Coolant Change?

[J DeMaio]

Well guys, I think it's time to change the coolant, t-stat, and hoses in my truck. I wanted to ask because this has been a big talk in the 2 nd generation forum. As i understand, there are two different part numbers for the thermostat. What is the one I want? I'll be doing this tomorrow. I'll get the hoses from Autozone but get the thermostat and antifreeze from one of the local Cummins shops (there are two within 5 miles of me). I notied where my hoses are starting to leak and there is a gel like substance around the edges of the hoses, they're probably the originals. What is the easiest and best way to bleed the system while filling? Thanks a bunch!

 

[ETOBICOKE]

Coolant fill

Just fill up the rad full, leave rad cap off, start the engine and turn on the heater. Keep an eye on the fluid level you will have to add a small amount of coolant soon after starting. When the engine comes up to temperature and the thermostat starts to open the level usualy drops quickly this is when you need to top it up. When the coolant level stays constant put the cap back on. Don't forget to top up the plastic overflow tank when you are finished. This should get all the air out, coolant level self regulates via the overflow tank, so it may require topping up, do this when the engine is cold.



Neil

 

[Lordsman]

Cooling Maintenance

Mix distilled water with your new anti-freeze. Keeps your cooling system from fouling. Since your changing all your hoses & t-stat, point it a little downhill and all the old stuff should drain out. May want to flush first if system shows corrosion or fouling.

 

[Jones]

Hey J,

I usually goe for the thermostat that will keep me in the heat range I want for my driving conditions so you might want to toss that into the equation too. As far as opening the system goes,

the t-stat housing has a pipe plug screwed into the top of it so you can bleed the last of the air out of the system. I usually unscrew that and screw it back down when I get liquid and not bubbles out past the threads. Sometimes running them will burp all the air out and sometimes not.

Hope this helps, Jones

 

[J DeMaio]

Thanks Guys, does it hurt to pour some stop leak in the radiator with the andifreeze? What is the best antifreeze to use, Fleetguard pre-mix or any kind?

 

[ETOBICOKE]

Stop Leak

Generaly I prefer not to use stop leak, although some rad shops use it all the time. Some say it can clog up the radiator and since our trucks don't seem to have problems with coolant leaking, it would not be needed. My grandad used to use a handfull of black pepper for pinhole leaks, but only as temporary repair to get home.



Neil

 

[J DeMaio]

Well, neither Cummins shop had the antifreeze or the thermostat, so I went to my local Auto Value parts store. I picked up the hoses, 3 gallon of antifreeze, and thermostat (with rubber seal). I finally got the job done, it was a bear! Hoses were shot and there was a fair amount of deposit in the old coolant. The thermostat I got was a 180*, they said this is the only one they have for this truck. My system took about 2 1/2 gal antifreeze to 2 1/2 gal of water. I idled it for about a half an hour and had the heater on, gauge seems to be more responsive now, before it seemed to take a long time to warm up. Does your coolant gauge usually stay to the right of the second line, and sometimes fluctuate? Should be ready for more years of service, by the way I believe the hoses, coolant, and thermostat were original, they had a few miles on them.

 

[ETOBICOKE]

Temperature Gauge

My temp gauge usualy reads at the division just left of half. Needle always seems to stay in the same posisition once the engine is up to temperature, summer and winter. I have on several occasions had the gauge fluctuate up and down slightly, this was just the thermostat cycling, would do so on a cold day without the winter front, and travelling on the highway.

You may be able to attribute the faster gauge response that you have now to the new coolant cleaning up the coolant passages and sender.

My truck still has the original hoses and thermostat, I just keep checking them over every oil change. Was very impressed with the quality of the hoses used in these trucks when I first took delivery, everything is heavy duty. Usualy most ccolant hoses fail because they have oil leaking on them, this not much of a problem with the Cummins engine, top end of these engines stays dry.



Neil



ps, if you have a look in the owners manual, it sort of indicates that no two temp gauges will read the same, so don't wory if yours reads slightly higher or lower than mine or others.

 

[Matt S]

J DeMaio,

Did the t-stat look one out of a car? The one I got from the auto store did but it would cycle way too much for me. I ended up ordering one from Dodge to get the right part and it fixed my cycling problem.

 

[J DeMaio]

No, it looked pretty much like the old one I pulled out, it was a bit shorter. It is a 180* one, they said this is the only one they have.

 

[mark93]

Hi J.

Normally my gauge indicates right on or just to right of the 2nd Normal Range mark. With the original thermostat it would run between the 1st and 2nd marks, which is a bit cool.

On a recent trip when operating at full load and in hot weather the gauge read between the 3rd and 4th lines (the 4th line is Normal Maximum-back off if the needle at all moves past this mark. ). The service manual says that in Hot Weather with a Heavy Load this is normal.