H Boomer 8n RPM Automatically REV's to full on cold start.

[Kbauer]

Hello, this is my first winter with a tractor and this issue has just started happening now that I've been starting up the tractor in the cold and and was wondering if it is supposed to be doing this as it warms up or if it's an issue.

when i first start the tractor it starts up fine then the rpms slowly starting going up and up until I start to get worried because they are pinned at the top so i shut it off. but once i put it in gear and use it and the temp gauge is up to normal temperatures it idles fine and will work normally.

any ideas if this is the computer warming itself up or something else.

Thanks,
Ken

 

[xtn]

My Boomer 50 (same tractor but HST and cosmetics) does not do that. ?????

 

[Kbauer]

I'm thinking its moisture somewhere that is freezing. because once it's warmed up it's fine.

also i sometimes forget my definition of cold is sometimes different than others. it was about -18C or 0F so it was pretty cold out.

 

[AndyG]

It should not do that. The RPMs should stay where you put the throttle lever. I'm not familiar with the 8N but I'm sure that it is a mechanical engine with a cable throttle. I can't think of a reason that this engine should race when its cold. Something is amiss in the governor or fuel pump. Is there water in the oil? Water is usually seen a milky engine oil on the dip stick.

 

[Kbauer]

just for some more info on this;

Last night i just let it do it's thing when it started. it was -25C -13F and it started ok. then sat at 800-1000 rpm for a couple minutes, then it rev'd itself up to 3000 and sat there for 10 seconds, then went back down to 1000 again, then back up to around 2500, then back down to 1000 again, then up to 2000, then back down to 1000 where it stayed idling. during this time the temp gauge went from coldest to ended up at the midpoint.

I will check the oil this weekend.

Thanks for the help

 

[WM75Guy]

It's not quite that cold here and mine does not do that.

 

[AndyG]

My TC40 surges RPM on cold start up but the high/low cycles seem to be much faster than yours and not quite as drastic. Raising the throttle slightly above idle causes things to smooth out quickly. I have a 350 Cummins in a truck that also surges upon cold start. Usually the engines surge immediately and get smoother with time. The fact that the 8N starts out smooth then starts surging is perplexing. Hopefully someone with more diesel knowledge will chime in on this one.

 

[Kbauer]

another FYI. i've ordered both heater kits for the tractor since it should be plugged in anyways in this cold. i'll update this again after I've installed them and see if the surging stops.

these are the kit #'s incase anyone else is interested.

• Transmission Oil Heat Maintainer Kit #. 87537603
• Engine Coolant Heater Kit # 86590117

 

[jinman]

I think the throttle linkage is similar on most of the mid-sized Shibaura powered Boomers. My TC45D once revved very high on starting in cold weather after a large snowfall. The throttle had stuck partially open and the governor was frozen so that it could not drop the engine rpm or move the throttle-rack back to normal. I manually pulled on the throttle while moving the throttle lever towards idle and got the rpm down to normal so that the engine could warm up without revving. Once thawed, it never was a problem. I'd bet your problem was something similar.

If you can get an extension cord and hair dryer to the tractor, I'd bet 10 minutes of thawing or less around the throttle and throttle cable will give you good results.

 

[AndyG]

What do you think caused the governor to stick Jim? There should no not water in the gov. Ken do you park your tractor outside?