Low cooling temperature

Hi everyone, newbie here!! I have a 2001 GP 3800 series, anyhow, I noticed today that my temp guage barely went over 100 degrees, NO check engine light came on. About a year ago, same problem, service light comes on, I scan it, change thermostat,(fail safe type) all is good. Facts to know: I NEVER flushed the coolant since I owned the car (7 years), I HAVE mixed green with red antifreeze in the past, ( I didnt know the difference back then). My theory is the stat could be stuck open from accumulated gunk floating around since it was never flushed. Any suggestions on this is GREATLY appreciated.

One more question, How exactly is the best way to open the radiator drain on the lower left side? I could barely reach it and if i remember, i tried needle nose pliers to crack it open and it wouldnt budge. I didnt want to break it.
THANKYOU!!!

I apologize for the long post!!

Welcome to AF.

100 degrees? Doesn't the low scale on the temp gauge start out at 160 degrees? The Dex-cool is only good for 5 years or 150K miles, whichever comes first so you are way overdue. Bad idea to mix green with orange Dex-cool so you need to flush the cooling system.

On draining the radiator go from underneath. Remove the plastic trim and use the tool shown in the tech procedure posted at our Tips & Maintenance. See link.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=935938)

isnt there a problem with mixing the two that it causes them to clog up the rad?

isnt there a problem with mixing the two that it causes them to clog up the rad?

What I do know for a fact is when the two coolants are mixed you will get sludge in the cooling system sooner or later.

It might be adviseable to undo the upper and lower rad hose and run a garden hose thru after the used coolant has been collected to confirm the radiator core is free-flowing.

I would exercise caution running a garden hose with unregulated pressure on a radiator direct. Reason is in most cases the city water supply pressure is too high. 50 psi plus. So make sure it is not turned up too high. Good way to blow the seals located on the plastic coolant reservoirs where the radiator core meets up.

50+ psi is entirely possible in the cooling system if you run WOT with a closed tstat, so not sure how to advise there. Granted the radiator is "protected" somewhat by the closed tstat although there is the bleed orifice to contend with but most is shunted somewhat by the flow control washer for the heater core.

Also...sealing up a garden hose to transfer full city-water pressure to either of the radiator hose(s) might mean a couple hours on the lathe turning up an adapter. Normally I have better things to do with my time and raw materials. My suggestion is to pour water in the top hose or port of the radiator and see what pours out the bottom.

Thankyou for your responses and yes, I made a mistake, the coolant guage starts at 160. Today it seemed to go up to 185 and I thought maybe the obstruction in the tstat (assuming there is one) had cleared itself, then it went doen to 165-170 which is not normal. Maybe the one year old thermostat is bad??

I myself would start with replacing the stat (since its a cheap part) and flush and fill the cooling system with the proper mixture of 50/50 or 60/40 Dex-cool with distiller water.

Thanks again everyone and also BNaylor for the tool tip. I will post my results after I take this on.

Hello guys,

I have the same problem if not similiar. I just got the code which came back as P0128 (2001 SE 3100). Can someone please tell me how can i fix this problem?:crying:

Hello guys,

I have the same problem if not similiar. I just got the code which came back as P0128 (2001 SE 3100). Can someone please tell me how can i fix this problem?:crying:


The P0128 DTC is common if you live in a very cold climate area but if in a warmer weather area a problem. It means the PCM module has detected that engine warmup time via the ECT sensor is taking too long to properly warmup. Engine temperature rise too slow.

In most cases it is a defective thermostat but could also be a an ECT monitoring issue.

What does your temperature gauge at the IP read after sufficient engine warmup time?

I guess I can post on here because I am having similar problems. I moved from Florida about 2 months ago, and never had a problem until moving back to Indiana. The running temperature of my car ('00 GTP) is barely above 160, even after long periods of driving. It used to warm up right to the first line (185 I believe, and hopefully this is normal). There is a code set but have not retrieved it yet. Also I have noticed a decrease in fuel mileage but this could be due to winter gas (if I reset on highway, I get about 25 mpg, when i used to get near 29). I'll take any ideas you guys have for me. Thanks.

I guess I can post on here because I am having similar problems. I moved from Florida about 2 months ago, and never had a problem until moving back to Indiana. The running temperature of my car ('00 GTP) is barely above 160, even after long periods of driving. It used to warm up right to the first line (185 I believe, and hopefully this is normal). There is a code set but have not retrieved it yet. Also I have noticed a decrease in fuel mileage but this could be due to winter gas (if I reset on highway, I get about 25 mpg, when i used to get near 29). I'll take any ideas you guys have for me. Thanks.

