P220 Engine Swap/Observations/Rants

[boovuc 1,090]

Well the 1991 loader 520H finally gave it up over the past month. I noticed before Christmas that it was a little harder to start and it had a miss until it warmed up. Once warmed up, it was great. Plenty of power, never smoked, no unusual knocks/noises.

I decided to do a compression check on that rear cylinder so I warmed it up just a little and gave it some cranks. (30 PSI). 

Can't be. Must not be sealed properly! 2nd & 3rd attempts. (30 PSI). 

The plug was a little dark but the cylinder when running is hot so I know it's firing! I couldn't believe it would even run that low although I'm sure it has better compression once it is near running temps.

I would have never run this thing knowing it was going that bad that quick! I believe I lost a valve seat. This makes this engine toast because on the old paperwork, the seat has already gone to .030 and a note stated the original dealer wouldn't try to fix it again. (Wish I would have gone over the entire mess of paperwork before I bought it)! Makes me wonder two things. How well did they do their machine work/repairs at the dealer and how bad did the first PM beat this machine). I know it was a mower so I'll guess it was never cleaned and blown out and I question the oil changes. I found the name of the original owner from the dealer paperwork and looked up the owner's property online. Over two acres!

I only ran it a little over 4 years before it went again and I always cleaned it out and changed oil regularly. Even on the loader, it didn't do nasty stuff for long intervals. It had it's hours cut by 75% and I didn't run it much at all to begin with. Maybe 150 to 200 hours since I bought it in 2011. Mmmmmmmmm.

The front cyl is only at 92 PSI so it wasn't the best either!

 

I have a spare motor, (1996), I bought from Joe's Outdoor Power years ago. Other than taking the tins off and cleaning it up on the outside, I fogged the motor and kept it as insurance. I was going to swap them out when I wondered what that fog would do if those heads were really carboned up. Wow. All I can say is this......if you really want to clean the carbon deposits out of an engine, fog it and let it sit a couple years! Glad I took it apart before putting it on. It made sense since it was sitting on a bench. Duhhhh! Today I'll adjust the valves and I'm going to take the crankcase breather out and give it a cleaning in some acetone. I have to replace the main multi-pin connector on it too. (Wish our member "Cable" lived closer to me)! I'm taking my good old time on it. No snow and I have the blower and the plow if we do get any! 

 

There is always a chance and I'm hoping beyond hope probably that I have a valve issue that isn't seat related. I would love to keep a good spare on my bench. Once I get the original Onan out of the tractor and on the bench, I'll take some pics of what is found. (Should have taken pics of the heads on the spare motor before cleaning them up! 

Thank God I have the original motor here plus the 416-8. The tins have been off the spare for years and I can't remember how they go back on!

I'm really glad I don't do this for a living and you can be glad I don't work on your machines!    

 

 

[JackC 617]

Got to have spares.  That is how I justify owning so many. Swap and go with back up horses or parts rather than broken down and fix just when it is most inconvenient. You also wind up with on premise spare parts galore.

[slammer302 2,155]

Sorry to hear about your bad motor I would take my time and do it right the first time witch sounds like what ur doing

[boovuc 1,090]

Valves are adjusted and valve box covers are on, intake manifold/carb is back on, de-carbonizing is complete, heads are back on. Crankcase breather baffle "crap" was solvent washed, dried and repacked. It is back together. The muffler/exhaust is back on. The 9 pin connector is.......................the 9 pin connector is.....................the pin remover I was using was slightly embedded in my %$@#%$# finger for a few seconds. Damn I wish Cable lived here! 

Time to heal and tomorrow night, I'll look at that connector again. And maybe not use as much force pushing the pins out of the melted connector! 

[Cable 179]

Boo, sorry to hear about your engine.  Good thing you were prepared with a spare. The engine harness isn't too hard to remove.  Send it to me and I will put a new 9-pin on it. Be glad it isn't the tractor frame harness.  PM me for my address.

[decksetter 50]

I've had that idle bounce smooth out completely after a valve adjustment. I've had multiple engines work their intake valves tight so there was no clearance at all, then the valve wouldn't hold tight against the seat.

No wonder the seat pops out after a few thermal cycles without pressure from the valve holding the seat tight in its place.

[boovuc 1,090]

That is kind of what I would like to see in that engine when I finally pull it and take it a part, decksetter.

 

My spare engine now looks like a Wheelhorse 520 engine! It didn't for years with the shrouds and muffler/intake off of it!

Need to steal a bolt or two from the original motor and get my 9 pin connector fixed. I have another drive pulley coming from Joe's. I'll use the current PTO that is on the tractor now.

Hopefully this weekend we will see how that spare engine idea I had works out!

 

 

[decksetter 50]

Are there any differences in wiring between the 91 and 96 engines? Might want to check the diagrams before you start with the swap. I had issues putting an 89 engine in a 91 tractor. My issues were mainly with the starter and seat switch.

[ericj 1,578]

no difference between 91 and 96 tractors the difference is between 89 and 90.

 

 

 

 

 

eric j

[JackC 617]

I've had that idle bounce smooth out completely after a valve adjustment. I've had multiple engines work their intake valves tight so there was no clearance at all, then the valve wouldn't hold tight against the seat.

No wonder the seat pops out after a few thermal cycles without pressure from the valve holding the seat tight in its place.

Now that is a great point. Thanks.

[boovuc 1,090]

Thanks Eric & Decksetter. I never really thought of any diffs with the circuits between the 520's.

