CP3 experts: cranking the engine for 15 seconds with the lift pump off harm the CP3?

[brods]

Came across some recommendations from several manuals to crank the engine without fuel until the oil pressure comes up. Then start as usual. The crank without starting procedure was recommended after an oil change or after the engine sat unused for a period of time. Freightliner was after 3 days, Volvo was after a week and Cummins was after 30 days. Here is the Cummins recommendation:

Whenever an engine has been inoperative for more than 30 days, Cummins recommends disconnecting the wire to the fuel shut-off valve and cranking the engine until oil pressure registers on the gauge before starting the engine. This practice will prevent "dry starts" and allow oil to bearings and shafts prior to starting the engine. A toggle switch can be wired into the starting system for this.

www.cummins-uk.com/sa/pages/en/customerassistance/performancetips.cfm



The 12v guys just have to disconnect the shutdown solenoid. With the CP3 things look more complicated. I figure manually energizing the starter solenoid with the ignition key off will prevent the injectors from firing. Without power the FCA will be open so the rail pressure should stay low. So should the lift pump be energized to keep the CP3 lubed? Anything else?



Especially when fuel was $5/gal, the truck sat for a few weeks at a time. I’d prefer to do some type of pre-lube before starting it after it sit a while. This seems like the poor mans pre-luber...

 

[TCDiesel]

If it is Dry possibly, No need to worry if wet.

 

[brods]

Thanks.



You posted a picture of a CP3 disassembled in another thread, do you know if there are any brass parts in it? I found some brass particles in the pan of fuel drained from the fuel filter housing during a filter change today. Can't be 100% positive they weren't already in the pan, but it was wiped clean before the fuel went in there. Should I be concerned? No, I haven't tried cranking it with the key off yet...

 

[TCDiesel]

No brass Parts, But I have no Idea what the Brass came from, had to be in the pan?

 

[brods]

Or it was in the fuel.



As long as its not the CP3 Oo.

 

[Tinman]

I don't know the differences, but the CP3 in the Jeep Liberty doesn't have lift pump at all. It is a neg pressure system from the tank. That cp3 has a mech lift pump in it. Don't know if our pumps have that or not. But those Liberty cp3s done have pressure when they start. I don't like this system and it has some issues, so our Libby now has a Faucet lift pump. I gonna swap out the fuel canister with my 06 and the libby this summer. My 06 will sometimes sit for weeks at a time so I'm interested in the what people think about this. Did you fine how Cummins recommends this starting technique on the CR motors?

 

[brods]

..... Did you fine how Cummins recommends this starting technique on the CR motors?

They don't. After the first rep sent me on a wild goose chase, the second Cummins rep sounded like he knew his stuff. He said they do not recommend the procedure with the CR motors because of the fuel system, but didn't have any details. As far as the engine itself, he said the procedure is fine.



Our CP3 pumps do have the internal gear pump to pull fuel, the question is if they can pull any through a shut off in-tank pump. I am trying to confirm with Bosch if it is ok to crank without the lift pump. Right now I plan to run the lift pump just as a precaution, that is unless Bosch (or Twest or others) can point out potential problems by doing so.



It would be great if the Smarty offered a “no start cranking” software option to block the injectors from firing. Similar to the programming on a gasser to clear a flooded engine. Hold the accelerator to the floor while cranking and the injectors do not open.....

 

[AH64ID]

You would just have to guess when oil pressure comes up as the gauge on your dash is fake.

 

[brods]

Either a cheap pressure switch (similar to the stock 6 psi one) wired in series with a light or a real oil pressure gauge will indicate when the oil pressure is up.



Looking over the wiring diagrams it appears not too difficult to make a fairly foolproof system for an automatic transmission truck. A couple of relays, fuses and a pair of momentary switches should do it.

 

[Tinman]

You would just have to guess when oil pressure comes up as the gauge on your dash is fake.

Good reason for a mech gauge, which I have.

 

[AH64ID]

Good reason for a mech gauge, which I have.

Yeah I put one on too... It's pretty silly that our trucks don't have a real gauge from the factory. . The OEM "idiot gauge" is only accurate at ~1300 rpms with 15w-40.

 

[rbattelle]

Wouldn't it be simpler to just start the engine every, oh, 25 days instead? I guess if you're out of town, that's a different story.

My Cummins troubleshooting manual for the common rail engines makes no mention of doing this after an oil change. Rather, it specifically requires the oil filter be filled so that the lag in oil pressure is minimized.

It's funny, farmers use these engines in their agricultural equipment that sits unused through the winter months. In the spring they'll turn the key and off they go. [I'm sure some follow the above procedure, but I bet most don't].

These engines are also used in backup generator systems that sit unused for up to a year! If the power goes out, does someone go out and crank the engine before startup?

