Longacre coolant pressure switch unreliable

[ETR]

For those of you that have coolant pressure warning lights, what switch are you using?  I like Longacre stuff, but I've had terrible luck with their 3psi switches.  The first two were duds out of the box, and the third lasted one weekend.  It's lit all the time and there's corrosion and signs of leakage through the body of it.  The same thing also happened with another car I previously drove for, it went bad and we stuck tape over the light during a stop.  I don't crank down on them during installation.

 

This is not good for something you need to have the confidence in to SHUT DOWN when that light goes on.  I see this one here at Pegasus looks different, might give it a try.  What have you had better luck with?

 

[mcoppola]

That Pegasus part looks like a good one, as it says it's designed for use with glycol based coolants.

We've had good luck with a Standard PS15T switch that can be found almost anywhere car parts are sold.

We use 1 for OP, 1 for coolant pressure, and keep a spare or 2 in the parts box.

https://www.amazon.com/Standard-Motor-Products-PS15T-Pressure/dp/B000CKTJ78

[MMiskoe]

I've had trouble if they are on the bottom of the hose, crap collecting in them.  However, if at 9-oclock/3-oclock or high noon they seemed to be fine.

 

Yours does sound like a different problem however.

[red5001]

I was having similar trouble.  I just installed one and it doesn't appear to work.  I have put a know pressure on to verify the sensor works.  I was thinking changing position in the hose as well.

[hotrod]

We've used this one I like the Allstar brand all made in the US & good quality. Some sending units have to be grounded to work if you have it in a inline rubber hose it might not work.

https://allstarperformance.com/water-pressure-warning-kit-all80250/

[hotrod]

Manifold with mechanical water temp & water pressure sensor. Ground wire goes to chassis. 

[MR2 Biohazard]

You could wire up a fuel pressure gauge that has a low fuel pressure warning light.

https://pitstopusa.com/i-6520236-quickcar-extreme-fuel-pressure-gauge-w-built-in-led-warning-light-2-5-8.html

 

We rune a 0-30psi 0-5volt sensor that goes to the AIM dash and we set alarms when below 5psi and above 2000rpm, that way it can idle to get warm and build pressure without the alarm going off.

 

I have the longacre 3 or 4 psi one on the old car, but it does go off at times when it should not as it is not as reliable.

[mender]

In the Fiero I use Hobbs switches, 4 psi for coolant pressure and 30 psi for oil pressure, hooked up to big bright shift lights. 

 

 

 

[red5001]

I will have to look at the hobb switch.  look to be better quality.  A quick test with air showed the 3-4 psi switch I had didn't switch until ~6psi.

[mender]

And the Hobbs switches are adjustable to make sure you get an accurate switching point.

 

I had a hose pop off on the first lap at Laguna and was able to immediately pull into the pit due to the coolant pressure switch and light. The engine didn't have time to overheat so most likely saved the engine.

Edited October 16, 2020 by mender

[Rodger Coan-Burningham]

4 hours ago, mender said:

And the Hobbs switches are adjustable to make sure you get an accurate switching point.

 

I had a hose pop off on the first lap at Laguna and was able to immediately pull into the pit due to the coolant pressure switch and light. The engine didn't have time to overheat so most likely saved the engine.

 

Great idea, would not have thought of this.  Thanks.