About 5 years ago, with 25,000 miles on the coach, one of those hoses broke on my 2001 Marquis.  After towing and replacement, the tech showed me the old hose.  It was encased in a high temp cover and routed over the exhaust manifold.  It started out rubber and with enough heat, ended like a clay pipe, which snapped each time it was bent by hand.  I changed to ELC and removed the superfluous  filter and hoses, thereby eliminating the potential for more problems.  I have driven about 50,000 miles without the filter or another breakdown.  In my opinion, Gerald has the solution.

Larry

Having received an e-mail from Marty alerting me to this thread, and having a coach identical to Marty's, I also removed the filter and lines as I changed to ELC on my last coolant change. (Being honest here, Marty did a lot of the work since he lives right across the street and I am an accomplished follower of the "Huck Finn" method of project management.)

I found, after removing the hoses, that areas of the hoses were brittle due to heat exposure - and that was in areas covered by the heat ablative covers. While the use of silicone tubing helps, remember that the temperatures the tube is rated for is internal temp, not external temp, and that it is the external temperatures that the tube is exposed to that causes the damage - hence the heat shield tubing.

Having spent many years working on both small and large airplanes I have seen the necessity of changing ANY type of flexable fluid line if it has in any way become even slightly stiff or brittle (if it's brittle you already waited WAY too long!)

If you are using standard coolant, I would suggest that you inspect the lines annually at a minimum - you don't need to remove them, just run your hand along them and flex them. If any stiffness is detected, change that line. If you have made the change to ELC, pull the lines and plug the ports as Gerald recommended since the system is no longer required.

The opinions expressed above are those of the author - your opinion may vary.

Jay

Ensenada. Mexico
C12 2000 Marquis
Coolant loss due to filter hose failure
Managed to add 20 gallons of water in 4 stops to keep engine under
225 deg to reach Estero Beach RV Park/Hotel
Removed alternator
Disconnected 3/8 hose at manifold
Proved leak with water hose connected
To
Tomorrow will run loop of hose between fittings
to by pass filter
Assume return line goes to manifold where lower rad hose
connected as it is the only other hose in the area 1ft below alternator
Upper hose comes from block above and beside alternator
It ran to steel pipe run under heat shield towards trans
Assuming these 2 hoses are coolant lines
Thanks to Gerald for long distance help and advise
Anyone with pics or advise with good description of this
system please text me at 315 608 1504
Thanks.  Jeremy en route Cabot San Lucas

Jeremy,
To make a temporary repair just turn the two valves off at the coolant filter housing and cut the leaking hose off an inch or two from the engine and insert a 3/8 inch bolt in the shot piece of hose with a hose clamp. This will stop the leak until you can repair it properly.

The other end of the coolant filter hose does not run to the lower radiator hose, however it runs to the intake manifold. If you are running Cat ELC (extended life coolant) the filter is not needed and can be bypassed, however if you are running ethylene glycol coolant, the filter is necessary and should not be bypassed.

Gerald