[Raedwulf]

I just replaced my freeze out plugs (3 on exhaust side) They had rusted out. It has a new radiator and was fine until they failed. It got really hot and was blowing steam out of the center freeze out, the other two hadn't failed. Any way after replacing them I ran it for about an hour and the temp. gauge came up to the first mark like it had before (So as usual) . Then I drove it about 5 miles, and it stayed there. When I got home i checked the heater core rails (hoses) ...Hot but could keep hand on it, Top hose hot again I could keep my hand on it. radiator was hot on the hose side .......The bottom hose was not hot, so I opened the radiator and put my finger in, and the water was cold.....Are they this cold blooded? My thoughts are a stuck thermostat?? I don't want to open it up if it's not necessary. But i have a flush chemical in it now and it doesn't seem to be circulating. I am going to go out on a longer test ride today, but any insight would be appreciated.

 

[24hrsparkey]

It takes much longer than 5 miles to get the system to OT.
Your Temp gauge ( if its functioning ) will indicate when the thermostat opens ,, then drive some more , then OT has been achieved .
OT = 160F - 190* F depending on what stat you have installed.

 

[H3LZSN1P3R]

You ever flush the coolant? Also pop the rad cap start it and have someone throttle the truck if the coolant moves before the truck is at op temp the stat is stuck open and if the coolant does not move after the truck hit op temp then the water pump may have failed

 

[2002CTD]

You ever flush the coolant? Also pop the rad cap start it and have someone throttle the truck if the coolant moves before the truck is at op temp the stat is stuck open and if the coolant does not move after the truck hit op temp then the water pump may have failed

Agreed. Failing / failed water pump is my first inclination.

 

[Antonm]

The water pumps are kinda stupid simple by design, about the only thing that can fail is the bearing, and when that fails it leaks coolant externally. Put an new thermostat in it (cheap and easy to to do), then drive for a longer than 5 miles (especially considering its winter time now, depending on where you live/ the outside temp, you may even have to block off part of the radiator to get it up to temperature).
.
.
.

 

[Engine Ear]

I just replaced my freeze out plugs (3 on exhaust side) They had rusted out. It has a new radiator and was fine until they failed. It got really hot and was blowing steam out of the center freeze out, the other two hadn't failed. Any way after replacing them I ran it for about an hour and the temp. gauge came up to the first mark like it had before (So as usual) . Then I drove it about 5 miles, and it stayed there. When I got home i checked the heater core rails (hoses) ...Hot but could keep hand on it, Top hose hot again I could keep my hand on it. radiator was hot on the hose side .......The bottom hose was not hot, so I opened the radiator and put my finger in, and the water was cold.....Are they this cold blooded? My thoughts are a stuck thermostat?? I don't want to open it up if it's not necessary. But i have a flush chemical in it now and it doesn't seem to be circulating. I am going to go out on a longer test ride today, but any insight would be appreciated.

Problem could have several causes that I can think of: air lock, stuck thermostat, or worn water pump. First off, you can decrease your troubleshooting time by idling with cardboard sheet over the radiator to choke off air flow. You need to carefully watch your temperature gauge to avoid cooking the engine though. But with poor coolant flow, does your gauge really sense true temperature? Just keep a good watch for other signs of overheating. An IR temperature gun can help to locate hot and cold spots if you have or can borrow.

A warn water pump should be obvious, as the bearing will be wobbly and cause the belt to do a dance, and the pump will likely leak. Suppose the impeller could be corroded, but this is unlikely. However, while changing the frost plugs, you could have dislodged dirt into the system that might have stuck in the impeller. The pump is not hard to remove once the system is drained. Only 2 bolts to take out, and quite easy to reach. It is sealed in to the engine with an o-ring, so you run the risk of dealing with a brittle or crushed o-ring. Would be good to have a new one on hand, but unsure if it can be bought by itself, as they are supplied with a new pump.

Could be an air lock, and all you can do is to run the engine a while with the rad cap off. This should eventually vent any air out of the system.

Could be that your thermostat is stuck open. If you do not know how old it is, it is time for a new one anyway. Did not see which truck you have in your posting info. If 1998.5 or newer, precision of the thermostat is important for the temperature to be precise to get good performance and fuel economy due to the computerization. I had one stick open on the highway. Temperature gauge shot way down to nothing at highway speed and light load. Stopped at next exit and problem cured itself after having stopped a few minutes and restarted. Later, fitted a new thermostat. Best to pay the premium price for a quality thermostat. I had an issue to get the thermostat and its gasket or o-ring together. Dodge dealer did not have them packaged together and I would have had to pay an outrageous price and wait a few days for the o-ring or gasket. Cummins had some similar issue about getting both. Bought the best one that my local independent parts shop had. The o-ring or gasket was included in the box. Don't remember the brand, but it's been working fine four about 4 years. My 12 valve is not heavily computerized, so I feel that I can get away with an after market thermostat that may not be as precise as an OE part. Note that the thermostat has a bypass circuit to enable both sides to warm, or it would not open. It can be seen as a small hose that runs from the head to the upper end of the housing. It has a small valve or orifice of some kind that I think threads or press fits into the head. Need to make sure that this circuit is clear and hose is good.

