Low oil pressure after replacing cooler lines

[tuckerman]

Help!, I just replaced my oil cooler lines, fittings in the block, o-rings in the oil filter housing and oil filter. The job was messy but went ok. No leaks. Oil pressure ok. After driving @ 1/2 hour on the highway w/good oil pressure the oil pressure dropped to almost nothing when I got off the highway. Still no leaks, oil level @ 1 quart high. I have a 97 heavy 3/4 ton 4x4 w/ 206,000 mi. Thanks.

[RobK]

Did the lead come off of the sender?

[Hubert]

What did you replace oil lines with? My initial thought is you may have reduced flow to cooler and oil is hotter now so it will have a little lower pressure. Where do you live?

Did you change oil with work? Brand, type, or other?

Could be sender related like mentioned and just a coincidence. One of those that makes you feel you messed up something.

Lots of people have changed lines but this is first time I have ever read oil pressure loss with oil cooler lines.

[DennisG01]

I agree with the above statements. I doubt it's something you did - if it was, it would've been apparent right away. It's more likely something coincidental happened - maybe a fleck of dirt got stuck on the sensor. I once had that happen to one of my boats. Changed the oil, went to the lake, ran good, all of a sudden the warning buzzer went off - no oil pressure. Stopped the engine, checked the oil - it was full. Scratched my head for a little while, started it up a few more more times and then all was good. Never had another problem after that.

[tuckerman]

I used stock gm lines. Rotella oil fram tough guard filter. Last night I changed my oil again. It was snowing so I didn't get to run the truck on the highway, but I plowed with it for about 1hr no probs. I also let it idle in the driveway for 1/2 hour. I also replaced the leaky block heater, which was easy. It also seams that both filters have a slight leak at the oil filter housing. Is the normal? Should I replaced it with a stock one or is there an alternative?

[Hubert]

What do you mean both filters had a leak? Both individually leaked or are you running something different.

No matter what brand of filter I sometimes get an aggrivating seep from filters. Small price to pay rather that than overtighten them. You probably already wet new gasket with fresh oil on install. Mine work a little better if I hand tighten them as far as possible let the seal sit squeezed a few seconds or minute then give another little snugging partial turn to nip it up a bit more. Some days I use a filter wrench sometimes not depending on how strong my grip feels. This helps me.

Many times the O rings in the 4x4 filter base adapter seep/leak.

[tuckerman]

After taking everything apart again. One of the new lines collapsed and restricted the flow. It seems as though the filter went into bypass because of the restricted flow. Tomorrow new line from GM. Hope they take the old one back.

[tuckerman]

Dealer took defective line back, no problem. Replaced line, problem solved! Truck drove 70mph for 10 exits on I95 and held oil pressure when got off the exit. Lucky I didn't do any harm. This should be good for another 200k.

[DennisG01]

Glad to hear it all worked out in the long run!