782 giving me fit's

farmall fred · #1 04-07-2016, 11:21 AM

I have a 782 I picked up on the cheap that I want to put the sickle bar mower I just got and yesterday. I thought I would be able to finish it up. I swapped in a Mag 18 from a 1872 and was finishing it up and noticed a slight oil leak at the crankshaft seal behind the PTO clutch so I picked up a Kohler seal, cleaned the bore well and installed it dry as recommended. I reinstalled the PTO clutch and muffler and after I finished the rewire so I could shut down the Mag engine I started it up. As soon as I revved it up I noticed a lot of oil dripping out from under it. I removed the grill and the whole inside of the cooling shroud was covered with oil. I was very careful installing the seal and lubed it before installing. I was so upset, that I locked up the shop and went in the house. This engine will carry 80 psi oil pressure when first started and I am wondering if the high oil pressure is causing to much oil to be flung off of the main bearing and the oil return cannot handle it. The end closure plate has much RTV oozing out around it from the previous owner and I am also wondering if the oil return might be plugged. I guess I will have to remove the engine and remove the closure plate and check it out. I also need to look into the recommended oil pressure. O well I was hoping to start on my 1872 build this weekend.

Later
Tom

olds45512 · #2 04-07-2016, 11:32 AM

That sound like way to much pressure, I believe the manual says it should have no more than 50psi but don't quote me on it. I had a mag 18 that carried 60psi and I had to replace the lines running to the oil filter and when I did it only had 40psi, turned out one of the original lines was collapsed on the inside causing restriction.

aagitch · #3 04-07-2016, 11:52 AM

make sure you purchased the correct seal. I believe some people have accidentally ordered the one for the flywheel end and it's a different size

farmall fred · #4 04-07-2016, 07:55 PM

It turns out that the parts store ordered me the wrong seal. I looked it up my self on line today and came up with a different number. I decided to remove the engine from the tractor and get it up on the bench to work on it and as soon as I removed the PTO I could see that the id of the seal was to large, but the od was correct. If I would have just checked the id against the old one I would have noticed the difference. My mistake for getting in a hurry. The worst thing is if I had looked in my spare parts cabinet I already had the correct seal. Lesson learned always check to see if you have a spare and also do not get in a hurry and install new parts with out making sure they match the old ones. I am usually good about this but got in a hurry.

Tomorrow I will get it back in the tractor and hopefully get a chance to get my sickle bar mower attached. I have a thread on it in the implements section.
Later
Tom

farmall fred · #5 04-09-2016, 10:29 AM

Update on the Mag 18 saga. Yesterday after I installed the new seal and reinstalled the closure plate I decided to do a leak down test on the Mag 18 before I reinstalled it into the 782. The engine has 120 psi compression but the right cylinder has a intermittent miss and I decided to find out the cause. Left cyl has 10% leak down, right cyl had just over 20% Both leak out the exhaust. So I pulled the valve covers and noticed that the rotators are on the intake valves instead of the exhaust and the exhaust valves only have .006 of clearance. I an wondering if who ever rebuilt it switched the jugs side to side when he reassembled it. So I picked up two new head gaskets and I will remove both heads, remove the valves to see if they are not mixed, hVe the valves faces and touch up the seats. I do not want to have to remove this engine again. I will let you know what I find when I get it tore down. So much for a quick and easy engine swap.
Later
Tom

ol'George · #6 04-09-2016, 12:30 PM

FWIW:
The left and right jugs are a bit different on the M-18's as far as
the right jug has the bosses for the mounting of the mag. ignition milled flat and drilled/tapped so it can be mounted.
The left side only has the cast bosses, it lacks the machining.
The seats on the exhaust are hardened, the intakes are not.

The latest/later M-18's had 30* ex. valves/seats,and they use different clearances.
it is covered in the service manual section 10.

If you don't know, you have to grind the valve stems to adjust the clearance.
look the manual over, before you dive in.
I doubt the heads were switched,

possibly the "mechanic" installed the rotators on the intakes mistaking them for the exhaust, and set clearance accordingly.
just my guess.
--- a helpful hint.
Be careful pulling the valves out of the guides so you don't damage the intake valve seals, they are pricy.
If you get as far as setting the clearances do it with the seals removed saving the repeated in/out while checking/grinding of the stems.

