Cylinder Bore Glazing

[MVDestiny]

I've heard a lot of talk about 'bore glazing' but it seems to be a subject that most people have an opinion on, but it can be difficut to get to real facts.

If you run a diesel on tick-over for a lot of hours without load, I understand that this is not good for the engine and will glaze the cylinders - is this still true on modern engines?
I run my engine normally between 1300 - 1500 revs for optimum speed vs economy, the max rated speed is 2600, (John Deere), is this too slow?

 

[Divemaster1]

Bore glazing was a problem with two stroke dieseles (like mine) when they were at idle a lot... We run ours at lenght at 12 - 1300 (max rated 2300) and do not experience any problems ... but we also do runs at length at 18 - 1900 for speed (19 knots at 1900 RPM).

Problem with bore glazing is very rare with modern four stroke engines, and with your wonderful iron lumps, I'd be very happy at 13 - 1500. Main thing you need to ensure is that you get the engine temperature up to a reasonable level...and I'd hazard to guess that you'd be at approx 75 Degree C on water at the speeds you are cruising at, which I'd also be happy with. Keep on going, give her good oil and clean fuel, combined with good air supply and you'll have years of happy, trouble free engine use...

 

[Morpheous]

Someone once advised me that diesels don't like being at the same revs for hours on end, so I modify my speed quite regularly when cruising distances. No idea if there is any truth in it though

 

[Poignard]

Someone once advised me that diesels don't like being at the same revs for hours on end, so I modify my speed quite regularly when cruising distances. No idea if there is any truth in it though

Ships' main engines and generator engines run at constant speed for weeks at a time without harm. Any AC generator has to run at constant speed to maintain the supply frequency.

Plenty of other examples, e.g. Sark Electricity Company.

 

[Trundlebug]

I think it's still true for modern engines, I don't see why it should have changed. Although the materials and oil quality may be better, the fundamental design and function of diesel engines hasn't, so I would imagine this particular trait is the same.

I don't think the low revs are a problem, nor running at constant revs (it's what diesels are good at), it's the lack of load that causes them to glaze.

As long as they're working, and have good oil as mentioned above, they'll be fine.

 

[[2068]]

Someone once advised me that diesels don't like being at the same revs for hours on end, so I modify my speed quite regularly when cruising distances. No idea if there is any truth in it though

Maybe for the first few hours running-in to get the rings bedded in. I can't see how this would make a difference after that, other than being something for idle hands to do.