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RonaldNC · 08-21-2016, 04:29 PM

Yesterday, I blew the hose at the bottom of the coolant reservoir. I have the ISB 340 HP engine. Fortunately, it happened just before I pulled into a fuel station for diesel. I found that the hose had ripped just below the hose clamp and I was able to cut the hose shorter (lucky there was sufficient slack) and reattach it. It was a bit messy, but I was also lucky that there was a NAPA store two blocks away to get more coolant.

Now my question... I noticed that there are two smaller hoses that are attached to the top of the reservoir. Can someone tell me where they go and what is their function? It's hard to see where they go without putting the coach on jacks. It's not an overflow, as there is another hose located by the cap.

Thanks!

Ron

dennis45 · 08-21-2016, 04:41 PM

Quote:

Originally Posted by RonaldNC

Yesterday, I blew the hose at the bottom of the coolant reservoir. I have the ISB 340 HP engine. Fortunately, it happened just before I pulled into a fuel station for diesel. I found that the hose had ripped just below the hose clamp and I was able to cut the hose shorter (lucky there was sufficient slack) and reattach it. It was a bit messy, but I was also lucky that there was a NAPA store two blocks away to get more coolant.

Now my question... I noticed that there are two smaller hoses that are attached to the top of the reservoir. Can someone tell me where they go and what is their function? It's hard to see where they go without putting the coach on jacks. It's not an overflow, as there is another hose located by the cap.

Thanks!

Ron

You should have one hose (1/4" or so dia) off the top of the radiator going to the steel expansion tank. You will have another teed into this one off the top off the 1 1/2" pipe off the thermostat housing to the radiator which is the high point of the system.
Then there will be another off the filler neck on the expansion tank, just below the pressure cap that goes to the bottom of the plastic overflow reservoir. This one allows entrained air to bleed off below the pressure cap and into the bottom overflow tank. As the fluid expands it will bleed off into the overflow and when you shut the engine down, fluid will bleed back into the cooling system.
Air is bled off out the top of the plastic overflow tank.

RonaldNC · 08-21-2016, 07:53 PM

Quote:

Originally Posted by dennis45

You should have one hose (1/4" or so dia) off the top of the radiator going to the steel expansion tank. You will have another teed into this one off the top off the 1 1/2" pipe off the thermostat housing to the radiator which is the high point of the system.
Then there will be another off the filler neck on the expansion tank, just below the pressure cap that goes to the bottom of the plastic overflow reservoir. This one allows entrained air to bleed off below the pressure cap and into the bottom overflow tank. As the fluid expands it will bleed off into the overflow and when you shut the engine down, fluid will bleed back into the cooling system.
Air is bled off out the top of the plastic overflow tank.

Dennis,

Thanks for the response. I'm a little confused... the 1 1/4" hose that blew is on the bottom of the plastic coolant reservoir (this is how my manual refers to it). Is this what you are calling the "plastic overflow reservoir"? Are you saying that there is another "steel expansion tank"?

Sorry for my ignorance...

Ron

dennis45 · 08-21-2016, 09:04 PM

Quote:

Originally Posted by RonaldNC

Dennis,

Thanks for the response. I'm a little confused... the 1 1/4" hose that blew is on the bottom of the plastic coolant reservoir (this is how my manual refers to it). Is this what you are calling the "plastic overflow reservoir"? Are you saying that there is another "steel expansion tank"?

Sorry for my ignorance...

Ron

Ron,

Sorry, I assumed (and you know what that does) that you have a steel expansion tank AND a plastic reservoir. From what you are saying, you are one of the chassis that uses a Plastic Reservoir (expansion tank) and do not have the secondary overflow reservoir.
The hose you refer to is off the top of the engine and allows the coolant to expand into the plastic reservoir.
These have been known to cause problems in the past and in some cases are replaced with a steel tank that is able to handle the pressure off the cooling system better.
I am not really familiar with how the air bleed connections are plumbed into this system but I would think there will be one smaller hose connected to the side of the tank off the top of the radiator to allow air to make its way out of the system and into the tank. The other smaller one below the filler (pressure) cap likely just goes below the engine somewhere and drains to the ground. Just guessing on that.....

RonaldNC · 08-21-2016, 09:24 PM

Quote:

Originally Posted by dennis45

Ron,

Sorry, I assumed (and you know what that does) that you have a steel expansion tank AND a plastic reservoir. From what you are saying, you are one of the chassis that uses a Plastic Reservoir (expansion tank) and do not have the secondary overflow reservoir.
The hose you refer to is off the top of the engine and allows the coolant to expand into the plastic reservoir.
These have been known to cause problems in the past and in some cases are replaced with a steel tank that is able to handle the pressure off the cooling system better.
I am not really familiar with how the air bleed connections are plumbed into this system but I would think there will be one smaller hose connected to the side of the tank off the top of the radiator to allow air to make its way out of the system and into the tank. The other smaller one below the filler (pressure) cap likely just goes below the engine somewhere and drains to the ground. Just guessing on that.....

Thanks. Actually, I have replaced the plastic tank with a Source Engineering metal tank. It is configured the same as the original tank. I referenced the plastic tank so it wouldn't confuse someone that is familiar with my model.

I guess I'll just have to put on my coveralls and crawl around underneath to see where the hoses go.

Thanks again!

Ron

dennis45 · 08-21-2016, 09:28 PM

Quote:

Originally Posted by RonaldNC

Thanks. Actually, I have replaced the plastic tank with a Source Engineering metal tank. It is configured the same as the original tank. I referenced the plastic tank so it wouldn't confuse someone that is familiar with my model.

I guess I'll just have to put on my coveralls and crawl around underneath to see where the hoses go.

Thanks again!

Ron

Good luck, sorry I could not be of more help.

P/S. One more reason I love my side radiator.