Overheated Robin EH72-FI (28 hp) in PT-425 solved

[joshlee]

/Users/joshuaromig/Pictures/100_0164.JPG Would a bolt work better with a nylon lock nut work better here instead of the pivot pins? The pins are rolling and wearing the holes open.

The picture didn't go through.

 

[Gator6x4]

Very beautiful work. May I be so bold and suggest protection for the muffler. My luck about the second time I used it I would back up and hit something with the muffler.

 

[Marks481]

Kent, how are you liking your muffler arrangement after a few months with it?

Did you find somewhere that would sell you a short length of 1.25" flex tubing, or did you have to buy the 25' length (which is the only length I have seen sold)?

EDIT: I found a place that sells 1.25" stainless for $4.10 per foot:

.: TAC :. Transportation Accessories Company - Flex Tubing

I am interested because it is time for me to put a muffler back on. My neighbor came over while I was mowing and offered me a pair of noise canceling headphones (in addition to the foamees I was wearing). I think he was hinting that I was a bit too noisy.

 

[Kent]

I have 23+ feet of flex pipe left over from the 25' roll I had to buy, so would be happy to cut off any length you need. The roll was about $50 with shipping, so I figure $2/foot for you, plus my shipping to you. May not be a bad idea to get double the length in case you bend it backing into a tree.

It is Walker 40001 flex pipe, 1-1/4" ID, 1-3/8" OD.

One thing to keep in mind is the minimum bend radius of the flex pipe. The pipe bend shown in my pictures is pretty much the minimum radius. Not all that flexible. But it is sturdy stuff. Though not stainless the flex pipe is galvanized, and is not rusting, just blackish.

Note that I have since directed the exhaust tip to point backwards, not sideways as shown.

I have about 40 hours on the new engine/muffler/fan set up. So far working perfectly! I have not yet backed into anything, so no dents or dings on the muffler or flex pipe. It has been a cold Winter in VT, and as predicted (hoped) the side fan only came on only once, when I used the snowblower (requires full throttle). Otherwise when just plowing (usually at about 3/4 throttle), the fan stayed off, allowing the engine to build up a nice working temperature.

By the way, the garage where I keep the tractor never dipped much below 30 degrees (it is under the house). The fuel injected Robin started up very quickly every time (unlike the original 25 hp which would crank for a while before firing up, occasionally flooding when I mishandled the choke).

 

[SpringHollow]

We have yet to see the ground since December and you are mowing! Snowed again last night.

Ken

 

[Marks481]

I have 23+ feet of flex pipe left over from the 25' roll I had to buy, so would be happy to cut off any length you need. The roll was about $50 with shipping, so I figure $2/foot for you, plus my shipping to you. May not be a bad idea to get double the length in case you bend it backing into a tree.

Thanks for the offer, unfortunately I already ordered from the link I posted. Time to dust off my welder and starting modifying the canopy!

By the way, the garage where I keep the tractor never dipped much below 30 degrees (it is under the house). The fuel injected Robin started up very quickly every time (unlike the original 25 hp which would crank for a while before firing up, occasionally flooding when I mishandled the choke).

Now you are just showing off....

We have yet to see the ground since December and you are mowing! Snowed again last night

I don't think it got below 30F at my house this winter... and not a wisp of snow in sight. My plow blade has sat all lonely in the storage shed for the two years I have lived here...

 

[Raw Dodge]

I guess this explains the engine life problems a few have had...i hope the people at power trac are watching this thread..and make the necessary corrective action on new machines. .

 

[Marks481]

...i hope the people at power trac are watching this thread..and make the necessary corrective action on new machines. .

I can guarantee they are not. The internet only recently arrived at Tazewell... And we are only a small percentage of their business compared to their mining machinery.

The existing evil welded square steel exhaust manifold and muffler have been part of their design for the past 11 years. The exhaust manifold on mine had a steel lip across of about 1/3 of the inlet from one of the cylinders, which couldn't have helped the heat issue. Get rid of the manifold and muffler and your engine will be a lot happier.

Unfortunately adapting the stock Robin exhaust manifold and muffler requires surgery on the canopy (as you can see in Kent's pictures above). But after having monkeyed with my own manifold design, I have decided his route is simpler.

 

[PTWannaHave]

Awesome post, Kent !!

 

[Kent]

Hi - I was asked to post more pictures of the modifications, including the placement of the temp sensor and the wire harness schematic:

https://drive.google.com/folderview?id=0B34rGjNSGixVQmg3Wlc4WmhIVTg&usp=sharing

As an aside, picture 751.jpg shows the connection to the always-hot terminal on the starter solenoid as well as the stock temperature sensor wire screwed into the crankcase (upper right). I forgot to mention earlier that I put a woven fire proof shield around this wire all the way up to the FI module. This was an early attempt to solve the shutdown problem prior to going all the way by installing the stock exhaust header and side fan. I thought maybe the wire was picking up ambient heat in the tub. I just left it in place, figuring it wouldn't hurt even if it didn't help.

 

[marrt]

Thanks Kent for posting those pictures. I'm getting ready to make some modifications and, if you don't mind, will steal some of your ideas.

