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3500 Coolant Leak


88red4cyl

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The Monte Carlo has started losing coolant and leaving spots on the ground. I highlighted the areas in red that had the most coolant on them. I tried to check out the weep hole on the water pump, but I can't find the weep hole on this car.. I know that the head gaskets and crossovers leak on this motor, but I'm not sure these areas would be wet with coolant if it were either of those. Possibly the crossover, but it'd have to be spraying coolant out to the side for it to be head gaskets and have the belt area be wet, right? Any ideas?

 

diagram_zps3d021b2c.png

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I'd be willing to bet it is the water pump that is failing. It seems to be a common problem on these engines, and quite frankly, on most vehicles too. I replaced it on my wife's '06 Impy last April. It was pretty easy to do. I also replaced the T-stat and flushed and refilled with fresh Dex as well. The T-stat was interesting though, as the new location on the bottom of the motor had be searching for awhile before I found it. The weep hole is located beside the pump shaft, behind the pulley, so you'll never see it unless you remove the pulley itself.

Edited by carkhz316
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I'd be willing to bet it is the water pump that is failing.It seems to be a common problem on these engines, and quite frankly, on most vehicles too. I replaced it on my wife's '06 Impy last April. It was pretty easy to do. I also replaced the T-stat and flushed and refilled with fresh Dex as well. The T-stat was interesting though, as the new location on the bottom of the motor had be searching for awhile before I found it. The weep hole is located on the side of the pump shaft, behind the pulley, so you'll never see it unless you remove the pulley itself.

 

Was your belt wet? Mine is dry, but I can see where some has gotten on it at some point and thrown the coolant towards the radiator (a line of coolant on the splash shield thing under the radiator)... I'm just confused as to how the coolant got above the water pump, but isn't covering everything...

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Was your belt wet? Mine is dry, but I can see where some has gotten on it at some point and thrown the coolant towards the radiator (a line of coolant on the splash shield thing under the radiator)... I'm just confused as to how the coolant got above the water pump, but isn't covering everything...

 

The belt and blowing air can throw it everywhere. He's right that you most likely have a bad water pump.

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It initially wasn't wet per-se. It started as a occasional drop here and there that would leave me topping off the coolant every few months. It only really started weeping when I would put nearly 15psi of pressure on it with my pressure tester. Then, with the engine running, it would sling coolant around a bit, just above and around the pump area, but not all over like you'd expect, surprisingly.

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Took a few pictures this morning in case it would help to see the physical area on my car instead of on a diagram of the engine. There may be some glaring info I've looked past in my description or something.. And something my wife mentioned this morning when I was taking the pictures, was that the heat was taking longer to start blowing warm. It used to come on within 2 miles or so, and now it's taking it 5 or 6 miles to quit blowing cold air.. I figured it may be because the overflow bottle only had a small dribble left in the bottom of it, but I thought it may be worth mentioning in case it points to a bigger issue with my other symptoms.

This is the highest point where I have standing coolant.. There's a few drops here and there higher than this, but it's pooled here. The top pulley is the power steering pump, the one to the right side is just a pulley, and the one under it is the water pump.

100_3603_zps1dc7fe10.jpg

This is the side of the water pump (taken from the front of the car)

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This is the line of coolant I have pretty much straight across from the belt area (and it goes up the whole length of the radiator). Belt is bone dry though..

100_3600_zpsac9bc0ff.jpg

 

And this is the little bracket thing directly above the water pump..

100_3601_zps07841cf4.jpg

Edited by 88red4cyl
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Thanks guys! It must be an incredibly slow leak, because everything I put a half gallon of Dex-Cool in it last night, and it was still full this afternoon.. The only thing that's really gathering any coolant is the ac compressor and the frame right below it.. Everything else looks wet, but you don't really get any coolant on your finger if you touch it.

 

Buck, how'd you determine that you needed to do the crossover gaskets? Just decided to do them, or did they start leaking a lot? I'm curious as to how that problem presents itself when it gets bad..

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Had no heat and kept getting air in the system. All I saw was coolant seeping from the heads on the drivers side, and a lot of coolant from all over on the pass side too. I assumed it was all headgaskets, but most turned out to be from the crossover, those gaskets were trashed.

 

The water pump also failed a couple of months ago.... but IIRC it was just making a ton of noise, I don't remember it leaking. I can't remember. I'll ask Kenny if he does.

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I think mine is either head gaskets or crossover as well.. There was a puddle under it probably a foot across this morning.. I should be able to easily see if there's that much coming from the water pump.. :(

 

I think this is my least favorite GM engine ever... You can't see anything to help you diagnose leaks because there's so much shit in the way..

