Thermostat Help
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From: MD
Thermostat Help
I installed my new thermostat today and it is too loose. My original thermostat was in there nice and tight, but I can move this one around with one finger. I measured my water pump and the height of the groove is 4.5mm, so I used the thinner oring that came with the thermostat. I tried reinstalling it with the metal washer, but it still moves. What gives? Should I try the thicker oring?
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From: ~Carefree Highway~
The steel shim is not used with the 4.5mm waterpump.
Posting for RL members:
http://forums.pelicanparts.com/porsc...wo-orings.html
The movement of the thermostat is correct. There has to be a slight gap for the coolant to pass when the thermostat is cold.
J_AZ
Posting for RL members:
http://forums.pelicanparts.com/porsc...wo-orings.html
The movement of the thermostat is correct. There has to be a slight gap for the coolant to pass when the thermostat is cold.
J_AZ
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From: MD
Alrighty thanks. I saw your post on Pelican, but it was so loose and based on the thermostat I removed I thought it was supposed to be tight. There is a bypass pipe (not the blocked off plastic piece on the front), so why would coolant need that super small gap to get around the thermostat?
Last edited by Chunkerz; Mar 29, 2013 at 10:28 PM.
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From: Palm Beach, Florida
Nordschleife Master
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From: Palm Beach, Florida
iirc that is not a bypass pipe, it's the return from the heater circuit and the blocked off pipe is turbo cooling so not used on the na.
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From: Palm Beach, Florida
That doesn't make sense to me, maybe I need a lesson in the 944 cooling system. When the engine is cold the flow just goes around the engine, radiator is completely blocked off at one end by the thermostat. There is no pressure in the radiator circuit, it just pumps around the engine until the thermostat opens. Even if theoretically all the coolant passages got blocked in the engine the reservoir cap would take the strain. What am I missing?
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From: MD
I don't know **** about the cooling system. I was just assuming something. The looseness of the thermostat worries me. My old water pump was a 4.5mm Lasso pump, just like my new one. The thermostat was nice and tight and only used the thin oring and the clip. I couldn't move the thermostat no matter how hard I tried. With my new one I can move it by looking at it.
The thermostat I removed from my old pump was made by Lasso and my new one is made by Whaler. Maybe the Lasso one is bigger?
The thermostat I removed from my old pump was made by Lasso and my new one is made by Whaler. Maybe the Lasso one is bigger?
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From: Just CA Now :)
There is an internal bypass port in the throat of the water pump. When the thermostat is "open" and coolant is circulating through the system, the other end of the thermostat seals off the bypass port. When the car is cold and the thermostat is "closed" the other end of the thermostat is pulled away from the bypass port, allowing coolant to circulate within the pump to avoid excess pressure, hydrolock, etc. The thermostat can spin a little when first installed, but after it's been in there a while and the seals swell, they tend to get comfy in one position.
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From: MD
Thanks for the info! I tested the thermostat to make sure it worked before I went through the trouble of installing it and it started opening at 75ish degrees celsius. It says it's a 71 degree thermostat, but 75 is close. I have no idea what temperature my fans are supposed to come on at. My original thermostat was 80 degrees, so I'm assuming the fan switch is somewhere around there.
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From: Just CA Now :)
By the way, that's why you want to replace the seal in the throat of the pump whenever you install a t-stat. If it doesn't seal well when the t-stat opens, then some of your coolant will go through the bypass and reduce the flow to the cooling system...
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From: ~Carefree Highway~
Chunkerz said he has purchased a rebuilt or new pump and the rebuilder/manufacturer should have put in a new seal.
If you are not changing the old WP, the seal can be removed/replaced
The WP seal mentioned by Tom is where the thermostat disc sits on inside the WP.
MVC-011F.JPG
To remove this seal a special tool is needed.
Water pump inner seal tool.jpg
Buy one of these "Plumbers Helpers?" size? and grind down the end until it fits to do the job.
Thanks again Tom.
J_AZ
If you are not changing the old WP, the seal can be removed/replaced
The WP seal mentioned by Tom is where the thermostat disc sits on inside the WP.
MVC-011F.JPG
To remove this seal a special tool is needed.
Water pump inner seal tool.jpg
Buy one of these "Plumbers Helpers?" size? and grind down the end until it fits to do the job.
Thanks again Tom.
J_AZ
