Yahoo Message Number: 95973 (http://groups.yahoo.com/neo/groups/Country-Coach-Owners/conversations/messages/95973)
On my C9 I have always see high oil pressure when cold. The gauge in the cluster would maxed out and the SilverLeaf would read 127psi cold but would come down quick and run 45 to 50psi hot on the road and 24+or- at idle. One of the guys over on IRV2 was having some problems with his coach an 06 American Revolution 40L CAT C9 here is his reply to my post about high oil psi.
Here is his post
So the sensor was swapped and the tech said the engine is running great with one exception. Now, I will need some seat time to gain confidence myself, but the tech is extremely confident this will resolve the smoke/HUEI faults and such. Ok.
BUT. BUUUUUUUT. He noticed something else. Something I have noticed, but my medallion gauge cluster has shown as "normal". My engine oil pressure when the engine is cold is pretty high. I have noticed when under load and cold the gauge show 120psi. While running the C9 through some tests after replacing the sensor/thermostats/coolant the tech, while engine cold, was able to do a data capture with the engine oil pressure at 137PSI. He almost shut her down. Apparently that is enough PSI to literally blow the oil filter off.
Apparently CAT had an issue with the oil pump in my C9 with the oil pressure relief valve. The "revised" pump addresses this.
Pressure is fine when warm
Another $1,200.
Ugh.
His reply to me about my high oil pressure.
127 is way too high. Sorry. I am not sure of all of the possible issues this could cause, but my shop foreman at Petersons Cat has witnessed when someone starts their C9 cold it will rupture the oil filter and dump 8 gallons of oil or so on the ground. This doesn't necessarily harm the engine, it will die due to no oil at the HUEI, but whomever's ground you just were parked on will not be happy. Perhaps that high of an oil pressure could cause internal issues too. The oil pump has a pressure bypass valve built into it for just this situation. When oil is cold, bypass some of it in the pump so that the pressure stays below CAT's design limit of 87PSI.
The pump that came in our motor apparently doesn't do this well. CAT redesigned the pump and bypass valve and recommends replacement if you have this symptom. The pressure valve IN the oil pump IN your oil pan is not serviceable. A whole new redesigned pump is needed.
I always thought it "odd" that my analog oil pressure gauge would max out (at 100) when cold. My medallion digital gauge would register high pressures, like 117, but would say underneath the reading "Normal". I thought it was normal. It is not.
The $1200 I am paying includes the labor and parts and on it's own isn't necessarily an unfair price. They have to save my oil (it has 500 miles on it), drop the pan, pull the pump and replace then do all new gaskets and put it back together. The issue is really that this is on top of all the money I spent to diagnose and replace the temperature sender in the above posts I got my coach at 17K and now it is at 22k, just something more to think about. The list never ends!!!!! Floyd 2006 Inspire 51744