How is Coolant Level Detected in Montana?

kcarlen · #1 04-13-2007, 07:33 PM

I have a 2K Montana, with 140k. Just today, I have had the low coolant lamp come on several times. The temperature is OK, and the coolant level in the resorvoir seems fine, actually higher than I would have expected. I don't have any visible leaks, and I don't see white exhaust. The oil level seems to be good, and it is clean, as it should be.

Where is this level detected? I have removed the resoirvoir, and there is no sensor there. Is it located in the RAD somewhere? OR is it a calculated thing from the computer?
I am not sitting too well, with not knowing much more about this other than the others that have had the same problems, only to have to have the head gaskets replaced.
When I bought the van in 2004, the dealer said that the gasket upgrades were done. And I beleive him, we haven't had any problems with this van up until now.
Anyone know of where this sensor is?
Maybe it is just a faulty sensor!
BTW, it all happened on Friday the 13th.
Cheers, and hope someone comes forward!

HC2000 · #2 04-13-2007, 09:13 PM

Hi Kcarlen,
My 99' montana has its sensor a few inches below the radiator cap. It has a connector which attaches here. Mine failed around 55 grand and I disconected it and the low coolant light went off. I later replaced it, and have several acquaintances whom have had the same problem. As for the Friday the 13th, it is just a man made number on a man made calender. I would not fret over that one too much. Regards, HC2000

kcarlen · #3 04-14-2007, 05:37 AM

You have made my weekend. Hopefully, this is it.
Both of my brothers have a venture and Montana, and they have both had to have the head gasket thing done.........
Thanks for your help!

HC2000 · #4 04-14-2007, 12:26 PM

Hi Kcarlen,
You are welcome. I now have about 80 grand on my 99' and have done the intake manifold gasket replacement, rear wheel brake cylinder replacement, and left front drive axle seal as well. The van has been very practical for our children with the duel sliding doors and built in car seat. We probably would have sold it a few years ago but we will have to drive it awhile because the resale on domestic mini-vans in our area is in the basement.
Regards, HC2000

kcarlen · #5 04-14-2007, 01:02 PM

Thanks once again HC2000. Saved my weekend. With a little more research based on your information, I looked for the sensor, found it under a mess of old leaves, and unplugged it. I started the van without the sensor attached, and no message. Good. Now I jumpered the connection and hoped to see the message Low Coolant. Yes!
I found this link if anyone else is interested.

http://www.pharmacy.arizona.edu/staf...antsensor.html

I really want to replace it...but it is still cold here in Canada.
I will just keep watching the level periodically. I would think that there is a temp sensor anyway, if the level gets to the point where it is dangerous.....

kcarlen · #6 04-14-2007, 08:21 PM

Went for a quick drive tonight. Within 10 minutes, the engine went up to 100-125 (Almost full scale). Into the RED. I pulled over, opened the hood, and felt the rad cap. It was cold. The resorvoir was full, and the FANS were on, cooling the system down.
I was freaked out after that. I went into the store, killed about 15 minutes, and then came out and checked the temperature. It was normal, about 75-80. Started driving, and it started creeping back up, but not past 85 this time, then started going back down again.
Just to check, I opened the hood again, and felt the cap and observed everything else. All seemed ok.
So, I drove back home. I checked for leaks, there are none. OIL is still the same level,
Do you think I have air in the system or something? All of this seemed to start after I took the damn cap off this morning.
Now, I am worried about driving to work on Monday. I guess that I had better bring my CAA card.
I heard about bleeding the system. Is this done with the bleedscrew on the top side of the return hose/casting? I see a bleedscrew, but I am unsure about how to do this. Is it while the engine is running?

HC2000 · #7 04-14-2007, 10:43 PM

Hi Kcarlen,
you could not have introduced enough air in the system to warrant a bleeding just by removing the cap. You may have not had the cap tightened fully. Make sure the tang on the cap is seated against the "stop" tang on the radiator. As the coolant heats, as you probably already know, it must be under pressure as to not reach the boiling point. If the cap was not fully seated on the short drive, this may have caused the spike in the temp. regards, HC2000

cdru · #8 04-16-2007, 09:19 AM

There are also 2 bleeder screws for removing trapped air in the system. If the coolant goes low enough that air is introduced into the system, you can create an airlock. Air naturally rises to the highest points and if the air can't escape, the coolant can't push it out the way. Eventually this can lead to hot spots, overheating, etc.

