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kraig 09-29-2013 12:07 AM

3rd pressure coolant hose on ISL 425 on 08-09?
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After reading the threads about heater/aqua hot hoses, I thought I would see what I had my ISL 425 built in May 2007. Both my heater/ aqua hot hoses were OEM THERMOID brand heater hoses made for cars and light trucks with manufacture date May 2003, so it was 4 years old when built. It was their cheapest hose. The hoses are 10 years old now and were not a heavy duty hose for diesel engines. Although they did not fail, I replaced all of them with Goodyear Hi Miler Blue hose. I replaced all the hoses all the way to the heater and Aqua hot. I did add 4 shutoffs near the engine if I ever had a problem.

The reason I am posting this, there is 3rd pressure hose buried way under the a/c and alternator bracket, left of the heater feed hose. If you have to remove the alternator, the battery feed is hot even with the disconnects off. This 5th hose ran along side of the other heater hoses except there is 360 degree loop (maybe they had extra hose) above the parking brake and continues inside the frame through the rear bulkhead. I can't find a a 3rd return hose. I replaced this feed hose away from the engine and put in a 5th shutoff, but could not replace the rest of the hose. It doesn't tie into the other 4 hoses since I did test each of them by blowing air through them. After I put it all back together, no leaks, so it does not tie in somewhere.

Does anyone with 2008-09 with the ISL 425 smog engine have this extra hose. If open the rear engine, I can see both of them directly under alternator. Mine is an APEX, but I don't what would be additional.

Melorene 10-20-2013 08:47 AM

I have a 2008 rig with a 425 isl and have had the heater hose rupture at the engine connection at the clamp and now again the hose ruptured mid coach behind the aqua hot in the frame rail where they put a y splice.. don't know how the repair tech at ISTATE Truck in Montana got to it but he was able to cut out the bad part and splice in a new piece.. said couldn't pull in a new one as the hose has tie wraps in the frame rail.. how did you run new hoses? don't want this again.. must be as you said low grade hoses.. Mel

kraig 10-22-2013 01:34 AM

WRV did run both the Aqua Hot and heater hoses inside the frame rails with tie straps. I did replace all 4 hoses completely. It wasn't easy. On mine WRV used Green single tape and double tape for the heater to mark hoses on both ends. For the Aqua Hot they used red tape. Where I could I cut out the old sections, but you cannot use it to pull in new hose. Starting at the heater you can run inside the frame along side the diesel tank until you get first bulk head behind propane tank. There you use metal hole saw for the bulkhead and then outside the frame through the compartments. I just tie strapped to the steel propane tank line. The problem is when you get to the holding tank, water hose, aqua hot, electric cord compartment. The first bulkhead is a vented screen which is easy to cut through. The last bulkhead ahead of the rear end is hard to get through. There are plastic covers at the top, however WRV screwed them on from the inside, so they are worth less. I could not break the plastic. I used a metal hole to drill big enough holes to run 4 hoses including the Aqua Hot through the bulkhead. Look out for the holding tank and wires. From the bulkhead by the rear end, I was able to run inside the frame and tie strap.

To run hoses to back of the Aqua Hot was not easy. I had previously removed the Aqua Hot and had to cut an access hole through the bottom of the deck. On some of the later coaches WRV made a access plate you can feel for by pushing up on the foil covering. One of the hoses on the Aqua Hot was 1/2" and on mine they used 5/8" and clamped it down. Anyway you need a couple feet of 1/2" hose and 1/2 to 5/8 connector. Also Roger Berke recommended that I leave a loop of 3 extra feet laying on top of the Aqua Hot, so you have slack when you need to remove it.

I also put 4 shut offs near the engine in case I ever had a leak. Any of those could be shut off and still run the engine. I have a 40 footer, so I bought 3 50' rolls of 5/8 heater hose.

Naturally you have all drain all the coolant. I think it was about 12 gallons. As far as getting all the air out of the system, I did warm up in driveway quite a while, but that wasn't enough. To get the air out I had run on the road and temperature went to about 210 before I got all the air out. Cummins told me before max temp is 225.

Also you have to pull the alternator and move the A/C compressor.Even with the battery switches off, the alt. is hot. You have to disconnect the starting battery. The alternator bracket has to be removed to get to the hose clamps.