Edited by 88red4cyl
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Replacing the crossover gaskets will probably solve 99% of the problem, and it isn't all that hard. Remove alt and ps pump, voilia! crossover is ready to come off

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Replacing the crossover gaskets will probably solve 99% of the problem, and it isn't all that hard. Remove alt and ps pump, voilia! crossover is ready to come off

 

Thanks Buck... Is there any spot it's prone to leak in that I could check before I start tearing stuff apart?

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They're just two triangle shaped gaskets, one on the end of each head. The crossover takes the place of the coolant passages in the LIM in other W engines like 3100, 3.1, 2.8, 3.8, L67....

 

So it's leaking EXTERNALLY instead of into your oil! See, aren't you glad it's designed this way now? :lol:

 

So it would be leaking from them, down the sides of the engine... It could be just one that's bad.

 

I'd take the ps pump off, the belt obviously, the plastic stuff in the way(overflow tank over on that side? I don't remember), and the water pump pulley. Then I'm sure you can see what is actually leaking and you won't have wasted any work because pretty much all that will need to come off anyways wether its the crossover or the water pump.

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They're just two triangle shaped gaskets, one on the end of each head. The crossover takes the place of the coolant passages in the LIM in other W engines like 3100, 3.1, 2.8, 3.8, L67....

 

So it's leaking EXTERNALLY instead of into your oil! See, aren't you glad it's designed this way now? :lol:

 

So it would be leaking from them, down the sides of the engine... It could be just one that's bad.

 

I'd take the ps pump off, the belt obviously, the plastic stuff in the way(overflow tank over on that side? I don't remember), and the water pump pulley. Then I'm sure you can see what is actually leaking and you won't have wasted any work because pretty much all that will need to come off anyways wether its the crossover or the water pump.

I'll have to take some pics as well, because I can't find any documented info on the crossover gasket job anywhere with pictures.. From what I've read on g6 forums, don't some of the exhaust manifold bolts need to be taken out to get the crossover off? My Haynes manual doesn't document how to remove it either...

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I'll look it up, gimmie a bit. I've done it, however I did the headgaskets at that time so the exhaust manis had to come off anyways. Not that that's a huge deal. Anyways, gimmie a minute

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Engine Coolant Crossover Pipe Replacement (RPOs LZE/LZ9)

Removal Procedure

 

 

Remove the intake manifold cover(plastic engine cover). Refer to Intake Manifold Cover Replacement or Intake Manifold Cover Replacement .

Remove the generator(Alternator). Refer to Generator Replacement .

Remove the drive belt idler pulleys(serp belt 'blank' pulleys). Refer to Drive Belt Idler Pulley Replacement or Drive Belt Idler Pulley Replacement .

Remove the power steering pump. Refer to Power Steering Pump Replacement .

Reposition the coolant recovery reservoir hose clamp at the fill tube fitting(overflow tube clamp).

Remove the coolant recovery reservoir hose from the fill tube fitting. Position the hose out of the way.(overflow hose)

 

Reposition the radiator inlet hose clamp at the crossover pipe (3.5L shown, 3.9L similar). (lower rad hose clamp)

Remove the radiator inlet hose from the crossover pipe. (lower rad hose)

 

Reposition the thermal bypass hose clamp at the crossover pipe.

Remove the thermal bypass hose from the crossover pipe. (small, 6" long bypass hose)

 

Remove the coolant crossover pipe bolts.

Remove the coolant crossover pipe.

post-3298-143689123962_thumb.jpg

Edited by Night Fury
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Buck has the right idea if it isn't the WP, but the best thing you can do to narrow it down is to get a cooling system pressure tester and check for leaks with that. Often times hitting that 10-15psi mark is enough to start making any weeping leak a full-on leak thats easier to diagnose.

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Thanks guys! I jacked it up and looked around a little bit to help satisfy my curiosity. I had my wife start it while I was underneath (safely supported on jack stands) and rev it while I looked for the leak with my flash light.. Didn't find a single thing though.. It's been home 2 hours, and not one drop underneath it... My wife did notice that the heat quit blowing hot in the 5 minutes the car was shut off while i jacked it up and when it was restarted.. Not sure what that means, but oh well.. The only thing I could even find with standing coolant on it was this.. For reference, that's the crank on the left, the wp up top, and the ac compressor bottom right..

100_3620_zps46587127.jpg

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If the engine isn't running, the hvac fan removes all the heat from the coolant in the heater core very quickly, and with no water pump to continue the flow of hot coolant........

 

Completely normal

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If the engine isn't running, the hvac fan removes all the heat from the coolant in the heater core very quickly, and with no water pump to continue the flow of hot coolant........

 

Completely normal

 

Took the car a good 4 or 5 minutes for the heat to come back though.. Is that normal?

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