Community Forums

nodine · 09-05-2018, 06:23 AM

Posting this just in case we are not the only ones with the problem. As you can see from our signature we have a 2006 Diplomat which is a rear radiator ISL. For the past two years we have been having problems with the engine overheating and are now in the process of correcting the problem. My first inclination was to remove the radiator and inspect and clean but now plan to try replacing the thermostat and coolant and do another extensive radiator cleaning and see if that solves the problem. Of course we will replace all the hoses at the same time. Hoses should be here this week. The reason we came to this conclusions is because we have an oil leak problem behind the fan. Oil leaking from this source is only inches behind the fan and blown onto the radiator by the fan.

The following photos will help to explain where the leak is. The first photo is not of my coach but of DutchStar Dons (formerly Diplomat Don) 2005 Diplomat when he replaced his radiator. The engine oil fill next to the hydraulic fluid tank connects to a cover on the front of the ISL via a 1.5 inch I.D. Marine grade fuel fill hose. On our coach that hose has developed two cracks adjacent to the connection at the engine. The other three photos show the parts I removed and cleaned up. Thought others might like to inspect their coach for the same hose failure.

Bob

MonacoMan84 · 09-05-2018, 10:04 AM

I am experiencing this exact problem and will inspect this immediately thank you so much for the info.

flamebuster · 09-05-2018, 01:24 PM

Great tip. I would have never thought of that hose being a problem. I will have to check mine. Is the end of the hose dry and brittle or did it turn to soft mush? Just curious to the condition of the hose to get an idea of it's possible pre-failure state..
Doug.

nehog · 09-05-2018, 07:05 PM

That engine looks identical to my ISC! The belts, accessory placement (alternator/AC compressor, etc.) the belt routing (how I wish I had that picture when I had to replace my broken belt and could not figure out the routing!)

And a big thanks for the heads up on the oil-fill hose failing. I will check mine when I do my next oil change in a few weeks.

Ivylog · 09-06-2018, 02:54 AM

A ISL 8.9L engine is a stroked (piston travels further) ISC 8.3L engine so this problem applies to a bunch of other rigs.

nodine · 09-06-2018, 05:09 AM

Quote:

Originally Posted by flamebuster

Great tip. I would have never thought of that hose being a problem. I will have to check mine. Is the end of the hose dry and brittle or did it turn to soft mush? Just curious to the condition of the hose to get an idea of it's possible pre-failure state..
Doug.

Doug,

My take on what caused the problem is the construction of the hose. It is a high grade marine fuel fill hose that is wire reinforced by a spiral of wire that is between the inner and outer layer of the hose. The wire is to keep the hose from collapsing or kinking. We usually see the wire inserted inside the hose and not a part of the construction. The two cracks appear to be at the location of the wire between the two layers of the hose. I am assuming the years of flexing due to engine movement caused the failure. The fill end is attached to the frame of the coach and the other end to the engine. The engine moves slightly on the motor mounts. This hose is quite stiff. I found the original hose on ebay but decided to go a different route. I purchased automotive fuel fill hose at NAPA and reinforced it myself by wrapping 12ga wire around a wood dowel and pushing the wire into the hose. I first tried the hose without reinforcing it but it kinked at the bend were a curve is necessary in the routing.

Bob

YC1 · 09-06-2018, 06:24 AM

This file might help. I had to replace my thermostat long ago. My radiator was and is pristine clean. It just overheated on a tall hill called the Grapevine.

The new thermostat looks a lot different than the old one.

Scroll over the yellow note on the pdf for more information.

Thanks Bob for the heads up on the hose.

nodine · 09-06-2018, 10:22 AM

Quote:

Originally Posted by YC1

This file might help. I had to replace my thermostat long ago. My radiator was and is pristine clean. It just overheated on a tall hill called the Grapevine.

The new thermostat looks a lot different than the old one.

Scroll over the yellow note on the pdf for more information.

Thanks Bob for the heads up on the hose.

Myron,

Just got the thermostat out and the old one and the new one are the same size. Both about 3 inches tall. They are different P/N and different temperature. The old one has stamped on it 160 and the new one 180. The old one has black o-rings and the new one has green o-rings. Other than that they look the same.

Bob

05 American Eagle · 09-06-2018, 05:34 PM

I found on my old coach, with a rear radiator, was the fan clutch failed and the fan speed was not keeping up with load. I put a GoPro inside the engine compartment and the fan never changed speeds.

Once that was replaced the problem went away.

YC1 · 09-06-2018, 10:08 PM

Bob, did you happen to test them in boiling water? Just curious.

nodine · 09-07-2018, 06:26 AM

Quote:

Originally Posted by YC1

Bob, did you happen to test them in boiling water? Just curious.

Hi Myron, going to do that this morning before the wife wakes up and catches me using her pot.

Bob

nodine · 09-07-2018, 06:28 AM

Quote:

Originally Posted by 05 American Eagle

I found on my old coach, with a rear radiator, was the fan clutch failed and the fan speed was not keeping up with load. I put a GoPro inside the engine compartment and the fan never changed speeds.

Once that was replaced the problem went away.

Our Diplomat does not have a clutch on the fan. Replaced the belt in 2016 and I know it is tight because I can't move the fan with my hand.

Bob