It should be the right one if the shop paid attention while they were installing it.

You may have a relief valve sticking in your oil pump causing your pressure to be up so high. Normally it sticks to the low side, and it's kind of a long shot, but that's a possibility if everything electrical checks out.

 

will pick up new oil pressure sending unit for gauges from auto-zone and let you all know after tomorrow

 

how is the relief valve in the oil pump freed if it is stuck? These guys would have paid attention to the sending unit for gauges.

 

I thought about that a bit more. If the valve would have been stuck, you would have had high oil pressure on the mechanical aftermarket gauge too. So scratch that thought.

Keep on the electrical train of thought. Again though, you have a 400 motor with good oil pressure and your gauge reflects it. If it were my truck I wouldn't worry about it, but if you want to pursue it, then the ICVR is your next best move.

 

Dave145
I just got another new oil sending unit from Auto Zone , noticed it has a thin layer on the threads that looks like paint but is probably a liquid Teflon. The other new sending unit that is installed probably had this as well so should this white film be removed before install, could it be causing a problem with grounding and thus the gauge reading so high?

 

That is thread sealant/Teflon. If there is a bit between the threads, that's fine. If it's on the threads, I normally scrape it off.

A gauge reading high means there is little resistance in the circuit. Hence why grounding the sending unit wire causes the gauge to swing all the way to full pressure.

You should have received a sending unit with a large bell shaped top on it. Thread it in till it stops turning, give it an extra half turn with your wrench and you're done. Plug it in and let it rip.

 

its a complete cover of the valley and peaks of the thread as I look at the one in the box , will remove the new one in engine and wire brush the stuff off, then see what happens.what is in the truck now is the large bell unit, the new one I have in box is the large bell also. The one for the idiot light is very different

 

the one in the box that i just got has it over the threads as well as in the valleys , will remove the new one in the truck and wire brush the threads to remove it. the one in the box and in the truck are both large bell type. The one for the idiot light is very different. Could the amount of sealant/Teflon be causing the gauge to read so hi because of bad grounding to the block? thus causing all the salvaged gauges that I put in to read close to the same which all were high?

 

sorry for the repeat my puter is not showing what I post in a timely manner and making me think it was deleted before posting

 

I doubt the amount of sealant is causing a high gauge reading. If anything it would make it lower instead of higher

 

When the oil pressure was checked with a mechanical gauge, what were the actual readings (psi)?

 

Most of that sealant is scraped off when you install it and Dave145 is right, higher resistance would make the gauge read lower, not higher. I would not scrape it off the threads... there is a reason it is there.

 

Can you post a picture of your gauge when it's supposedly reading out of line? Just wondering exactly how high "too high" of a reading would be.

I'm nobody to say what's "right" and "wrong" when installing something, but I usually just scrape the sealant off the raised threads and leave it in the spaces between them just for that "feel good" feeling. That way I know it won't leak and it will have good ground contact.

But electronically speaking (provided this new sending unit reads the same as I suspect it will), here's what I see based on the context provided so far.

-We have 3 gauges. All 3 are OEM gauges and read the same.

-We have good oil pressure. As asked earlier, please post exactly what the pressures are that you're seeing. This will help determine if your gauge readings in the truck when warm are accurate.

-We have tried 2 sending units. For now I will assume they will have the same output. Please update when new one is installed.

-The wire at the sending unit is good and makes good contact.

-The ICVR is receiving 12v in, and outputting 5v consistently.

-Ground to ICVR is good and has a redundant in place as well.

End of the day, the circuit has too little resistance to get the gauge where you'd like to see it. That or you could say the gauge has too much voltage applied to it to get it to sit low enough, but if that WERE the case then ALL your gauges would read higher than usual. Besides "in the normal spot", where do your temp and fuel gauges sit?

I can't say I exactly see a problem here. I'm not an engineer of any sort, so maybe I'm missing something, but in my experience with both these trucks and several other classic cars that I own, nothing seems out of the ordinary.

Pictures and pressures will be our best friend now if the new sending unit doesn't help.

 

Dave145
After talking with the friend at the shop and telling him what I did with the ICVR and gauge grounding , he drove it and said basically new sender will change gauge, grounding the gauge will give it a stretch and change its overall movement, he told me the psi readings at idle and running rpm sorry forgot them but he did say they were exactly what specs called for in psi . He also said that the gauge was reading in the "normal range" . Since we changed most of the stuff from sending unit to cleaning and grounding the ICVR as well as a different salvaged gauge - all this affecting the position of the needle in the gauge .... Realized that he was correct and just have to get used to a new range and normal when looking at the gauge ! .. Feel better but when it all went down with the gauge it had me worried ... Thank you all for your knowledge and patients it has expanded my knowledge

 

Not a problem that's what we are here for!