Truck tends to run fine for about the first 20 mins of startup, idle or driving. But, after it's been warm (normal operating temp of 190), it tends to drop the oil PSI and then truck hesitates, and it usually cuts off. Then I have a hard time getting it to start back up. Truck has over 320K on the odometer and runs great when the oil PSI is up so I know it has plenty of compression. I believe it's a sending unit or the oil pump/pickup. Could someone give me some kind of idea on what it might be? Love this truck and would hate to let it sit in the yard just because I don't have the cash to rebuild the entire engine. And to anyone who wants to lay down a smart-*** answer, I will NOT sell this truck and buy a new one. Thanks in advance to everyone!
2007-05-02 10:47:48 · 5 answers · asked by hotrod29728 2 in Cars & Transportation ➔ Car Makes ➔ GMC
Also wanted to add that the oill PSI does not completely go away. But, it does drop down to around 10-15 lbs. Trucks has a digital dash and I just had it replaced so I know the sending unit in the guages themselves are in perfect working order. It has been doing this before I had the cluster replaced anyways...
2007-05-02 11:15:31 · update #1
Do try to replace the sending unit as explained above and also, try switching to a thicker oil as high-mileage vehicles like yours will have lower oil pressure due to wear and loose fitting bearings and such....a thicker oil like 15w-40 may help bring the pressure up with out going to a rebuild or new pump. You could also shim the pump pressure valve spring to bring up the pressure but it would require dropping the pan to access the pump.
2007-05-03 03:32:55 · answer #1 · answered by paul h 7 · 0⤊ 0⤋
How cold is it outside? Many vehicles won't shift into 4th or overdrive until the engine & transmission have warmed up - if it's real cold outside it may take a while. Other than that: 1. Check the AT fluid level - read owner's manual to find out how. Many times engine and transmission must be warmed up (10 miles minimum)and left running with AT in park and vehicle on flat ground. 2. Control system (valve body) failure: like the solinoid that activates TC lockup/4th gear may have quit. 3. Hard part failure. I believe that on the 700R4 a fracture of the sun/orbital gear will cause this -but you also loose reverse. 4. Torque converter failure. If the TC lockup function has failed the transmition may intentionally stay out of 4th gear/overdrive. sorry. good luck!
2016-05-19 00:57:27 · answer #2 · answered by ? 3 · 0⤊ 0⤋
the oil sending unit the one w\ 3wires if there are 2 of them is wired into the fuel pump. it is shutting the engine off this has saved many engines. replace it if problem continues oil pressure is low try a higher wt oil. till you can work on the moter it needs rebuild
2007-05-02 17:02:53 · answer #3 · answered by tott1 5 · 0⤊ 0⤋
The oil pressure sending unit will shut off the engine if thier is no pressure.Try changing the sending unit.Make sure thier is a good electrical connection to the sending unit or the engine will shut off.
2007-05-02 11:01:46 · answer #4 · answered by (A) 7 · 0⤊ 0⤋
this is stupid the oil pres needs to drop to less thn 4 lbs of pres to shut off how much fuel pressure does it really have when the problem occures?
2007-05-09 19:05:33 · answer #5 · answered by coaltruck344 4 · 0⤊ 0⤋