Over filled radiator all of a sudden.

[bchauvette]

M944A1 w/NHC250, All of a sudden the coolant tank level is too high. Just enough for the overflow to drip on a race track with engine shut off. With the engine cold I took the cap off and coolant came out. Any chance of some sort of air bubble? Transmission cooler leaking? Bad thermostat? It has been running in the 190-200 range since day one. The fan clutch cycles frequently. Much more than Ken's M923A1. Will be replacing the thermostat and cap tomorrow.

 

[zout]

How high was the coolant in the resevoir previously to this ?

 

[andy3]

Butch,

It wasn't a hit day when this happened. Can you tell if there is any oil in the coolant? Is it manufacturing coolant or just a bit high and overflowing a touch?

 

[Coffey1]

My truck runs a consent 160 when it's 95 or better it runs 180.
My fan clutch rarely comes on.

 

[Olpa77]

I had a similar problem on a 855 Cummins in the past. My truck kept pushing coolant out. When the truck was cool if I removed the cap the coolant was under pressure and would spill out. The culprit was a faulty air compressor. It was pushing air through the coolant lines putting extra pressure in the cooling system.

 

[bchauvette]

My truck runs a consent 160 when it's 95 or better it runs 180.
My fan clutch rarely comes on.

I hate you. , Just kidding.

 

[bchauvette]

I had a similar problem on a 855 Cummins in the past. My truck kept pushing coolant out. When the truck was cool if I removed the cap the coolant was under pressure and would spill out. The culprit was a faulty air compressor. It was pushing air through the coolant lines putting extra pressure in the cooling system.

How in the world did you figure that out? That ties in to my air bubble questions. When I took the cap off it was like it was burping.

Putting the thermostat and cap in today. Taking a test drive going down main Street with her dressed out for the fourth.

The level was per the TM, Doghead are you proud of me?

 

[Olpa77]

How in the world did you figure that out? That ties in to my air bubble questions.

I took it to Cummins because I thought it was the head gaskets. I have no clue how they tested that. I would start with the thermostat and cap like you plan.

 

[WillWagner]

How in the world did you figure that out? That ties in to my air bubble questions. When I took the cap off it was like it was burping.

Putting the thermostat and cap in today. Taking a test drive going down main Street with her dressed out for the fourth.

The level was per the TM, Doghead are you proud of me?

If you checked it cold and it was "burping" you can t/s it cold. just take the radiator cap off, and, if it is bubbling, drain all the air from the tanks and see if it stops. If it does it warm, do the same, but leave the cap off, run it at idle or a bit above idle 'till the coolant starts pushing out then shut it off, the bubbles should still be there, and drain all the air from the system. If they stop, it's the compressor head. Very easy to rebuild!

 

[andy3]

Butch, don't leave us in suspense. What'd you find?

 

[bchauvette]

Changed thermostat and cap. runs only a little bit cooler. The fan clutch engages a little bit less. Actually runs at exactly what the thermostat and fan clutch are rated for. When I pored the coolant back in it ended up right at the proper fill point. I carefully monitored the temp, fan clutch and overflow tube while going to the Upstate get together. I didn't see any evidence of overflow tube blow out.

While parked at the get together we noticed a sort of percolating sound. I completely drained the air system through the emergency glad hand. Sound didn't go away. Took the cap off and the level was right (Ken correct me if this is not correct). Left the cap off and over a period of an hour the coolant drained back emptying the expansion tank!! It stills feel like it is developing some sort of air bubble. If it is the compressor head the air is not making its way to the expansion tank but creating a major bubble. I had a British car that required bleeding when filling the coolant system. Feels just like that.

B.T.W. Blew an other axle seal . Left rear-rear.That makes two now.

 

[Coffey1]

OK here's the correction. Yes you bled tanks down but what we need to do is run it with cap off and see if there's bubbles coming up into tank.
I may be wrong but that's what I read.

 

[bchauvette]

OK so I checked the coolant level after the truck has been sitting over 5 days. The expansion tank was definitely pressurized and empty. re-filled to proper level and started the engine. As the engine ran the coolant level came up and over flowed with the cap off. Engine never reached operating temp. during the testing. Due to vibration it was impossible to check for bubbles. How ever with the engine off the was a single small bubble coming up about every two seconds. The bubbles seemed to stop with the air bled off.

How do I go about getting a compressor head rebuild kit? Do I have to go to Cummins? After Market sources? Tips ,suggestions, part number?

 

[Olpa77]

You can go to https://quickserve.cummins.com and set up a free account. You will need your ESN number from the tag of your engine. In the parts catalog you will find all your parts numbers and some diagrams for your engine. I prefer Cummins or Bendix compressors. I once installed a cheap trux brand and it went bad within a few weeks. You can go to just about any heavy truck dealer and give them them your ESN and they can find what your looking for. I personally prefer Freightliner but it really don't matter.

 

[bchauvette]

You can go to https://quickserve.cummins.com and set up a free account. You will need your ESN number from the tag of your engine. In the parts catalog you will find all your parts numbers and some diagrams for your engine. I prefer Cummins or Bendix compressors. I once installed a cheap trux brand and it went bad within a few weeks. You can go to just about any heavy truck dealer and give them them your ESN and they can find what your looking for. I personally prefer Freightliner but it really don't matter.

Thank you so much for your reply. We got a great bunch of guys here. Remember " Everybody doesn't know something at sometime" .

NHC250 compressor head rebuild thread w/pics cumming soon.

 

[Olpa77]

Not sure what kind of coolant your adding but make sure it has DCA or SCA additive in it. Green stuff is okay as long as your adding DCA additive. They sell test strips to test your coolant. Lack of DCA will cause cavitation of your liners in diesel engines. You might already know this info already, I just thought I would throw you the tip. I've known many folks ruin a good engine by not putting the proper coolant in diesel engines. Good luck I can't wait to see the pictures.
http://www.cumminsfiltration.com/html/en/training/faq/cooling.html