# Tractor help! **URL:** \ **Category:** In My Humble Opinion\ **Created:** [July 19, 2015, 10:46pm UTC](https://boards.straightdope.com/t/tractor-help/725652 "2015-07-19T22:46:31Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![StGermain](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stgermain/32/2868_2.png) [@StGermain](https://boards.straightdope.com/u/StGermain)\ **Post date:** [July 19, 2015, 10:46pm UTC](https://boards.straightdope.com/t/tractor-help/725652/1 "2015-07-19T22:46:31Z")
My old 1970’s Yanmar is sick. Are there any mechanics around who would venture a diagnosis? My observation: I started her up and started bushhogging. She ran fine for about 30 minutes, then petered to a stop. She does this sometimes, and usually if I let her think about it for an hour or so, she usually starts up and goes okay, for a while. I went in and got some lunch and went back out for more mowing. She started up okay, but seemed to be vibrating a lot. The engine was making a loud knocking noise. She petered out and I left her in the field. My stepfather, who isn’t a mechanic, but used to work on ship’s engine rooms in the navy took a look. These are his observations: > [@](#): > > We tried to start it later and had no luck. The engine would fire but acted as though only one cylinder was firing or there was a problem with the valves. I did not see any blowback either from the intake or crank dip-stick area when we were trying to start is so apparently the pistons and intake valves are OK. At the time I also checked the oil and water and both were where they should be. > > Turning the engine over on the starter did not produce a knock and the engine coasted down without an abrupt stop. The compression release made a significant difference in how fast the engine turned on the starter. > > We bled the fuel system, both at the pump and the injectors and did not see any air but did see fuel. > > I drained the crankcase and saved the oil. There was a large amount of brass, both flakes and splinters (but no chips) in the oil. I looked at one of the larger flakes and it appeared that the flake had been hammered (not scraped) but there were scrape marks on the chip. > > I looked at the rods-one rod was quite loose at the crank but both appeared to be tight at the wrist pin. The pistons appeared to be whole and I did not find any aluminum in the oil I drained. The cam had some indication of wear on the lobes but nothing that would indicate a broken cam or valve lifter. > > I turned the engine over by hand after opening the compression release and could not feel any drag or binding. I could not turn the engine over until I opened the compression release. > > One last thing- StG feels that our difficulty in starting the engine was due to her not dis-engaging the clutch which may have been a problem not related to the knock and brass. The clutch is badly in need of replacing the disk and possibly the face plate as it is difficult to shift from neutral to low without excessive “grinding”. Does anyone have any thoughts, besides my neighbor’s, which was “Buy a new Kubota and let me drive it.”? StG ---
**Author:** ![enipla](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@enipla](https://boards.straightdope.com/u/enipla)\ **Post date:** [July 19, 2015, 11:22pm UTC](https://boards.straightdope.com/t/tractor-help/725652/2 "2015-07-19T23:22:55Z")
First, buy your stepfather a few cases of beer. I had an Allis Chalmers (1980?) to take care of our drive. Spread gravel, that sort of stuff. Loader with box scraper. It just got too tired. And I got VERY tired of trying to keep it running. I traded it in 2 years ago for a Kubota. B26 something or other. 4x4 power steering loader and box scraper on the three point hitch. PTO at rear and underneath (I don’t mow though it’s just rock and trees where I live). I spread 14 tons of gravel on the drive last weekend with it. Piece of cake. And the best part is that it always starts. My Wife thinks that it might be a good idea to get the backhoe attachment for it. I’m wondering just how much work I have ahead of me. 😃 ---
**Author:** ![48Willys](https://avatars.discourse-cdn.com/v4/letter/4/db5fbb/32.png) [@48Willys](https://boards.straightdope.com/u/48Willys)\ **Post date:** [July 20, 2015, 1:31am UTC](https://boards.straightdope.com/t/tractor-help/725652/3 "2015-07-20T01:31:33Z")
Without seeing & hearing it myself, I can only guess as to what the problem is. Your stepfather’s desciption is the next best thing for us to use to make a GUESS as to what the problem is. Since the engine is a diesel, that eliminates any ignition problems. It can almost only be a fuel delivery problem, or a valve train issue. I have seen some really weird stuff in my many years working on engines, so I am aware that anything is possible. Since your stepfather was able to successfully bleed the fuel system, finding no