#95 compression is about average.

farmall fred · #7 04-09-2016, 09:19 PM

Today I finished tearing the Mag 18 apart and the jugs are not mixed, but the rotators were on the intake valves instead of the exhaust. I did not like the looks of the exhaust valves as the heads looked like they were starting to curl and they were worn so I tore down a KT-17 I had and the valves in it looked new. I took the valves to the parts store I used to work at and refaced the valves all of them and the ones that were in this Mag 18 looked like they had been ground in a re-facer with a worn chuck, Since the KT 17 valves were in better condition with no wear on the stems I used them, I was just curious if the valves I took out were ground correctly. I then reground the seats with a seat grinder my buddy has and they also were not true. After grinding and narrowing the seats I set the valve clearance and then hand lapped the valves and they came out excellent. I am confident that the engine will run much better. I am just surprised that it had 120 psi compression. Tomorrow I will reinstall the heads and recheck the leak down. It was kind of fun grinding the valves and seats as I have not done any for other 25 years since I left the parts store. Hope to get it assembled and back into the 782 tomorrow and if it runs ok I will start on mounting my sickle bar mower on it. This 782 will be dedicated to sickle bar mowing the road ditches around my farm. Later
Tom

farmall fred · #8 04-10-2016, 10:15 PM

Today I finished the assembly of the Mag 18 and got it reinstalled in the Sickle Bar 782. It started right up and after adjusting the carb it runs and idles well on both cylinders. I was beginning to wonder if I was ever going to get it finished. seemed like every time I tried to fix one thing something else would crop up. When I was cleaning up the deck surface of the left cylinder I noticed it had been sleeved back to standard bore size and the other side is bored .010 oversize. Also there was no rubber reed valve or matting in the breather on the valve cover, no wonder the air filter was full of oil. Evidently this motor has led a rough life. At this point the way it runs with no blow by or exhaust smoke I think it will work just fine for its intended use and should last for quite some time. I was hoping to get the sickle bar mounted up on the 782 today but decided to come in from the shop a little early today. I can finish it up tomorrow.
Later
Tom

J-Mech · #9 04-10-2016, 11:24 PM

Ohhhh..... It has a standard bore on one side, and .010" over on the other?

Unless you don't put many hours on it, I don't think it will last "a long time". Twin cylinder with one hole larger than the other will cause issues. One will work harder than the other, one will run rich the other lean.... so one cylinder will tend to run hotter than the other. Might last a while, but depends on how hard you use it, and how well you tuned it. Keep it clean, and hope for the best.

As a note to others: Always match bore sizes.

farmall fred · #10 04-11-2016, 09:45 AM

Quote:

Originally Posted by J-Mech

Ohhhh..... It has a standard bore on one side, and .010" over on the other?

Unless you don't put many hours on it, I don't think it will last "a long time". Twin cylinder with one hole larger than the other will cause issues. One will work harder than the other, one will run rich the other lean.... so one cylinder will tend to run hotter than the other. Might last a while, but depends on how hard you use it, and how well you tuned it. Keep it clean, and hope for the best.

As a note to others: Always match bore sizes.

I am betting it will last a long time. When I worked in the machine shop years ago it was not unusual to have engines come in the had one or more cylinders bored oversize to repair damage. I do not know about Kohler but most all piston manufactures shorten the compression distance of oversize pistons to keep the compression ratio the same and to maintain balance they would match the weight to same as stock. Now for performance or high rpm use I would never chance mixing bore sized or pistons from different manufactures. On I side note I once bought an engine from a Farmall M for parts and when I tore it down it had three cylinders with the stock 3-7/8 bore and one with a 4 inch overbore sleeve and piston. The fella that I bought it from had ran it for over 30 years like that and it never gave him any problems. When I later asked him about it he said that he had a problem with it and at the time all they could get was the overbore kit for the bad hole. I would never do this my self but it does work. As I will using this tractor for ditch mowing duty only it will not get many hours a year so for me this is a way to not have to spend a bunch of money on it. There is no way I will spend the money it costs to rebuild a KT or Mag Kohler. Just not worth it in my book. But J Thanks for your concern and thoughts.

Today I hope to finish this sickle bar tractor project.
Later
Tom