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82 K5 6.2 diesel

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motojeff16

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i am having a problem with my truck every time I stop at a light or a stop sign. my oil perssure guage goes to 0 PSI for about 4-8 seconds then returns to 30 psi at. the oil level is correct on the dipstick has anyone ever ran into this? im afraid its gonna spin a bearing or somethimg worse
 
Is it a electrical gauge,or a mechanical one (that has a tube feeding oil to the gauge?)...If its electrical it might just be the sending unit--if its mechanical its an indication of potential trouble..

This symptom is sometimes seen when the oil pump pickup screen gets plugged up with sludge,and can only suck oil in from a small area on the screen--or the screen itself may have come off and landed in the oil pan,so every time the oil runs towards the front of the pan during a stop,the oil pump pickup sucks in air ,and it'll lose pressure momentarily..you may hear the lifters clack or a bearing start knocking till the oil pressure builds back up..its not a good thing to let continue..
 
I went through a similar issue on my dually. Replacing the sending unit didn't fix the issue so I put a T in the line and added a mechanical gauge. I found that the mechanical gauge had good pressure but the electrical gauge did not. I ended up selling the truck before finding the root cause, but I suspected it was the gauge itself or a bad connection between the sender and gauge.
 
Hopefully its just his sending unit or dash gauge thats flukey...

A friend of mine had a old 66 Chevy Impala with a 283,the oil pressure light used to come on during a rapid stop or hard cornering,so he decided to try a new sending unit,it did the same thing --then he put a mechanical gauge in it instead,and it acted like motoojeff's did,during a quick stop or taking a hard corner,it would dip down to zero or close to it,the engine's lifters started clacking ,then it would go back up to 30 psi or so and quiet right down again..

After a few months of doing this,the engine started having the oil pressure drop just sitting there idling,then go back up and the lifters would clatter and go silent..after the winter passed,he decided to pull the engine up off the mounts and try installing a new oil pump...(he'd bought the car just to beat around during the winter)..

When we got the oil pan off,we found the little nylon "tube" that connected the oil pump drive shaft to the oil pump had snapped in half,and the drive shaft was wobbing around,and evidently would slip out of engaugement with the pump,and it stopped turning!..we also found a pile of nylon cam gear teeth stuck to the pump screen,and a few got sucked into the pump and mashed between the gears..so we ended up doing the timing chain and gears while it was apart too...(used a steel cam gear too!)..and a metal drive sleeve in place of the crap nylon POS that GM used originally..

The timing chain was so sloppy it wore a hole in the timing cover and had been leaking too!...when we put it all back together it ran quite well,despite having been run with no oil pressure intermittently..we didn't dare pull a rod or main bearing cap off and look to see if the bearings were down to copper or not though!..He drove that car 3 years and then pulled the engine out to put in another chevy when that car was too badly rotted in the rear frame to be trusted any longer..
 
kennyw said:
I went through a similar issue on my dually. Replacing the sending unit didn't fix the issue so I put a T in the line and added a mechanical gauge. I found that the mechanical gauge had good pressure but the electrical gauge did not. I ended up selling the truck before finding the root cause, but I suspected it was the gauge itself or a bad connection between the sender and gauge.
Click to expand...

FWIW, my gauge goes to the high side when the wire from the sender is disconnected. I just put this picture up in my thread a few days ago (from before I got my truck back together). The oil pressure sender is disconnected at the engine block.

184-Rolling Over.JPG

So...bad sender-maybe. Loose wire-not likely if the gauge is dropping.

184-Rolling Over.JPG
 
thanks guys ill change the sensor this weeken and see of it fixes it if not the pan will come off and i will look deeper. thanks for your help. does anyone know if you can drop the pan while the engine is still in the truck. its a 82 K5 4X4 if it comes to it.
 
I've read conflicting posts on removing the oil pan on a 6.2 in that era 4x4 ,some guys claim it can be manuvered out without having to jack the motor up,just jack it up by the frame so the axle droops down all the way---the Motor's and Chiltons manuals I have say to remove the drivers side motor mount thru bolt,and jack it up enough to let the bolt go back in above the mount,I guess if it wont come out without needing to be lifted up,you dont need to lift it up much to get it out..you'll have to take off the dust cover on the tranny and the 2 strut rods if its automatic too...I think the starter can stay in place,it doesn't say anything about removing it..

I'm going to have to drop the pan on my truck soon,its rotted and I'm sick of losing oil and fearing the J-B weld will come off and let it run dry in 30 seconds..I'm tempted to pull the engine right out,it needs exhaust manifolds also--and it might be due for head gaskets,and one piston might have been wounded when a glow plug broke and got crunched up in the cylinder...--if I had a gas straight 6 or V8 to stick back in it ,I would be tempted to stab that in it and not use the 6.2 ,but I'm also debating if the truck is worth all that work period now..
 
I was able to re&re the pan on my 6.2 without having to jack the motor up or anything. FWIW my gauge itself was the culprit on my truck. Oil pressure read ~5 psi at most, but it had no other indicators of low pressure. I swapped the gauge out of the cluster with a known good gauge and it had normal/good oil pressure. Had the same issue with a fuel gauge on my '83 pick-up. Used to work, but full was reading 1/4 tank, and it'd slowly go down to empty as the tank got empty. Swapped a known good diesel fuel gauge in and it works great now. The factory gauges can be the problem...
 
Yeah, having an extra set of gauges around helped me work through several gauge issues. Definitely worth keeping if you have the space...
 
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