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Posted: 2/7/2017 7:18:54 PM EDT
Going to do a ring and valve job on the 16hp ONAN in my JD 316 before spring here. Onan SPECIFICALLY stated that you should NEVER lap the valves, cut them or replace ONLY. Really, they had a lot of warning everywhere about that. I figured I'd better listen.
I did source a valve seat cutting kit from India on fleabay, was $65 shipped. Not bad. The valve cutter proved to be more difficult. The only machine shop around here I know of that still does this type of work is now closed. The old man retired. Its just not done. If you don't lap the valves on a small engine, you replace. Just how things go around here. New valves are $65 EACH, and hard to find made by Onan. Crazy. Anyway, I designed a jig that uses a standard 50mm DC spindle that you use for a cheap CNC router (I happen to have just that type of spindle lying around, it could be a dremel or whatever). It is 3D printed, well its printing now anyway. Just thought I'd mention it in case anybody happens to need the file they can PM me, the diameter of the valve stem can be easily adjusted if you have Fusion 360 (freeware). ETA: Pics are always nice. Here is a rendered image. The "back" side of the image lays flat on the workbench, likely clamped. The two axis are exactly 44*, per OEM specs. It will be done by morning, and from there I will see if anything needs to be changed.  Attached File |
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Posted: 2/12/2017 11:10:18 PM EDT
[#1]
Will try it out tomorrow.
 Attached File |
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Posted: 2/13/2017 12:35:59 AM EDT
[#2]
Very neat.
Having said that, I have lapped Onan valves without issue. |
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Posted: 2/13/2017 10:27:39 AM EDT
[#3]
Quote HistoryQuoted:
Very neat. Having said that, I have lapped Onan valves without issue. |
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Posted: 2/13/2017 12:24:21 PM EDT
[#4]
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Posted: 2/14/2017 11:58:34 AM EDT
[#5]
So the pilot for the valve seat cutter is too big, by about .1mm
You get what you pay for... Good news is not all is lost. My brother is a metal worker, and has a nice lathe. I'll be stopping over there, probably today, to turn it down so it fits. Better than too small I guess. Might have to re-name this thread my Onan overhaul thread.. |
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Posted: 2/14/2017 3:41:28 PM EDT
[#6]
Try pressing a piece of brass or bronze tubing of the correct diameter into your boss for the valve.
Alternatively, you could use steel tubing and keep it lubricated. |
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Posted: 2/14/2017 4:57:46 PM EDT
[#7]
Just got back after turning the guide down. Cut the first valve seat, looks great!
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Posted: 2/14/2017 9:44:03 PM EDT
[#8]
Quote HistoryQuoted:
Just got back after turning the guide down. Cut the first valve seat, looks great! We don't believe you. Prove it. Only pictures will work. 
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Posted: 2/15/2017 2:39:47 PM EDT
[#9]
Quote HistoryQuoted:
We don't believe you. Prove it. Only pictures will work. Anyway, some more pics:  Attached File Attached File Attached File |
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Posted: 2/15/2017 2:43:14 PM EDT
[#10]
Where it sits for today. I have to run to town tomorrow anyway, and I need some grade 8 small bolts to pull the crank gear off. Still has pistons and crank in it, after that just the cam bearings need to be pulled before honing the cylinders then washing the block.
I am deciding if I want to paint it while its squeaky clean 
ETA: Oops, forgot to upload the pic...  Attached File |
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Posted: 2/15/2017 5:15:54 PM EDT
[#11]
So while I'm doing nothing, I took out the T gauges and micrometer and started taking measurements of the cylinder.
Cylinder #1 has so far ranged from 3.2513 to 3.2526 BEFORE honing. Now I sit and debate. Two .01" oversize pistons would be around $225. Rather not spend that. I'm thinking when I take the rings off, if they aren't broke and ring gap is within spec (or close enough), they go back on and I leave the cylinder walls alone, no honing. If I have a broken ring, I have to hone for the new rings. Time will tell once its apart... ETA: Cylinder bore size is 3.25" nominal |
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Posted: 2/15/2017 11:58:39 PM EDT
[#12]
I'd hone and install new rings. No way I'd put old rings back in.
