Thursday, October 30, 2014

Onan gets an IAT sensor

Installed an IAT sensor in the Onan's air inlet tube. Megasquirt needs this temperature to calculate air density. Junkyard GM sensor!

 Used a socket to make a hole in the tube
Installed. The crankcase vent tube didn't live thru this and split.

New governor for a TH 425

Got a new Allison AT540 governor to see if it would adapt to an TH425 transmission. It does! The Allison governor has no speedo gear but the gear from a TH425 fits on it. The Allison governor has no can as it fits inside the transmission in it's original configuration but it will fit inside a TH425 can. It does fit, shift and the speedo works. The Allison governors were available in several different rpm ranges to go with whatever engine was driving it. This particular governor is for 3000-3400 rpm and is a code 462. Sonnax makes them new.
Part number on the Allison governor
Speedo gear swapped from the broken TH425 governor on to the Allison.  I think the weights and springs could be swapped and then it would act like a TH425 governor.

Saturday, October 25, 2014

Onan gets an oxygen sensor

Got a 1 3/8" 16 gage J pipe to make an exhaust pipe with bung for an O2 sensor
Made a new 1/4" thick flange to fit on the exhaust manifold. Made a step bore to fit the larger 1 3/8" pipe.
O2 sensor bung
Ready to tack weld
Welded up.
Gasket made of Chesterton 199 inserted graphite, supposed to be good to 1650F and 2000 psi. This stuff is brittle and I made two gaskets to get a good one.
Dummy sensor to plug the hole. It is fairly well protected from road spray when the generator door is closed.

Sunday, October 19, 2014

Onan efi coolant temp sensor

Mounted megasquirt controller under the bed.
Bracket uses a tab and wingnut
Clear plastic shield so the leds can be seen
Wire harness from Diyautotune
Onan end harness
Aluminium adapter for coolant sensor will mount on a head bolt and have a 3/8 pipe thread for a GM coolant temp sensor. Megasquirt needs engine temperature for cold start enrichment. Some air cooled installations have used oil temp but it is slow to change. This should work as the squirt is very programmable for stuff like this.
Used thermal paste as there is no coolant. Adapter has a two step bore with the deep part just a little larger than the probe part of the sensor.
Thermal paste between the head and adapter
No mods to the cover.