Diesel Idling

[Craig P.]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by quikduk:
I too fueled up at Flying J outside of Barstow yesterday. Cash price was $3.55-9/10 versus $3.61-9/10 for credit...and I had min. cash on me...and it was still cheaper than my local Pilot.

OAN, I spoke to a few "guys" at Flying J who all thought diesel would be over $5 by next year some time. </div></BLOCKQUOTE>
Go to Flying J's web site and apply for a Flying J RV value discount card. You will always get the cash price no matter how you pay, plus an additional 1 cent off per gallon.

I have a co-worker that makes his own bio-diesel from used veg oil. If diesel hits $5 a gallon, I might just buy myself a 50 gal. drum and start making the 100 mile round trip drive to his house and try some.

[SargeW]

All the reasons for extended idle of the older diesel engines were valid. However, with the new technology of modern engines and the reformulated fuel, extended idleing is actually BAD for the engine.

Extended idle, say over 10 or 15 minutes allows the temps in the cylinders to drop significantly. The lower temps do not fully burn the diesel fuel. This causes a condition know as "diesel wash". Diesel wash is the condition where unburned diesel fuel washes down the walls of the cylinder, and effectively "cleans" the cylinder walls. This causes excessive wear on the piston rings and leads to early faliure of rings and related componets.

Cummins recommends NO extended low RPM idle for that reason. Makes sense to me to shut her down when you don't absolutely need to have the motor running.

Sarge

[RustyJC]

Cummins put out a service bulletin on bent pushrods (or "push tubes", as Cummins calls them) on the early 24 valve ISBs due to extended idling. The valve stem cooling is so effective on the 24 valve engine that the valve stems and guides become sufficiently cold to build varnish and gum from the lube oil. This can lead to valve sticking and result in bent pushrods. Cummins' recommendation was not to idle the engine for extended periods, but if idling was necessary, to engage the exhaust brake to (1.) put some load on the engine and (2.) raise combustion chamber (and, thus, valve) temperatures to prevent varnish and gum formation.

Rusty

[J Walker]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> but if idling was necessary, to engage the exhaust brake to (1.) put some load on the engine and (2.) raise combustion chamber (and, thus, valve) temperatures to prevent varnish and gum formation.
Rusty </div></BLOCKQUOTE>
The exhaust brake might be able to be engaged at fast idle but definitely not at normal idle. I have not tried it at fast idle but I think fast idle is about 1100 RPM and exhaust brake cut-off is 1000 RPM. Another bad thing about extended regular idle is the engine cools down and the fuel can condense on the cylinder walls and wash away the lubrication oil. This is an often cited problem. Just thinking about it, if the fuel washes away the oil, then the fuel will remain mixed with the oil and perhaps degrade its operation.