My John Deere 650J warning light came on because the oil pressure gauge showed zero pressure. This happened within the first few minutes of operation - the dozer hadn't been operated in the previous three weeks. I shut it down, checked the oil level, looked for leaks and any other abnormalities. I couldn't see anything wrong, so I started it back up. This time the oil gauge was pegged on maximum pressure at RPMs slightly above idle. I operated it for an hour at reduced RPM. While operating, the gauge indicated that the pressure came down a little, but was still way higher than usual. Has anyone seen an issue like this? Possibly a pressure sensor error??? The machine has 3,502 hours on it. Thanks for any help - This forum is great!
I would put a manual gauge on it and check to see if the factory one is right. I suspect that it has a faulty sensor showing low one time then high I have had that happen before although not on my 650.
I would have to agree. Get a analog measurement and compare it with specs. But I would like to add think twice before operating it. Even when you think the light might be wrong. Becasue it might be right. Also have you had any service done on the car? For example it could be a filter that needs to be changed out or the bypass valve in the filter is going out. Also is the oil your using correct for your environment. maybe it's to thick. With so little hours I would start to think about what service issues that might cause this.
I have replaced the wire from the sender to the ecu a couple times on this size of machine after confirming I had good engine pressure, I have never found where it broke though. Good luck
Thanks for this great advise. The common theme in all of your recommendations is to get a manual / analog reading of the actual oil pressure which is great advise. Can any of you tell me how to measure this pressure on a Deere 650J or just general advise on how to get this measurement?
Get a generic oil pressure guage at a auto parts store with 8' of tube. Find the pressure sending unit , remove it and install the fitting or adapt a fitting to thread into the oil pressure port. Connect the tubing from the fitting to the guage , zip tie the tube temporary and zip tie the guage where it suits , start the machine , check for leaks , run it to see what the pressure does.
The sensor is located on the left side of the engine (if you are sitting in the cab) in the middle of the block, it is a three wire sensor. You will probably will have to remove the side panel to access it. The fitting should be 1/8 NPT. Slow idle no load spec is 15psi minimum. Full load full speed is 40psi minimum. There are other ports you can use to record pressure if you plan on running the machine with the sensor out as the ecu will derate you if it sees no oil pressure.
This machine has an ecu? I'm getting behind. Would it be possible to fit a tee fitting to avoid the derate?
Yes it has an ecu, they have been used for several years now. I suppose you could tee a gauge in, I had never thought of it as I usually don't want to leave my gauges in a customer machine. The oil gallery should have a couple extra ports with square plugs in them but I have never tried using them although the manual shows to test pressure there.
The oil gallery plugs require a 3/16 square drive socket that ill bet you dont have. I have seen pressure regulators and senders go south on those engines....try a new sender and then chec oil pressure at the sender port if replacing the sender didnt fix it. derate wont matter if your looking for pressure at idle and WOT.
Thank you all for your help. I am an my to test the oil pressure and will post results this week.
2 weeks later and now youre going to check the actual oil pressure? No wonder the world is leaving America in the dust....
I checked the oil pressure with an analog tester, the pressure was above spec. Then I replaced the sensor and all is well. Thank all of you for your help. This forum is great! And by the way Cutting Edge, the dozer was not operated during the two weeks you questioned. In addition, I must have missed the news story about America being left in the dust. Now I suppose it will be up to Canada to lead the free world. Good luck with that!
India and China are at the helm.....we're bbq'ing and drinking beers up here
Uhh you might want to check your facts on that. The USA is not being "left in the dust" as you said by any measure. The Good old USA is number 1 by GDP, China is number 2, and India is number 9 or 10 depending on which agency you cite. This isn't a political blog, so I am signing off on this discussion. By the way, Canada is #11 in GDP rankings. Also, thanks for your help on the oil pressure.