Leaving you engine on tickover

[emlclcy]

I was talking with a diesel fitter friend last night and he said that leaving the engine running at tickover to charge the batteries was a bad move, basically it can glaze the bores making the piston rings not seal correctly.

he recommended a higher rpm with the engine under load.

So do you leave your boat in gear when charging?

cheers

carl

[Athy]

If it's moving, yes. Otherwise, no, as this contravenes CART's by-laws.

[bigste]

Putting it in gear is a big no no. I think it may be against C&RT rules. I've heard the same about glazing and if I needed to charge would do it in neutral at a slightly higher speed than tickover.

[by'eck]

Definatly do not leave it in gear unless you are moving, but yes increasing revs above idle will allow alternator to produce more power as well as being cooled by its own fan more efficiently.

 

A good sized alternator in relation to the amp hour capacity of your battery bank will charge batteries quicker as well as putting adequatee load on the engine. As an example, for a 4 x 110 Ah bank would suggest at least a 100 amp alternator assuming a 12 volt system.

[Tony Brooks]

No point in spending longer charging than you need so as long as you have an ammeter (either fixed or clamp hand held type, set the revs in neutral at the point where the charge is its highest. Regularly monitor the charge and as it drops gradually reduce the speed to maintain the highest charge the ammeter will show.

 

This maximises the load on the engine and if you have a calorifier gives you the fastest water heat up.

 

With today's large alternates and battery banks it is very likely that for a fair time the engine load will be higher than when cruising at canal speed.

[Athy]

Mr, 'eck mentions an alternator fan in his post. I am by no means sure that mine has one. Is it supposed to have?

[Neil Smith]

Does bore glazing still happen on old vintage engines that at full revs are not much different than a modern engine on tick over.

 

Neil.

[Athy]

Does bore glazing still happen on old vintage engines that at full revs are not much different than a modern engine on tick over.

 

 

Surely "bore glazing" is that expression which creeps across the listener's face when an owner is talking about his vintage engine?

Edited January 21, 2016 by Athy

[Dalslandia]

Does bore glazing still happen on old vintage engines that at full revs are not much different than a modern engine on tick over.

 

Neil.

 

It's about piston speed and side load

[nicknorman]

Does bore glazing still happen on old vintage engines that at full revs are not much different than a modern engine on tick over.

Neil.

It's not to do with absolute revs, it's to do with cylinder temperature ie how hard the engine is working - relatively.

[Flyboy]

Mr, 'eck mentions an alternator fan in his post. I am by no means sure that mine has one. Is it supposed to have?

All alternators have fans. Some have an external one behind the pulley and others have it inside the casing.

[koukouvagia]

Does bore glazing still happen on old vintage engines that at full revs are not much different than a modern engine on tick over.

 

Neil.

 

The Kelvin instruction manual has this sentence:

25. IDLING.--The engine may be run without load for any length of time, provided that it is run slowly. If permitted to run at speed without load, the cylinder will cool down and the engine will knock.

[mark99]

Athy - looks like a turbine blade.

Edited January 21, 2016 by mark99

[blackrose]

I thought that bore glazing didn't happen on modern engines if the correct API CC (or above) oil spec was used?

[nicknorman]

I thought that bore glazing didn't happen on modern engines if the correct API CC (or above) oil spec was used?

I think it is not a great problem, but don't Vetus have a big thing about it? Oh and it's API CC (or below) surely? It is the use of modern high spec oils that can cause a problem.

[Guest]

We rarely run the engine in neutral for charging purposes (Vetus) and use a genny. Should we run the engine in neutral, we tend to run it at between 1100 to 1200 rpm, which as has been suggested, gives the highest charge (at a reasonable rpm) and fastest water heating.

Running in gear when stationary affects the infrastructure of the canal and is a nuisance to passing boats, causing me to collide with another boat on one occasion.

[Guest]

I think it is not a great problem, but don't Vetus have a big thing about it? Oh and it's API CC (or below) surely? It is the use of modern high spec oils that can cause a problem.

