Oil Pressure?

[PhilsLB7]

Hey guys! Needing a little help. So I've noticed when I go to start the truck first thing in the morning, the oil pressure stays at 0 for a longer period of time. A few mornings it has stayed a 0 long enough for the message center to indicate check low oil pressure. As soon as the message comes on (truck started for about 10 seconds now) immediately goes off and the oil pressure comes up to 80 and stays normal throughout the drive. After I drive the truck for a while and it warms up never have another problem with low oil pressure during start up until the next morning when it has been sitting and the temperature outside has been somewhere in the 40's (day temp is in the 50's and 60's).

So here is what I am thinking:
- I don't believe it is a gauge or stepper motor problem since the check low oil pressure comes on in the message center.
- Now I am thinking out in the engine. Oil pump going bad? Most of you have said it makes some kind of noise when going bad but I have not noticed any noises. Also, I haven't noticed any oil leaks under the truck or in the engine compartment.
- Next I am thinking it could just be the oil itself but the last oil analysis said everything was good and just monitor. Oil filter has been replaced every 5K. No smell of diesel in the oil and visually it looks O.K. Could it just be the weight of the oil is heaver in the cold morning and then changes after warm up?
- Last place I thought about was the oil pressure sensor. But if it were the oil pressure sensor would I not see this more often than at start up? Is there any way to check the oil pressure sensor?

Unfortunately I do not have EFI Live so there is no way for me to log anything. This I why I am having to go old school "process of elimination" to figure this problem out.

Sorry for the novel but any help or suggestion would be greatly appreciated.

 

[S Phinney]

The sending unit is electronic. It could malfunction. Test the oil pressure with a mechanical gauge then you'll know for sure if there is an engine problem.

 

[PhilsLB7]

I have seen this suggestion before. But where would be a good location to put a mechanical gauge (and where to buy a good inexpensive gauge at that)? If the sending unit was malfunctioning periodically would this also cause the message center to show check low oil pressure?

Again this is a strange situation. Today I had no problems and last nights temperature was in the upper 30's.

 

[S Phinney]

I'm sure you could tap into the oil gallery that runs along both sides of the block. There are several threaded plugs that you could reduce into a size that would work with your gauge. Mechanical gauges are cheap compared to the electronic ones. I believe you could get one for around 65 bucks. I not for sure if a malfunctioning sending unit would but I think it probably would. It is what sends the information.

 

[dmaxadermist]

i had a problem myself with oil pressure and i checked my oil pressure with a mechanical gauge the place i checked mine at was on the oil filter housing,, there is a plug with and allen head on it.. (at least on mine, LB7 ) hope this helps

 

[PhilsLB7]

Thanks for the suggestions guys. Do I need to put teflon tape on the threads? My guess is yes.

i had a problem myself with oil pressure and i checked my oil pressure with a mechanical gauge the place i checked mine at was on the oil filter housing,, there is a plug with and allen head on it.. (at least on mine, LB7 ) hope this helps

What did you find out about your oil pressure problem? Was it the sending unit?

 

[dmaxadermist]

well when i checked mine i didnt and there was oil running everywhere i only ran mine long enuf to see if i had oil pressure so if you are aiming to let it run a few minits then yes for sure use some kind of teflon tape or sealer and your very welcome

 

[dmaxadermist]

oh and i forgot to say i havent narrowed mine down still im pretty sure it is the sending unit but i am trying to make sure thats what it is because the sending unit is 100 bucks and a pain to change so i am still researching and lookin

 

[lotsofmiles]

edit- there is a thread in here with test instructions . sorry I cant link it right now.

sending unit was a 5 minute job on the lbz.

 

[MAXLLY]

IIRC- your guage pack may still be under warranty, simply have it replaced. The guages on these trucks are junk (my opinion). I checked all my warm idel temp levels and when i recieved the nerw pack tey were all different.... they check now which means they must have been no good when using the original guage pack.

just a thought... it could be free.

 

[BlkMax]

Thanks for the suggestions guys. Do I need to put teflon tape on the threads? My guess is yes.

I would not use tape!!! If you want a sealant, use one of the liquid/paste sealants and make sure that the liquid/paste does not cover the first thread or the tip of the pipe threaded fitting. You do not want the teflon tape rolling around in your engine.

I had low oil pressure with my LB7 until I switched to Rotella T full synthetic.

My low pressure was after warm up at stop lights, etc. It did not seem to be the gauge, and the MIL did not light up, but the stock setting for my MIL light is 7psi according to EFILive.

 

[PhilsLB7]

edit- there is a thread in here with test instructions . sorry I cant link it right now.

sending unit was a 5 minute job on the lbz.

It you find the thread, please let me know. I would like to read it.

I would not use tape!!! If you want a sealant, use one of the liquid/paste sealants and make sure that the liquid/paste does not cover the first thread or the tip of the pipe threaded fitting. You do not want the teflon tape rolling around in your engine.

I had low oil pressure with my LB7 until I switched to Rotella T full synthetic.

My low pressure was after warm up at stop lights, etc. It did not seem to be the gauge, and the MIL did not light up, but the stock setting for my MIL light is 7psi according to EFILive.

Which liquid/paste sealant do you recommend?

I am currently using Amsoil 15W-40 and have had no problems until earlier this week. What continues to confuse me is I haven't had any problems with low oil pressure at start up in the last three days. However, it may get worse as we get colder weather.

I went by Auto Zone today and found a SunPro 2" mechanical oil pressure gauge for $17. All the fittings (1/8" and 1/4" NPT) and tubing are included. From what I remember, SunPro is a decent gauge. What do you guys think?

Again I really appreciate everyone's help. I'm still a novice when it comes to these engines but I am not afraid to get my hands dirty.