Thread: Fuel Cooler Removal Td5

The fuel cooler is on the return line to the tank, not the supply line, and is there to reduce the heat generated from the injectors

great post here:

http://www.aulro.com/afvb/1460718-post37.html

Originally Posted by Psimpson7

great post here:

http://www.aulro.com/afvb/1460718-post37.html

That's handy to know about the regulator and the pump but I think the PO is more interested in removing the fuel cooler.

I'm thinking the same. I watched the fuel temp with Nanocom in a recent trip.

I have heard of some people not wanting to run the fuel tank too low because the fuel is circulated through the system and back to the tank. The belief was that as the fuel would be cooling in the tanks and if the fuel is low it doesnt stay in the tank long to cool and it would heat up.

Well the Disco 2 has a 90 L tank and I put 87 L in filling it up the spout. Your guess is as good as mine as to how much extra fuel I get in the spout but I suspect the tank got down to 5 - 8 L.

At the low point the fuel temp was about 67 degrees (+/- 1 or 2).

After filling it only took about 20 minutes for the fuel temp to get back up to the same.

So I'm with the PO. I think the fuel cooler is more of a fuel heater. Maybe it needs it's own radiator so it's not being circulated with hot water from the engine.

Happy Days.

The link I posted in my second post was to clarify the position of the 'fuel cooler' in the fuel circuit. i.e that it is not in the supply side, but the return.

The earlier coolers (upto 2004 ish) actually has a thermostat inside it that only opens at 82 degrees. before that it should bypass the fuel.

Wrong.
D2 has a 95 litre tank.
I'm fairly sure Pete has a pretty good understanding of what the bits of the Td5 do/don't do
Given our climate, and the Td5s aversion to excessive heat I'll be leaving mine in place.
There are plenty of better ways to get better power out of your Td5.

Originally Posted by Disco Muppet

Wrong.
D2 has a 95 litre tank.

Given our climate, and the Td5s aversion to excessive heat I'll be leaving mine in place.

Cool. I'll drive further past empty on the fuel guage. LOL.


It's interesting that there is a thermostat on the fuel cooler that remains closed until water temp reaches 82 degrees. This is indicating to me that it is actually a fuel heater. Why else would it need a thermostat. There should be no problem with cold water circulating the cooler. As this would be making the fuel colder but waiting until the water is hot?

I'd like to know what the fuel temp is before the cooler. Saying this, I dont know the location of the current fuel temp sensor.

I thought for a moment that its to keep the fuel temp constant so as to reduce a variable from the tuning. Cold fuel is denser so less is needed but hot fuel is less dense so a greater volume is needed. If the fuel is made to a constant temp the mixture is constant matched to the volume (if that makes sense). But then I thought why would it be on the return line if that is the case?

As I said previously, it only takes about 20 minutes to increase the fuel temp to about 67 degrees. As I dont know the location of the fuel temp sensor, I dont know if this is the temp of all the fuel in the tank.

Just another idea. Maybe the higher temp makes the diesel more volitile? That would be a reason for heating it rather than cooling.

Happy Days

Here's a comment from a member of another forum.

" viscocity of the diesel changes significantly between 20 and 80 and as the diesel at 80 is a lot more fluid, the injection and atomisation will be a lot more effective."

Happy Days.

And some more.

"Warm diesel ,at a constant temperaturehas a better spray pattern/ ignition characteristic as noted by several contributors, But there is an advantage also in having warm diesel in the tank. It pumps more easily and the diesel filter will not be affected by fuel gelling . Remember that the TD5 diesel filter sits forlornly in the freezing environment just above the right rear wheel. Whereas in the Tdi and many other cars this filter is warm and cozy in the engine compartment. "