TDI fans on when parking

[DeanC]

I thought my car was simply always picking the wrong time to do an EGR regen because my fans seem to be on when I park about 3 or 4 times out of ten. Popped the engine cover off today to have a casual look at the new TDI vs. the MK5/6 gen one and spotted a big old water to air intercooler starring back at me so I reckon that's the culprit following 'spirited' driving.

 

[AndrewJB]

You mean DPF regen

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[DeanC]

That I do.

 

[Suicida1 Zombie]

Quite new to these big diesel engines but what do water to air intercooler's actually do?

 

[DeanC]

Cool the air entering the engine down using your coolant to increase efficiency. Normally cars use an air to air intercooler like a radiator. I think the last 2 generation golfs had big issues in the winter with the intercoolers freezing so they implemented a water to air one.

 

[Suicida1 Zombie]

So will all the TDI's have this or just you guys with the 184 beasts?

I ask as I have had the fans run on for a while a few times when parking up (Even after switching the engine off) after hammering it and I had always assumed it was something to do with the DPF too.

 

[DeanC]

I'm mot 100% but I think all the mqb cars have it. One of these on the inlet:

 

[gaffer1986]

I believe the water to air intercooler is 25 times more efficient at cooling air than an air to air intercooler. That way the intercooler can be smaller and closer to the engine making the intake pipe from the turbo to intake valve shorter which means the turbo has less air to compress which reduces turbo lag. I think the EA211 engines have one too.

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[marty_34]

this happens to me sometimes, fan stays on for a minute or two after ive parked up.

mines only the 150 engine not the 184 so I assume must be an integral part of the set up, but I'm no expert or mechanic!

 

[gaffer1986]

I can't think why a water cooled intercooler will need the fans to run after the engine has switched off.

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[DeanC]

To cool the coolant down

 

[gaffer1986]

When the coolant isn't circulating, I can't see how cooling the water in the radiator would help.

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[DeanC]

Oh is not electric. Assumed it would keep pumping it around.

 

[gaffer1986]

Electric water pump? That's sounds like a good idea, not sure if it's electric or not, most water pumps run off the cambelt.

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[DeanC]

Yes. A lot of cars do now for efficiency. I know the mk7 golf bluemotion does and assumed they all did.