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Posted: 2/16/2017 1:04:44 PM EDT
[#13]
Boy oh boy, decisions, decisions.
Taking readings and looking at the MAX bore diameter, it is already due for a boring and honing to the next oversize. Two pistons/rings will be about $250 plus the machining. Grrr, more than I want to spend. If i just hone and install new rings, it out to be better than what I have now, should it not? I hate to hone and find out it is just too far gone for just rings, then I am stuck with new pistons.. Tempted to replace the cam bearings and throw it back together and get a few more years out of it before I decide what to do with it. |
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Posted: 2/16/2017 4:28:10 PM EDT
[#14]
So I did a bit more digging, as I could not find the wear tolerance for the cylinder bore diameter. I finally found it. The MAXIMUM wear diameter is 3.255". The largest measurement I got was 3.2537".
Bore taper and out-of-round were also within spec. Looks like as long as the rods/crank looks good, she gets new bearings, seals, rings, and is back in business! |
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Posted: 2/16/2017 4:52:00 PM EDT
[#15]
I've got some Onan pistons here, but they're about a 1/4" too big.
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Posted: 2/17/2017 4:27:45 PM EDT
[#16]
Got that darn crank gear off for final tear down today, finally.
As was known, the cam bearings were bad. The lateral play of the rods in the crank is out of spec, but the rod to crank clearance is good, so I may just throw the rods back in, especially if the pistons check out to within spec. I'm thinking I may run the block and crank to a machine shop I found that is still operational (found through a friend who had me call a place that couldn't do my block, but referred me to a guy about 45 minutes away that can bore the block) so they can professionally clean the block, at which point I may as well give it a fresh coat of paint! Pic of the mess I made:  Attached File |
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Posted: 2/17/2017 5:03:15 PM EDT
[#17]
Ring end gap was within wear tolerence, but I accidentally broke one getting it off (2nd ring), so it gets honed and new rings anyway
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Posted: 2/23/2017 8:40:42 PM EDT
[#18]
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Posted: 2/23/2017 9:42:11 PM EDT
[#19]
I'm glad you are posting this.
I was gonna ask you to do a step-by-step, but I was thinking more of a "here's how you do this job" step by step, which I figured you'd be good at. I'm probably the only user here interested in such a rudimentary "shop manual" style post, and that would be a lot of trouble. But if I end up buying a 316, maybe I'll just ship my valves to you to be fixt. 
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Posted: 2/23/2017 9:45:17 PM EDT
[#20]
Quote HistoryQuoted:
I'd hone and install new rings. No way I'd put old rings back in. Even with the little I know, I would agree. Kitties, the girl with grease under her nails. (hard to find a guy who thinks that's sexy.  )
ETA: Not that I've broken an engine down that far. I'm skeerd. 
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Posted: 2/23/2017 10:17:26 PM EDT
[#21]
Quote HistoryQuoted:
Even with the little I know, I would agree. Kitties, the girl with grease under her nails. (hard to find a guy who thinks that's sexy. )
ETA: Not that I've broken an engine down that far. I'm skeerd. Quote HistoryQuoted:
Quoted:
I'd hone and install new rings. No way I'd put old rings back in. Even with the little I know, I would agree. Kitties, the girl with grease under her nails. (hard to find a guy who thinks that's sexy. )
ETA: Not that I've broken an engine down that far. I'm skeerd. I have about $200 or so in parts in it. |
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Posted: 2/23/2017 10:19:01 PM EDT
[#22]
Quote HistoryQuoted:
I'm glad you are posting this. I was gonna ask you to do a step-by-step, but I was thinking more of a "here's how you do this job" step by step, which I figured you'd be good at. I'm probably the only user here interested in such a rudimentary "shop manual" style post, and that would be a lot of trouble. But if I end up buying a 316, maybe I'll just ship my valves to you to be fixt. |
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Posted: 2/23/2017 10:20:48 PM EDT
[#23]
Just noticed some blue on the gear in that last pic. It isn't there in real life, kind of a weird camera effect.
