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

[MuncyBob]

......and now this happens!

 

[J_J]

What kind of stress did you put on that motor shaft?

Your two options are .

Rebuild the motor with new shaft.

Replace with new motor.

 

[MuncyBob]

Nothing out of the usual. I do run it on a lot of sloped/hillside areas(it sits now precariously on a hillside) and make turns on that would stress the shaft, but I thought the PT should be able to handle that. I'll probably be calling Terry to order a new motor and when I have time look at rebuilding the old one. Any resources/step by step instructions to rebuild would be appreciated.

 

[MuncyBob]

Well, good news(sorta)....instead of buying a new pump Terry in Tazewell will put in a new shaft and rebuild for considerably less...just means more down time waiting for it to come back. He also suggest I get an impact wrench to get it back onto the shaft...said hand tightening the nut will not be good enough....I've been meaning to buy one anyhow.

 

[MossRoad]

Ouch! Sorry for your troubles. How many hours on the machine?

 

[MuncyBob]

Just over 800.

 

[MuncyBob]

Finally got the Robin exhaust installed. I have several feet left over of the Walker flex pipe..so if anybody needs any.

 

[MuncyBob]

I ran the 422 last night for 1.5 hours with the 48" grass cutter going at full throttle. I STRONGLY encourage anybody with the Robin engine and stock PT exhaust to consider replacing with the Robin exhaust. Sure it will cost ya a few bucks(mine was $190) and a bit of time fitting it to the PT but man, what a difference! As stated earlier in this thread, the tub temps are way down and I was pleasantly surprised that I also gained a few HP as was evident when mowing up some hills. Previously I would either have to back up some of my steeper hills or find another approach but now I can go right up the slopes except for my steepest one. I also am not getting the backfire at shut down either.
I really hope this has solved my hot temps issue, just wish I had done this many hours ago and may have saved me a rebuild last winter!

 

[ponytug]

Congratulations!!! That is a wonderful.

I'm always impressed at how finely balanced air cooled gasoline engines are.

Thanks for sharing this.

All the best,

Peter

 

[cqaigy2]

Thanks for the report! I may do that if or when my nephew's custom exhaust gets ripped off on something.