Skip to main content
Gerry | Vanagon
Checking account...
← vanagon.com home · Continue the discussion in the forum
Subject:Re: without thermostat?
From:Chris Mills
Date:Sun, 24 Mar 2002 21:19:24 -0600

>I am in the process of rebuilding my engine after both heads blew.

>I am really concerned about high temps so I was thinking of running the
>engine without the thermostat.
>
>I know it won�t warm up correctly but we are having a heat phenomenon in my
>country (it�s called "el ni�o") whichwill last all year, so the outside
>temperature won�t be a problem.
>
>Can anyone tell me their opinions on running without thermostat?

The thermostat will not make the engine run hot unless it sticks closed. It 
is designed to fail in the open position. The thermostat slows the flow of 
coolant so it will stay in the radiator longer and be cooled more. Also you 
engine will never maintain a constant temperature. It will heat up climbing 
hills, cool off coming down hills, and it will probably cool off idling in 
traffic.

In short it is a bad thing to remove the thermostat. If it was a good thing 
most cars would never come with a thermostat from the factory because auto 
makers are always looking for ways to maximize profit by creating a more 
simple machine (simplify the design and cost eliminating excess parts).

The other thing is that the fuel injection computer watches the engine temp 
and sets the mixture approximately. When the engine is cool or cold it 
gives the engine a richer mixture. That means it will run richer when it 
shouldn't and can dilute the motor oil with excess unburned fuel (and speed 
engine wear out), extra pollution created by excess fuel, and worse fuel 
economy. Also the engine will be busy expanding and contracting because the 
thermostat is not functioning and will wear out much faster.

My advice (worth .02 or less) is keep the thermostat.

If you are really concerned about engine temps then listen to the engine 
fan. They only come on (if they are still setup correctly and not been 
altered) the engine is hot, when they go off the engine is cooler. If they 
are on continuously (and have been normally cycling) then there is a problem.

With a properly operating fan system and temperature gauge you have plenty 
or warning before the engine melts.

Hang in there. Take care!

Chris M. <Busbodger - "TEAM SLOWPOKE">
Cookeville, Tennessee

ICQ# 5944649
scm9985@tntech.edu

'78 VW Westfalia (67 HP -> that is...67 Hamster Power)
'65 Beetle - Type IV powered
'99 CR-V AWD station wagon
'81 CB900 Custom moto-chickle
2.5 Corvair engines for my Trans-vair Conversion