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> Cooling flaps, Is this thermostat good
Ron914
post Mar 17 2026, 03:40 PM
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In searching for reasons my car seems to be running too hot of oil temperature I investigated the thermostat /flap system . @Superhawk996 @emerygt350

The thermostat seems good so I will connect it up to the flaps and test .

I have a question about the return spring on the flaps , it seems to take a fair amount of force to push it down(closing flaps) than I would expect . Does this seem normal ? I am concerned this amount of force will expand the thermostat before I get it hot .

I pulled the thermostat and tested it with a heat gun , relaxed or cold it measured 38.29mm and after heating it expanded to 48.73mm
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L-Jet914
post Mar 17 2026, 06:35 PM
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Here is the spec the thermostat bellows should be expanded to at 65-70c (149-158F). Also a link to the factory service manuals. http://p914-6info.net/Manuals.htm


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Superhawk996
post Mar 17 2026, 07:28 PM
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Honestly I would leave the thermostat out of the mix until we figure out why you’re running hot.

Adding it into the system at this point will only add more confusion.

Yes it does take a good bit of force to get the flaps to the closed position.

I can’t remember - have you ever looked into the tin and verified the actual flaps position when defaulted to the fail safe, fully open position.

Similarly, did we ever verify your oil cooler side flap is present and connected properly?
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SirAndy
post Mar 17 2026, 07:42 PM
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I doubt the thermostat is your problem. They're supposed to fail in the full cooling position and only pull the flaps if they're working.
If you disconnect the thermostat wire, the flaps will go to the "full cooling" position.

Then continue your trouble shooting.
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930cabman
post Mar 18 2026, 04:57 AM
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QUOTE(SirAndy @ Mar 17 2026, 07:42 PM) *

I doubt the thermostat is your problem. They're supposed to fail in the full cooling position and only pull the flaps if they're working.
If you disconnect the thermostat wire, the flaps will go to the "full cooling" position.

Then continue your trouble shooting.
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Should "go to the full cooling" position. This must be verified
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emerygt350
post Mar 18 2026, 05:08 AM
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I agree with the above. With the thermostat out and the flaps full open do you get the hot oil issue? Does the behavior change at all?

It's been so long I forget where we left off.

Definitely check to make sure the oil cooler flap is in the right position.
Hot oil can be a timing issue too. Where are we for timing at the moment?
We did verify the sensor and gauge? Have you verified the gauge is tell you the truth?

Just saw that other post, must digest all that info and then think a little.
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emerygt350
post Mar 18 2026, 06:00 AM
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I replied to the other thread. Synopsis, verify the presence of that tin on the motor and try retarding the timing. Get that bluetooth AFR setup.
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914werke
post Mar 18 2026, 06:45 AM
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No just from your pic it looks to be in expanded state meaning it already sprung a leak
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bdstone914
post Mar 18 2026, 07:29 AM
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It is bad but that will not cause the heating problem. They leave the flap covering the cooler when they fail.
I would make sure the flip rod moves allowing the flap to force air over the oil cooler
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bdstone914
post Mar 18 2026, 07:35 AM
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It is bad but that will not cause the heating problem. They leave the flap covering the cooler when they fail.
I would make sure the flip rod moves allowing the flap to force air over the oil cooler
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SirAndy
post Mar 18 2026, 09:12 AM
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QUOTE(bdstone914 @ Mar 18 2026, 06:29 AM) *

It is bad but that will not cause the heating problem. They leave the flap covering the cooler when they fail.
I would make sure the flip rod moves allowing the flap to force air over the oil cooler


With the thermostat detached, the passenger side flap should be DOWN and over the oil cooler which is the FULL COOLING OPEN position since it is a vane that directs airflow.

If the flap is UP it is in the CLOSED NO COOLING position and your cylinders and the oil cooler get no air flow.


(IMG:http://www.914world.com/bbs2/uploads/post-15673-1699293458.jpg)

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SirAndy
post Mar 18 2026, 09:23 AM
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FULL COOLING OPEN position, this is what the flaps should look like with the thermostat disconnected.

Note that the passenger side flap is covering the oil cooler to direct full airflow to the cooler.

(IMG:http://www.914world.com/bbs2/uploads/post-104-1276788656.jpg)
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914werke
post Mar 18 2026, 11:02 AM
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QUOTE(SirAndy @ Mar 18 2026, 08:12 AM) *
With the thermostat detached, the passenger side flap should be DOWN and over the oil cooler which is the FULL COOLING OPEN position since it is a vane that directs airflow.
If the flap is UP it is in the CLOSED NO COOLING position and your cylinders and the oil cooler get no air flow.

(IMG:http://www.914world.com/bbs2/uploads/post-15673-1699293458.jpg)

(IMG:http://www.914world.com/bbs2/uploads/post-15673-1699293530.jpg)

THIS IS IMPORTANT As I have encountered a # of motors where the PO had fixed this flap in the up position permanently
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Spoke
post Mar 18 2026, 11:14 AM
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@Ron914

Are your cooling flaps all the way open? From the picture you showed the arm looks to be at a forward angle. Here's yours and mine. Mine looks like the picture Andy showed.

I don't run a thermostat so the cooling flaps on my 914 are always open.

Are you sure there's no obstructions or critter stuff in there?

Yours:
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Mine:
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