D17 Thermostat Questions

Here is a photo of the Gas Thermostat assembly.  I don,t see how a normal automotive thermostat could work.  I would source the correct replacement from an AGCO dealer.  Maybe Sandy Lake.

Thanks for the diagram and information. I checked the old thermostat in a pot of water on the stove and it opens at 180 degrees. I 'm going to study how everything fits together that would allow the coolant to bypass the thermostat to run so cool. The black round gasket appears to be ok. Interesting. It isn't rocket science but I'm curious what is going on. Should have left the radiator dirty I suppose.

Check block and radiator tanks with infrared gun.....probably not running as cold as you thought and a dirty radiator is not the answer.

Edited by SteveM C/IL - 05 Jun 2020 at 8:32am

Thanks for everyones' help on this.  I am now officially confused.  The new 3 piece thermostat I had purchased from Steiner (thermostat, adapter collar and black rubber gasket) does not fit into the thermostat housing, as far as I could tell.  Here are photos showing the original thermostat along with the new one.  I could see how the smaller new thermostat has to fit into the brass adapter, and would be the right height so the rubber gasket would seal at the top.  However, the brass adapter is simply too large to fit into the recess of the housing.   Perhaps they sent me the wrong part number, although it looks identical to the D17 thermostats on other vendors websites.

I tested the original thermostat in a pan of hot water, and it opens at ~ 180 deg and seems to be functioning ok.  After cleaning everything up, I put the old one back in.  It does seem to be working, as using an oven thermometer, the water circulating in the top tank is ~ 160 + deg.  It does seem the gauge is wrong, as it is showing half-way below 160 deg in the white region.  So idling the engine brings the water temp up to 160.  Once I work it, the gauge does get up into the green above 160 deg.  So it seems that with the clean radiator the engine is only barely getting up to temp at idle, which is not surprising.  I'll be ordering a replacement temp gauge, although at least I know everything is functioning correctly now. 

It is odd that the new 3 piece thermostat is incorrect.  Either they sent the wrong part, or I was too stupid to figure it out.



Edited by Oldwrench - 08 Jun 2020 at 10:01am

That thermostat will work. Glue the rubber ring to the outlet side of the thermostat with some 3M Super Weatherstrip Adhesive. The thermostat sits on the brass saddle. I prefer to glue the gasket to the housing. Makes for one less loose part to have to hang on to as you put it together.