I kind of wish I had the loader ready with about 6 inches of wet snow out there right now. It still runs with the old motor but why blow it up when it may be a salvageable engine!

 

(Going to try to blow this snow. Hopefully my next project isn't a KT17 swap in the C-175)!  

[decksetter 50]

I've set the valves without pulling the engine before. Doesn't take that long once you've done it a couple times.

[boovuc 1,090]

OK...........Old Onan is off the tractor. Spare Onan is on the tractor. Neighbor helped me lift them on and off. Drive belt is on, PTO is on, Starter is hooked up. Replaced the fuel line from the tank to the fuel pump and the fuel pump outlet to the carb. Linkages are hooked up. 9 pin molex connector is replaced & hooked up. Replaced the vacuum hose from the manifold to the gauge. Dumped 1.5 qts of 10w-30 synthetic blend in it and will re-check once my filter gets full. . Replaced the plugs, new filters. Need to replace the battery cables and prime the line with gas and I should be ready to fire it Monday night or Tuesday depending on how much snow we pick up. Wasn't sure how to set up the throttle initially. I have it on there and will see if it runs then play with it.

The spare has a pretty significant oil leak once we got it on the bench. Looks like the crank seal behind the drive pulley. Quite a bit of oil on the mount base as well.

[Cable 179]

How did your changing the 9-pin connector go?

[boovuc 1,090]

Mangled some but I had practice before doing the gold pin. If my hands weren't so sore I think I could do this better. Kind of reminded me of fly tieing. Your pin seemed stouter than the Molex branded pins I used on the rest. I admit I replaced half of them and others looked good so I bent the posts back out and resetted them.

[Cable 179]

Sounds as if maybe you were not able to extract to good pins from the shell?  What is your conclusion on the Molex extractor? 

 

I admit that the factory crimps are very often better than the ones I can make even with a professional crimp tool, therefore, only the burnt up ones get replaced.

[boovuc 1,090]

The Molex extractor is OK. Reminds me of a big hat pin with a pearl at the end of it. Once I got the hang of it, it wasn't too bad. Some pushed right out, others needed a little more umph but they all came out eventually.

The 416 has a few more connectors that are going to need replaced. I need an end on one connector, (spade male), i found on the 520. I think the battery gases in the tower top reek havoc on the wiring around the battery.

 

No time to try to finish and fire it up tonight. Our 1 to 3 inches is at 6 to 7 and counting. Powder snow that started at 10PM Sunday night and it really hasn't stopped up to this post time.

Only the WeatherUnderground out of Minnesota had our Central Pa forecast correct 24 hours out!  

[boovuc 1,090]

One shot of Calico Jack Spiced! One shot of Calico Jack Cherry. Add 5 round small ice cubes and a 12 ounce diet caffeine free diet Pepsi. Bottoms up!

 

The spare Onan runs after a four year sleep. Had to swap fuel pumps and cleaned out the carb........again. Success! 

Runs real smooth. No smoke! No knocks, ticks or clicks. I'll have to adjust the governor some as I believe I can exceed 3600 RPM at full throttle. All the gauges work. Safety switches work! The idiot lights work too.

Thanks to Joe's Outdoor Power for selling me this puppy 4 years ago as a backup I knew I would need someday. Thanks to Redsquare member Cable for the advice and a gold replacement pin for my burnt connector on the spare.

Didn't think it would be that big of a deal to open the heads and de-carbon then just put it all together and add the muffler, drive pulley & PTO and drop it in the 520. It was and I guess doing it alone on a time budget doesn't help! The snow storms didn't help either! 

 

I'll get some pics of what is causing my 30 PSI rear cyl compression this weekend in the original motor. On the same motor I need to look for the exact cause of the oil leak on the PTO side of it too. I would love to fix it and have another spare but I'm not holding my breath for a good outcome. We'll see!

 

Oh and the one thing I would like this thread to convey to others who may read it in the future.................................if your going to store an Onan for years, de-carbon it then fog it. Otherwise, you have the small engine equivalent of a bachelor's oven with Easy-off Oven Cleaner applied!    Glad I opened the heads up before I tried to run it!

[decksetter 50]

What do you mean by "fog it"?

My 520 is getting close to 800 hours, I got it with about 700 I think. I don't know if it has ever been decarboned and I don't plan on doing it. I don't plan on ever taking the heads off unless I have to. I set the valves with the engine on the tractor. I run Seafoam in all the gas I put in it and hopefully that takes care of the carbon issue these seem to have.

Honestly if intake valves always work themselves tight on these things I could see that leading to the carbon problem as well. Just another theory though. I'm curiously awaiting what you find in your other engine.

[boovuc 1,090]

Hey Decksetter!

 

"Fog it" is the slang of using a fogging spray, (fogging oil), that you spray in the spark plug holes of motors you are going to store for a long time.

The Onan I've been working on has been sitting on the side of my bench in the garage for 4 years before I needed to put it in service.

Onan suggests pulling the heads every 1000 hours to de-carbon. Many clean theirs every 500 hours.

I bought the motor and took the tins off of it to clean the fins but never de-carboned it. Before I installed and started it, I thought now is the time to de-carbon it since it was handy on my bench and I found the fogging oil lifted the carbon off. It was everywhere with many large chunks and some of it was very hard. I don't doubt I would have screwed the rings big time had I run it without opening it up.

 

On looking at the engine I pulled, I can't wait either but I'm not touching the old engine until the loader is completely together and I straighten up the bench. It looks like a tool explosion in there right now. I'm about as organized as a train wreck in that garage. I should have a GPS locator for every hand tool I touch!