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KenK

Under hood temps running hot

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KenK
I have replaced the engines in two 919 a/c tractors with 16hp briggs.I have found that there is a lot of heat blowing on my left leg.On the original 19hp motors there was a heat shield on the top front of the engine which I don't have now.It looks like most of the hot air exits the top front of the engine through the head and blows at the headlamp panel.I think I'll have to make some heat shields to force the hot air down through the grille.Has anyone else run into this problem?

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olcowhand
Heard of that a lot. You'll need to find a way to vent that heat as the engine is just recirculating it & cooling is minimal. Many newer lawn tractors with vertical engines have louvered hoods & a foam seal on engine around the flywheel screen so when the hood is closed it gets all it cooling air from outside the engine compartment. In the summer heat many of us are suffering now, you could toast an engine without good cooling with fresh air. If you have to use in hot weather before you find a way to vent, you could simply remove the hood for the time being. May look redneck to some, but your engine will love you for it! sm01

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PhanDad
I also installed a Briggs 16HP engine in a 7100 series tractor. I don't especially feel any hot air blowing on my legs and I wear shorts when mowing. I didn't install the top heat shield you mention, but did install the "inlet" shield. It can be seen behind the fuel filter in this pic:


This shield makes most of the incoming cooling air come from beneath the tractor (and acts as a guard for the driveshaft). Only issue with the "inlet" shield is sucking up grass clippings and blinding the engine inlet screen. I haven't experienced this problem, but do check the screen often. Maybe without the "inlet" shield you are recirculating some of the cooling air as suggested above. In my setup, the hot air exits from both the louvers on top of the hood and out the front grill.

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BrianP
Glad I found this topic. The last few times I've used my 7016 to mow my yard I have also felt hot air coming out from beneath the hood on my leg. Not only that, but I can watch the lense of my ammeter gauge progresively fog up with condensation. I too have wondered if I'm missing a shield to direct the air down through the grille of my machine instead of it blowing on the back of the headlights. I don't want to take the whole hood off, but I am seriously considering removing the headlights, (the sockets are too coroded to use but I have replacements), since I for one don't mow at night. Actually, here in the Carolina summers if you wait until afternoon to mow, you're certain to get chased off your machine by the afternoon thunderstorms we have almost daily. Has anyone here fabricated or retrofitted such an air shield? I sure don't want the underhood area any hotter than necessary.

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olcowhand
A shield to redirect the air might be better, but a thought just came to me.....if you could get a small radiator fan for a car radiator & mount in just inside the grille. They are insulated by their plastic mounts, so reversing the polarity would reverse air to blow out forward..out of the grille. If the tractors had 10 to 15 amp alternators they would handle it easily. Or go with a smaller fan, say like off a 4-wheeler or water cooled street bike. Might be easier than fabbing a shield.

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PhanDad
Another thought about my setup - I'm using a Nelson muffler so there isn't a muffler mounted high in front of the engine as stock. I'm sure the presence of the muffler would add to the heat issue. However my A/C Homelite T-12 has the muffler out front and there is no top shield and I haven't noticed any hot air blowing on my legs. There are no louvers on the hood but the hood does have an extra layer of sheet metal directly above the engine to minimize hood temperature. The inlet air for the engine comes from above the frame and I don't notice any recirculation of cooling air. (The frame has a solid bottom like the FDTs and hence no engine air inlet screen blinding issue.) I do have the top shield which I may install someday. If there's any interest, I can post a pic and some dimensions next week.

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KraigRG
I've been toying with the idea of putting a fan on my Landlord's engine. I was planning on using one or more computer fans. You can get them in various sizes and they run on 12 volts. My idea, although I haven't got it all worked out yet, would be for the fan to cool in summer8D and provide heat in the winter for when I'm out playing in the snow. Again I haven't got all of the ducting, etc. figured out yet. Maybe one day I'll have some extra time to play with it.:D:)

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BLT
The way the engine block shield around the fins is fashioned on the upright cylinder, the left leg or foot is likely to get warm. It is not unusual to see temps above 200 def come pouring out. An additional fan might not help. Also note that if the fins are blocked partially due to debris, the temperatures will increase quite a bit.

