To get maximum airflow--and the only reason I know this is because it took me a few tries to get right--is both air direction (switch hot lead) and fin direction (flip fan blade over). At first I had the leads right such that the fan was blowing inward, but I had the fins backwards, so not much air was actually moving. Flipped the blade over and wow, that was more like it.
Overheated Robin EH72-FI (28 hp) in PT-425 solved
- Thread starter Kent
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jfischer
Silver Member
- Joined
- Feb 11, 2015
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- 174
- Location
- Manassas, Virginia
- Tractor
- Hustler X-One, Power Trac 425, Sold and Retired my JD318
Hey Kent, I have not been doing a lot of playing since I did put the fan on, but I tried the fan before I did, and found out you had to change both polarity and the direction of the blades. It sounds like as small jet when you turn it on.
Also have been doing a lot of reading on air cooled head temps and to really take it right you need to put a temp sensor somewhere around the spark plug, but I have been taking it in that area, and think what I am getting now is acceptable for temps. The muffler is still hot as heck on the outside, but do think it is moving the heat out of the engine compartment, and I have never had any vapor lock problems or such, and starts up fine after it has been cut off hot.
Instead of a heat sensor, I put mine on a manual lighted switch, so it could give it a second to warm up, and then in the Winter I don't think I will be needing it as much, so might not use it as much then, just kind of play that one by ear.
I will keep an eye on it, and tell you of my results.
Also have been doing a lot of reading on air cooled head temps and to really take it right you need to put a temp sensor somewhere around the spark plug, but I have been taking it in that area, and think what I am getting now is acceptable for temps. The muffler is still hot as heck on the outside, but do think it is moving the heat out of the engine compartment, and I have never had any vapor lock problems or such, and starts up fine after it has been cut off hot.
Instead of a heat sensor, I put mine on a manual lighted switch, so it could give it a second to warm up, and then in the Winter I don't think I will be needing it as much, so might not use it as much then, just kind of play that one by ear.
I will keep an eye on it, and tell you of my results.
Sad to say I have an update on overheating "solution". Two days ago it was 88 degrees (hot for VT) and I decided to try pushing the Robin by finish mowing a half acre field that had grown up to about a foot deep of thick hay grass. I went slow to not bog the engine and get a good cut, but about an hour into the job the engine shut down, overheated, and wouldn't restart until after an hour+ cool down. Interesting that the overheating was NOT due to the temperature wire/FI computer shutting down the fuel pump as before (still power to the pump and it was running), but something else, I suspect maybe vapor lock?? Lots of bubbling in the fuel filter and before shutting down the engine cuts out then surges a few times before shutting down completely.
Last Fall I cut the same field and also another half-acre field with the brush mower in one swoop also in 80 degree weather, with even taller grass, but could not push the engine to overheat. So I assumed my fix was invincible.
Oh good, another problem to solve! Or at least I can promise to be smarter by choosing the right implement for the job at hand (never finish mow tall grass) and taking a break every now and then.
The exhaust manifold bolts are tight. What else could have changed?
I am realizing that the CFMs of the fan seem about half what they were last Fall when the fan was like a tornado and kept the engine cool. I am going to take it apart today to clean/lube if possible, but if that doesn't help I will explore another fan manufacturer with a stellar reputation for long life and more waterproof (perhaps SPAL, which means I would have to change to a larger fan).
Last Fall I cut the same field and also another half-acre field with the brush mower in one swoop also in 80 degree weather, with even taller grass, but could not push the engine to overheat. So I assumed my fix was invincible.
Oh good, another problem to solve! Or at least I can promise to be smarter by choosing the right implement for the job at hand (never finish mow tall grass) and taking a break every now and then.
The exhaust manifold bolts are tight. What else could have changed?
I am realizing that the CFMs of the fan seem about half what they were last Fall when the fan was like a tornado and kept the engine cool. I am going to take it apart today to clean/lube if possible, but if that doesn't help I will explore another fan manufacturer with a stellar reputation for long life and more waterproof (perhaps SPAL, which means I would have to change to a larger fan).
