remote thermostat with built in bypass

[exdeath]

Been on the hunt for a self contained remote thermostat housing with built in thermostat controlled bypass (ie: when the thermostat opens, it has an extended section with a valve that also closes the bypass opening)

Just thought I'd try here and see if anyone knows of any. So far all I've found are exactly this for Land Rover and 70-80s BMWs but those are non serviceable capsules and I'm hoping to find a 2 pc housing where the thermostat can be replaced.

 

[franksta]

Is this for the coolant or an add-on oil cooler?

 

[exdeath]

Originally posted by: franksta
Is this for the coolant or an add-on oil cooler?

Coolant. Looking into doing a custom revamp of a stock system which uses a poor thermostat housing design which allows full bypass to operate in parallel with the radiator even at operating temperature.

 

[herm0016]

type of car and engine may be helpfull.

 

[exdeath]

2003 SVT Cobra 4.6L S/C DOHC Ford modular, but it's irrelevant as I'm looking for a specific type part of my own choosing for something custom.

Just wondering what types of vehicles already use what I'm looking for so I don't have to fabricate something.

Best thing I've found so far is the a Land Rover thermostat that they call a "pressure relief thermostat":

http://web.tiscali.it/elise_s1/

http://cgi.ebay.com/ebaymotors...QrdZ1QQsspagenameZWD1V

http://cgi.ebay.com/ebaymotors...QrdZ1QQsspagenameZWD1V

Note in the third that the thermostat includes a plunger/valve that blocks the bypass when the thermostat is open.

Just looking for other options if anyone has encountered something similar on their various cars.

The issue with my car is the bypass hose is the same size as the main hoses and there is no provision for blocking the bypass at operating temp so their is still a large amount of bypass in parallel with the radiator when it should all be going through the radiator at that point, resulting in recirculated hot coolant and heat soak.

There is a Evans cooling kit that relocates to a remote bypass thermostat, but I'm not fond of that thermostat's design and the bypass on that one is TOO small and doesn't close adequately. Preferably the bypass would be the same size, just able to be closed completely when the thermostat is open.

 

[herm0016]

can you just put something to restrict the flow in the bypass more? not sure where to look for something like that.

 

[SJP0tato]

Originally posted by: exdeath
The issue with my car is the bypass hose is the same size as the main hoses and there is no provision for blocking the bypass at operating temp so their is still a large amount of bypass in parallel with the radiator when it should all be going through the radiator at that point, resulting in recirculated hot coolant and heat soak.

Not criticizing, but how do you know it's a problem?

I'm curious to see if you've made sure you're not fixing something so it "seems" better without solid proof the action you're taking has a positive result. Have you checked the coolant temp with an accurate gauge during various operation modes? Have you dyno tested the motor at warmer vs cooler coolant temps? Some motors put out more power and are more efficient the hotter the coolant runs (at least up until the coolant starts to boil, then trouble starts).

The worst scenario would be to spend time and money engineering up a solution, for a net effect of worse fuel economy or power.

Then again maybe this is a common well known issue with this year/make/model, in which case there must be some solution already suggested someplace?

 

[fbrdphreak]

If I'm not mistaken, a couple of the cylinders on the SVT Cobra's motor run hot, don't they?

 

[exdeath]

SJPOtato: Spirited driving in the summer Arizona heat temps can get around 200 and timing gets pulled around 190 and you can certainly feel the difference. Would like to get it around 180. Problem is the stock is supposed to be 180 but doesn't fully open and block the bypass till like 210. Regardless of fan setting or speed the large amount of bypass allows the car to heat soak and take a while to cool between hard pulls. There aren't any known after market replacement stats that fit properly or have the right sized bypass valve, but I'm investigating one that supposedly fits but needs a donor spring to make it 180 deg. Seems better than replacing the whole housing.

fbrdphreak: yeah 7 and 8 but thats easily fixed by knocking out a freeze plug and providing the driver side head a flow through exit path that merges with the passenger side exit path. Don't ask...

 

[AMCRambler]

Are you building up an '03 Cobra? Or are you dropping the 4.6L into another car? Sounds like an interesting little project you've got going there. My curiosity is aroused.

 

[SJP0tato]

Originally posted by: exdeathSpirited driving in the summer Arizona heat temps can get around 200 and timing gets pulled around 190 and you can certainly feel the difference. Would like to get it around 180. Problem is the stock is supposed to be 180 but doesn't fully open and block the bypass till like 210.

Ah yes, I'm here in AZ with you, so I can understand the heat issue.

The thermostat not opening fully until past 180 is pretty common with most OEM/OEM-equivalent thermostats I've seen/heard of. What about the band-aid fix of a "cooler" thermostat that starts opening at 160: http://www.rpmoutlet.com/03cobrastat.htm

Might be worth a shot to see if it helps keep the temps down. That in conjunction with proper usage of "Water Wetter" might be just enough to keep things where you're wanting them.

Best of luck!

 

[exdeath]

Thats the primary issue, no after market thermostats fit properly or cover the bypass completely. I've got a thread on the SVT forums going and I guess the latest thing someone tried is a Stant that fits perfectly in the stock housing and covers the bypass completely but it only comes in one temp and you need to replace the spring with a 170 deg from another Tstat. Reportedly there is a 20-30 deg drop in temps even after multiple WOT pulls then cruising in traffic and sitting. The other common fix is drilling the stock Tstat so a little hot coolant can blend into the cold side and open it sooner but that has its own issues of keeping temps TOO low and long warm up. I've got a 160 deg Tstat on hand, but thats a little too low for my liking so I decided against putting it in at the last minute.

AMCRambler: yeah, went from a KB vert to a stock coupe and starting the mod process all over again, and exploring different ways of doing things this time around. I'm around 450 RWHP on stock blower with a 2.76 upper (14 psi) and 19 deg WOT at the moment, nothing special yet. Tempted to play on an open track in the future so I'm looking into cooling/piece of mind/suspension mods before I get power crazy again. The coupe is so much stiffer, it makes the stock bushings feel so much worse.