Community Forums

Terry W · 10-01-2015, 04:36 PM

I've looked around and everything I can find says the heater hose, engine to Hydro Hot and engine to heater is all 5/8" is this correct? I also read about a 5/8 to 1/2 reducer being needed. I don't know if that was on all years or just some. I have an '05.

Thanks

TeJay · 10-01-2015, 05:10 PM

Usually you can determine the hose size just by looking at it. Sometimes size can be confusing. A 1/2" hose with good quality material (thicker side wall) may be as thick as 5/8" hose made out of thinner side wall material. There are basically those two sizes: 1/2" & 5/8" and that's inside diameter.

What are you trying to do?? Are you replacing hose? If some of it is bad it's best to replace all of it.

TeJay

wolfe10 · 10-01-2015, 07:50 PM

Tim,

Sorry, respectfully, I have to disagree. The engine portion of the heater hoses are exposed to LOT more severe conditions than the portion run in the basements.

Replacing the portion in the engine room using quality barb to barb fittings and hose clamps is a very reasonable solution.

Brett
2003 Alpine FDDS

TeJay · 10-01-2015, 08:11 PM

The hoses in the engine compartment, are subjected to a harsher environment due to the heat. That will accelerate hose deterioration. But we don't know the history of this unit and it's frequency of coolant service. The owner may not know either since we only know its age.

That said, if the coolant has not been serviced it will/can become corrosive or acidic and the hoses can and will deteriorate from the inside as well. IMHO It's always best to error on the side of caution.

This is a 2005 coach. That's potentially 10 years on these hoses. If this were my new to me coach I'd replace all of them.

TeJay

kraig · 10-01-2015, 11:16 PM

I changed out all my hoses and they were all 5/8, except about 2" piece of 1/2 off the hydro hot. On WRV used 1/2 to 5/8 90 degree elbow. It is easy to see the different hose size, if you have already cut a hole in the OSB. In order to change the hydro hoses, you have to cut an access hole in the OSB to the rear of the hydro hot. You have to be very careful and it is not easy not cut any hoses or wires. I cut a small hole first, then enlarged it as I could see.

TeJay · 10-02-2015, 05:42 AM

Here's a little known diagnostic trick I always shared with my classes when we discussed: the DVOM (Digital Volt Ohm Meter) DC electricity, or the cooling system.

A DVOM is easier when reading voltages in the 1, .1, .01 range. The older mechanical VOM were not as easy to read smaller voltages.

With your DVOM set to read DC volts place the ground probe on a good bare metal ground then place the positive probe into the coolant at the top of the radiator touching only the coolant. What might you read and WHY??

Have you ever wondered why when you introduce any other metal (aluminum foil, a fork or spoon) into your mouth and touch a filling you feel the awful pain??? You've just added the third ingredient to make a battery: 2 different metals and the acid in your mouth.

In the cooling system you have the three necessary ingredients to create a battery: at least two different metals (cast iron, steel, aluminum, brass, copper) all present in the cooling system and an acid if the coolant has some age on it. If the cooling system has had the coolant serviced recently the voltage created would be 0 or very close to 0. The more acidic the system the voltages would be in the .01 or .1 and with a very corrosive systems we'd see voltages in the 2,4, or 6 volt or higher range.

We got into the habit of checking all vehicles that we serviced in the shop. After doing this for awhile you get a good sense of just how caustic the cooling system can become.

Age is always a factor with coolant condition but other things are introduced that we just don''t always consider. When an engine is cold and first started sometimes small combustion leaks occur but seal up after the heads get hot. That would introduce caustic exhaust gasses into the coolant contributing to the acid build up.

You can't always use how the coolant looks to determine its condition but if you measure the voltage created you added a different dimension to the diagnostic question, "Should I change the coolant or not?"

The acidic conditions in the cooling system do contribute to internal rotting of all coolant hoses as well as internal corrosion of some metal parts.

TeJay

wolfe10 · 10-02-2015, 07:14 AM

Here is what I use with the Diesel RV Club (an FMCA Chapter) to test "regular low silicate for diesel with added SCA" coolant. It is not designed to test the OAT-based coolants.

Part Details

They have a reasonably short shelf life (do not use if expired), and come in quantity of 12 foil wrapped 4-packs= 48 test strips, so best to buy when you are getting together with a group of other diesel owners.

Like you, we find a very high percent of neglected coolants-- either acidic or improper concentration of SCA.

Brett
2003 Alpine 38FDDS

kraig · 10-02-2015, 10:51 PM

Another reason I replaced all my heater hose is WRV used a lighter weight car heater hose. You tell by squeezing the hose and looking up name and number on the hose. I doubt I had the only Alpine with car heater hose.