8 HP Model U Thermoil engine

Bud Berry

Content Tools

R.D. #1, Box 224, Drums, Pennsylvania, 18222

I purchased this 8 HP Model U Thermoil engine in 1979 from the son of the man that purchased it new from Sears, Roebuck in 1918? They used it to run a small thresher and feed grinder till the 40's.Then it sat for ten or more years and the son acquired it and ran a coal cracker for about seven or eight years.

Everyone who used this engine tells about starting problems. The instructions say: prime first, then set compression relief lever, turn flywheels with crank nine or ten times, remove crank, close compression relief valve and if the Lord is willing the engine will start.

But not every time! I am a light weight person and not too much on muscle and this method won't work for me. The person I purchased from said they put gas in it (one day when their Dad wasn't home). Well, the engine started and ran away from the governor and being young boys they were afraid of it and they ran away! After getting their heads together, they used a clothes prop and opened the compressor relief to stop!

After having this engine for one year I figured the best way was to use a Pony motor. I used a 2 HP Briggs only to find out I would need at least 4 HP to turn the Thermoil through compression.

I finally got a 4 HP header (hit and miss). This would surely have enough power to complete 4 cycles of compression and start the Thermoil.

I made a slide table to tighten the belt so I could control the Pony motor when the Thermoil started (see picture #2). I have my hand on crank of slide table and the Thermoil just fired for the first time (cloud of smoke). Now I will slack off header and the Thermoil will run on it's own power.

This works very well for me! The Thermoil runs very well but can give problems starting. The header will crank the Thermoil for as long as it takes and never complains as I would tire of cranking in two or three times. The first time I started the Thermoil

I had it in my garage with doors open and it started! I had the governor wide open and till I locked the header up and got the belt off, the Thermoil was bouncing the back wheels of the cart 4 inches off the garage floor! This, plus filling the garage with smoke so quickly, I had a few exciting minutes until I got everything under control.

I like the Thermoil very much. After starting it will run at 300 RPM all day with no problems. It knocks and bangs and smells just like a diesel. I have enclosed two pictures. Picture #1, I have my hand on the compression lever and have just closed compression. Picture #2, The Thermoil fired first and second time. I am locking off the header so the Thermoil can take over.

I usually start the engine with no water in the hopper and after it starts I add water intermittently. Once I filled the hopper with cold water and tried to start it but it just wouldn't start. My friend said the header was turning it over too slow so he held up governor of header and adjusted fuel. The Thermoil was now turning over much faster but it still wouldn't start. After a few turns it blew out the head gasket!