Thermostat fan controlled external oil cooler, replace flaps?

[Stuartzickefoose]

Hey all. Late model t4 engine.

I was wondering if I put a thermostat controlled external oil cooler in place, can I safely run without a thermostat on the flaps on the stock 2.0?


Thanks!
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Stuart Zickefoose

2011 Jetta Sportwagen TDi 6 speed manual

206-841-7324
[email protected]

[SGKent]

yes. The cooling of the cylinders and heads is different than the cooling of the oil.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[airschooled]

Flaps prevent over-cooling of cold heads, cylinders, and pistons. By allowing those parts to heat up faster, we achieve thermal homeostasis faster, when the engine expands to seal best, run best, and last longest.

The oil cooler, even thermostatically controlled, wouldn't manage the thermal expansion and warm-up of the engine metallurgy. We see this on a CHT and oil temp guage, since head temps respond instantly to load, and oil temps take a while to react to speed.

Your choice what to do here.

--

You'll always need the left flap in place, no matter what, on an air-cooled T4.

See "Type 4 Flap Trick" by Colin "Amskeptic," from his upcoming book.

The flap, in the "fully warmed up" position actually designates flow the oil cooler which would otherwise be under-cooled.

See ya on the road!
Robbie
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[Stuartzickefoose]

Figured. Thanks guys.
_________________
Stuart Zickefoose

2011 Jetta Sportwagen TDi 6 speed manual

206-841-7324
[email protected]

[Wildthings]

If you are driving it during the cooler months a working flap system is a must. A cold engine will have more gas and water condensing on the cylinder walls and will be less thermally efficient.

[orwell84]

I ran for years without a thermostat until a late fall camping trip where we let the engine idle a long time in below freezing weather to run the gas heater. After a long day of hiking we came back to find the crankcase full of gas and had to scramble for some oil and change it.

With the thermostat in cold weather, the oil temp will peg at 180. On cold spring or fall mornings, it really improves drive-ability after starting.