Duramax Fuel Coolers and Winter Operation

retmil46 · **Posted:** Sat Aug 18, 2007 9:36 am

Yesterday I called Piedmont Diesel Service in Albemarle NC and talked with one of their techs who has been thru training on Duramax trucks. I asked him specifically about the fuel cooler and what if any design features or precautions were taken for winter operation in cold climates.

Short answer - None

Long answer - Use an appropriate fuel treatment for cold climate operation

End of story.

oldnavy · **Posted:** Sat Aug 18, 2007 9:45 am

retmil46 wrote:

Yesterday I called Piedmont Diesel Service in Albemarle NC and talked with one of their techs who has been thru training on Duramax trucks. I asked him specifically about the fuel cooler and what if any design features or precautions were taken for winter operation in cold climates.

Short answer - None

Long answer - Use an appropriate fuel treatment for cold climate operation

End of story.

VW used a cooler on there automatic transmission cars because they had higher pressure pumps then standard tranny cars, but they had a thermostat in the coooler system to by-pass it when needed. System worked great. I guess GM just took another shortcut to save a few dollars and shafted the buying public.

retmil46 · **Posted:** Sat Aug 18, 2007 10:00 am

Are you talking about the thermostatic tee on the fuel filter? From what I understand, this is what VW used in place of an electric fuel heater - they used return fuel heat in place of an electric resistance element, to prevent cold weather plugging of the filter.

They might have a thermostat on the fuel cooler, if the fuel system diagrams I saw on the TDI forum are correct - it showed the fuel cooler being plunbed in on the supply line to the engine. You'd definitely need a thermostat in that case.

oldnavy · **Posted:** Sat Aug 18, 2007 12:04 pm

retmil46 wrote:

Are you talking about the thermostatic tee on the fuel filter? From what I understand, this is what VW used in place of an electric fuel heater - they used return fuel heat in place of an electric resistance element, to prevent cold weather plugging of the filter.

They might have a thermostat on the fuel cooler, if the fuel system diagrams I saw on the TDI forum are correct - it showed the fuel cooler being plunbed in on the supply line to the engine. You'd definitely need a thermostat in that case.

No, not the plastic T at filter, I seem to remember it was at or near the cooler. I am not really sure of the location and never looked for the thing, I just remember it being talked about on one or two ocassions.

LanduytG · **Joined:** Sun Dec 11, 2005 6:59 am **Posts:** 188

The fuel cooler on the Dmax is in the return line and the fuel is hot enought that gelling because of a cooler is not and issue. On my Dmax I have seen 148* return, but that was with a low tank.

Greg

oldnavy · **Posted:** Sat Aug 18, 2007 6:26 pm

oldnavy wrote:

retmil46 wrote:

Are you talking about the thermostatic tee on the fuel filter? From what I understand, this is what VW used in place of an electric fuel heater - they used return fuel heat in place of an electric resistance element, to prevent cold weather plugging of the filter.

They might have a thermostat on the fuel cooler, if the fuel system diagrams I saw on the TDI forum are correct - it showed the fuel cooler being plunbed in on the supply line to the engine. You'd definitely need a thermostat in that case.

No, not the plastic T at filter, I seem to remember it was at or near the cooler. I am not really sure of the location and never looked for the thing, I just remember it being talked about on one or two ocassions.

My source said there is no thermostat in the cooler as the temps run too high even in the winter to warrant a thermostat or block off the cooler in any way. He stated about the same as Greg did as for as temps go, 85* to 175* is the typical range of temps on the VW TDI so even in the winter at a low temp of 85* with a full tank you should not have a problem from the cooler gelling till after shut down and that would still be a problem if you had no cooler in the line. So in the winter it may behove you to have some anti-gell on hand or added to the fuel.

retmil46 · **Posted:** Sat Aug 18, 2007 7:22 pm

One other thing the gent at Piedmont Diesel Service told me -

During the summer, when someone calls in complaining that their truck (no matter the brand) is running like crap, stalling out, hard to start, no power, etc, there's two standard questions they ask them -

"How hot is it where you're at?"

"How much fuel do you have in the tank?"

If the answers are low 90's and above, and less than 1/4 tank, they tell them to go fill their tank and the problem will go away. And better than 90% of the time, it does.

oldnavy · **Posted:** Sat Aug 18, 2007 7:34 pm

I try to never let mine get below 1/2 tank in the summer time if I can help it for that reason.

Duramax Fuel Coolers and Winter Operation

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