See original post for some background if you like: http://forums.yesterdaystractors.com/viewtopic.php?t=1323859&highlight=
Back in Dec. 2015 I posted on this topic and never got around to sharing what I found. Been through a rough patch just and can't believe it's been that long. Anyway, my 1958 851D had a problem of excessive blue smoke and heavy oil consumption since I purchased it. With use this problem became sever, burning two quarts per hour and finally becoming difficult to start. Once started the tractor ran great, no excessive blow by (in my opinion at least), knocking or roughness and plenty of power.
Upon investigation I found that my fuel had become contaminated. I drained the tank and significantly more fuel came out than I remember putting in. With clean fuel the engine started easily again and seemed to smoke less. I had only put in about gallon of fresh diesel and there was probably a pint or so of old fuel in the tank. So some smoking was not too worrisome. However soon the problems returned and I found the fuel contaminated again.
My post on this received some thoughtful responses but no convincing answers. One even suggesting a mischievous neighbor kid! My suggestion that engine oil had somehow made it into the fuel refuted as all but impossible. I have to agree that after studying pump schematics that did seem unlikely.
And the problem was.... a bad umbrella seal!
I refurbished the injector pump with a seal kit and discovered that the bottom umbrella seal had become separated. The upper umbrella seal was still intact. The internal gaskets, o-rings and what not were also in tact. The pump housing where the umbrella seals contact (pilot tube?) has significant wear but this pump does not have any brass insert to replace so I guess I will have to live with that.
Now the tractor starts and runs great! I burn about five gallons of diesel per pint of engine oil. No more fuel contamination and I do not smell like an old rag after sitting it for a hour! Some good news at last.[/url]
Back in Dec. 2015 I posted on this topic and never got around to sharing what I found. Been through a rough patch just and can't believe it's been that long. Anyway, my 1958 851D had a problem of excessive blue smoke and heavy oil consumption since I purchased it. With use this problem became sever, burning two quarts per hour and finally becoming difficult to start. Once started the tractor ran great, no excessive blow by (in my opinion at least), knocking or roughness and plenty of power.
Upon investigation I found that my fuel had become contaminated. I drained the tank and significantly more fuel came out than I remember putting in. With clean fuel the engine started easily again and seemed to smoke less. I had only put in about gallon of fresh diesel and there was probably a pint or so of old fuel in the tank. So some smoking was not too worrisome. However soon the problems returned and I found the fuel contaminated again.
My post on this received some thoughtful responses but no convincing answers. One even suggesting a mischievous neighbor kid! My suggestion that engine oil had somehow made it into the fuel refuted as all but impossible. I have to agree that after studying pump schematics that did seem unlikely.
And the problem was.... a bad umbrella seal!
I refurbished the injector pump with a seal kit and discovered that the bottom umbrella seal had become separated. The upper umbrella seal was still intact. The internal gaskets, o-rings and what not were also in tact. The pump housing where the umbrella seals contact (pilot tube?) has significant wear but this pump does not have any brass insert to replace so I guess I will have to live with that.
Now the tractor starts and runs great! I burn about five gallons of diesel per pint of engine oil. No more fuel contamination and I do not smell like an old rag after sitting it for a hour! Some good news at last.[/url]
