Coolant leak on Cummings Diesel engine

[Klueck]

We are sitting up in the north Georgia mountains and were preparing to head south, when we noticed a small coolant leak.

We have a Cummins 370 ISL engine with a side radiator.

The leak appears to be coming from a hose near the radiator. It's been very cold here and we though that might have effected some of the hoses or clamps.

DH tightened up the hose clamps (which were a tad loose) and we hoped it would stop.

Unfortunately, we still have a slow leak when the engine is running.

We are nowhere near a Cummins dealer and are unsure what to do next.

DH bought another clamp and thought he would double clamp where he thinks the leak is. He also bought some of that silicone tape that is heat resistant, hoping that would help. It started raining so he didn't get to try the clamp or tape.

My question is, if we can't get the leak stopped, do we dare try to head south if we watch the engine temperature and check for leaks as we go? We aren't too far from I-75, so we will have rest areas along the route.

[Snomas]

I had a similar slow leak (bottom hose) problem in Albuquerque,NM last spring and cummins just put on a second hose clamp that stopped the leak. I also had a top hose leak and just tightened the clamp to stop the leak.

[artguys]

On diesels it's known as a cold water leak...check clamp tightness and nothing to worry about.

[Airstreamer67]

MrWizard wrote:
there was NO stop engine light
the temp gauge started going nuts
going high, dropping down, then going high again
i foolishly pushed on to the next exit off I-40 in Az instead of pulling over on the interstate

The temperature gauge can sometimes be misleading if water is lost in the cooling system. Perhaps this is why it seemed to go "nuts" in your case.

When the cooling system is full, the temperature gauge probe works fine because it is surrounded by water.

However, as the water level begins dropping, it begins to leave the probe "dry" surrounded only by air, thus leaving the gauge unable to accurately measure the water temperature. In your case, I bet the surges of water and air caused by the dropping water level caused the gauge to drop and rise with the water surges.

A lot of engines have been ruined by water leaks which leave the cooling system without water and the temperature gauge not accurately reporting the engine temperature.

I've got two alternative systems to help avoid this problem: an engine oil temperature gauge, which should catch the overheating problem quickly, and a low water-pressure indicator, which provides an alarm when the water level falls, since the water system pressure should fall as well.

[2oldman]

ScottG wrote:
You have a "Cummins" - no G.
Just sayin.

I think he left it that way in the heading just to irritate us.

[JackMS]

Be sure you are certain which hose is leaking. Sometimes a leak above can be dripping where you can't see.

[randallb]

Monaco used some very cheap hose from the surge tank to the lower radiator hose (depending on hose layout) because it allowed them to stretch it over the surge tank fitting which was actually 1/4" larger in diameter than the T in the lower radiator hose. It will convince you that you have a loose clamp but the hose is actually splitting where it is stretched to go over the surge tank. This may or may not be your problem but it was mine. I was initially convinced that the lower radiator hose was leaking at the T fitting.
Randy

[wolfe10]

With a leak only in cold temperatures, first suspect is hoses/hose clamps.

The larger the diameter of the hose, the more susceptible it is to leakage when the metal it surrounds shrinks.

Either double clamp or use "constant torque hose clamps".

[Klueck]

OP here.

First, I do know that Cummins is spelled without a "G", but I accidentally added the g in once.... I guess no one noticed when I spelled it correctly.

Second. We made it over 500 miles with no problems. We kept a close eye on the temp gauge, and checked for leaks every time we stopped. We're thinking the cold weather may have been the cause of the problem, but we're going to have the system checked out at a Cummins shop very soon.

Thanks to you all for your ideas.

[Mr_Mark1]

MrWizard, now that you mention it, I remember you telling the story and the repairs needed.

MM.

[MrWizard]

there was NO stop engine light
the temp gauge started going nuts
going high, dropping down, then going high again
i foolishly pushed on to the next exit off I-40 in Az instead of pulling over on the interstate

[Mr_Mark1]

MrWizard wrote:
just so you know, on my cummins they called it a "surge tank"
when mine cracked i lost all the coolant and overheated the engine and did major damage

Did you not have sufficient notice that the tank was leaking? Certainly, the 'stop engine' light illuminated.

MM.

[MrWizard]

just so you know, on my cummins they called it a "surge tank"
when mine cracked i lost all the coolant and overheated the engine and did major damage

[Mr_Mark1]

Klueck, it sounds like the leak is rather small. As long as you have plenty of fluid in the coolant box, you should be fine.

We had a leak from the heater hose back in Sept. of 2012. Apparently, there was a shield that was missing and the hose rubbed against the engine causing a small hole that grew bigger. Amazing that it took just over 50,000 miles to appear. Anyway, we were 60 miles from Cummins Central Power in Kansas City, MO, heading back to TN. I went to Walmart and bought 10 gallons of antifreeze and put in 7 gallons.

We drove cautiously the 60 miles while I watch my temp gauge. It stayed at the correct temp the whole way. When we drove up to the Cummins facility, the tech came out and we had a steady stream dripping from the hose. We still had fluid in the coolant box.

They replaced the hose by splicing it (at least a 35 ft, hose) and I needed a new coolant box as it has lost it's 'pressure' feature. Cummins in Kansas City did a wonderful job and worked us in without an appointment. We stayed in their free lot with electric and water connections the day we arrived with an early morning appointment the next day. Since the job took until late afternoon, we stayed again the second night so we could leave fresh and early the next morning.

If fact, I had such good service from them that I planned my BIG 60,000 mile service this past Sept. (2013) when passing through Kansas City heading back to California (engine and genny service).

Safe travels,
MM.

[MrWizard]

ivyblog
the silicone tape goes on the outside of the hose
it is self vulcanizing..it sticks to itself/fuses and becomes solid rubber
sometimes called emergency tape
it is for stopping the leak
it is Not going affect how the hose is fasten to radiator nipple