They certainly did on the 415/417 engines (no longer made it seems), where it was stated not to leave the engine idling for "more than a few minutes." When I pressed them on this, they suggested raising the revs slightly if battery charging. On the oil thing they always said "a good quality diesel oil, either mineral, semi, or synth."

When I asked the man who built Thornycroft engines the question (same base engine as a Vetus 415) he didn't seem to think that running in neutral did any great harm!

[dunfixing]

Cylinder glazing is caused by low cylinder temp. Not low revs.

If your cooling system has a thermostat fitted then there should be no problems, most diesels engines run about 75 - 80 degC.

Charging 20 plus amps should be enough load on your engine.

[blackrose]

I think it is not a great problem, but don't Vetus have a big thing about it? Oh and it's API CC (or below) surely? It is the use of modern high spec oils that can cause a problem.

 

Above, below? I don't really know? If it's below then the logical conclusion is that you could chuck any old shite in there? There has to be a minimum spec surely?

[Athy]

Cylinder glazing is caused by low cylinder temp. Not low revs.

If your cooling system has a thermostat fitted then there should be no problems, most diesels engines run about 75 - 80 degC.

Charging 20 plus amps should be enough load on your engine.

So older engines, which tend to achieve lower running temperatures, are more susceptible to this glazing? Mine runs at about 55 to 60 degrees centigrade.

[nicknorman]

Above, below? I don't really know? If it's below then the logical conclusion is that you could chuck any old shite in there? There has to be a minimum spec surely?

 

Regarding no glazing, no, the worse oil the better. But of course regarding engine wear and life, yes of course. The oil is a compromise between its ability to lubricate and it's propensity to encourage bore glazing. Where that compromise is set depends to some extent on how the engine is to be used. If it is used hard all the time, a high spec oil is preferred because it won't result in glazing. However if the engine is often operated at low power for prolonged periods (typical canal boat engine) then a more modest oil spec is preferable, otherwise glazing may occur.

[MtB]

Cylinder glazing is caused by low cylinder temp. Not low revs.

If your cooling system has a thermostat fitted then there should be no problems, most diesels engines run about 75 - 80 degC.

Charging 20 plus amps should be enough load on your engine.

 

When first I start up the 21hp Kelvin the load from 24v 20a alternator initially slows the engine speed right back back down to tickover once it self-excites, whatever the throttle setting!

[churchward]

So older engines, which tend to achieve lower running temperatures, are more susceptible to this glazing? Mine runs at about 55 to 60 degrees centigrade.

Bore glazing is a rare occurrence for an engine normally found happening in a new or newly restored engine where low temp and a combination of oil and fuel (high ash fuels don't help) contaminants form a glazed barrier between the piston and the cylinder. In true glazing you can see through the glaze to the bore hatching underneath. However, as I say rare compared to bore polishing which is about wearing the bore to a smooth shine removing the bore hatching.

 

I don't see that a low RPM diesel/older engines being more susceptible to either issue.

 

One issue with an idling engine is that the pistons can move differently to an engine under load. When under load the piston is pushed and pulled against the piston wall allowing the oil scraper to do its job (why bores eventually wear a little oval in shape) but idling they can move more directly/centrally up and down in the bore and the oil control ring(s) will be less efficient. When the bore have worn enough to be a little oval this can cause oil to pass the rings and cause a bit of smoking which goes away/gets less when under load. This effect is often mistaken for bore glazing.

[Guest]

Cylinder glazing is caused by low cylinder temp. Not low revs.

If your cooling system has a thermostat fitted then there should be no problems, most diesels engines run about 75 - 80 degC.

Charging 20 plus amps should be enough load on your engine.

Won't lifting the revs slightly lead to a quicker warm up, though? Seems to on our Vetus.

[OldGoat]

It's not so much the potential threat of bore glazing BUT more importantly charging at tickover speed is bad for the engine as it causes chatter (uneven power distribution from the engine) which can - at least cause wear and eventual failure in the crankshaft pulley keyway. Happened to me and cost me a new engine.

 

ALWAYS run the engine a bit above tickover (mine's 850 rpm) so say 1100 - 1200 rpm for a modern style engine That will-

• charge the batteries quicker
• make the engine work harder
• heat the water quicker
• and avoid any pulley chatter

Solved.