got a 388 pete with a 600 isx cummins. Half way through a service the truck will start losing oil pressure on the highway to around 26 psi and sometimes lower causing the engine shutdown lite to come on. If i change the oil filter the pressure is fine. Cut open filters 1 out of 4 were plugged. Trucks been at the cummins dealer for 2 wks..they had it on the dyno,oil sample,checked computer,checked gauge they said they can't find the problem. They said drive it till it happens again then have it towed right to them. anybody have any ideas on what the problem could be.
isx oil pressure problem
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The earlier 9000 series Fleet Guard filters were prone to plugging. They should be out of the system by now. I never dealt with this issue since I have always run Donaldson filters on my ISX.
Not sure of the FG current recommended filter number, but someone should be able to chime in with that info. Or, you could just change brand of filter you are using. I have not heard any problems with Baldwin or Wix (Napa) as well as my experience with Donaldson. I went with Donaldson early on because of past experience with that brand and also because it uses a synthetic cellulosic mesh media instead of a traditional paper style media. The mesh media is more durable and uniform in structure and actually allow more oil flow while cleaning as well or better than a traditional media. And the cost (at least thru my supplier) is competitive with the other brands. FG usually has pretty good filters, but they have goofed in the past, and the LF 9000 and 9001 are good examples of that.
Every once in a while this problem crops up with someone and it always seems to be the filter is the culprit, and not the ISX itself. If it were the ISX, then it would show up in the oil samples and the various particulate counts would be thru the roof. Likewise if the oil was breaking down and viscosity was rising to too high of a level, that could create a lower flow thru the filter. But that would show up in an oil sample also. If your oil samples are fine, then I would target the filter.Last edited: Jun 14, 2011
serozhah Thanks this.
I have been driving a ISX cummins in one of our freightliners.
Oil pressure has been at or below 25 at 1600rpms on the highway.
After 2 oil changes the oil pressure has dropped to zero and the warning lights and buzzer all come on.
We have decided that its either a faulty sensor or the gauge is screwed up.
We just disconnected the buzzer and have kept driving the truck.
That was nearly 8000 miles ago.
Great running motor.
Thanks for the info. Took the truck back to cummins after the shutdown light came on. They took the filter off and cut it open they said it was completely clogged with soot. Haven't heard anything else yet its a company truck so I gotta talk to the higher ups. All I know is my ### is burning from switchin seats all you drivers know ain't nothin worse then going from truck to truck while yours is in the shop
I would not trust the repair shop, If they are a contract repair shop for your company and the company is strong financially then they could easily be taken advantage of.
Typically company units will be up to date on oil changes. Hints no sludge.
Respectfully they very well could be a respectable repair shop.
But immediately when you said that the shop found sludge in the oil filter I thought "who picks up the bill for this".
I'm pretty sure you did not see them actually take the filter off the truck, cut it open and discover sludge or soot. All of this done in front of you?
I have worked at MANY shops in my life and this can so easily be the norm.
If the motor has that much soot or sludge that is has a oil filter clogged the ###### motor needs to be torn down.
same exact thing happening on mine...low oil press..then at 20lbs trck shuts down.
fresh oil change and all is well again.We have had to really tighten up the mileage on our service intervals.
The real reason that is causing this problem?..the last tech i talked to felt it was because this engine only has 1 oil filter.
Consider adding another,was his advice.
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