Ryan

 

[AH64ID]

Wouldn't it be simpler to just start the engine every, oh, 25 days instead? I guess if you're out of town, that's a different story.



My Cummins troubleshooting manual for the common rail engines makes no mention of doing this after an oil change. Rather, it specifically requires the oil filter be filled so that the lag in oil pressure is minimized.



It's funny, farmers use these engines in their agricultural equipment that sits unused through the winter months. In the spring they'll turn the key and off they go. [I'm sure some follow the above procedure, but I bet most don't].



These engines are also used in backup generator systems that sit unused for up to a year! If the power goes out, does someone go out and crank the engine before startup?





Ryan

My dad had a 3406 Cat in his boat, you could pull the throttle thru a detent and turn the fuel off, so the above procedure was in the manual. With the release of the 3406E there is no capability to turn off the fuel manually, so the procedure went away.

 

[rbattelle]

I'd be interested to see how you activate the starter apart from the ignition switch. In the "old days" you could simply manually energize the starter relay.

Looking at the wiring diagram, it looks like there are only 2 wires on the starter - power from the battery and a +12v signal from the starter relay. I think if you simply run 12v to that signal wire the starter will engage. Very easy to hook up with a switch in the cab.

Shoot, if this works out, I might even give it a shot! Hard to beat the convenience of sitting in the cab and pushing a button.

Actually, let's be honest - it would be even cooler to plumb in an external oil pump. But that would also require installing a second pickup in the pan.

Ryan

 

[brods]

Imo the "manual crank" switch should be as fail safe as possible so the wife, kids or someone else borrowing the truck can't accidently engage it. It should also insure no modules or sensors are back fed electrically. I figure it is not too hard to wire an automatic truck it in such a way so that the it has to be in park, the key has to be in the ignition and you need to press and hold two push buttons to make it crank. Two buttons so it can't be engaged accidentally by pressing one button... the "what is this button for?" (as they are pushing it). It will be disabled when the key is in the run or start position so the starter can't be engaged while the engine is running. Probably will add a cheap pressure switch and light to see when the pressure gets up.



As you've pointed out both the starter and the lift pump can be powered directly by tapping into the circuits downstream of the factory relays in the fuse box ... um... . the "Integrated Power Module". The open factory relays will prevent any back feeding.



There is at least one nice pre-luber pump system that appears to have addressed most of the problems with pre-lubers in the past, but at $700 for a system it is just not in the budget.

 

[brods]

No good.

AH64ID approximately how long did your Dad have to crank the Cat to get oil pressure?



Did some preliminary testing and after sitting for a few days it looks like the engine has to be cranked minimum of 30 seconds to register any pressure at the filter head. One equipment manual with the 5. 9 recommends to operate the starter for up 15 seconds at a time and after every 30 seconds of cranking allow the starter to cool down for 2 minutes before cranking again.



Some rough estimations: normal starting of the engine brings the oil pressure up in 3 to 5 seconds. Thats about 35 to 60 engine revolutions under load. Cranking the starter for 30 to 45 seconds is about 100 to 150 engine revolutions (assuming about 200 rpm during cranking).



I have no way of knowing which causes more wear on the engine components and cranking the starter for 15 seconds straight, multiple times, just doesn’t feel right. This is not the simple solution I was hoping for and it would be even less attractive in the winter time where the cranking rpm would be lower likely requiring even more cranking time to achieve pressure.



I guess that leaves accumulators or motor driven pumps as the only options for effective prelubing. Anything else out there?

 

[rbattelle]

I've been wondering how you were coming along on this! I'm sorry to hear it's not really practical.

it would be even less attractive in the winter time where the cranking rpm would be lower likely requiring even more cranking time to achieve pressure.

Not to mention you'd need STRONG batteries to do that much cranking. I don't know about you, but I run 15W-40 year-round and when it's 0°F outside I need a ton of power to turn the truck over.



I'd be nervous adding a preluber to the oil system. Actually, I'm nervous working with the oil system anyway. It's the engine's life-blood. One tiny mistake and you're in trouble. One small leak in a fitting on a long highway drive and you're screwed.



Ryan

 

[chipster]

push button

just run a wire from the batt pos with a fuse to a push button, to a normally closed oil pressure switch, and on to the starter solinoid. when the oil pressure gets over 10 lbs (or whatever pressure you buy) the switch opens and the push button won`t work. you don`t need the key in the switch, or an oil pressure gauge to look at. when the oil system builds pressure the starter will quit crankin`, simple!!!:-laf:-laf

 

[gitchesum]

Just pull the top of the starter relay in the PDC off and manually engage it.

 

[AH64ID]

AH64ID approximately how long did your Dad have to crank the Cat to get oil pressure?

15-20 seconds maybe?



Those engines had sat for 9 months a year, so I think it was a good thing.