 

[MossRoad]

Gotta send him a dollar for each one! :laughing:

 

[Marks481]

Well I just got the Robin muffler/exhaust and I gotta say that it is a very sturdy build. Not flimsy sheet metal like I expected. I guess I will have to do some surgery this weekend.

 

[MuncyBob]

Well I just got the Robin muffler/exhaust and I gotta say that it is a very sturdy build. Not flimsy sheet metal like I expected. I guess I will have to do some surgery this weekend.

Looking forward to your hearing about your adventures! It will be at least until next weekend that I install the 2nd fan and probably another month or so before I get the Robin muffler.

 

[KMA]

I did the Robin muffler on my PT422 w/ EH72FI a few years back. I believe it helped with the heat issues, along with my other mods (re-routing fuel line, additional fan) but it's still something to worry about. The PT tub design isn't made to deal with the heat generated. I had a Subaru engine tech tell me their engines were not meant to work in the conditions seen in the PT. Here's my muffler mod:

http://www.tractorbynet.com/forums/...engine-swap-completed-pics-3.html#post3256257

Instead of hard mounting it and using flex pipe, I made a new manifold from 1" pipe and mounted it similar to the OE muffler. My engine moves quite a bit and I wasn't sure if a flex pipe would hold up over time. Let us know how it goes for you. :thumbsup:

 

[Marks481]

I have 23+ feet of flex pipe left over from the 25' roll I had to buy, so would be happy to cut off any length you need. The roll was about $50 with shipping, so I figure $2/foot for you, plus my shipping to you.

OK, I might be interested after all. The stuff I got (advertised as SS exhaust flex tubing) is not pressure tight. It is just flexible electrical metal conduit. And they sent me the wrong size (1" vs. 1.25").

Is the stuff you have pressure tight?

 

[Kent]

The Fan Control Switch (thermostat) I used was WHITE-RODGERS, Mfr. Model # 3F01-121.

Fan On Temp. (F)120
Fan Off Temp. (F)110

I bought it from Grainger Industrial Supply - MRO Products, Equipment & Tools, Item # 2E246.

 

[jfischer]

Kent, I know this might have been asked to you before, but what were the temps on just the exhaust mod, without the fan running on the side. How much cooler running was it over the stock PT exhaust.

I wrapped my stock exhaust this last weekend, and know that the temps on the muffler itself went up from last time I measured it, so it is getting more heat out to there, but still bothers me with all the heat I can feel under there.

I guess I am just wondering if the muffler and the header is worth getting, or if just adding the fan to blow across the engine and out the exhaust side would be enough.

Did you put the stock heat shield back in behind the battery also?

 

[Kent]

Kent, I know this might have been asked to you before, but what were the temps on just the exhaust mod, without the fan running on the side. How much cooler running was it over the stock PT exhaust.

I wrapped my stock exhaust this last weekend, and know that the temps on the muffler itself went up from last time I measured it, so it is getting more heat out to there, but still bothers me with all the heat I can feel under there.

I guess I am just wondering if the muffler and the header is worth getting, or if just adding the fan to blow across the engine and out the exhaust side would be enough.

Did you put the stock heat shield back in behind the battery also?

I had some temps in my original post, but didn't intend to perform a scientific study of all the possible permutations. My first attempts were to solve an alleged vapor lock problem (move the fuel pump, beef up fuel lines, use an ethanol-fixing gas additive). When those didn't help I then went for the muffler and fan fixes. Yes, the stock heat shield remains in its stock location, only now with the temp sensor disk attached to trigger the than on and off. Depending on what model year you have I think the arrangement of the major components under the hood differ. In mine in the front is the fuel tank, battery, heat shield, and then at the back, the engine.

If I were you I would just go one step at a time. Try it with just the fan + stock exhaust and see if that solves your problem. The fan is easy to add, just zip tie it to the screening. The muffler requires a bit more work for sure.

I do not have any idea about what is the "ideal" temp to run at. All I know is that with the FI engine Subaru put in a temp sensor wire that isn't on the carb engine. I had no idea I had a problem with overheating when I had the carb engine (very hot, but still running)...only when I swapped engines did the problem pop up and I had to redo the manifold/muffler and add a fan.

 

[jfischer]

Kent, I have a 2015 of which I have put about 13 hours on it now. I am always one to try to prevent problems, and know that heat is a BIG issue. I couldn't believe on my JD how much the insulation on the firewall that seals the hood and all up makes a difference, as it pulls from the belly pan, and pushes it out the front of the tractor.

So, I wish I could put a fan on the exhaust side to pull it out, but think that will be too hot, as I have read others seemed to have tried that before. The fan seems to be the next step I should try, and is pretty cheap and easy to try. I just wish they had a bigger charging system on the machine.

I don't have any PTO attachments, and the hardest I have been working it now is digging a lot with the hoe, but can't tell a lot of difference in the heat change, other then the wrap made it keep the heat more on the exhaust header, and seemed to have brought the muffler temp up about 50 degrees. I did clean the inside of the exhaust ports on the header pipes where they welded them a bit off center before welding them, but can't tell much with that. It will soon be coming up to the first oil change, and will change over to synthetic and hope that will save the engine some.

I will test to see what the temps are on my 27hp Kawasaki in my Hustler zero turn somtime, as I know the old Onan in my JD runs pretty cool now with the way it can suck the heat out.