I am just the driver and they want me to be the mechanic as well, no surprise..... So this engine has Jake brake problems, sometimes they work great other times not so well. But here is where it got interesting to me and I would like a little insight before I do anything! It has a three stage Jake but they are telling me only two solenoids. The parts dept is saying the third stage is done with the turbo!? So what gives? are they full of it? and if not how is the turbo making up for the third stage? THANX in advance.
Vgt turbo closing the vanes and it pressures up the engine. They work really well, if you have driven a diesel pickup you might have used a engine brake like this
What is boost PSI On position 1, 2, 3, jakes activated. There are several issues with those turbos causing weak jakes--a big one is soot packing. Also what is oil psi--the upper end has so many ware points everything under the valve cover could be a issue. How many miles or hours on this ISX?
No boost gauge and this engine has almost 700K on it, it has had a in frame at some point. The oil pressure looks normal for a Cummins (high pressure at anything above idle and lower at idle). The truck runs and pulls great.
Check boost psi.
I watched the oil pressure today, it is 45 PSI cold and 35 PSI hot @ operating speed. I think it is somewhere around 20 PSI @ idle hot. It makes more noise in the 2nd stage but holds better in the third stage (when everything is right) It is almost like something is sticking. When it does act up I can cycle it a couple time with the fuel pedal and it will work like it should.....
any suggestions how to? I looked this morning but not really close, I didn't see a bung anywhere to install a gauge. But that don't mean it's not there, I may have just not seen one.
You may have nailed the problem right here, they were using this truck off road to move dirt before I hired in. it smoked like hell for the first few days when I started. and I worked it like a diesel needs to be worked and it cleared up...
Any NPT threaded port on intake manifold.
It will be next week, Monday at the earliest that I will even look at the truck. I spend enough time in this truck 5 days a week is enough to suite me!
At my age I find 6 hours is enough.
I looked this engine over yesterday morning and I think I found two ports I could plumb into. That may or may not happen today, I should have gathered up my stuff last night! If I can find everything pretty quick this morning I will give a shot at some testing today.
The spool valves in the engine brake rocker arms act as detents and "Park" the rocker arms when the brake is off. once the shafts and ends of the spools wear and the springs weaken with age the brake rocker arms can start bouncing off the cam lobe and with the spool valve in the open position oil get replaced with air in the passage in the brake rocker arm causing the brake to be weak intermittently. The longer between engine brake activations the more noticeable it is. Two new shafts and a brake tune up kit will fix the problem.
And probably cam wear, very common.
Quickest and easy thing to try is replace the exhaust gas pressure sensor and make sure the tube to the sensor id clear. this sensor provides the info to the ecm so the vgt turbo knows where to position its self in operation.
They have been working the ever loving crap out of me, so much so I was ready to quit Friday. I may or may not pursue this matter any more.
They bought a kit and two solenoids, I tore into the front half, cleaned everything real good and replaced the three control valves, springs, covers and snap rings. put both solenoids in and buttoned it up. (I ran out of time) It seems to have helped it. I will know more after a few days of hauling. God know when I will get to the back half, we got rained out is the only reason I got to do the front half.
Question, are the rocker shaft bolts reusable or one and done?
I have always reused the bolts with no problems.
Correct-reusable, just check for possible thread stretch.
By the way, I had a rear self destruct since I started this thread. running down the interstate @ speed pulling a slight grade, the engine reved up and wham! I let out of the fuel and everything seemed alright, called the boss and told him what had happened (still rolling down the road three miles later) Traffic was slowing down and when the Jake came on all hell broke loose! I was only a block away from a KW dealer, locked the power divider in and drove it right into their shop lot. I don't know what happened or let loose, that one engine rev was the only sign it ever gave that something was up. anyway a new center section and one axle later and all seems well.
Things happen.
It has had three days of use or 1000 miles, it is not right yet but what I have done has helped a lot. Keep in mind I only got to do half of the job.
Shortly after my last post the old girls oil pressure went south. It has been in the shop ever since, Got a in frame overhaul and I picked it up last Friday. 15-20 miles down the road and after it was warmed up the oil pressure took a crap again. Like 10 LBS hot idle and 25 Lbs hot @ WOT. I have washed my hands with it. I don't know everything but they said the bearings were in very bad shape but no mention of what the crankshaft looked like or if they took a mic to a rod journal to determine if it had wear. They won't listen to anything I say so not my truck or engine and not my problem. My boss even thought they could have gotten the crank out of the engine with it still in the truck. LMAO!! I took great pride reminding him that No they couldn't because the flywheel was still attached with the clutch and the input shaft from the transmission threaded right thru the center of all of it.
well here is a update, The Peterbilt is in another shop spread eagle again. maybe they will get Humpty Dumpty put back together again. LOL