Otterstat question

[burch]

Hey All,

Sorry if this same question has been posted before. I didn't see it in my search, but here we go:

Just installed a new otterstat. Tested by idling up to temp, fans came on at the appropriate temp, and then turned off at the appropriate temp during the cycle. Interestingly, after the first cycle, the fans then came on again at a much lower temperature (approximately 175 deg F), stayed on for about 10 seconds, and then turned off. This happened every few minutes, never letting the coolant get back up to the original ~205 degree temp.

Is this expected behavior?

[Chris 16409]

It's probably faulty. I seen that behavior from otterstats that are failing. In my experience they are pretty unreliable. Dave M on the forum has come up with a much better solution. Toby Peterson was selling his adjustable fan switch for years which is a great replacement. Unfortunately, his supplier is no longer making a critical part he needs and is not selling them currently.

[sdg3205]

I have also seen new otter stats fail quickly. Makes me wonder if the package was dropped in shipping or something.

[Bitsyncmaster]

It's normal to get shorter fan run times on the first few cycles of the engine warming up. It does that because the radiator is cold and as soon as the thermostat opens that cold coolant is returned to the engine.

My electronic otterstat is not a big seller because it requires wiring a new relay socket which many owners are scared to do.

[burch]

Thanks for the info guys. I'll do some more tests on it, see what happens.

[DMCMW Dave]

I have also seen new otter stats fail quickly. Makes me wonder if the package was dropped in shipping or something.

They are insanely fragile. Drop it on the ground and you may as well throw it away.

[jackb]

It's normal to get shorter fan run times on the first few cycles of the engine warming up. It does that because the radiator is cold and as soon as the thermostat opens that cold coolant is returned to the engine.

My electronic otterstat is not a big seller because it requires wiring a new relay socket which many owners are scared to do.

I'm still interested in getting your electronic otterstat (no issues with mine, simply to get as an upgrade) when funds allow.
My understanding from our earlier PMs and the instructions on your webpage is that the relay socket is for the controller, but I still don't understand where it gets the temperature from? Can you explain how it works in better detail? (asking here instead of more PMs so the info is available for others potentially interested in switching/upgrading over to yours)

[Bitsyncmaster]

I'm still interested in getting your electronic otterstat (no issues with mine, simply to get as an upgrade) when funds allow.
My understanding from our earlier PMs and the instructions on your webpage is that the relay socket is for the controller, but I still don't understand where it gets the temperature from? Can you explain how it works in better detail? (asking here instead of more PMs so the info is available for others potentially interested in switching/upgrading over to yours)

My otterstat taps into the wire going to the temperature gauge (the sender wire). So it reads the engine temperature the same as the gauge shows. You set the temperature where you want the fans to turn on via a dip switch on my unit. You can keep the OEM otterstat wired as stock so you now would have a redundant otterstat function. If you set mine to turn on the fans before the OEM otterstat then the OEM otterstat would be the backup. If you set mine to turn on fans after the OEM otterstat then mine would be the backup. Or you can remove the OEM otterstat and just use mine.

Mine will also give you an audio warning beep if your engine overheats. I have programmed a little higher than the fan on temp to give you the warning but the user can also set the warning temp if needed. One of my customers needed to set his warning temp a lot higher because his engine would heat up a lot even after the fans turned on.

So you need to tap into that sender wire, the wire that drives the fuel relay (that powers my unit), a ground wire and the wire that drives the fan relay (that turns the fans on).

[jackb]

My otterstat taps into the wire going to the temperature gauge (the sender wire). So it reads the engine temperature the same as the gauge shows. You set the temperature where you want the fans to turn on via a dip switch on my unit. You can keep the OEM otterstat wired as stock so you now would have a redundant otterstat function. If you set mine to turn on the fans before the OEM otterstat then the OEM otterstat would be the backup. If you set mine to turn on fans after the OEM otterstat then mine would be the backup. Or you can remove the OEM otterstat and just use mine.

Mine will also give you an audio warning beep if your engine overheats. I have programmed a little higher than the fan on temp to give you the warning but the user can also set the warning temp if needed. One of my customers needed to set his warning temp a lot higher because his engine would heat up a lot even after the fans turned on.

So you need to tap into that sender wire, the wire that drives the fuel relay (that powers my unit), a ground wire and the wire that drives the fan relay (that turns the fans on).


Ok, I think I get it...
The factory wiring has it set up so the temp sender (at the water pump/thermostat) only controls the gauge, and the otterstat (in the coolant pipe on the drivers side) only controls the cooling fans.
Your electric otterstat piggybacks off the signal from the sender, to activate the cooling fan relay connected to its output.
The old input to the fan relay, coming from the original otterstat, remains in place.
Is that right?

[Bitsyncmaster]

Ok, I think I get it...
The factory wiring has it set up so the temp sender (at the water pump/thermostat) only controls the gauge, and the otterstat (in the coolant pipe on the drivers side) only controls the cooling fans.
Your electric otterstat piggybacks off the signal from the sender, to activate the cooling fan relay connected to its output.
The old input to the fan relay, coming from the original otterstat, remains in place.
Is that right?

That is correct. The fan relay remains also connected to the AC compressor and OEM otterstat via diodes. My unit also has a diode inside it so any or all those devices can turn the fan relay on,.

[David T]

Erratic behavior by the "O" switch can also be caused by air in the system and/or a bad thermostat. The thermostat is supposed to open before the "O" switch turns on the fans. Also if you have the very early plumbing you should upgrade it to the later style where the "O" switch is on the bottom of the pipe. While the "O" switch is fragile, once installed and working satisfactorily, it should last a while. My guess in your case, the thermostat is not opening and closing the way it should. Typically a bad "O" switch won't turn on the fans. A thermostat stuck open won't keep the motor at operating temperature, ie, it never warms up. It is supposed to stay closed till it gets to 180. Replace the thermostat and rebleed the system.

[DMCMW Dave]

I've also found that seriously overheating the engine will damage the otterstat. You'll find this out when you get it cooled off, filled back up, and bled, and the fans no longer come on.

Although sometimes it may be that the otterstat failure caused the overheat, so it's hard to tell for sure.

And where Bitsyncmaster mentions removing it, he really means disconnecting it. If you remove it you have a huge leak in the coolant pipe!

[kbrown84]

i have used the modern "otterstat" from DeLoreanGo on my car for the last 6-7 months...its worked flawlessly, and seems to very robust in quality. 58471