air, it is likely just fine. My GUESS is, It sounds like one of the bronze exhaust valve guides may have seized on the valve. It then moved up & down with the valve. This probably wollowed out the block it was press fit into. Which may have caused the guide to beat itself into pieces, creating the “brass” chips & chunks. This would cause both the hammerd look, as well as the scraped look that your stepfather observed. Note" bronze and brass look very similar when they are dirty & oily. The engine running for 30 minutes or so & then stopping, yet being able to restart it after it cools off, is typical of a seizing valve guide. The engine gets warm & the valve guide seized to the valve, causing the engine to miss & then to quit. When it cools off, the valve is free to move & the engine will run again, until it gets warm again. If not fixed, this often results in a bent valve, or a broken valve guide, or a broken valve, or a severly worn camshft & its followers (lifters), or any combination of the above. If the valve itself breaks, the peice that is broken off often will knock a large hole in the piston. Any of the above is bad. The rod loose on the crankshaft is a deal breaker. The engine needs to come out & needs rebuilt or replaced. Which one will depend on how much damage was done to the crankshaft & the block. Some folks will try to rebuild the engine in the tractor. That may be possible, but IME, it is not worth the major hassle it becomes. In any case, you would need to pull the engine to fix the clutch problems. If the rod bearing failed it will knock loudly. If the engine is run with a failed (knocking) rod bearing, it often will litterally beat the crankshaft to death. The crankshaft may not be able to be saved. If this is the case, it usually means that a new engine is in order. If I am correct on this guess, the block will have to be machined to take an oversized valve guide. I am not familiar enough with Yanmar engines to know if there is enough material (metal) in the valve guide area to be able to oversize the valve guide hole enough to effect this kind of repair. If not, a new engine is needed. If a new engine is not cost effective, you MAY be able to source a good used one from a tractor wrecking yard. In any case, the repair will be fairly expensive. Have a tractor mechanic that is familiar with Yanmars have a look at it. After all, I may be wrong & it will be a cheaper fix than I think it will be. I hope so! IHTH, 48. PS, I agree with stepfather, the clutch problem is a seperate issue. Fix it while the engine is out. ---
**Author:** ![48Willys](https://avatars.discourse-cdn.com/v4/letter/4/db5fbb/32.png) [@48Willys](https://boards.straightdope.com/u/48Willys)\ **Post date:** [July 20, 2015, 1:48am UTC](https://boards.straightdope.com/t/tractor-help/725652/4 "2015-07-20T01:48:34Z")
> [@enipla](#): > > First, buy your stepfather a few cases of beer. > > I had an Allis Chalmers (1980?) to take care of our drive. Spread gravel, that sort of stuff. Loader with box scraper. It just got too tired. And I got VERY tired of trying to keep it running. > > I traded it in 2 years ago for a Kubota. B26 something or other. 4x4 power steering loader and box scraper on the three point hitch. PTO at rear and underneath (I don’t mow though it’s just rock and trees where I live). > > I spread 14 tons of gravel on the drive last weekend with it. Piece of cake. And the best part is that it always starts. > > **My Wife thinks that it might be a good idea to get the backhoe attachment for it**. I’m wondering just how much work I have ahead of me. 😃 Bolding mine. Buy it for her. Then let her use it. She will have fun & you get a new toy. Win, win.🙂 ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [July 20, 2015, 10:22pm UTC](https://boards.straightdope.com/t/tractor-help/725652/5 "2015-07-20T22:22:52Z")
> [@enipla](#): > > My Wife thinks that it might be a good idea to get the backhoe attachment for it. I’m wondering just how much work I have ahead of me. 😃 Twenty years ago, my neighbor used a Kubota backhoe to dig a ditch for a water line. The mechanism that swung the backhoe arm from side to side involved a hydraulic actuator pulling on a chain. The neighbor said that that arrangement was always causing problems. Just something to think about when looking at backhoes. ---
**Author:** ![wolfman](https://avatars.discourse-cdn.com/v4/letter/w/a8b319/32.png) [@wolfman](https://boards.straightdope.com/u/wolfman)\ **Post date:** [July 20, 2015, 10:41pm UTC](https://boards.straightdope.com/t/tractor-help/725652/6 "2015-07-20T22:41:30Z")
1970s? Sorry, can’t help you with one of those new-fangled modern tractors. 🙂 I spend way too much time as a kid helping keep an ancient-even-then Ford 9N going. But I bet that damn thing is still going today, as long as someone is spending the 20 hours each spring to figure out what is wrong now.