861 oil leak between engine and adapter plate

[FarmerBlair]

Sorry about the long post.
I knew it would cost more than the tractor's value but decided to finally have the engine professionally rebuilt on my 861 (gas). But I've been having nothing but problems getting the work done right. I paid over $5k to a tractor repair shop for a complete engine rebuild, along with a new clutch. I got it back 7 months later and discovered a rear engine seal leak among many other issues. I didn't know how serious the leak was until later when mowing on hilly ground and nearly lost all oil pressure. The repair shop would not cover the cost to fix it because it was a couple months past the warranty, even though they admitted they had such problems with rope seals being too short. They wanted another up to $1200 to replace the seal. There's only about 10 hours on the rebuilt engine.

I took the tractor to another shop in Lancaster PA that my neighbor farmer recommended. The shop found the bearings were also shot, so I told him to go ahead and replace those (again) while replacing the seals. This cost another $1200 on top of the engine rebuild costs.

I just got the tractor back, and it leaks oil at the back of the oil pan near the bell housing. I replaced the gasket myself. I smoothed out out hardened RT sealant that caused the leak along the gasket. But now I see oil dribbling down the adapter plate between the engine and tranny. It was doing that before, but now I can tell it isn't from the separate pan leak.

I asked the last mechanic (in PA) whether he split the tractor to replace seals and he said he did all the work from underneath. He said he used a 2-piece rubber seal that he worked in and then sealed the sides with an RT sealant like you hear about. He mentioned about probably having to pull the crank if he went with the rope seal. At the time I wasn't sure that was true, but didn't ask further. I'm not a mechanic.

So far I don't see engine oil leaking out the bell housing opening (with the plate with a cotter pin off) as its running, even with the front end of the tractor elevated. I left it running for at least 30 minutes so I'm hoping that's that.

But what about this weeping oil between the engine and the adapter plate? Is this from a leaking main oil seal? Oil starts dribbling down the plate after a couple minutes of running.

Had another thought is can you replace bearings from underneath (through oil pan)? Or is that just a partial job?

Thanks for any input.

 

[M-MAN]

Sorry you are having such trouble
finding a good mechanic who will stand
behind his work.

Yes you can replace the bearings and
seal after removing the oil pan. IIRC
there's two grooves and putting the seal
in the wrong one isn't unheard of. You
need to find an old independent
mechanic.

 

[showcrop]

That would be quite a trick to find a rope seal that is too short, LOL. They always come about 20% extra. When the rear main seal is leaking, between the plate and block is where it is going to come out since there is no gasket there. I am a believer in the two piece neoprene seals, but it is not easy to get the silicone for the side seals in with the engine upside down on a stand. I used a milk shake straw over the tip that comes with the tube of RTV. It is possible that the problem is not the rear main seal, but instead the transmission input shaft seal. A split is required to replace that but it is otherwise a lot easier than the rear main. Generally you tell the difference by the color of the oil because the engine oil is usually black while trans oil is usually yellow. Although a lot of people are using UTF in the transmission these days which absorbs moisture and turns brown.

 

[FarmerBlair]

Thanks Showcrop. I'll keep an eye on the color of the oil coming out. I asked the shop to replace all the seals when the tractor was split for the engine rebuild, including the input shaft seal. Since I wasn't there watching them, I can't assume they did anything right.

I see Walmart and others sell a fluorescent tracer dye additive for trans and engine oil for locating leaks. I'll try some of that added to the engine oil to see if it identifies the leak source.

 

[Kurt J]

As M-MAN says there are 2 grooves outside the Rear Main Bearing. The groove closest to the bearing is for lube to return to sump. You can verify that by looking at the bearing cap. There is a hole in the bottom for the oil to flow back to sump. The outside groove is for the seal. See the pic below.

 

[Hobo,NC]

Tracer Dye, you will need a good ultraviolet light and a special pair of glasses made to pick up the dye. The glasses come in the dye tool kit. The glasses make the deal happen : )

 

[Getnbetter]

Hi Farmer, I'm actually working through some issues with a engine rebuild that I did over the nnalert winter. Primary issue was the major leak of oil out the weep hole on the bell housing. That is clear evidence that the rear main seal is not working well. Sounds like you have oil dripping just behind the oil pan but not coming from the oil pan gasket, so its dripping down the engine side of the mating plate for the engine, trans. I believe the typical cause for that drip (which mine had prior to rebuild and was part of the cause for me to rebuild) is the side seals on the rear cap. Those can be trouble to seal as well but I think easier to fix because you dont need to deal with the crank directly.