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DMedal
regarding the computer fan, or anything short of an real automotive radiator fan: the engine fan makes a real blast of air. I had occasion to notice mine running at about 1/2 throttle when some dirt of something went through the fan. You aren't going to get flow anything like that out of a small fan, I am thinking. So ducting and baffles is much more likely to yield success. To put it another way, a computer fan has to exhaust maybe a hundred watts of heat at maybe 200F. An IC engine produces thousands of watts waste heat at a much higher temperature. It's going to need a major blast of air. -Don

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RayS


Here is the dimensions of the heat shield on the top of the engine. You could also use a B series nelson muffler like Bill has and I would think that would lower the under hood temp. considerably since the muffler would be outside the hood.

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PatRarick
Had the same problem with the V-twin Vanguard conversions I did on my 900 series tractors. I fabricated underhood exhaust systems similar to the original along with heat shields. On hot days, it got so hot that I had occasional vapor lock problems. Came to the conclusion that my heat shields were directing the heat backwards, so I removed them. There was no change. Installed the inlet shield, and the problem surprisingly disappeared. I've since come to the conclusion that the engine heat under the hood was being recirculated and the inlet shield eliminated that problem.

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DMedal
Pat- Is your input shield similar to Bill's in the picture above? Have you had issues with getting grass on the screen? And how does one check the screen with that shield in place anyway? -Don

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PatRarick
quote:
Originally posted by duckman
Pat- Is your input shield similar to Bill's in the picture above? Have you had issues with getting grass on the screen? And how does one check the screen with that shield in place anyway? -Don
Yes it is. Never had any problems with grass plugging the screen or cooling fins in the four years I've used the shield. The shield is open enough to see the screen pretty clearly.

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skunkhome
quote:
Originally posted by olcowhand
A shield to redirect the air might be better, but a thought just came to me.....if you could get a small radiator fan for a car radiator & mount in just inside the grille. They are insulated by their plastic mounts, so reversing the polarity would reverse air to blow out forward..out of the grille. If the tractors had 10 to 15 amp alternators they would handle it easily. Or go with a smaller fan, say like off a 4-wheeler or water cooled street bike. Might be easier than fabbing a shield.
I can't imagine any fan going in the grill in front of the motor unless you have a can muffler out to the side. The muffler on my 3414 is touching the grill. I would think just getting the muffler and exhaust out from under the hood would greatly improve cooling. I may go that route when my muffler finally gives up the ghost.

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Roy
Rod, Don't need the drawing. Was only curious as to where it came from. Post it in the DIY or Technical Tips Forum as I think others may find it useful. A drawing of the flywheel inlet shield would also be useful if one were available. Re: PhanDad's picture above. Thanks,

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HubbardRA
The flywheel shield is only a strip of metal that attatches to the frame on each end and is bent to go around the inlet to the engine. I had to build one for the 61 Wards when pulling. It was called a driveshaft joint shield.

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BrianP
Glad to see someone posted the dimensional drawing for how to fabricate the front heat shield. I may also fabricate the inlet shield that also seems to improve cooling as opposed to just recirculating the under-hood air. Of course, I could always install an "early" 7016 hood, (the one with the outboard headlight pods)which would probably solve the problem. My particular 7016 has a chrome extension for the exhaust hole in the hood. If I put on a Nelson can muffler it would look kind of goofy, besides my stock muffler is still in good shape. By the way, what gauge metal are you folks who're into fabrication using? Are you using steel or aluminum? Just curious.

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quantico
I know how easy it is to have clogged fan intake with the fan out of sight... This was the case on a tractor that I purchased recently... anything to lower temps is a good thing... I would think you would need a fairly powerful fan to move any heat away from the engine..


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RayS
quote:
By the way, what gauge metal are you folks who're into fabrication using? Are you using steel or aluminum? Just curious.
I made one from galvanized HVAC ducting that is in your house. Not sure of the thickness 22 gauge or something like that. Very thin.

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