Hope you get it figured out soon.

 

[H3LZSN1P3R]

The water pumps are kinda stupid simple by design, about the only thing that can fail is the bearing, and when that fails it leaks coolant externally. Put an new thermostat in it (cheap and easy to to do), then drive for a longer than 5 miles (especially considering its winter time now, depending on where you live/ the outside temp, you may even have to block off part of the radiator to get it up to temperature).
.
.
.

I have seen lots of old ones with damaged impellers an it not leaking….

 

[Antonm]

I have seen lots of old ones with damaged impellers an it not leaking….

Really, in 6bt Cummins engines you’ve seen lots of failed water pump impellers?

Well, you’re the only one then. These industrial/agricultural engines are certainly not known for failing water pump impellers, but I suppose anything is possible.
.
.
.

 

[H3LZSN1P3R]

Really, in 6bt Cummins engines you’ve seen lots of failed water pump impellers?

Well, you’re the only one then. These industrial/agricultural engines are certainly not known for failing water pump impellers, but I suppose anything is possible.
.
.
.

Never said specifically just the 6bt but yes i have seen a few….

 

[bigfish95971]

Heat may have ruined the old thermostat. Replace and make sure it is 190.

 

[Raedwulf]

"Could be an air lock, and all you can do is to run the engine a while with the rad cap off. This should eventually vent any air out of the system" That sounds like my next ritual! The first 3 rusted out . I bought the truck 3 years ago and the radiator was replaced, and coolant was obviously replaced. I replaced the water pump a year ago ....The first 3 Freeze plugs I bought were too small and I Replaced them with the correct size . The new Dormans were a different design and have a very small contact area ....I took it on that longer test drive and a second one blew out .I like the air lock theory . I made 3 new ones out of aluminum stock with a flange on them so they can be put in deep and flat ....Then I'll run it home with the cap off. I agree that they need a longer drive to warm up. Hopefully this will end the saga of the freezeout plugs. I am in Fl. and frozen blocks are very uncommon. PS thermostat functioned as designed

 

[Engine Ear]

Sounds like you're getting it sorted. The aluminum frost plugs might last a few years, but aluminum in an iron block or head is not likely to have a long life due to galvanic corrosion. If the right one's can't be found, ya gotta use what ya can find or make though. You may need to go for a drive with rad cap off to get water pump to full RPM's to break the air lock. Or just give it some pedal with engine running while parked. When air lock breaks, coolant could gush out cap though. Of course keep an eye on your temp gauge.

 

[GAmes]

.I like the air lock theory

If you would take the time to either research it on this forum or open the factory service manual you wouldn't. Air won't cause a freeze plug to pop out or leak and there is a mechanism the 12 valve possesses to vent air from the system. The correct procedure is to fill it with coolant, install the radiator cap and operate the engine. After it cools enough to remove the cap you add coolant. From the FSM


REFILLING COOLING SYSTEM
Clean cooling system prior to refilling. Refer to
Cooling System Cleaning section of this group.
(1) Install the cylinder block drain plugs (Fig. 36).
(2) Close radiator drain plug.
(3) Fill the cooling system with a 50/50 mixture of
water and antifreeze. 5.9L Diesel Engine Only; The
diesel engine is equipped with a one-way check valve
(jiggle pin). The check valve is used as a servicing
feature and will vent air when the system is being
filled. Water pressure (or flow) will hold the valve
closed. Due to the use of this valve, the engine
must not be operating when refilling the cooling
system. Refer to Thermostat Operation—5.9L
Diesel Engine in the Thermostat section of this group
for more information.
(4) Fill coolant reserve/overflow tank to the FULL
mark.
(5) Start and operate engine until thermostat
opens. Upper radiator hose should be warm to touch.
(6) If necessary, add 50/50 water and antifreeze
mixture to the coolant reserve/overflow tank to maintain
coolant level. This level should be between the
ADD and FULL marks. The level in the reserve/overflow
tank may drop below the ADD mark after three
or four warm-up and cool-down cycles.