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Posted: 2/24/2017 6:41:42 AM EDT
[#24]
Quote HistoryQuoted:
I'm glad you are posting this. I was gonna ask you to do a step-by-step, but I was thinking more of a "here's how you do this job" step by step, which I figured you'd be good at. I'm probably the only user here interested in such a rudimentary "shop manual" style post, and that would be a lot of trouble. But if I end up buying a 316, maybe I'll just ship my valves to you to be fixt. Kitties- just craigslist a old briggs or Tecumseh engine start with one of them real easy to do. Rat - keep up the good work !!! I love how you could make your own valve grinder or the ability to make such, heck if it was mine a little lapping compound and some time would be what I would have used. |
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Posted: 2/24/2017 6:45:12 AM EDT
[#25]
Quote HistoryQuoted:
Got that darn crank gear off for final tear down today, finally. As was known, the cam bearings were bad. The lateral play of the rods in the crank is out of spec, but the rod to crank clearance is good, so I may just throw the rods back in, especially if the pistons check out to within spec. I'm thinking I may run the block and crank to a machine shop I found that is still operational (found through a friend who had me call a place that couldn't do my block, but referred me to a guy about 45 minutes away that can bore the block) so they can professionally clean the block, at which point I may as well give it a fresh coat of paint! Pic of the mess I made: https://www.AR15.Com/media/mediaFiles/165887/NCM-0213-148461.JPG thats one thing I hate anymore with working on small engines, everything has become throw away, trying to find a machine shop that can or is willing to do work on a small engine is hard anymore. now everyone says throw that away and buy a new cheep Honda, or similar to slap in it, with the influx of honda clones bringing prices way down its almost cheaper to do so. |
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Posted: 2/24/2017 12:51:15 PM EDT
[#26]
Quote HistoryQuoted:
thats one thing I hate anymore with working on small engines, everything has become throw away, trying to find a machine shop that can or is willing to do work on a small engine is hard anymore. now everyone says throw that away and buy a new cheep Honda, or similar to slap in it, with the influx of honda clones bringing prices way down its almost cheaper to do so. I think this is a shame about almost any machine that is built today. (For a homeowner, anyway.) First because the skills will be lost, and second, because of the waste involved. I like that things are more affordable, but I hate the loss of quality, and the mentality that we use something until there is just no more good in it. 
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Posted: 2/24/2017 1:56:21 PM EDT
[#27]
Quote HistoryQuoted:
I think this is a shame about almost any machine that is built today. (For a homeowner, anyway.) First because the skills will be lost, and second, because of the waste involved. I like that things are more affordable, but I hate the loss of quality, and the mentality that we use something until there is just no more good in it. |
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Posted: 2/24/2017 4:10:56 PM EDT
[#28]
Well then,
I go to install the camshaft today, no fit. It won't get into the front bearing. Fits in the rear bearing fine. I take the bearing out, expecting to find rolled metal or something where I installed incorrectly, but it looks good. I put the bearing back in, no joy. So I wonder if this bearing is made just a bit tight. I am going to order a new bearing and try again. My dreams of having the 316 running this weekend have just died
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Posted: 2/24/2017 10:17:49 PM EDT
[#29]
Onan engines are very good engines. But, they are also very overpriced to work on.