The first screw is located almost straight over the water pump on the top corner of the engine. The other screw is located on the housing that is connected to the upper radiator hose. When filling the coolant open these screws until fluid runs out. If your engine acts like it is overheating again, open one or both of the screws a little and see if coolant or air/steam comes out. If air/steam comes out and you can repeat it more then once, you may have a more serious problem such as a head gasket leak.

kcarlen · #9 04-16-2007, 11:39 AM

Ok, started driving to work today. Still, no leaks or indications in the oil before leaving this morning. Lasted about 3 km, then went into the RED. Hot engine light came on, I called CAA for a pickup.
I opened the top bleed screw, closeset to the thermostat, and a whole lot of Steam came out.
The rad cap is still cold.
I am now waiting for the bill.
So, from what I have learned, the head gasket thing happens with very little warning.
First on Friday, the low coolant level. Saturday, the first overheat EVER. Sunday out for a quick drive, and OVERHEAT immediately. (within 3km).
Monday, the van is immobilized.
Thanks GM.
Thanks all that replied.

cdru · #10 04-17-2007, 07:43 AM

I would be prepared for a head gasket issue. When mine went, it went all of the sudden. While a head gasket going is never a good time, I had just replaced my intake gaskets the weekend before. So it was two weekends in a row that I got to tear apart the top end of my vehicle. If it had only gone the week before, it would only have taken a few hours longer to go all the way to the head gasket. Oh well.

So if it is something more significant, are you planning on doing it yourself?

kcarlen · #11 04-17-2007, 12:48 PM

No, It is at the shop. Still.
First diagnosis was a water pump. OK'ed that, then a couple of hours later they called saying that there was exhaust gasses in the coolant.
Now it is one head gasket.
They are going to do both, with my pump at approximately $2200 CAD.
Killer.
GM sucks.

ksboys3 · #12 04-19-2007, 09:55 PM

its probably the temperature sending unit. your car wont overheat that fast.

Quote:

Originally Posted by kcarlen

Went for a quick drive tonight. Within 10 minutes, the engine went up to 100-125 (Almost full scale). Into the RED. I pulled over, opened the hood, and felt the rad cap. It was cold. The resorvoir was full, and the FANS were on, cooling the system down.
I was freaked out after that. I went into the store, killed about 15 minutes, and then came out and checked the temperature. It was normal, about 75-80. Started driving, and it started creeping back up, but not past 85 this time, then started going back down again.
Just to check, I opened the hood again, and felt the cap and observed everything else. All seemed ok.
So, I drove back home. I checked for leaks, there are none. OIL is still the same level,
Do you think I have air in the system or something? All of this seemed to start after I took the damn cap off this morning.
Now, I am worried about driving to work on Monday. I guess that I had better bring my CAA card.
I heard about bleeding the system. Is this done with the bleedscrew on the top side of the return hose/casting? I see a bleedscrew, but I am unsure about how to do this. Is it while the engine is running?

kcarlen · #13 04-20-2007, 07:42 AM

No, it was the head gasket. (Blowing exhaust gasses into the coolant)
Just like I suspected.
$2500 later, I have a new rebuilt intake, heads, thermostat and waterpump.
Seems to work good now.
Boy, I hope this doesn't happen again in my lifetime.

ksboys3 · #14 04-20-2007, 08:08 AM

i had the same job done on my van. ($2200) back in the shop a few days later. told me it was the temperature sending unit. replaced it and havent had a problem since. just wondering if that wasnt the problem all along.

cdru · #15 04-22-2007, 11:07 AM

Quote:

Originally Posted by ksboys3

its probably the temperature sending unit. your car wont overheat that fast.

It will when exhaust gases are being injected into the cooling system. They will collect in the highest point in the engine...which just happens to be near the temp sending unit.

Quote:

Originally Posted by ksboys3

i had the same job done on my van. ($2200) back in the shop a few days later. told me it was the temperature sending unit. replaced it and havent had a problem since. just wondering if that wasnt the problem all along.

There is a simple test you can run on the antifreeze to test for exhaust gases. There shouldn't be any, and I'm guessing that is what the shop tested for. The temp sending unit could be the problem, but combined with some other things he was experiencing just replacing the sending unit wouldn't have fixed the problem.

POST REPLY TO THIS THREAD