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D17 leaking oil from spark plug

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Putnamd17 View Drop Down
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Joined: 19 Aug 2024
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    Posted: 14 Sep 2026 at 9:24pm
My d17 series 4 gas, has some oil leaking from the spark plug closest to the fuel tank, I checked the compression and it was about 157, there is some smoke coming from the exhaust as well, I am thinking this is a valve seal issue. Anyone run into a similar problem before?
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DrAllis View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 14 Sep 2026 at 9:31pm
There are no valve seals or valve stem umbrellas. The valve guides and valve stems are probably worn out. The piston ring grooves are loose top to bottom, the sleeves have a heavy ring edge at the top and the ring gaps are too wide. In short, everything wears out at the same time. A 98% chance it is time for an overhaul.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 6:21am
How do you use or intend to use the tractor?? As long as you aren't fouling a spark plug all the time, you could run it for a long time with this condition, using it for light jobs/short run times. If you intend to grind feed weekly and expect to operate it mowing, raking and baling hay, then your days are probably numbered.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 6:41am
I was hoping to use it for some light plowing with a 2 bottom and bailing about 5 acres of hay.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 6:42am
I had a mechanic go through the engine and look over everything he said he wouldn’t be concerned with anything at the time he went through I asked him about my cylinders and he said they had a lot of life left yet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 11:06am
"Go thru the engine"..?? what does that mean exactly ???    He had it apart and looked at the cylinders?? and now it smokes blue out the exhaust ??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 11:08am
Your oil leak isn't as simple as a valve cover gasket leaking ?????????
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 12:29pm
I do not see any oil coming from the valve cover, he went through and mainly replaced all the seals and such said the cylinders looked good he had the engine out and completely apart on an engine stand, I do not see much blue smoke there was some white smoke but only for a little bit
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dirt Farmer Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 12:40pm
What are the chances that the crush washer is missing on the spark plug and what you are seeing is seeping past the threads
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 1:16pm
A fairly typical result of an "oil burning" AC engine is engine oil leakage around a spark plug. That's just a fact on these engines. So, does it use oil or not?? and you just bought the tractor so you don't really know ??  If he didn't have the cylinder head removed, he only saw the cylinders from the bottom side, which is kind of meaningless.


Edited by DrAllis - 15 Sep 2026 at 1:18pm
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Putnamd17 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 1:38pm
I know he had the head removed, it uses some oil but there is a small rear main leak so I’m not sure where most of it goes but it seems like I’m loosing more oil than what’s coming out of the rear main. It is not a very large leak, it has a new head gasket should I be running different spark plugs in it? Hotter ones? It has the 3/4 ones recommended in the book in it
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 2:14pm
If you aren't fouling a spark plug, there is zero reason to go to a hotter heat range plug.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 2:22pm
The spark plug is completely covered in carbon very black.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8070nc Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 4:33pm
Id put a new set of plugs in it and run it some and see what happens and figure it out from there
1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 6:45pm
It's sad to think that he had the engine out and in a stand?? and the rear seal wasn't replaced?? or he replaced it and it still leaks?? Could be either one......
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 7:42pm
It was replaced and still leaks

Edited by Putnamd17 - 5 hours 4 minutes ago at 9:04am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 2026 at 8:35pm
He doesn't know how to install a D-17 gas rear seal correctly. You haven't said how long you've owned this tractor.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 4:14am
Maybe 2 years but the first year it sat around didn’t work at all only was ran to move it, and he just went through the engine a few months ago so was hoping to start using it
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 4:15am
Work as in pull anything only moved from on shed to another
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: Yesterday at 5:49am
He had to remove and reinstall the oil pan to do the rear crankshaft seal. If one isn't proficient at those tasks with this engine, it could be leaking at either or both areas.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SteveM C/IL Quote  Post ReplyReply Direct Link To This Post Posted: 16 hours 17 minutes ago at 9:51pm
Wow! Had the head off and didn't give it a simple ring job?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Clay Quote  Post ReplyReply Direct Link To This Post Posted: 7 hours 11 minutes ago at 6:57am
Was this the first time the mechanic worked on an engine without supervision?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 5 hours 23 minutes ago at 8:45am
That might be a little harsh. Each brand and model of engines has its own quirks. I never knew that some small block Chevy engines needed to have Permatex or some sort of sealer on the head bolt threads or you would probably wind up with leaks when completed. I don't work on small block Chevy's, so why would I know that. Likewise, rear crankshaft seals, pan and arch gaskets take some expertise on these AC engines to keep things dry. If he didn't use some sort of sealer on the head gasket, that might be next. But, taking on jobs that one knows nothing about is a risk to the Tech doing the work and the owner of the machine. 

Edited by DrAllis - 5 hours 22 minutes ago at 8:46am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 5 hours 12 minutes ago at 8:56am
He’s a good mechanic he’s just a case guy not many ac guys in my area that I know of
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Putnamd17 Quote  Post ReplyReply Direct Link To This Post Posted: 5 hours 10 minutes ago at 8:58am
What’s this about sealant on the head gasket? I’m going to have the head removed again so wanna make sure it gets the new one installed right
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DrAllis Quote  Post ReplyReply Direct Link To This Post Posted: 4 hours 43 minutes ago at 9:25am
Get it apart and tell me what type of head gasket material it is made of.
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