Rich, I'm pretty used to starting a PSD in the cold, it's -15 here this am, and realize what the GP are doing. After the first rev of the crank, how much of that warm coffee feeling is left?

I don't think the GP's have enough "umpf" to heat much mass. I do understand that the GP may been heating while the engine is running....and the WTS lite is off.

There seem to be two lines of thinking here, 1) cycle the GP's for a longer time, that helps prevent/minimize romps, 2) Switch to a 5w oil.

Combining both is an approach as well. I've had my best luck going to a 5w oil

I happen to believe the "romps" are oil system related, whether low HPOP pressure, IPR issue or injector issues. I don't see how cycling the GP's affect the oil side.

Maybe I should hook up AE and record some cold start data? What should I look for?

Also...Never had the romps when it was new...it seems that they have come on as the miles have added up.

 

The Rotella 10w-30 is CJ-4, CI-4Plus, CI-4, CH-4, CG-4, CS/FM rated.

 

I responded that he should cycle the glow plugs longer because he mentioned that the engine had initially started, then died after cycling for only 30 seconds. If he had more heat built up in the cylinders, the engine probably wouldn't have died. That is why I mentioned cycling them longer. The heating of the oil will largely come from the heat caused by the combustion cycle itself, not from the GP system. So yes, you are right, cycling the GP's won't help very much with the romps, but it will help the truck start and stay running, which will build heat and thin the oil and so on. The best cure for romps if you aren't plugging in, is thinner oil.

 

As I understand it (because I can't see inside there):

The GP gets red-hot right quick. Red-hot metal in close proximity to other metal in the cylinder will spread the heat. If the truck starts fine on a 50-degree F day without a lot of GP time, then the GPs just need to warm up some of the surrounding metal a little to aid with the start. A "warm" truck might have temps in the cylinders closer to 100 degrees F. The fuel doesn't ignite with the ambient temperature alone of a fully-warmed truck (200 degrees F), it does it from the heat of compression (300 - 500 PSI, depending on condition of engine). The lower the heat OR compression, the less likely the fuel will ignite.

Injectors and oil play a role in that our injectors are HEUIs - oil powered. Starting ICP is about 700 PSI, applying almost 5000 PSI to the fuel in a new injector with stock nozzles. This provides good starting atomization and better atomization requires less heat to ignite the fuel. As our injectors age, clearances expand and the ICP has less "impact" on the plunger in there - reducing atomization. Nozzles can also auger out with use, further diminishing the atomization.

Cold 15-40 oil is sluggish, where cold 5-40 oil is far less sluggish. The quicker movement of oil aids in the atomization of the fuel. Remember, the oil has to snap into the injector in a few milliseconds - about 3 to 5 hundredths of one second.

The perfect scenario is a fully-warmed new engine with peak compression, 5-40 oil, and new injectors. Each element removed or reduced adds to the challenge of starting - until a threshold is crossed and you get hard starts, romps, or no-starts.

• Compression is beyond our control, so there's no suggestion here.
• Ambient engine temperature can be controlled by a heated garage, longer glow plug times, or plugging in.
• The owner has a choice of oil.
• Injector wear is another item beyond control - absent a re-stick.

 

I'd be curious as to the mileage that people starting see romp starts.

I just walked in from starting mine. it's been sitting for a week. And it was -15 this am. I plugged it in for almost 2 hours. I turn the key, wait for the WTS lite to go out...it almost starts. Two nears starts, then it goes...short romp time (like 4-5 cycles) and running as I type.

Mine is 198k miles, new injector o-rings at about 160k. Newer batts. I think the romping started becoming more apparent at around 150k and has trended worse as the miles have gone up.

I went hunting to SD last weekend, left Black Friday. The 15w-40 Rotella had 5500 miles on it, I changed to 10w-30 before I left. Knowing that if it got cold around Pierre, and I had no provision to plug in....it probably wouldn't start. But morning temps in Pierre were high teens to mid 20's. Had no issues with starting.

 

In my case hard to know, as this is the first real winter (sub freezing, sub zero) I have had it. Came from Houston, never an issue. Hard to go wrong with 5-40 synthetic oil. I had a fuel gel issue, so keep a good anti-gel additive in it.

 

For some reason, I never got the romps when running 15W40 until it had >115,000 miles on it. It seemed to magically develop the romps when below zero at or above 115,000mi. Now I just run Rotella T6. I can tell by the way it starts how much it likes the T6. It has to be better for the motor to run fully synthetic oil in the winter.