99 Ram 1500 5.2 135000 miles and bought as is from wrecker company with no past history. Drove for approx 50 miles and it was fine. Then the oil pressure dropped from 35/40 down to 0 all of a sudden. Pulled over and turned the motor off and let sit for 2-3 minutes. After restart the pressure goes back up. Did this twice in about 15 minutes time. When the pressure drops after 30 seconds or so the valves start tapping. I assume it is the oil pump. Does anyone have any ideas if the oil pump would act like that. Also, how hard is it to change the pump on this model.
Thanks

 

Either the oil pump is bad or a bearing. Are you low on oil by any chance? What does the oil look like? There are a few possibilities there.

 

check your oil, oil pump or bearing...

 

Stupid question but did you check the oil level? If its too low the same thing can happen.

 

Thanks for the replys, the oil level is full. The truck set up for 3 months at the tow truck company. The driver was stopped by the cops and sent to jail for whatever reason and vehicle was towed to tow truck company yard for storage. Apparently the driver was given quiet some time in jail. In Louisiana the tow trcuk company can seize any vehicle not claimed after 90 days. They did and I bought it from them.
I checked the oil level before initially starting it and kept checking it daily. Only drove it for 50 miles or so before this happened.
Thanks

 

driving ok for 50 miles is good indicator that the motor is probably ok. if it wasn't, it would knock or tap within the warm up period.

i'd replace oil pump, filter. clean or replace pickup screen or tube. pull valve covers and check drains. check overall for sludge and de-sludge it as needed.
http://www.pavementsucks.com/tech/rearmain.php


just as a guess, i'd say the pickup screen is getting blocked.

 

Is it possible that it could just be something electrical such as pressure switch? Just wondering since it drops from 35 to 0 all of a sudden then will jump back up within 5 seconds or after turning off the engine and restarting.

Thanks

 

could be. oil pressure sensor is on the back of the block, beside the distributor. pretty hard to get to. about $25.

 

Thanks for the input. I have decided to go ahead and change the oil pressure switch and the oil pump. The aftermarket pumps have the standard pump or high volume pump. As noted 5.2 V8 motor 1999 ram.
Have looked on the internet and have seen mixed thoughts about whick pump is better. Does anyone have any hands on experience with high volume pumps in 5.2 motors? Thanks

 

Get a standard pump. If you do have some clogged oil galleys the high volume pump will make the prob worse. It will suck all the oil out of the pan and you'll have more probs.