What's the proper way to use the jake brake

[Rawze]

Some related info:

* I usually tell others that the jake should have a 30 seconds delay, and a minimum of at least a 5-second delay if u can't wait that 30 seconds for it. This is because I have seen an occasional ISX that has dropped a valve on cold days and jake set at 0 delay. Also happens on brand new engine sometimes. - Can you get away with it?-- Most of the time, Likely, but why risk a $36,0000 engine over it? - Not worth it just so that you can shift a bit faster.

* If you have 100% factory programming (emissions still in tact, etc), then the jake can easily handle up to 2400 RPM. If you have de-mandate programming (truck is deleted) and someone went in there and turned up the jake brake settings like a dumbarsse to try to make it stronger ... your prone to dropping a valve at high rpm. I see this mistake being made a whole lot when reviewing other peoples custom programs.

* I have seen (but it is fairly rare) where someone climbs a huge mountain, getting their truck and engine really hot because of heavy load and steep grade (like when climbing cabbage or 4th july, veil, Donner, etc.), and they are giving it all its got... Then crest the top of the mountain, its minus -15 or lower degrees-F outside, and they have zero delay jake ... That sudden inrush of super-cold air hits those very hot cylinders, and "boom", a cracked liner or valve. - Hence the recommendation of a 30-seconds delay for the jake.

Granted, all these situations are fairly rare to happen (except in the case of bad programming), but they should be at least known before someone decides to set their jake on 0 delay, thinking that it could never happen to them. I have mine set on 30-seconds. I haul 80,000 lbs over every one of the big mountains in the worst cold weather that has been seen. I just do not like knowing about the slight risks of having to rebuild my engine because I am impatient and want to shift faster. Besides that, I have yet to see an ISX that I could not speed-shift like a race-car (while test driving the truck only) with no jake turned on at all. - Just ask anyone who has been at my house and seen me do it while stress testing their truck.

This is just my own experiences, others may vary.