I'm currently rebuilding the engine on a John Deere 690B excavator. I've come across a few questions that I'd like to ask, but I'm seeing conflicting reports on what's on-topic here.

Your help center seems to say they're on-topic:

Questions related to the maintenance and repair of motor vehicles and their accessories, internal combustion engines, even in applications other than automotive so long as the question is related to engine or engine accessories.

This well-received answer from a moderator to a question asking if the scope should be broadened to include excavators (explicitly mentioned in the question) says that they shouldn't be included.

The two answers to this question asking whether large (nowhere near an excavator, though) machinery should be on-topic seem to favor including it.

So I'm looking for some consistency here: Are questions about large diesel engines on-topic?

4 Answers 4


Absolutely this is on-topic here. 'Nough said.


If you go back and look, you'll notice that when I answered that question three years ago, I mostly focused on helicopters (out of that long list of all possible vehicles) as an example of "out of scope." The big problem that I saw there was that the information isn't transferable. Discussions about the Jesus nut can be super fun but won't really assist someone with engine trouble.

So I'm looking for some consistency here: Are questions about large diesel engines on-topic?

This is a more focused question than the old "let's broaden the scope to include anything that moves!" discussion and is worth a different answer. I agree that these sorts of issues will be in scope. I won't be able to contribute a lot but I look forward to the answers....

  • Agreed, Sir Mister of The Godly Hammer! Sep 8, 2016 at 1:38
  • 1
    In any case, helicopters would be more in the aviation stack.
    – anonymous2
    Sep 8, 2016 at 13:03

I'm ambivalent about aircraft, admittedly everything is different, but it's interesting to compare with terrestrial vehicles. Also, I think you (I) can learn a lot from the ways of the A&P mechanic. When you adjust the Jesus Nut you don't want to be wrong…

Anyway, I'm not sure how much aircraft types would want to hang out here for aircraft related discussions, but it does seem like there are engine related (at least) issues where there would be good overlap.

As for heavy equipment and big engines, absolutely!


We have a similar conundrum on https://bicycles.stackexchange.com/ over electric and petrol-kit bikes. The consensus there was that the bike parts are on topic, but the petrol engines were totally off topic. Electric bikes remain a grey area.

WRT to the question, an engine is an engine whether its in a car, truck, piston-powered aeroplane, tractor, or generator.

Jet engines, avionics, airports etc would be off topic.

The hazy bit in the middle would be your tractor's hydraulic PTO, which should be similar to power steering, but enough differences remain. Likewise, three point linkages or towed/powered equipment may be on thr boundary. There's no harm in asking, but the answers may not be drawing from a large pool of knowledgeable answerers.

  • 1
    Jet (turbine) engines are off-topic :-( What about steam? Kind of seriously... I think I'm against calling any prime mover off-topic (at least if it is a reasonable application), but for sure we may not get many responses for some of the more esoteric ones.
    – dlu
    Sep 20, 2016 at 18:04

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