Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

hot 720


rocks70

Recommended Posts

my ac720 mowing tractor is 550 degrees at the cyl head and 260 at the oil filter.is this a normal temp? i think its way to hot mabe i should pull the engine and chech the fan.also it loses power when its that hot. any ideas guys?

Link to comment
Share on other sites

Depending on the part of the head measured, certain places can reach that much on an air cooled engine. I would however do a flow inspection of the cooling fins. A backshot of a compressed air gun to the outlet fins can sometimes pooof back a buildup enough to see or dislodge it. What throttle setting were you using at the time vs workload?

Link to comment
Share on other sites

quote:Originally posted by rocks70

was at full throttle in high grass


id="quote">
id="quote"> temp taken close to the spark plug
Link to comment
Share on other sites

Hmm, a month back,discovered the 16hp Briggs in my old Sovereign wanted a new head gasket. It was losing power as it got hotter too.

Don't know why - while head was off, decided to reach inside the shroud, and pulled out 2-3 handfuls of mouse nesting!

Runs much gooder now.

Link to comment
Share on other sites

quote:Originally posted by rocks70

oil temp has me worried 260 seams way to hot


id="quote">
id="quote">If you get a handle on the high air flow temp, your oil temp might drop down to 200-210 deg F which isn't too bad on hot days. There is no way to check as that is something held close to the chest of air cooled engine people for good reason.
Link to comment
Share on other sites

I know it sounds like a lot of work but if you haven't had the engine out for awhile, I would pull it. You can only get so much debris out with the engine in the tractor. It might take an hour or two but would be well worth it. Once you pull it out you can give everything else the once over, and at the very least have a clean engine and a piece of mind.

Link to comment
Share on other sites

quote:Originally posted by dentwizz

High air cooled engine temps is one of the big reasons that you don't want to put junk oils in the engines.


id="quote">
id="quote">Amsoil, Amsoil, Amsoil!!!!
Link to comment
Share on other sites

well this am went to start it and found a blown head gasket i think the over heating did it? any thoughts guys?

Link to comment
Share on other sites

I would agree with pulling the motor and clean all the cooling fins good, are all the covers on the engine and the belly cover in place, those covers are very important to keep things from over heating

Link to comment
Share on other sites

You mentioned that you use this tractor as a mower, if the belly pan is missing that will clog up everything under the hood. When I cut my grass with the 9020, 9 times out of ten there is debris over the oil cooler fins. when I finish cutting I always take compressed air and try to get all the debris out of fins and anywhere else I see it. That way the debris has less of a chance to collect and clog fins. On these engines the tins "heat shield" are very important for proper air flow/cooling. You may also want to check your head and see if it is warped. Are you using the correct spark plugs? I have heard these Onans are finicky is you don't use the correct plugs.

Link to comment
Share on other sites

I run H10's my concern with my 720 is the amount of air that's pushed out around the oil filter supposed to have a ring around it and been unable to locate one.

mine ran hot too but heads were leaking ,have since resurfaced heads and new gaskets. I ran for a while without cover on bottom made big difference when I put it back on.

like what was said about debris, I had a lot of old oil and dirt built up so a good cleaning would be inorder

Link to comment
Share on other sites

well took head off this am and its junk found 2 used heads on ebay for $40.00 got them coming.all the heas bolts were loose.

004 new.jpg

005 new.jpg

57e06185cf7e9_004new.jpg.6ab6ec21af6043f27e3e152739c046bd.jpg

57e06185dda6b_005new.jpg.5a6025af3ef1124d35dd9c3cbc0f5a92.jpg

Link to comment
Share on other sites

quote:Originally posted by 720nut

make sure you have them surfaced. Is it cracked or burnt through ? Good welder could repair.


id="quote">
id="quote"> brunt right thru
Link to comment
Share on other sites

when i get a few dollars ahead im going to order a new vanguard engine for it like i did for the other 720 that we also use for mowing

Link to comment
Share on other sites

H10 is what I run as well, but I believe the proper plug is H8 but I have not located any around here probably have to order them.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Who's Online (See full list)

    • ShaunE
    • SmilinSam
    • a_sannine
  • Recent Status Updates

    • gwiseman

      gwiseman

      As you know SimpletrACtors.com has changed some recently. Working through this so PM me with questions, suggestions, and/or challenges you have. Appreciate your patience and feedback.
      · 0 replies
    • gwiseman

      gwiseman

      Site programming updates were made 3/23/2024. As a result some things have changed including dues payment options. We will continue maintenance and work with technicians to regain credit card payment option and clear up minor challenges. On positive it appears attaching pictures is now easier. Good day. Gene 
      · 1 reply
  • Adverts

×
×
  • Create New...