View Full Version : Thermostats in 2 strokes

09-05-2002, 01:30 PM
Does anyone reckon it is bad for your average two stroke to have the thermostat so it is fully open at all times - in SE Qld anyway?? I guess the engine won't heat up as quickly but on the other hand it can't shut down on you and let no water through. Would just like some opinions on this as my thermostat has been modified to be fully open because it was stuffed. I used to do the same thing to a couple an old HQ with no problems through winter but then they weren't outboards so ??
Cheers Luke

15-05-2002, 09:57 PM
Engine manufacturers use thermostats for 1 reason and 1 reason only - to get the engine up to operating temperature as quickly as possible. Engines are designed to operate at a given temp, and when the engine reaches that temp all internal clearances should be correct, fuel ignition is at it's best and wear at it's minimum.
What most people dont realise is 90% of engine wear occurs during the first 5 minutes after a cold start. Ever wondered why taxi's can get over 500000 km from an engine easily - it never gets cold. Without a thermo you engine stays colder longer therefore will wear more.

Thermostats also stop engines from overheating though this applies to engines fitted with radiators and not outboards. You may have noticed your old HQ's would get hot very quickly if placed under heavey load while travelling slowly?

Basically, every engine will run better and last longer with the correct thermostat fitted.


16-05-2002, 04:15 AM
Thanks Kev,
was starting to wonder if I was going to get some feedback on this one. I have noticed the water coming out of the telltale never gets as hot as it used to. Will have to put a new one in then.
Cheers Luke

18-05-2002, 06:14 PM
hi guys
just another point on the thermstat issue, they also slow the flow of coolant down to maintain that optimun temp (radiator cooled engines of all types) if it flows through to quick it does not have a chance to cool
from the grey headed old mechanic