2004 cooling system issues

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supergrapes

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Hi all:
I'm having some issues with the cooling system on my 2004 montana. Here's the history:

had the van for about 3 years, no cooling issues during the first two years. The temperature gauge sits just below the halfway mark, always. Then, about a year ago, I was driving up in the mountains (I live at sea level, but I was about 5,000 ft above sea level) and I noticed that the temp gauge was climbing. I'd driven in these mountains a bunch with this car and never had a problem, so I figured, oh, my coolant must be low or something and I slowed way down to lower my RPMs and get the temperature down. Checked my coolant when I stopped, and it was fine.

Since then, I've had issues with the car... not overheating, per se, but getting hotter than usual. When it's cooler outside (85 or so, or less), I have no cooling issues whatsoever. However, as soon as it hits 90 or so, if I'm at freeway speeds for more than 20 minutes-ish, the gauge will pop just a bit over the halfway mark, sometimes a little higher. And then, if I have to go up an incline, it'll start climbing. It's never gone into the red zone, but it's gotten fairly close. I feel like it goes in cycles: like, it'll rise, and then fall back down to just above half, and then rise again, etc. I don't think it would ever actually get into the red zone on its own, but I don't want to test that for obvious reasons. I do what I can to control the temperature by slowing down when I need to.

Even though the coolant level seemed fine, I added a little, and when that didn't work, I drained all the coolant and ran distilled water through and then refilled with coolant. Still having the same issues.

I guess my first question is, is this normal? It's been well above 100 degrees most days this summer where I live, and obviously the car will get hotter in this weather, and even hotter up hills. It's so minor and controllable that I know it's not some major issue, and maybe it's just due to the heat and hills. But I'm thinking this isn't normal.

Any thoughts on good things to check next? I ran water through the system, but I didn't like flush it with pressurized water or put in "flushing" chemicals or anything, are those worth trying? The fan turns on and works, is there anything else that would affect it just not cooling as efficiently as it could be? Any thoughts would be VERY much appreciated.

thanks!
JW

EDIT:

I should have mentioned a few other things. One, the check engine light is NOT on. Two, I originally thought that my car was leaking coolant, because sometimes when I parked it I would see dripping. It turns out that the dripping is just water. Is this relevant? I assume it's just condensation the settles in overnight, because I can't figure out where water would be coming from, but I thought I would mention it just in case, because I figure anything dripping from my van could be important information. Thanks!!
 
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use a chemical flush and replace the thermostat to be safe
 
Cool, thanks. I can do that.

There's no chance it's like a head gasket thing, right? I don't see any smoke out of the tailpipe and the coolant level doesn't seem to be changing, and I drive a lot... but just want to make sure!

The thermostat could be causing these issues? Also, is there a good chemical flush that is recommended? I was planning to just pick up some bottle of whatever from wal-mart or something...

thanks!
 
prestone or any brand name. You can also buy a test kit at an auto parts store to check for hydrocarbons in the coolant which would be caused by a head gasket failure. You could also do a cooling system pressure test including the cap.
______________________________
 
Thanks!

I ordered a new thermostat and will be putting that in this weekend, and doing the flush at the same time. Hope this solves it.

Should I be driving it right now? Is there a chance I'm causing damage? As I said, the temp needle never goes up into the red zone, and it's really only up even close to the red zone for maybe 30 seconds at a time before it starts to cool back down and even then only if I'm driving for like an hour....

thanks
 
without doing a cooling system pressure test including the cap, checking that the fans are coming on at the correct point, and making sure you have no hydrocarbons in the coolant the cause of the vehicle going into the red is undetermined so drive with your eye on the gauge
 
hi,
So, i've been looking for a hydrocarbon test kit and none of the shops around me seem to know what that is. They keep bringing out the tester to test the antifreeze levels. And I live in a large city so I've checked probably 20 shops.

Any idea where to get one of these?

Also, something else I didn't really notice until you mentioned radiator pressure. Sometimes when I'm at very high altitudes or if it's really, really hot, when I turn off my van, it almost sounds like the coolant is boiling. Is this normal, or could this be something that indicates a really high pressure in the radiator?

thanks
 
yeah, I'll check google. Last resort for me I guess, I prefer to buy local because I have no idea what I'm buying! ha. But judging from the fact that it's boiling, maybe I don't need to check that for a while...

Hmmmm.... pressure too low? I wonder if I did something wrong changing the coolant. When I take the cap off, even when cold, the coolant is so high that it runs over. I figured that meant that I had plenty of coolant in there.

Or is there some other reason that the pressure might be too low, other than too little coolant?

thanks!!
 
did you pressure test the cooling system including the cap?
 
Hi,
Thanks for the reply and all the help so far. I have a radiator test cap kit that I rented. Is this the right kit: I'm supposed to connect the test kit cap in place of my radiator cap, and pump the kit to the specified pressure and monitor the pressure. If the pressure drops, I have a leak in the system. Problem is, I can't find what the pressure I'm supposed to pump to is. Any idea how high I'm supposed to pump this test kit? The cap says 15 PSI, but I don't know if that's like max, or normal operating pressure, or if the test kit is supposed to go higher, or what....

Another question: While looking around to try and find the proper pressure to pump the test kit to, I found the coolant capacity for a 2004 pontiac montana. The internet says around 10 liters... is this right? I feel like when I flushed it, I feel like maybe 6 liters came out, and when I put new fluid in, it only took maybe 4 liters. But, as I said, even now, it's so full that when I take the cap off, coolant spills out. Why would my car only take ~4 liters, and could this be causing low pressure?

thanks again for all the help. Really, really appreciate it :)
 
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Hi-

So I went ahead and pumped to 15psi. Looks like no change in pressure after about an hour. I guess I didn't really expect there to be a leak, as I'm definitely not losing any coolant. My system seems full. Just when I took the cap off now to attach the pressure tester, about 2 cups maybe spilled out.

I followed a website how-to video when I was changing my coolant. They just drained it out the bottom of the radiator, and flushed with distilled water, and then refilled, so that's what I did.

What does that mean, drain the block plugs? are the block plugs the air bleeder screws, or something else?

I'll check the manual you sent for coolant change procedures... is it possible that failing to remove the block plugs is causing all these issues?

I also definitely put in waaaay less coolant than the manual says I needed, but the system still seems full. What might be causing this? Is it possible that some of the system is blocked off or something?

thanks!
 
did you test the cap?
the block plugs are in the sides of the engine block. Not removing the plugs will leave some coolant in the engine and depending on age when removed can assist in removing sediment from the block. Just dont break them off in the block.
you have to recheck the system when completely cold after a couple of cycles to let all the air bleed out
 
Hi-

So, I'm going to do a complete cooling system flush, this time with pressurized water instead of just letting things drain.

Would be great to know where the block plugs are, I'd like to take them out to flush out as much crap as possible.

Where are the block plugs? I didn't see anything in the manual you sent, and I can't find that specific info on google. Side of the engine block.... can I get to them from the bottom or top? How will I know which plugs are the block plugs?

thanks!
 
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