12H CAT graders hard to start in cold temps

[from_the_county]

It only starts to smoke right before it starts

 

[Nige]

Ok, that means the HEUI system isnt coming out to play. Off the top of my head I
would say your problem is a low cranking speed. Until sufficient oil pressure is generated in the hydraulic system the electronics stay deactivated which is why no smoke comes out of the chimney.........,.

 

[from_the_county]

We are going to change batteries they are two years old on two of the graders but one grader the batteries are about Six months old. We use 10 weight oil in the hydraulics. would you suggest different oil? We really only struggle with this problem about 10 days or so during the winter but it is a real pain those few days.

 

[Nige]

10W oil should be fine for the hydraulics. I would not suggest going any lower on viscosity than that.
However I would suggest going lower on engine oil viscosity. 15W40 is really only good for starting down to about 15DegF, 10W30 goes down to 0 DegF, 5W/30 or 5W/40 down to -22 DegF, and 0W40 down to -40 DegF. Remember to change the oil grade plug if you change oil. If you want a complete copy (with photos) of the document that Mobiltech posted above send me a PM with your e-mail address and I'll gladly send you a copy.

You never answered my question about altitude above sea level. It could be a factor.

Personally I would get the auxiliary start receptacles installed on them so you can boost them externally by simply plugging in another machine or an external battery cart.

For a simple way of explaining the way your injection system works on that engine you have to understand the difference between "Desired Injection Actuation Pressure" and "Actual Injection Actuation Pressure". Desired is calculated by the electronics, Actual is what the pressure sensor downstream of the HEUI pump measures. When you are cranking the engine cold the Actual pressure has to rise to the Desired pressure before the electronic system will activate the fuel injectors. That's why you get no smoke out of the chimney until just before the engine actually fires up, up to that point the electronics were disabled.

When the ambient temperature is really cold the efficiency of your batteries falls and that plus parasitic loads from the engine oil, hydraulic pump, etc, cause the starter to turn a tad slower than normal. Actual pressure rises very slowly therefore it takes longer to fire up.

Do the graders have Cat or aftermarket batteries in them..? Although they are more expensive I've never found a better battery than Cat ones. Whatever battery you buy needs to be rated at a minimum of 1150 CCA if you want to really spin the starter motor when it's cold outside.

 

[Delmer]

He's in Arkansas so the elevation is probably below 1,000'.

I'm of the opinion that a diesel in good shape should start down to 0 without any starting aid, maybe the intake heater isn't helping because by the time the engine gets fuel it's already blown the warm air out? Ever try cranking for ten seconds, let the heater heat back up then crank again?

I'd put block heaters in before I'd replace batteries that new. 20 is not that cold for batteries or thick oil for that matter, but a warm engine makes a huge difference in letting it spin faster.

 

[Nige]

It's a HEUI engine and when the ambient temperature is cold it's all about engine cranking speed to get the oil pressure in the injection system up to a point where the electronics decide to come out and play. Hence my comments about engine oil viscosity, battery condition, and battery cold cranking capacity in no particular order.

A block heater would be an option but if the OP is saying they only see the problem approx 10 days a year personally I'd go for the auxiliary start receptacles in order to boost engine cranking speed.