 

[FarmerBlair]

(quoted from post at 17:51:50 05/06/21) Hi Farmer, I'm actually working through some issues with a engine rebuild that I did over the nnalert winter. Primary issue was the major leak of oil out the weep hole on the bell housing. That is clear evidence that the rear main seal is not working well. Sounds like you have oil dripping just behind the oil pan but not coming from the oil pan gasket, so its dripping down the engine side of the mating plate for the engine, trans. I believe the typical cause for that drip (which mine had prior to rebuild and was part of the cause for me to rebuild) is the side seals on the rear cap. Those can be trouble to seal as well but I think easier to fix because you dont need to deal with the crank directly.

Thanks Getnbetter. Considering the mechanic used an RT sealant of some sort in the side seals, how hard will it be now to fix this leak? Would you need to do an engine split? How would you (or can you) get this cured sealant out if you were trying to fix the leak from underneath through the oil pan? This sealant is pretty solid... not flexible. Just wondering if worth trying to do this myself rather than drive the tractor another 4 hours back to the mechanic that worked on it, and without splitting the tractor.

The pics show the oil leak behind the oil pan. I used the fluorescent dye added to the engine oil as mentioned I'd try. Worked great for isolating the leak to the engine side.

I assume I'll eventually be seeing oil dripping from the bell housing weep hole?

 

[FarmerBlair]

Just to clarify.... that fluorescent tracer is showing a leak between the engine and adapter plate, not at the oil pan gasket.

 

[Hobo,NC]

Hard to tell I am not their I am not sold its fluorescent dye are its the rear seal. fluorescent dye should be a no brainer it will be fluorescent green it would not be a guess. Have you shined your light at the other oils without added dye to see how it shows' up. Are you using the special glasses to highlight the dye.

 

[Getnbetter]

Looks like its leaking in front of the mating plate. Assuming it is just the side seals of the rear cap, you can do that easily. No reason not to try it and see if you can fix it.
Drop the oil pan and then take the rear cap off (just two bolts), the side seals will come out with it. replace however you think is best. There are several threads on this site about best way to fix this. When I put my tractor back together, I'm going to use the rubber seals with the pins AND some RTV. I had previously used the type that are supposed to expand after a soak in oil but they never did expand much.
If you do this, just make sure you use a torque wrench to put the cap back in, it holds the rear of the crank shaft and you want to make sure its tightened well.

 

[FarmerBlair]

Thanks Getnbetter, your points are much appreciated. The mechanic followed up and called me after I told him it looks like it is still leaking. He says he'll research what might be a better alternative rather than repeat what he already did. If I can find the time, I might try to do something with it myself since he's so far away... over $100 just in fuel driving there and back (twice!).

Good point Hobo about the oil dye. I compared the oil from the engine that was treated with dye, then took a pic of the dipstick with clean untreated oil. The untreated oil does have some green fluorescence, but much less intense. Here's pics. The first is engine oil with dye, and the next is dipstick after dipping in a clean quart of oil:

But the hydraulic oil is very different. It doesn't emit a green color, rather it is very blue. Not sure if its reflecting the UV light, or actually fluorescing blue. Either way, it is enough of a difference where it is clear that the leaking oil is coming from the engine.




No I didn't get any glasses with the bottle of dye. I'll have to check with NAPA whether they have the glasses. Thanks.

 

[Hobo,NC]

I believe ya... I have use dyes since they first showed up to me in the early 90's maybe in the 80's... You can be fooled the glasses are a must they leave no doubt... If the dye does not JUMP out to me I have my doubts glasses are not. Using it in fresh engine oil makes all the difference in the world it can be harder to detect if the oil is somewhat dirty : (...

If I were to sale you on it I would shoot the pix putting the glasses over the lends of the camera : )... If the guy was gonna warranty it I would haul it to'em. If I did the work and you fudged with it you just voided the warranty... Think about it... I don't warranty your work...