12.7 Detroits blowing radiator hoses due to coolant additives????

Has anybody heard of this before?

We have several fire trucks (97-05 model years) all with detroits, that are regularly blowing radiator hoses. They aren't rubbing anywhere and failing from weak spots, they are fairly new and blowing out in the center area. Almost all of them are the 90* hoses on the bottom of the radiator.

I personally believe it is a pressure problem from a liner or bad head gasket allowing engine compression to pressurize the coolant system. They do have a pressure relief valve of some sort in the cooling system that has been found to be plugged in a couple trucks. However, the diesel shop our central garage uses (for major work) is blaming the additives in the coolant. The coolant filters were being changed every 5-6 months when the trucks went in for service and were being replaced using filters with the strongest additives in them they could get.

 

What about a bad radiator cap? not venting pressure buildup?

 

That was one of the first things the mechanic looked at and they have replaced caps. Most of the hours on them are driving with minimal idle time. The rest of the time, they are stationary and pumping water. We've not had any overheating issues either.

 

Hmmm then pressure shouldn't be an issue. But why only the bottom 90 degree hose? Additives should logically destroy all the rubber.

 

Is the pressure rating of the cap correct? Also, are these OEM rad hoses or just cheap generic accordian type rad hose you buy at Napa? What about engine/rad mounts? Are they worn out and causing the hoses to flex excessively? Any fuel or oil contamination in the coolant?

 

Ya I'm thinking rad mounts are shot...good call.

 

There was a crane at one of my jobs that sat unused for a bit. The low point on the hoses was melted and looked like it was dripping off. When the boss came out to look at it he said it was from the coolant additives sinking down to the low spot.

 

The way everything is set up in there, the upper hoses are fairly straight and we haven't had any problems with them that I know of. One would think the rubber would be the same thickness on the elbow where it's molded as the rest of the hose? We've even talked about using a stainless elbow with a rubber hose on either side. We're at a loss right now.

 

Thanks for all the input.

Yes on the OEM hoses. I think the mechanic may have tried a siliconized hose as well instead of a rubber one. I will pass on the radiator/engine mount suggestion. Some of these hoses don't make it 6 months before failing. Would that be enough time for oil/fuel to degrade them? How much contamination would there have to be to cause this?

Most of these trucks get driven 6 and sometimes 7 days a week. I can't see using the strongest additive filters would cause much of a buildup issue, since we dump most of the coolant on the ground when this happens.

I'll keep this updated as we figure stuff out.

 

So this is happening on more than one unit and they are different year units? I would suggest inspecting these hoses daily. To me it sounds more like sabotage.
If on the slight chance it is due to coolant additives. Stop using them. I am guessing you are using green coolant. Flush the systems and go to long life red coolant and switch over to just a plain water filter.