I did the last post because I have a third pressure heater hose coming off the engine that I can't figure where it goes. It goes toward past the rear end toward the front of the m/h. I put a 5th shut off on that one. I had to splice into the old hose for that one. Maybe somebody might have an idea where it goes?

It is a lot work to replace the cheap OEM car hose.

Melorene 10-22-2013 09:28 AM

Wow, you did a lot of work. good that you have the ability and knowledge to do it.. at my age I will have to have it done, yuk. $$$$$$. sure don't want a line to rupture again. been twice now, once at the engine end and once mid way behind the aqua hot..

Melorene 10-27-2013 08:24 AM

How many hoses go up front for the heater? I see 2 on top rear of the engine but when I had the hose rupture at the engine, they spliced in a 1 foot piece. then when I had a rupture in the frame rail behind the aqua hot, I looped the line back at the engine hoping to stop the fluid loss by keeping the fluid in the engine and not going forward towards the heater so I could get to a shop to get it repaired but kept leaking anyway and had to be hauled in on a lowboy. am thinking of having the shop put a shutoff at the engine in case it goes again as we are leaving shortly for Arizona from Montana and don't want another blowout. Have been talking to Redlands to see if they can replace the hoses .

kraig 10-28-2013 12:36 AM

The heater has two hoses. The return is on the rear of the engine with green tape. The inlet pressure is on the front of the engine with green tape.

The Aqua Hot also has two hoses. The return on the rear of the engine with red tape. The inlet is on the front of the engine with red tape.

You should be able to loop one or both of them on the engine no problem as long as you match the same color electrical tape together. Then you could run it home ok but no heat or hot water, except for electric. Or you could put 4 shut-offs close to the engine.

I have third pressure hose on the front of the engine that goes through the rear bulkhead that I cannot figure out were it goes. See Picture

Melorene 10-28-2013 03:24 PM

thank you very much for all the valuable information and photo.. I printed it all out and will show it to the service tech.. Mine is not an apex so they didn't put colored tape on them. take care and happy travels. Mel

kraig 10-29-2013 12:09 AM

All the electrical colored tape was 1or 2 wraps on the end of each hose so WRV could hook each hose up correctly.

Melorene 10-29-2013 07:40 AM

I am have contacted I state truck to get them to put shut offs at the engine so if another hose fails I can just shut it off there, add fluid and continue.. I am not sure about the aqua hot as I thought it had its own fluid. so I guess there are heater hoses going out with radiator fluid in them for the front heater. I see 2 on the top front of the engine which one already had ruptured at the connection to the engine. Sure wish WRV was still in business. Hope to eventually get to Redlands and have them all replaced. always something to stress our travels. sure is nice when all works fine.

kraig 10-30-2013 12:52 AM

You are right the Aqua Hot has its own fluid. There is a radiator cap on top of the Aqua Hot.

However the engine preheat has inlet-outlet hoses with with engine coolant, the same as the heater hoses. You cannot see theses hoses on the aqua hot when you look at the aqua hot as they both connect on back side.

Melorene 10-30-2013 08:03 AM

Am getting a couple shut offs installed tomorrow and hope the tech knows what to do. Just want to make it to AZ and then to Redlands.. Sure is tough on us seniors when the Mfg is closed and am not able to do repairs like you great guys who help us on line. May just hope the aqua hot lines hold and just shut off the heater hoses.. again thanks Kraig..... Mel

Melorene 11-02-2013 07:26 PM

I talked to the tech who put in 4 shut off valves and he said that mid coach behind the aqua hot in the frame rail, they put a connection that was smaller than the hose and it swelled at the connection and if anyone hasn't checked it they should.. he had to get a small guy, opened L and R bins and crawled in and repaired it. still need the hoses replaced.. also check the hose connection, lift the bed and it is right there to see and it blew out there also before.. hope it helps.. mel

kraig 11-07-2013 12:34 AM

I think the hose you are talking about is 1/2" hose on the back of the Aqua hot, that they did not use the right size 90 degree connector. They should have used 1/2 by 5/8 connector but instead 1/2 by 1/2 connector with a 5/8 hose from the engine and tighten it down tight. It appears swelled but it is just too big a hose. If they used the same connector as mine, they will all leak sooner or later.

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