Radiator Thermoswitch

[Jack Houpe]

I love the idea of cooling the water after shut down for a short bit to reduce the heat soak. Can an electric water pump be installed/operated without removing the water pump on the motor?

I use an electric water pump with a "time off relay" it's programmable to minutes, mine is set to 2 minutes which does a good job, my fan circuit is also activated during that time, all these suggestions came from Mike Trusty at least 15 years ago, I've incorporated them in my turbo cars with great success.

Stop and go traffic with a high performance engine is a killer on the cooling system, my car still has the original coolant from 2008, Mike Trustys cooling system design is genius at the least.

 

[Seymour Snerd]

BTW, I installed a lower temp thermoswitch and the fans still don't come on.

Have you verified it's the thermoswitch that's at fault? IOW, how do you know that the thermoswitch is not closing at the specified temp? BTW you can test them in a pan of hot water with a thermometer and an ohm-meter. Or to test in reverse, with everything running if you pull the two wires of the thermoswitch and connect them, the fans should go on.

 

[Tim Kay]

Good suggestions Alan, yes I did both although I forgot to test the new one before I put it in (assuming new it'll be ok). I thought the old one was bad but I did the water\thermometer test as you mentioned and it worked but at well over 205 deg F. And the fans do come on if I put the wires together.

Jack, is the water pump on the front of the motor still in place or was it removed when the electric pump was installed?

 

[Jack Houpe]

Good suggestions Alan, yes I did both although I forgot to test the new one before I put it in (assuming new it'll be ok). I thought the old one was bad but I did the water\thermometer test as you mentioned and it worked but at well over 205 deg F. And the fans do come on if I put the wires together.

Jack, is the water pump on the front of the motor still in place or was it removed when the electric pump was installed?

In this installation I use a replacement alternative electric water pump, not a remote electric water pump.

 

[Terry Oxandale]

Just a side note on this, I've observed that once the thermostat sees the coolant temperature drop (in my particular set-up) from the pump running after engine shut-down, that it eventually routes only through the bypass (and very little through the radiator) at the thermostat operating temperature. What I hoped for (when I designed the plumbing) was to be able to quickly cool the engine down within a few minutes of running the electric pump. What I got was a temperature decrease of about 10 degrees (F) over a 10 minute period of running the pump with the engine turned off because once the thermostat closed, it was simply recycling the hot engine water right back into the block with very little flowing through the radiator. I'm using an almost identical set-up what Mike Trusty is using, which appears to be a well thought-out configuration.

 

[Jack Houpe]

Just a side note on this, I've observed that once the thermostat sees the coolant temperature drop (in my particular set-up) from the pump running after engine shut-down, that it eventually routes only through the bypass (and very little through the radiator) at the thermostat operating temperature. What I hoped for (when I designed the plumbing) was to be able to quickly cool the engine down within a few minutes of running the electric pump. What I got was a temperature decrease of about 10 degrees (F) over a 10 minute period of running the pump with the engine turned off because once the thermostat closed, it was simply recycling the hot engine water right back into the block with very little flowing through the radiator. I'm using an almost identical set-up what Mike Trusty is using, which appears to be a well thought-out configuration.

Terry what degree bypass thermostat are you using? I run the pump for only 2 minutes which seems to be working. On my twin turbo car it not only pulls heat from the engine but also the water cooled center sections of the turbos thus eliminating the need to let the car idle while turbos cool.

 

[Seymour Snerd]

yes I did both although..

I just don't get it. Mine comes on exactly when i would expect it to with the supplied switch. I wonder if we all have radiator flow in the same direction...

<later>

In answer to my own question we probably don't. Mine is hooked up backwards from the "official" layout, IOW the thermoswitch is on the same pipe as the thermostat (the supply/hot side). So that at least explains why my fans come on sooner.... ... one more thing to fix...

 

[Seymour Snerd]

Jack, is the water pump on the front of the motor still in place or was it removed when the electric pump was installed?

BTW there is at least one remote water pump described as a "boost pump" i.e. desgned to be used in series with a mechanical pump. Of course i don't remember where I saw that ...

 

[Terry Oxandale]

Terry what degree bypass thermostat are you using? I run the pump for only 2 minutes which seems to be working. On my twin turbo car it not only pulls heat from the engine but also the water cooled center sections of the turbos thus eliminating the need to let the car idle while turbos cool.

Jack, I'm currently using the factory SVO/Contour SVT thermostat, which I believe is a 190 or so thermostat. Recently I purchased a Reische 170 degree which opens wider and faster than the OEM. Next time I get around to draining the coolant, it's going in...but not sure this will resolve the problem of the bypass being closed once the temperature drops below the thermostat opening temperature. The LS motors can handle the higher temps, but it's un-nerving to see 200 degrees on the gauge.

 

[Seymour Snerd]

One good thing has come of all this: Tim measured the SPF thermoswitch threads as M22x1.5, and it turns out that's not an uncommon size for VWs, etc. Hella makes them that size in a wide range of temps. See http://www.hella.com/hella-za/assets/media_global/HASA_Thermo_Range_Borchure_LRes.pdf

Thanks, Tim!