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chris cross · 10-03-2005, 12:52 PM

On my 400 ISL, the coolant overflow hose just hangs down in front of the radiator. The Cummins manual makes no mention of a recovery system. This is the first engine I've had without one. Any opinions will be appreciated.
Thanks

chris cross · 10-03-2005, 12:52 PM

On my 400 ISL, the coolant overflow hose just hangs down in front of the radiator. The Cummins manual makes no mention of a recovery system. This is the first engine I've had without one. Any opinions will be appreciated.
Thanks

Dave Fernandez · 10-04-2005, 06:08 AM

Hello Chris:

Just to let you know that many vehicle manufactures have gone what is called a "Surge Tank" which acts like a coolant recovery system but is part of the pressurized cooling system.

Alpine uses a Surge Tank which is the big black tank which has a radiator cap on it. My 1996 Chevy Impala SS also uses a Surge Tank instead of a coolant recovery system.

I hope this answers some of your questions.

Dave

chris cross · 10-05-2005, 06:06 PM

Fredbob · 10-10-2005, 05:29 AM

Reply to Cris Cross

shelland · 10-10-2005, 07:38 AM

I was loosing some coolant on my coach as well. I put in a new 10 lb. radiator cap replacing the 8 lb. cap that was there and have never seen any loss since.

Stretch · 10-10-2005, 08:43 AM

Agree with fernandez, However, I have installed a coolant recovery system after the surge tank because I found that the MH was loosing coolant out of the overflow line. Not a lot, but significant amount. I just used a 1 gallon plastic bottle which fits between the frame and fiberglass body right under the surge tank. I just poked a hole in the plastic bottle and ran the overflow tube into it. Now if the coolant overflows into the bottle it will be returned to the surge tank next time the engine is off and the system cools down. Easy fix.

chris cross · 10-10-2005, 08:50 AM

Thank you Dave, Stretch and Shelland. I did put a 10lb. cap on after I left my original cap at a Flying J. I like the idea of a plastic jug recovery tank. I have also been losing a small amount of coolant and I'm sure this will be an interesting experiment as we're on a two month trip around the Olympic Penenisula and won't be home until mid November.
Thanks again,

Stretch · 10-18-2005, 08:18 PM

Chris:
If you insstall plastic tank befor the trip, I think you will find quite a bit of coolant in the bottom when you return. Try using a 1 gallon milk carton for a test. It fits perfectly between the frame members. I actually ad a quart or so fo coolant in the milk carton. Because when you stop the MH and it cools off the radiator cap is designed to allow coolant to flow b ack into the surge tank o its own.

EngineerMike · 12-16-2005, 02:11 PM

I like the idea of an overflow tank, if only for the improvement in making a regular coolant level check. The sight glass is not as optimally obvious.
I just checked mine, & w/ just under 3K on the chassis, the surge tank is nearly (or maybe more that nearly) empty. Had the OEM pressure cap tested (looks like a Stant, brand name, rated @ 16# on the '06) and it was holding only 10#. The main spring seems ok vs. the new cap, but there is a small lightly-return-spring-loaded washer in the middle of the 1.5" seal that floats open on the OEM cap, but pulls shut on the replacement I got @ NAPA. I'm guessing that's the leak. Since coolant may leave as vapor once the topping of the surge tank is pushed out, there isn't an obvious stain, drip, or other indicator of the leak. Hence, the opaque overfow is a good solution for easy quick checks.

SteveS · 12-17-2005, 07:52 AM

EM - It sounds like the small spring loaded washer that you are describing is designed into the cap to allow for coolant to be sucked back in to the system when cooling down after engine shutoff. Likewise, if it doesn't have an overflow, it allows for air to enter the cooling system (at cooldown) if it has exceeded the cap pressure during operation. It is required to keep hoses, radiators, etc from collapsing due to the cooldown vacuum created from expansion during operation. I have seen systems where the caps didn't allow coolant or air to return to the system and resulted in collapsed hoses usually but sometimes radiators are effected.

EngineerMike · 12-17-2005, 08:44 AM

Steve- I did some snooping around & it appears that caps come vented & non-vented for use with coolant recovery & without respectively (my humble conclusion from net surfing). The OEM cap, though rated @ 16# and only holding 10, was vented & without coolant recovery (i.e. appears to be the wrong cap design). I think some of the above coolant losses may also be use of vented caps. I'm gunna add a recovery tank for our impending Mexico trip and watch like a hawk, then get it fully checked out when we get back. I've got plenty of FleetGuard coolant & good water to add on the way if its an actual leak.

SteveS · 12-17-2005, 01:37 PM

EM - I'll bet you don't have a leak. I had the same problem with loosing about a gallon...never more and it took me a while to get up the courage to not add coolant. I stopped adding coolant and one day decided to check it again and it took about a gallon. Since then I added a "recovery tank" consisting of the coolant container with a hole drilled in the top for the overflow hose to pass to the bottom of the container. Haven't had a chance to try it out yet but I'd bet the problem is solved. I think I could have left it the way it was with no problem since it never seemed to lose any more than a gallon. As far as I could tell it never came close to overheating even though it was lower on coolant. Also, for a long time I could not find where the coolant was going but one day I happened to check it at just the right time and saw about one drop come out of the overflow hose.

EngineerMike · 12-17-2005, 08:00 PM

Turns out my estimate of coolant loss was overly aggressive (I need to retune my ear). I added coolant then distilled H2O for, how's this for coincidence, about a gallon. But it goes below the sight glass, and there's no way to dip-stick it, that I can see, the way the fill tube works.
I made a recovery tank out of the 5.6# Deli-Cat catfood jug (that was the last of the catfood, so I had to get rid of the cat too). 5/8" hole in the lid and the OEM overflow tubw works perfect. I didn't prime the tank; I'll see fluid thru the opaque plastic if it comes thru. I replaced the OEM vented cap w/a vented 16# cap (since I added the recovery). Miles will tell. What a finely tuned contraption; I love big toys.
Off to Mexico in the morning.