Mine truck is not a daily driver and it may sit up to a week without starting. Plus it's getting into the high 20's, low 30's at night. I haven't had any romps since switching to synth oil last fall. Same batteries for three years now. It's expensive to switch to Synth but it cured my romps.

 

I stopped by a diesel shop after work and they did a battery load test on both of the NEW batteries and he said the passenger batt tested out really good but the driver batt showed only a little over 10 volts. He said that with that being the case, when it gets cold at night it might kill it enough to make it weak.

So that being said, i took that battery to Checker where i bought it and they did a load test on it for the warranty exchange but the battery tested perfectly fine. So they can't replace it if it tests good. What the heck?!

So once i got home i borrowed a friends Midtronics Battery/Starting/Charging System Analyzer and did the tests with it. Testing it with the batteries hooked up to the truck i got these results:

Batteries are spec'd at 850cca and 1000 ca

Passenger-
980cca
10.92 cranking volts
14.25 v from alternator
Overall test was GOOD

Driver-
900cca
11.15 cranking volts
14.25v from alternator
Overall test was GOOD

So it tests out that everything is working fine. So i started to check for a constant draw off the batteries when the truck is off and couldn't find anything. I tested that by hooking the meter up between the postive batt terminal and the postive cable to test for a draw and got nothing. Did this with both batteries. So everything seems to be fine.

Anything else i am missing? Thought about the starter but other than the first start of the day, you can't notice any lag from the starter at all.Starts strong the rest of the day.

So one question, with the truck sitting since Saturday afternoon to monday morning, with low temps at around 34 degrees be enough to make it a little slow starting? I wouldn't think so?

I am officially stumped!!!!!!!!

 

As stated earlier the lighter weight synthetic oil will aid very much with this issue, hard to believe? Try sticking a little 15W-40 and a little 5W-40 in the freezer for an hour or so as see for yourself whether you believe that "thicker" oil will slow the cranking down!

 

I understand that the lighter weight oil will 'fix' the issue, but i know guys here that run 15-40 all winter long with the temps and have no issues whatsoever. And its not even winter yet, only gettin in the mid 30's. It seems that would just be hiding the issue.

 

I too run 15W-40 all year long but also my truck rarely sits for more than about 6 hours, when it does how ever, and was not plugged in I will have similar symptoms, even in the 40's, maybe some leave it plugged in, maybe they park it in a garage. Not an expert by any means just trying to help too. In order to start 10.5 volts in needed to fire I believe. ICP of 750PSI, glow plugs aid with the "cooler" fuel but many start without glow plugs? So the thought of oil "covering" up another issue, definitely possible. The HPOP must be able to pump the oil "up" to the control pressure, thus the possibility of an issue there exists, but it would also be much easier on the pumps "oil" and "hpop" if it were working with lighter "thinner" oil. Maybe this bump will help get the gurus out.

 

The thing that gets me is the one morning in the high 20's with the new batts installed the night before she fired right up. Could it be the possibility of the starter losing power? If that was the case you usually have issues whether warm or cold, no matter how long the truck sits.

 

Possible that you have a starter that is losing steam. When mine went out it turned over a little slower every day until it finally siezed.

Also I might have missed, have you checked your glow plug relay?

 

Got a new one in March, i also have little no white smoke at start up, usually a little black puff.

 

Starters usually start to grind, or ping, when they go bad...

But, if everything else checks out and the starter is still spinning slowly it could very well be your issue.

I would still get out the Fluke and make sure you are getting power to the GP's before I replaced it.

 

Ya i've had starters go out before in this truck and they just started grinding before anything.

As far as checking the GP's, that wouldn't necessarily cause slow cranking i wouldn't think. When i'm talking about slow cranking its the starter motor turning over slowly, like with weak batteries. But as i mentioned above, batts are new and everything tests out good.

Also Thanks for all the info everyone, hope i can get it figured out

 

Just a thought, have you checked where your ground cables terminate to the frame? Also, where teh positive ties in to solinoid and at starter? Corrosion anywhere in teh cables, or even weak/flimsy, ie broken wires in the cable can be the culprit too.

 

I checked the connections to the starter and all seems tight. Haven't had a chance to take them off and see if they are dirty and corroded. Also i haven't checked where the batteries ground to the frame. Those were my next things to try.