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rdvd · 07-25-2014, 05:52 PM

Looking for some input. Started the day thinking I would flush the cooling system. I have an 06 Diplomat isl 400 rear radiator. Opened the cap on the expansion tank and then the pick cock at he bottom of the radiator. Than pulled the hose on the bottom of the block to drain more antifreeze out. Also turn the heat on in the coach. Refilled with distilled water and flush. Started the Dp and let it run at operating temp. for about ten minutes. Let it cool down. Drained and filled again with distilled water. Know when I start the engine I get a STOP ENGINE light on the instrument pant. I put just as much water in that came out.

Any ideas where the problem might be???

Thanks for any input.

walt2137 · 07-25-2014, 06:18 PM

I think its air locked and the engine ran hot, there should be some place to bleed the air off at the water pump or one of the small hoses that comes off of the water pump.

rdvd · 07-25-2014, 06:24 PM

I'll look an see what I find. Thanks. I'll repost with what happens.

rdvd · 07-25-2014, 06:41 PM

Well i checked it out. There is a peck cock on the bottom of the water pump. Could that be it. Seems like a weird spot. Didn't see anything on the top side. I'm new to this motorhome. Only had 10mo. Tring to get all the maintenance to a starting point.

Thanks again.

walt2137 · 07-25-2014, 07:38 PM

I would thought it would be on top but open it up and see.

Arch Hoagland · 07-25-2014, 09:34 PM

I'm curious what you did with the old antifreeze.

R2Home · 07-26-2014, 09:30 AM

What is the thought process for using 'distilled' water? In the past we have always used water from the hose when we were 'flushing' out a system. I guess that with the newer radiators and not the old copper ones, the process might be different. I have always thought that servicing the radiator would be like the transmission, in the you would not be changing all the fluid, just a larger part of it.
Did you test the coolant before you started to see what water filer you would need? I know that several MH owners that I know have 'forgot' about the coolant filter, when doing their annual service.

adonh · 07-26-2014, 09:44 AM

Quote:

Originally Posted by R2Home

What is the thought process for using 'distilled' water? In the past we have always used water from the hose when we were 'flushing' out a system. I guess that with the newer radiators and not the old copper ones, the process might be different. I have always thought that servicing the radiator would be like the transmission, in the you would not be changing all the fluid, just a larger part of it.
Did you test the coolant before you started to see what water filer you would need? I know that several MH owners that I know have 'forgot' about the coolant filter, when doing their annual service.

Here is a very good article by Brent Wolff on using distilled water to flush the radiator.

Cooling 101_brent_diesel club.pdf

sknight · 07-26-2014, 10:01 AM

Distilled water doesn't have the minerals that can get buildup and corrosion started. Wanna know a secret? In 35 years in the business I've ever seen a bottle of distiller water in a shop. Not once.

It could have been air locked, could also be the coolant level sensor reporting falsely that it's empty.

rdvd · 07-26-2014, 10:58 AM

Ok, Opened the peck cock and antifreeze came out. I think its the drain for the pump. There is no other hose on the water pump. The only thing is the thermostat. How do you know if the pump is pumping? I tried to open the access door in the closet but can't get the bottom frame out. It also looks like its screwed to the floor with lag screws. Would help with see the water pump better and getting to the thermostat. As for the coolant. I'm putting it back in the water bottles till i get time to take it some where. I think Mobile takes it.

rdvd · 08-04-2014, 09:03 PM

Well here it goes. When I started this job. I didn't think it would be so involved. To make along story short . If you have a 06 Monaco Diplomat with the 400 isl cummins motor and want to change the coolant. The way to bleed the air out of the water pump is to remove the thermostat. The one why not to get air in the water pump. Is to only drain the coolant from the peckcock on the bottom of the radiator. If you remove any of the hoses or open the peckcock behind the oil filter. You will air lock your waterpump and have to remove the thermostat. I had to do this three time.

I do like all the new thingings I learned about my DP. Nexttime I hope to learn quicker.

never give up.

bukzin · 08-16-2014, 07:10 PM

Quote:

Originally Posted by rdvd

Well here it goes. When I started this job. I didn't think it would be so involved. To make along story short . If you have a 06 Monaco Diplomat with the 400 isl cummins motor and want to change the coolant. The way to bleed the air out of the water pump is to remove the thermostat. The one why not to get air in the water pump. Is to only drain the coolant from the peckcock on the bottom of the radiator. If you remove any of the hoses or open the peckcock behind the oil filter. You will air lock your waterpump and have to remove the thermostat. I had to do this three time.

I do like all the new thingings I learned about my DP. Nexttime I hope to learn quicker.

never give up.

How many man-hours, altogether, do you think you have into this project?

Also, did you change out the coolant filter?

Cato1966 · 08-16-2014, 07:22 PM

We are also brand new RVers with the same engine and will be doing the flush on ours in the next couple of weeks. You post was very informative. Thank you for posting.

Twomed · 08-17-2014, 08:17 AM

Tip...when you refill, add coolant at the head with the thermostat out until block is full. You will avoid air locks 99% of the time this way. Of course replace the thermostat while you have it out.