gaylemarlowe Report post Posted September 17, 2015 As mentioned in my other post, we just got back from our trip to Michigan. On the way back coming across Kansas, we were caught in that massive heat wave. Most of one day was 30-40 mph winds broadside and the temps slowly climbed from the 90's to 103 outside air temp. We fought it for as long as we could and then pulled off to find a overnight park. When coasting down and stopping at the freeway ramp I noticed the oil pressure was showing approximately 20lbs, but the temp was right on 200 as it always is. I watched it from there into the park and the oil pressure stayed at approx. 20 lbs at idle and went up to 45 as soon as throttle was engaged. Previously I had always run at 50 lbs at rpm and about 30 at idle. But, we had never experienced that hot of a drive ever before. We had the dash air going full blast and both roof airs running and it was just barely keeping it at 85 degrees. Absolutely brutal!!! Next morning, after everything had cooled down overnight, we started the remainder of the trip back to Colorado. Oil pressure was just a bit better, but not what I usually see. Coolant temp was always good. Oh, additional note, running 15-40 Rotella T. Question is: Anything to worry about? I am sure Brett will have a good response to this. Thanks Share this post Link to post Share on other sites
wolfe10 Report post Posted September 17, 2015 Gayle, Absolutely normal. Brett Share this post Link to post Share on other sites
dave111451 Report post Posted September 18, 2015 A good rule of thumb is a minimum of 10 lbs per 1000 rpm.Anything less I would worry about. dave Share this post Link to post Share on other sites
gaylemarlowe Report post Posted September 18, 2015 REALLY strange!!!! After cleaning and washing everything on or in the coach after our trip, I started the Cat to put it away in the garage. While setting there waiting for the air to build up, I happened to remember the responses to my spring post that I could not find the control to get a high idle speed for warmup. Some had suggested the sift pad, which I had already tried, and someone had suggested the cruise controls on the smart wheel. May have been Brett, but can't remember. Anyway, while setting there I tried the controls on the smart wheel and got the idle speed to go up. Great!! About 15 seconds after initiating the higher idle speed the oil pressure warning light and buzzer starts squawking and the oil pressure gauge goes to zero!! I immediately shut it down, went to the back to pull the dipstick and found it was just as I had checked it two days ago, 1 1/2 quarts low. Sat there thinking about what could have happened setting in the driveway. Broken oil pump shaft, plugged screen, broken sending wire???? Got back in, started it up, pressure is great, about 90 lbs cold. Waited for several minutes and everything is fine. Tried the fast idle again, and same thing occurs, lost oil pressure and alarms going off. Shut it down, checked the oil, everything okay. Started it again, tried it again, same result. Shut it off and waited, trying to think of what the connection is between oil pressure and fast idle control on the cruise system. No ideas sprang to mind. Started it again, oil pressure good, warmed it up using the pedal, drove it to and into the garage, everything good. Sooooo, what happened??? Anybody (Brett) or any other knowledgeable diesel guy have any ideas? 2005 Newmar Dutch Star 4320 Spartan Cat 400 Share this post Link to post Share on other sites
wolfe10 Report post Posted September 18, 2015 If you have access to a mechanical oil pressure gauge connect it and check oil pressure-- it is the quickest/safest way to determine whether this is really an OIL PRESSURE PROBLEM or GAUGE PROBLEM. Another option is to call your chassis maker and explain the situation. Get their help in diagnosing gauge/sender vs real issue. BTW, oil pressure issues are VERY rare-- much more likely to be a gauge issue. And, just for drill, carefully remove, clean and reconnect the oil pressure sending unit wires at the engine end. A little dielectric grease to protect them is a good idea.That is a pretty common failure point. Share this post Link to post Share on other sites
gaylemarlowe Report post Posted September 18, 2015 Thanks Brett. Will do all those things as I really need to see what this issue is. Even if I never try the fast idle thing again!! Share this post Link to post Share on other sites
wolfe10 Report post Posted September 18, 2015 Particularly since this started after you washed the coach, I would start by cleaning the connections at the sending unit(s) on the engine. Unless this with the check engine light, suspect this is a chassis maker speced sender, gauge and buzzer. Share this post Link to post Share on other sites
gaylemarlowe Report post Posted September 18, 2015 Duh!! Had not connected the issue to the wash job. And part of my wash practice is to clean the engine compartment. If that turns out to be the case, will be a little more careful in the engine area. Will let you know what I find. Thanks Share this post Link to post Share on other sites
gaylemarlowe Report post Posted October 19, 2015 Well, my gremlin is still there and not fixed. I took the sender out, put a gauge in and oil pressure is just fine. Cleaned the terminals, even tho they looked okay. Started it up and same result. Called Spartan and they told me it was most probably the ECU as there is only one sender and if it works okay without using the fast idle, but not when using the fast idle, then it is a Cat issue. They recommended I contact Cat. Called Cat and they told me it was definitely NOT the ECU if I was showing okay oil pressure during normal conditions. They said it has to be a fault in the chassis wiring. Where do you guys think I should try next? Would going to a Cat dealer and having it plugged in to diagnostics show anything? I am leaning towards a Spartan issue as they built the entire chassis. Share this post Link to post Share on other sites
dickandlois Report post Posted October 30, 2015 gaylemarlowe, Take a close look at the point where the connector for the sender wire(s) are crimped to the connector. At times there is more insulation then wire crimped to the connection and they fail to make contact, do to oxidation or the few wires that where making contact brake. ECMs work on 5 volt signals (voltage) Remove the oil sender connection. Have a helper watch the pressure gauge (with the ignition on) Do Not Start the engine. Connect a single 1.5 volt battery between ground and the sender connection and see what the oil pressure gauge reads. Ground is negative and the positive goes to the signal wire for the pressure sender. You should see the gauge read a pressure if the wiring is working. No reading then I would have the wiring between the sender and the ECM oil pressure input signal pin checked. Rich. Share this post Link to post Share on other sites