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MuncyBob
Platinum Member
Sorry to hear about this. I am very careful not to overheat with the mower these days. I will only cut for about an hour and then shut down for at least an hour before resuming. I must say that the CFR fan I have side mounted is not pushing as much air as I had hoped. I have tried all configurations(reverse blades & polarity). From the sound of the fan, I really had hoped for more air movement. If anybody finds a fan that is more like the tornado I was hoping for...I'm all ears.
marrt
Platinum Member
Has anyone tried reversing the direction of the hydraulic fan too? In theory, this may sound like a dumb idea since it would push heat from the hydraulic radiator back into the engine compartment. However, I'm wondering if the high heat of the hydraulic system may be part of the problem I noticed my fuel lines and filter rest on top of a lot of hydraulic hoses. Over time, this heats up the fuel lines since these hoses are 180 degrees or hotter.
I never really liked the hydraulic fan in suck mode anyway because of the reduction in efficiency (fans blow better than suck) and because it draws so much dust into the engine compartment.
I never really liked the hydraulic fan in suck mode anyway because of the reduction in efficiency (fans blow better than suck) and because it draws so much dust into the engine compartment.
jfischer
Silver Member
- Joined
- Feb 11, 2015
- Messages
- 174
- Location
- Manassas, Virginia
- Tractor
- Hustler X-One, Power Trac 425, Sold and Retired my JD318
I put a 10" one on the opposite side of the exhaust, and reversed the blades, and polarity, and it sounds like a jet, but blows a ton of air across the engine. Feels like a furnace on the exhaust side. Did you reverse both blades, and the polarity, and how big of a fan did you put on it? I think mine is the same company that made the one on the hydraulic fan, but is a 10" rather then a 12"
joshlee
Platinum Member
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- Jul 31, 2014
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- 623
- Location
- Beaver Springs, PA
- Tractor
- Power Trac PT1430 Year made 2016
Hi Farmall 140, you may be the nearest person to me that has a Power Trac? I live near Lewistown and just bought a PT-425 back in Feb. Does everyone have overheating problems with PT's? Except people that have the Kohler engines.
Marks481
Platinum Member
- Joined
- May 29, 2005
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- 978
- Tractor
- Power Trac 422 (2005)
I wouldn't say that. The PT422/425 runs hot, but doesn't normally shut down because of temperature. I have spent a couple hours bush hogging 12-18" grass in a pasture with no ill effects.
But that isn't stopping me from trying to make the machine run cooler. So I too have insulated the exhaust manifold, added an auxiliary fan to the side, relocated the fuel pump (stock fuel mechanical fuel pump in my model was mounted on the left side of the engine, at the height of the muffler which was about 4" away from it.... just asking for vapor lock, although I can't remember ever having a problem with that). Latest action was swapping out to a new exhaust manifold and muffler (following KMAs and Kent's lead). Less backfiring on shutdown, but my uncalibrated eye says it really isn't running any cooler.
I think you are right. I have rerouted my fuel hoses to run them far way from the exhaust manifold, but I still get bubbling in the fuel tank from vapor in the gas lines after I shut down from a long session of mowing. My fuel filter and fuel line is resting on top of one of the hydraulic pumps. Looks like time for a little more re-arranging.
MuncyBob
Platinum Member
Hey Josh, been to your neck of the woods several times. I had vapor lock/shut down a few years ago and a new fuel pump was needed and corrected the problem so far. My concern about overheating is due to the $1200 or so I just spent having my heads reworked and a valve job done. Mechanic told me it was most likely a heat related issue that caused my problem.
Jeff, the fan I have is the 8" CFR, I guess I should have gone larger. My next step is to cut out the mesh area at the fan hoping for an increase in air flow. I have tried all possible configurations of blade/polarity, I just expected more air flow...it sounds like it should be pushing more than it does. I have not yet purchased the Robin muffler kit but expect to soon.
Jeff, the fan I have is the 8" CFR, I guess I should have gone larger. My next step is to cut out the mesh area at the fan hoping for an increase in air flow. I have tried all possible configurations of blade/polarity, I just expected more air flow...it sounds like it should be pushing more than it does. I have not yet purchased the Robin muffler kit but expect to soon.
BobRip
Elite Member
As I understand it you have the new fan blowing inward and the old hydraulic fan blowing outward. This sound like most of your air flow would go from one fan to the next. Other areas in the compartment would not get much air flow. If what I am saying is correct, then I would try blowing air outward with both fans. Air will then come into the engine compartment from many areas.
