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That there's worth fixin'
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Discussion Starter #1
It's a mtd 990. Is it bad to run the motor at lower rpms. Not talkng about mowing but other uses, bottom plowing, cart pulling, etc. It seems like 3600 is awfully high. I was plowing (ripping really) in very rough ground the other day, temps in the 90's, lots of roots and rocks (1/3 throttle) and the trans got hot. Would it have stayed cooler if the engine rpms were higher? Thanks, Rick
 

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Premium Member
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Yes, it would have stayed cooler. It sounds a little counterintuitive but the hydro really depends on high rpm to turn the cooling fan. Running at low rpm while plowing with temps in the 90s is probably one of the worst things you could do.
 

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USMC
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Overheating is bad. Regular oil changes is a good thing. slkpk
 

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you had temps in teh 90's in MAINE? heck we have flirted with 90 but not made it yet.

higher RPMs turn the fan faster and keep teh hydro cooler. if you just must run low RPMs, at least get a decent high CFM electric fan mounted under there. but expect to replace it often as they are not made to be exposed to teh elements.
 

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Discussion Starter #5
Thanks for the info everybody. I'll keep the rpms up when working the tranny. Needs a good cleaning under there too. Fortunately, I wasnt on it all that long but trans did get hot. developed pressure in the case too. Must need a vent cleaned or something.

I have a Sears ss15 it's the same motor as the 990 and I'm used to running the sears low/med. rpms. Those old Brigg motors seem to do fine running slow. The motors dont seem to overheat like some have warned of when running low/med rpms. That hydro tranny sure does though. I confess I was pounding it pretty hard. Root ripping is what it amounted to. First hard test I tried with it. It definately passed!

Yes we had 90's here last week of April. weird cuz there was still snow here where it was piled up.
 

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That there's worth fixin'
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Discussion Starter #6
The electric fan idea sounds like a winner. Thanks, Rick

higher RPMs turn the fan faster and keep teh hydro cooler. if you just must run low RPMs, at least get a decent high CFM electric fan mounted under there. but expect to replace it often as they are not made to be exposed to teh elements.
 
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