)

One is located near the throttle body (driver side) the other is on the engine at the end of the hose (upper) coming from the radiator (passenger side)

richtazz

You found them. the 3.1 Vin-T engine in your 91 has small hex-nut bleeders. be very gentle, as they are brass and will snap off very easily if too much force is applied. The t-stat housing is on the drivers side near the throttle body, where the big upper radiator hose attaches to the engine. The smaller one on the passenger side is a coolant transfer passage for the heater core.

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gaiusmarius

Awesome!!! thanks Rich!!

let ya know when i finish up with this thing!

ericn1300

Here's a trick for bleeding the air in a 3.1 that my father's farm mechanic showed me with pics.

Step 1: With engine cold fill the radiator with coolant.

Step 2: Find a wide mouth plastic bottle that fits snuggly into radiator fill neck (a one gallon milk jug may work too, pic one). Use water for this because you will spill some, don't worry it won't be enough to dilute the coolant much. Invert bottle and insert firmly into fill neck. This will create a water reservoir that is above the air bubbles in the system

Step 3: Open the nut bleeder valve above the water pump (pic one) and you should see the bubbles in the bottle as it glugs glugs into the radiator. When the bubbles stop squeeze the bottle lightly until coolant comes out of the bleeder valve then close it.

Step 4: Open bleeder valve located on thermostat housing at the engine end of the upper radiator hose (pic 2). The hose has a high spot in it, press down on that and squeeze the hose to pump the air out of it until coolant only squirts out of the bleeder valve. Squeeze the water bottle lightly also to provide some pressure.

Step 5: Repeat steps 3 and 4 until all air is purged from the system.