Acceptable amount of blowby for a B7100?

[Eise]

Hi everyone,

I just bought my first ever tractor, a B7100. It has been sitting for some time and I'm working to get it back in order. I got the engine running okay, but there is some blowby. I made a video of it but I can't post links yet.. (need to have a minimum of 5 posts it seems ).

I'm new to tractors and I hear different opions concerning blowby, some suggest an engine rebuild a.s.a.p. others say just run it till it stops. Anybody care to offer some advise?

p.s. I'll post the video once I reach 5 posts..

 

[David Page]

Somebody will have a good answer but I don't know. Just wanted to welcome and congratulate you.

 

[85Hokie]

blow by is a situation where I am sure you know the combustion gasses are getting by the rings. Depending on HOW bad it is, is the determining factor. I've seen them like old fashion steam engines smoking......

I bought a B71000 and it smoked bad and had a good deal of blow-by. Running it regularly helped with the smoking and it still has blow by but not as bad as before, I use a good bit of lubricate in the diesel too.

Sometimes rings can loosen back up and help a bit with the blow by - sometimes they are worn and or stuck to the point where nothing but a rebuild will help.

You can run all kinds of compression tests and determine which if any cylinder is causing the blow by or if all need a good deal of help rebuilding.

Have you had a chance to run it and run it "hard" as in mowing or something that will pull on the engine? A hot engine will blow by a little less since the pistons have moved a bit in diameter in their respective bores - but a worn engine is a worn engine.
Post a few more and show us the video

 

[Eise]

Thanks guys,

Up till now I have only run the engine without load (mostly in neutral), I'm planning to use it for mowing once I find a suitable mowerdeck. I'm sorta hoping putting load on the engine for some time will reduce the blowby, I guess time will tell.

Well, I better keep posting so I can show the video.

 

[Eise]

Well, I reached 5 posts so I can post the video now: https://vimeo.com/276942513

This is with the engine idling, I had some trouble capturing the smoke. In person I'd say it was a little more visible.

 

[Jimc3165]

I'd say that was an acceptable amount for an old 7100. Mine isn't quite that bad but it does smoke and the oil pressure will drop to about 15lbs when hot. I'd also call that just smoke from the exhaust, generally when speaking about blow by it is pressure in the crank case or at the oil fill cap. Take the oil fill cap off and hold a piece of paper over the hole to see how much of the combustion gases is getting past the rings.

 

[Eise]

But that is the valve cover breather hose, not the regular exhaust. I made a video of the engine running with the oil filler cap off:

https://vimeo.com/277154008

The smoke does seem much more pronounced than when it's coming out of the breather hose.

 

[Jimc3165]

Duh, I mistook that for the exhaust. LOL

I can say mine is getting to the point that I am considering a rebuild. It just depends on your patience with old equipment and its ability to do the job you bought it for without doing permanent harm to the equipment.

 

[Eise]

Duh, I mistook that for the exhaust. LOL

I can say mine is getting to the point that I am considering a rebuild. It just depends on your patience with old equipment and its ability to do the job you bought it for without doing permanent harm to the equipment.

I think that last part is key, I don't mind running it in this condition as long as it does the job. But I don't want to cause any irreversible damage. Thank you for sharing your views.

Anybody else out there that as another view on the matter?

 

[hagrid]

I've seen old CAT engines with way more action from the slobber tube still make heavy power.

I'd run your tractor under load and use those observations to determine the need for further internal investigation.

 

[D2Cat]

As Hagrid mentioned, diesel engines will "slobber" when left idling too long. Maybe this engine has not been used much lately and just needs a good work out.

Hook a mower to it, or a plow, or some other implement and make it work hard for an hour or so. Might see a big difference.

 

[Eise]

I was told that the previous owner only used it to level the riding arena for his horses. I don't imagine that puts a lot of stress on the engine so who knows, I'll just put it to some real work.