Anybody Else Notice This?

[Username Taken]

Haha, no worries man we've all had that kind of brain fart when it comes to engine instrumentation.

I'm commenting to this post before finishing reading the thread, just to point out that a change in engine tone does not only indicate a minor load increase from alternator load and thus battery charging. It could be many things, but most likely IMO is a change in fuel injection pattern/timing associated with the physical warmup of the engine.

If you want to know if the alternator kicked in, clamp a multimeter to your battery and watch the voltage right after startup. My bet is that the alternator is working more or less right away (why would they delay this?).

Many alternators have a delay built into them. Sometimes it's because the Glow Plugs are on and the ECU doesn't want to overload the alternator, sometimes the alternator needs to be 'energized' before it starts charging. Sometimes, I don't know......

But I know it's the alternator kicking in. Well, I'm 95% sure that's what it is.

I was just making idle conversation and that's my bad because I'm 1,400 miles from my tractor and it's not right that I brought it up and can't follow through by putting a multimeter or something on my tractor to test it.

But right now, it's cold up there and it's getting down into the low teens or even single-digits later next week.

So I don't feel all that bad about it.

 

[deezler]

Yeah we're preparing (mentally) for true winter to hit us next week up here. Hopefully some decent snow in time for xmas!

Maybe I will voltage test my ck3510 upon a cold startup and see what happens..... My engine changes tone for all sorts of reasons, but it's a bit more complex than your cx2510 with no emissions aftertreatment.

 

[Dclerici1]

You start a cold motor at 1200/1500 rpm’s? Not afraid of the top end, rod/main bearings, or turbo bearings running dry?

 

[Robin Veerman]

As per several Kioti manuals, warm up the tractor at 1200-1500 rpm, or 50% throttle. A quality synthetic diesel engine oil will circulate upon starter activation….

 

[Dclerici1]

I’ve never started any engine with the throttle set at 1200/1500. I’ll start it set at idle, then run it up to 1200/1500 to warm up. If that’s what kioti wants then why don’t they just set 1200 as the idle rpm?

 

[Robin Veerman]

Because diesels don’t warm up very quickly at a low rpm, doesn’t mean that you shouldn’t have the option to idle it down, if you want to… The world has more than enough automatic systems as it is. But, I was just stating what I found online for several Kioti models.

 

[34Willys]

My KIOTI idles at about 1200 RPM. When started cold it's about 1050, then after a minute, it raises to 1200. Warm start idle is 1200 RPM. That's as low as the idle is.
Patrick

 

[Username Taken]

You start a cold motor at 1200/1500 rpm’s? Not afraid of the top end, rod/main bearings, or turbo bearings running dry?

I don't leave it at (approximately) 1,200 RPM for very long -- 5 seconds, maybe. Just enough to get the oil moving. I use 5w-40 Synthetic. It also gets the hydraulic fluid moving.

I then idle it back down to whatever the factory pre-set is. I think it's around 900. Unless it's cold out, then I'll leave it around 1,200 for a bit.

All your newer vehicles idle-up at start. I know that it's old-school (I'm old-school myself) to idle your engine low at start up, but that has been proven to be very incorrect. Took me a while to grasp that concept, too.

I also have a Ram CTD (cummins turbo diesel). I use 5w-40 syn in that as well. If it's not hot/warm out, I'll up the idle on it (high idle) to around 1,100 and let it warm up for a minute or two.

Your engine bearings, etc, are never dry. Never. Not even immediately after assembly at the factory. They always have some kind of residual oil on them. Synthetic is better at that than Dino oil but even then, today's conventional oils have improved by leaps and bounds over the old stuff.

The act of turning the engine over with the starter primes the bearings, etc, with oil. It should anyway.

I've heard car engines that do a 'death-rattle' thing right after an oil change start-up for a second or two. Very unnerving. Some Ford's are known for that. Because they like to side-mount their oil filters and the anti-drain back valves don't always function right.

I had one that did it after every oil change. Hated the sound. Made me cringe. Did it for 275,000 miles and it was still running good when I sold it.

 

[deezler]

It's not like 1500 rpm is particularly dangerous for your mains/rods/cams while somehow 1000rpm is always perfectly safe. I would argue there's essentially no difference in observable wear - you just need oil pressure either way, and it comes up quick.

More important to me than starting/warm-up engine speed, is to avoid much load while fully cold. Pressure on rotating/sliding surfaces within your internal combustion engine is what can (in rare circumstances) break through the oil film and cause real metal-on-metal wear. And this contact pressure is nominally low, but rises with requested load.

One thing I don't like about starting on full low-idle is that my Kioti-daedong engine doesn't immediately run smoothly at 900rpm on a cold startup. It chugs and stumbles a bit (just a bit) - but that means the rpms are fluctuating and the fueling is thus alternating up/down on what is essentially a poorly tuned control loop. So I bump the throttle lever up just a bit to start, and it instead immediately settles into a smooth cold idle at 1200-1300 rpm. Since I don't like blasting too much diesel exhaust into my garage, I then gently, slowly drive outside after about 5-10 seconds of idling, then see how much patience I have to keep sitting before driving at away and actually getting to work.

Modern engines can start up cold and get right to work, any joe homeowner has nothing to worry about with their hobby CUT.

 

[iptman]

I came in here today just to search up this exact issue before figuring out how to get my cx2510 out to my dealer. In my case it was the alternator belt being loose. I had to move the alternator a good inch to tighten up the belt and I'm now getting good RPM readings on the tach. So I guess that means the tach only reads voltage off the alternator? Is that how most diesel engines read RPM?

@Username Taken - maybe change the title of the thread to "Low RPM shown on tach" or something to that effect so others might find this issue easier. Post up if this ends up being your issue too.

Voltage before tightening...

Voltage after tightening...