It would help to post the code (DTC) so we don't speculate. A thermostat opening too soon or staying open (stuck) could cause your symptoms or reduce fuel economy due to longer engine warmup times. Are you using premium unleaded gas?

Are you using premium unleaded gas?

I sure do, every fill up.

And I will try to retrieve the codes soon. Moving across state this weekend, so it will be next week sometime.

?? What was the temp rating of the new thermostat? The afore mentioned sludge may be blocking the temp. sensor thus giving a faulty reading. The lower gas mileage may caused in part by the gasoline formulas in your state. Gasahol has a lower energy/heat content than regular gas. This is discussed in another thread at length.
Prestone makes a flush kit that can be installed into a heater hose. You do have to leave a hose undone somewhere as to not build up the high pressure. Just follow prestone's directions. Messy but still works.
hope this helps.

Novaz27

?? What was the temp rating of the new thermostat? The afore mentioned sludge may be blocking the temp. sensor thus giving a faulty reading. The lower gas mileage may caused in part by the gasoline formulas in your state. Gasahol has a lower energy/heat content than regular gas. This is discussed in another thread at length.

Prestone makes a flush kit that can be installed into a heater hose. You do have to leave a hose undone somewhere as to not build up the high pressure. Just follow prestone's directions. Messy but still works.
hope this helps.

Novaz27

Which member are you giving the advice to? There are three members with different issues that posted in this thread. Be sure to use our quoting system or address the reply to a specific member.


On using the Prestone flush kit you tee into one of the heater hose lines (return). The same tee is used to connect the water supply/source. Also, you can use the special discharge fitting that comes with the kit installed to the radiator filler neck which will reduce flushing water pressure. There is no requirement to disconnect any hoses that I know of.

We have a tech procedure posted at our Tips & Maintenance section that covers using the Prestone or a similar DIY flush kit. See below and link.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=935938)



Install the flush T from the Prestone Flush Kit in the heater return line hose from the heater core per the instructions on the label.

Top Heater Hose = return
Bottom Heater Hose = pressure

1. With engine cool, remove radiator cap and drain the radiator.
a. Turn drain plug (lower left engine-side of radiator) counter clockwise about 1/8 of a turn (may require a little force if it's not been opened in awhile--be careful because it's plastic). Use the end of a 1/4" drive handle. Plug will extend slightly as it loosens. Be sure to have a container in-place to collect the antifreeze.
2. Let all the antifreeze drain into a container.
3. Remove, drain and clean the antifreeze overflow bottle. Reinstall bottle.
4. Hook up a garden hose to the flush T and turn water on (Caution: not too high or you can damage seals/gaskets with the pressure). When water starts to run from the drain plug, start the engine and turn the heater on (make sure you leave the water running during this process).
5. When water runs clear (about 5 - 10 minutes), turn off car, then turn off water, and remove hose from T and cap it. Let remaining water run from drain plug. (Note: Not all of water will be drained out of system mainly the engine block. What I do is hook up a drain hose to the T connector, start engine and let the water pump push water out of the system. As soon as you see no water coming out turn engine off, remove drain hose and cap off T connector).
6. Close radiator drain plug and fill radiator with a 50-50 mix of extended life 5/150 antifreeze/distilled water (or buy premixed 50/50).
7. Start vehicle and bring to operating temperature to make sure thermostat opens. Add additional mixture as necessary until full.
8. Reinstall radiator cap.
9. Release any trapped air in cooling system by turning the plug on the top of the thermostat housing (be careful not to burn yourself). When only coolant (no air) flows from the plug, close it. You may have to repeat this several times to get all of the trapped air. Note: Raising the front end of the car where the radiator is higher than the engine helps bleeding.
10. Add additional coolant as necessary. Also, fill overflow bottle to recommended level. Be careful not to open radiator cap if hot. You may have to do this several times.
11. Check for leaks.
12. Properly dispose of old antifreeze.

HELLO. I was just posting general information to everyone. I have been doing my own vehicle work since the 60s. Just trying to help out. You all have a great forum here. I just have to learn the ropes of posting on the forum and learn how to type. You can teach an old dog new tricks if they are willing to learn.

NOVAZ27

Hello everyone. I was the original poster of this posting and I want to follow up with this issue. I replaced the thermostat with a stock 195 replacement. The fail-safe t-stat that I took out had the fail-safe engaged. Basically it was locked in the WIDE OPEN position and will stay that way until physically removed/replaced. I dont know why it did this; it was a 195 t-stat. I dont recall the coolant temp spiking up on the guage but problem seems to be solved, for now........

Thankyou to everyone, on this forum who replied and added their tips and solutions. :)