 

[Engine Ear]

If you would take the time to either research it on this forum or open the factory service manual you wouldn't. Air won't cause a freeze plug to pop out or leak and there is a mechanism the 12 valve possesses to vent air from the system. The correct procedure is to fill it with coolant, install the radiator cap and operate the engine. After it cools enough to remove the cap you add coolant. From the FSM


REFILLING COOLING SYSTEM
Clean cooling system prior to refilling. Refer to
Cooling System Cleaning section of this group.
(1) Install the cylinder block drain plugs (Fig. 36).
(2) Close radiator drain plug.
(3) Fill the cooling system with a 50/50 mixture of
water and antifreeze. 5.9L Diesel Engine Only; The
diesel engine is equipped with a one-way check valve
(jiggle pin). The check valve is used as a servicing
feature and will vent air when the system is being
filled. Water pressure (or flow) will hold the valve
closed. Due to the use of this valve, the engine
must not be operating when refilling the cooling
system. Refer to Thermostat Operation—5.9L
Diesel Engine in the Thermostat section of this group
for more information.
(4) Fill coolant reserve/overflow tank to the FULL
mark.
(5) Start and operate engine until thermostat
opens. Upper radiator hose should be warm to touch.
(6) If necessary, add 50/50 water and antifreeze
mixture to the coolant reserve/overflow tank to maintain
coolant level. This level should be between the
ADD and FULL marks. The level in the reserve/overflow
tank may drop below the ADD mark after three
or four warm-up and cool-down cycles.

Thanks for the manual procedure. I've gotten mine topped up and running without this, and had no problem. Sometimes even the seemingly simple things require reading the manual though. They do not directly say it, but it seems that the rad cap should be in place to run the engine after filling. Now I need to find out where the wiggle valve is located.

 

[Raedwulf]

Sounds like you're getting it sorted.

Well, I thought I was . I installed the new plugs ran it with the radiator cap off, took it for a test drive, the heat went up and dropped, so I believe the thermostat worked. Topped the water off and and it stayed warm, didn't get hot. My next plan it to drive it home (about 20 miles) with the radiator cap off. I don't want to lose the plugs on the way home. It is building up enough pressure to blow them out. I couldn't find any info on freezeout plugs blowing out.I am going back up there Wed. Night to get it.

 

[Engine Ear]

Well, I thought I was . I installed the new plugs ran it with the radiator cap off, took it for a test drive, the heat went up and dropped, so I believe the thermostat worked. Topped the water off and and it stayed warm, didn't get hot. My next plan it to drive it home (about 20 miles) with the radiator cap off. I don't want to lose the plugs on the way home. It is building up enough pressure to blow them out. I couldn't find any info on freezeout plugs blowing out.I am going back up there Wed. Night to get it.

Great that you have circulation. Beware that a thermostat can be inconsistent. Mine went wide open on the highway. After stopping a few minutes, it went back to normal and I drove it a few hundred miles without trouble showing until I got home and replaced it. With the disappointing after market frost plugs, maybe a set from Cummins is the way to go. Cooling them might help the fit. They can be put in the freezer before fitting, or even just dunked in ice water. A smear of grease in the holes and on plug edges might help. If not in ice water, carry from the freezer wrapped in a rag. The thin metal warms fast.

 

[GAmes]

If you are afraid the freeze plugs will pop out with inly 15 psi of pressure then you need to park the truck. Driving it with no radiator cap will result in lower engine temps and therefore less heat.

 

[Engine Ear]

Raedwulf says he has only 20 miles to go. Inder normal

If you are afraid the freeze plugs will pop out with inly 15 psi of pressure then you need to park the truck. Driving it with no radiator cap will result in lower engine temps and therefore less heat.

Raedwulf say he has only a 20 mile drive. Under normal conditions, the engine would only be just getting to operating temperature over that distance. Not sure that this is an issue. If the plugs feel like they are in solidly, a 20 mile trip should be ok with no rad cap. Instead of 190 deg., the engine my only get to perhaps 150 deg. For 20 miles, is that important? If it were me, I would carry lots of extra water and an extra plug though, just in case. When my water pump failed on the road, I got to the next exit by driving just a couple miles at a time with an eye on the temperature gauge, then stopping to wait for it to cool. A bit risky, but it worked. When my thermostat stuck open and temperature gauge went down to bottom, I drove maybe 10 miles to next exit. The engine has run fine for thousands of miles since replacing the thermostat. Of course my 12 valve has very limited computerization. Not sure how a truck with full blown computer control and electronic fuel injection would fare without proper temperature regulation. Maybe very bad performance and exhaust smoke?

 

[GAmes]

Raedwulf says he has only 20 miles to go. Inder normal

Raedwulf say he has only a 20 mile drive. Under normal conditions, the engine would only be just getting to operating temperature over that distance.

Maybe with your truck. I have heat within a couple miles and operating temp in less than 5. Of course, that is with a radiator cap installed.

 

[Raedwulf]

I am not concerned about driving it home, I'll keep an eye on the gauge. I have a new thermostat to install, and I will check the cap and wiggler for function. I blame them popping out on the plugs themselves. (I could be wrong) Crap design not enough side wall. It appears you need a special tool to set them to the precise depth. I tried to locate the needed size in the traditional cap shape and at O'riley's the counter guy found them on ebay but when I got home, I could not find the same source on e-bay and no one selling them had the specs (Size) posted so I made some. Cummins never got back to Me not a big money maker, I guess..