Well the ski season is over and I have a new laptop so I thought I would post a few warnings about Newmars in cold climates.
This is what happens if you start your Cummins with a side mount radiator at 25 below.
The engine loves the cold but the heat exchanger for the hydraulic fluids can't take the increase in pressure required to circulate the viscous oil.
Those side mount radiators on all the new diesel pushers require winter rated oil. The oil provided by Newmar isn't even sold in the Canadian market.
The symptoms include no power steering and a huge mess of hydraulic oil. There were no warning lights.
I see dozens of snowbirds heading south in January after spending Christmas at home with their families. I hope this post gives them a heads up. Breaking down in winter is no fun.

This message has been edited. Last edited by: jjbsmith,

I think this would be more of a Spartan issue.

I believe the chassis is supplied by Spartan with all fluids installed.

Cummins-equipped Dodge Ram pickups had a problem with high pressures in the power steering/hydraboost braking system under extremely cold startups. Symptoms were "growling" in the hydraulic pump and no power assist until the fluid warmed up for a few minutes. The solution was to switch over to a synthetic fluid that wasn't subject to the extreme viscosity changes at very low temperatures.

I'm not sure that's an option on the Spartan application, but it took care of the situation with the Dodges.

Rusty

quote:

Originally posted by Route 66:
I think this would be more of a Spartan issue.

I believe the chassis is supplied by Spartan with all fluids installed.

I wish it were a chassi issue but Spartan's story is they have no control over where the coach is sold, Newmar does.

quote:

Originally posted by RustyJC:
Cummins-equipped Dodge Ram pickups had a problem with high pressures
Rusty

Who took the blame Cummins, Dodge or the customer?

quote:

Originally posted by jjbsmith:

This is what happens if you start your Cummins with a side mount radiator at 25 below.

Someone just pointed out that -25 degrees celcius is about -10 degrees farenhieght.

FWIW: I operated my coach for 3 months this past winter regularly at temps between -10F and -20F (Note the F so that is -23C to -29C) including many starts after several days of cold sitting. Not a single issue with ISM, chassis, hydraulics, AquaHot, Genset, fluid over-pressure, etc...

My guess is this might have been a defect. Transynd (Allison) and AW-46 (power steering) are standard issue at any temp (within reason-see below) and the engine oil might change from 15w-30 to a 5w-20 depending on the cold severity.

According to PetroCanada, the xx-46 series of hydraulics have a start up temp minimum of -22F and the xx-32 series of hydraulics can start-up as low as -29F.

This message has been edited. Last edited by: RVDude,

Hi Jeff,
We have an ISL in an Allstar so this may be a factor. Last I heard from our service shop Spartan and Newmar were fighting over who should pay for the fix since the Allstar was still under warranty. Our service rep was fighting to make sure it was covered under warranty because the coach was at their facility from Sept till March for unrelated warranty work and the heat exchanger blew up when they were shuffling the coach in and out of the shop for repairs.
I was told that the oil was too viscous and that Spartan was concidering a service bulletin that would recomend a lighter oil and a pressure relieving bypass for colder climates.

jjb: I hope that Spartan steps up and repairs... They have been nothing short of superb on all my dealings and I would see no reason why not. You were NOT operating completely out of the norm and this should NOT have happened - certainly a combo of high cold pressure and potential defect.

With that said, we were both operating at the lower temp limits for the hydraulic fluid. As above, PetroCanada rates the xx-46 fluid at -22F. The interesting thing is the next step down, the xx-32 fluids are only -29F, not much more. However, I would suggest anyone consider, as I will next year, running a lower viscosity hydraulic fluid if staying in these major negative cold climes for long. I like Spartan's idea of adding a pressure bypass - I hope they consider it. And let us know if you hear any more on both your repair and the bypass. That's a good safety margin addition and really, we don't need much cooling in that department at -20F now do we? Hence, a bypass of the cooling unit is fine.

Good luck...

Jeff,
I was curious and maybe you have the answer. I look at the hydraulic lines and as far as I can tell this heat exchanger in the radiator stack is hooked into the big auxilary pump on the side of the Cummins. For sure this pump handles the radiator fan motor and the power steering. My question is, does oil in this heat exchanger circulate through the Allison?
I can see that the Allison pumps it's oil through a cylindrical heat exchanger in-line with the radiator hose directly connected to the engine. I assume this is so that the antifreeze can transfer heat to the Allison hydrulic oil in colder conditions. Same question another way are the systems separated?
Just speculation but maybe the big heat exchanger over-cools the power steering/fan motor oil?