RE: [DML] Overheating: Thermostat (otterstat) or Water pump or None of the Above

[Tom Tait <TTait@xxxxxxxxxx>]

First of all, bleed the air out of the system and refill the coolant tank so it is half full.  To do this  first top off the coolant tank, then open the bleeder valve on the top of the waterpump, and the small hose at the top of the radiator on the passenger side.  If you have the original radiator in the car with plastic tanks (the part the hoses hook up to) you must be very very careful not to damage or crack the tank - it will be brittle.

Bleed when the car is cold,  then warm it up, run the heater, shut it down and let it cool, and check for more air at both spots and repeat. Once it is totally bled out see if your water flow returns to normal.

The otterstadt and the thermostat are two different things.  The thermostat is a fairly typical thermostat mounted in the housing on top of the water pump.  When you replace it make sure to also replace the rubber gasket that comes with the new one.   Replace the pressure cap on your coolant bottle too, its cheap and if its more than a few years old its not worth chancing it.  A sticky pressure cap can cause your radiator to blow out, or worse, your heater core.

I highly recommend installing the water pump and radiator bleeder kits (DMC-NW carries both).  It makes bleeding much easier in the future.

Your otterstat is mounted in the bottom side of the metal coolant pipe under your (oil) dipstick.  Its easy to replace if the system has been drained.  While it is designed to be held in place switch just a metal clip, don't trust the clip.  There are two spade terminals on the back of the otterstat to hook the sensor wires up to, get a cable tie between the two of them and around the entire pipe and cinch it tight.  If the clip fails the otterstat will shoot out of the pipe, and 80% of your coolant will blast out of the car in just a few seconds (trust me).  If you happen to notice in your rear view mirror, shut down immediately, if not, go to the nearest ATM and take out several thousand dollars for repairs.  Either that, or install the cable tie.

Note that if you have a catastrophic failure of the otterstat or a hose that dumps al your water, the temp gauge on your dash will just sit there and do nothing as the engine quickly overheats, stalls, warps and fails.  If there is not sufficient water to flow over the temp sensor for the dash, it will not show the engine overheating.

Your thermostat is mechanical and it should open at operating temp and allow water to flow up to the radiator.  The water is pumped by the water pump.

The otterstat is an electrical sensor that triggers at a higher temperature, and kicks in the cooling fans.  The otterstat has nothing to do with controlling water flow.

When ever you do work on the cooling system, if its not working well, or if the level has gotten low for any reason, bleed bleed bleed.  Then a week later, bleed it again.


From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf Of Marvin
Sent: Monday, November 29, 2010 6:42 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] Overheating: Thermostat (otterstat) or Water pump or None of the Above



My Delorean is overheating. I notice water is not flowing through the system by observing the fluid in the water reservoir tank. I was able to get the water flowing by turning on the heater. The belts have been squealing, but that has been occurring for months with no observable affects. I'm ready to replace the otterstat, but I thought that only affects the cooling fans, and the cooling fans are coming on. Is this a water pump issue? Any suggestions. Thanks in advance.



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