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Posted: 2/24/2017 10:50:09 PM EDT
[#30]
Quote HistoryQuoted:
Onan engines are very good engines. But, they are also very overpriced to work on. |
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Posted: 2/25/2017 11:08:12 PM EDT
[#31]
Quote HistoryQuoted:
Well then, I go to install the camshaft today, no fit. It won't get into the front bearing. Fits in the rear bearing fine. I take the bearing out, expecting to find rolled metal or something where I installed incorrectly, but it looks good. I put the bearing back in, no joy. So I wonder if this bearing is made just a bit tight. I am going to order a new bearing and try again. My dreams of having the 316 running this weekend have just died did you get the old bearing and measure by chance ? just odd it is different size |
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Posted: 2/25/2017 11:49:55 PM EDT
[#32]
Quote HistoryQuoted:
did you get the old bearing and measure by chance ? just odd it is different size |
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Posted: 2/27/2017 1:15:43 PM EDT
[#33]
The replacement cam bearing will arrive today. I have been working on cleaning other sub-assemblies and such, getting them ready for install. The oil pump is rebuilt and ready, and I am waiting on the timing cover to dry so I can install the new seals and the governor arm.
In theory, I may even have the short block done today! I still haven't decided if I should open the starter up and go through it. No rebuild kits are available, so I'm probably going to clean it up and just bolt it back on. It worked fine, never an issue. I just rebuilt the carb last year, so I will just check/clean the jets and put it back on with the intake unless I find issue to tear into it. However, since carb kits for these are $75, I'll leave it alone unless it needs attention. |
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Posted: 2/27/2017 6:59:40 PM EDT
[#34]
Lucky you. I had a connecting rod explode on my 316. (Which is evidently not an uncommon issue with the Onan.)
I can't see dropping the $'s on rebuilding it when I can put a 22hp motor from Harbor Freight for a 1/3 of the price. Purists will scream and shout, but I just need it to mow some grass and haul a trailer around the yard. 
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Posted: 2/27/2017 7:53:24 PM EDT
[#35]
So the cam bearing came, same issue. Once pressed into the block, it is reduced in size enough to not fit the cam anymore: too tight. It was fine before pressed in, btw.
So upon more research, and my parts guy finding a blueprint diagram, my engine block cam bearing hole is not bored properly. Solution: using light sandpaper and oil, I am removing some of the cam bearing material until I have enough clearance. It worked, at least the cam now inserts with the specified amount of tolerance. Don't know how long it will go, but the bearing material in the bearing is plenty thick, so as long as it gets me 5 more years, I'm happy. That whole fiasco took a lot of time so installing the cam was the only thing that happened today. |
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Posted: 2/27/2017 8:12:09 PM EDT
[#36]
Quote HistoryQuoted:
So the cam bearing came, same issue. Once pressed into the block, it is reduced in size enough to not fit the cam anymore: too tight. It was fine before pressed in, btw. So upon more research, and my parts guy finding a blueprint diagram, my engine block cam bearing hole is not bored properly. Solution: using light sandpaper and oil, I am removing some of the cam bearing material until I have enough clearance. It worked, at least the cam now inserts with the specified amount of tolerance. Don't know how long it will go, but the bearing material in the bearing is plenty thick, so as long as it gets me 5 more years, I'm happy. That whole fiasco took a lot of time so installing the cam was the only thing that happened today. Gosh you were that far into it you should have just had the cam bearing machined to the proper spec
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Posted: 3/1/2017 4:51:44 PM EDT
[#37]
OK, I have it mostly together now, waiting on 2 things:
I forgot to buy the points gasket. Be in this week. I lost the darn governor shaft ball bearing. Going to get one in town sometime in the next couple days, or whenever I get to town (not spending $7 in gas on a 59 cent steel ball  ).
Other than that, the front PTO is on, valve train is in, heads are on, oil pan on, but the flywheel is waiting until I get the governor shaft ball so I can put the timing cover on. I'll clean up the starter, clean up the carb (without a complete teardown). Maybe, just MAYBE the engine gets installed this weekend. Maybe. My father is coming out for a visit on Saturday, so we will see. On my short list for the tractor itself: steering brakes upgrade mini loader bucket for the front (hopefully before spring). Going to be low capacity, only using the tractor's hydraulics. dirt style 4 way blade for the front Once the engine is installed and running, I'm going to check to see exactly how much pressure the hydro is pushing, make sure that doesn't need attention. |
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Posted: 3/3/2017 5:16:50 PM EDT
[#38]
Almost, almost.
