Fordiesel69 233 #1 Posted May 6, 2014 On aviation engines there is usually a CHT (cylinder heat temp) guage for each engine and before takeoff, the temp needs to be in range. With the ongoing onan issues, I am surprised that nobody made a kit or found an aftermarket source so owners could monitor the temp on the front and rear cylinders. For example, you clean and blow out all the debris before cutting, and then go cut 9 acres of dry grass. Who's to say that half way thru the rear cylinder isn;t getting plugged up. Share this post Link to post Share on other sites
Theroundhousernr 589 #2 Posted May 7, 2014 (edited) Pull the RR and check it out. One bolt and 3 wires. This is what I plan to do to check in on the rear cylinder . If no oil or moisture made a mess of things , I think I should be able to have it running and shoot down in with my air nozzle to clear it out. Neat idea though...... To some , it would be to much gadgets and gizmos but to someone like you or me .... its a challenge and fun. The front has a temperature sensor bolted in place of one of the shroud bolts. Maybe you could find something similar and less expensive and get some reading from it.... Like a Thermistor and have a warning light that trips off once the thermistor reaches a certain temperature. So I guess a thermistor mounted on the cylinder, wired to a variable POT, to a tranistor to switch on an LED. Something like this.... Who knows .. Might just be how the factory one works. Never looked into it... So you adjust the variable resistor to set the temperatue that the light goes on . If you want to you could also add another transitor and LED set to go off at different temperatues. One for operating temperature and one for overheating. Its just a crude drawing but can easily be done.... Kyle Edited May 7, 2014 by Theroundhousernr Share this post Link to post Share on other sites
KATO 115 #3 Posted May 8, 2014 (edited) This is an older thread that covered this topic quite well ...give it a read Edited May 8, 2014 by KATO Share this post Link to post Share on other sites
Save Old Iron 1,563 #4 Posted May 8, 2014 Kyle, if you try the thermistor route, be aware of the significant lack of sensitivity (delta temp / delta ohms) at high cylinder head temperature ranges. Check out the thermistor response curve image below. Add this lack of sensitivity to a major beta change in the transistor due to seasonal ambient temperature variations. plus the challenge of a potentiometer life in a highly vibrational environment - not as easy as one might think. K thermocouples are the way to go. http://www.a-levelphysicstutor.com/images/thermal/thermist-graph.jpg Share this post Link to post Share on other sites