Cue epic face palm: In my haste, I forgot to order the points gasket. Grrg. Also, I managed to loose the darn little bent metal thing that keeps the linkage on the carb, so I am 3D printing a new one from ABS plastic. Here is is, all ready for the points to be installed:  Attached FileI will still likely install the engine into the tractor this weekend, but it won't be fired up until those points get in. Luckily, there is plenty to do before that. OK, maybe like 2-3 hours worth, if I take my time, but anyway... |
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Posted: 3/3/2017 5:20:53 PM EDT
[#39]
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Posted: 3/3/2017 11:27:28 PM EDT
[#40]
Quote HistoryDude those 3D printers are cool I wish I had the skills there is some things I'd like to print ! Looking at that little piece it looks like a standard GM/Ford loor linkage holder ! Glad it's all going smooth for you !! |
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Posted: 3/4/2017 1:20:00 AM EDT
[#41]
I wonder if a few people made the request if Wiseco might not make up a few piston kits.
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Posted: 3/13/2017 10:05:45 AM EDT
[#42]
Since I put the engine back together, the weather has turned cold again. Since I work basically outside with the tractor itself, the engine has been sitting on the bench, awaiting install into the tractor.
Until yesterday! My brother was out, and he gave me a hand dropping the engine in. Its just sitting there now, won't be until late week until I start bolting it down, as the warmer weather doesn't return until then. But, its finally back in the 316! |
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Posted: 3/13/2017 12:56:41 PM EDT
[#43]
Quote HistoryQuoted:
Since I put the engine back together, the weather has turned cold again. Since I work basically outside with the tractor itself, the engine has been sitting on the bench, awaiting install into the tractor. Until yesterday! My brother was out, and he gave me a hand dropping the engine in. Its just sitting there now, won't be until late week until I start bolting it down, as the warmer weather doesn't return until then. But, its finally back in the 316! How much does that engine block weigh when it's assembled? |
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Posted: 3/13/2017 1:27:13 PM EDT
[#44]
Quote HistoryQuoted:
How much does that engine block weigh when it's assembled? |
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Posted: 3/15/2017 3:04:28 PM EDT
[#45]
Quote HistoryQuoted:
Not sure, around 80 pounds I suppose. So two-person heavy for maneuvering, but not heavy enough for one of those engine lifter thingies. I asked because you have interested me in your little tractor and I'm paying attention to how you manage it. |
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Posted: 3/15/2017 4:26:47 PM EDT
[#46]
Quote HistoryQuoted:
So two-person heavy for maneuvering, but not heavy enough for one of those engine lifter thingies. I asked because you have interested me in your little tractor and I'm paying attention to how you manage it. .
Its a super handy little tractor for what I need it for. Wish it were a 420 or 430, but this is what I could afford. |
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Posted: 3/16/2017 3:33:22 PM EDT
[#47]
Quote HistoryQuoted:
Yeah, I can lift it, just maneuvering is difficult with just yourself. I don't have an engine lift at the moment .
Its a super handy little tractor for what I need it for. Wish it were a 420 or 430, but this is what I could afford. |
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Posted: 3/19/2017 4:58:19 PM EDT
[#48]
SHE LIVES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Runs very well actually. I put 2 hours of hard work dragging the driveway, then changed the oil. It really is too wet to drag the driveway, but I wanted to work the machine, and I made her snort
ZERO SMOKE. It smoked before, all the time a bit, but especially during laboring. Runs perfectly clean now. RUNS SMOOTH. It has never run this smooth since I've owned it. The throttle is more responsive too. All in all, I'm extremely happy. I even installed an hour meter, so I can keep track of maintenance properly. I can't believe that was an OPTION on a $5000 tractor... The torque is coming back in the last half hour or so of running, so the rings and valves are starting to seat. I'll continue to run it hard the next 3 hours and then another oil change. After that, I will change oil again at 25 hours, then normal schedule. |
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