Now you can properly access the wearing down of your motor. lol. (an old buddy of mine said the real use of an oil pressure gauge is to watch your engine wear out)
Oil Pressure Gage
- Thread starter Mektek
- Start date
gmcman
Member
- Dec 12, 2011
- 4,656
Yeah, that's pretty much the story. I checked the oil pressure around 200K with a Matco oil and trans pressure tester and when hot my idling pressure was below 20 PSI, cold start was around 80 PSI so not much has changed.
My last oil sample showed very low wear metals so that's reassuring. Still good to have an idea of what's going on, I wish I had an idea of what the hot idling pressures are when new.
I would budget $250. About $225 for the gauge, sandwich adapter, and the gauge pod. Add in a few bucks for shipping, zip ties, grommet, and wire loom.
very nice write up and video
Thanks!
Mooseman
Moderator
gmcman
Member
- Dec 12, 2011
- 4,656
That's something I would definitely like to try. Curious as to where the trans begins to creep too much. I've found that even a small increase has helped the A/C when sitting in traffic. Even a 50 RPM increase could net 2-3 lbs of pressure and with 14 @600, that's almost a 20% increase.
An emergency came up so I had to backburner the project for now
. To get better access to the plug I'll have to remove the belt tensioner. And I have to be sure that the extra hardware doesn't prevent the tensioner from being lowered to remove the belt.
Apparently there is 1 or 2 other oil galley plugs on the engine so maybe I'll look for those.
I've never seen the oil filter sandwich adapter before. Sounds like I should take a bite out of it
My budget is definitely lower than gmcman.
. To get better access to the plug I'll have to remove the belt tensioner. And I have to be sure that the extra hardware doesn't prevent the tensioner from being lowered to remove the belt.Apparently there is 1 or 2 other oil galley plugs on the engine so maybe I'll look for those.
I've never seen the oil filter sandwich adapter before. Sounds like I should take a bite out of it
My budget is definitely lower than gmcman.
gmcman
Member
- Dec 12, 2011
- 4,656
You could try to use a T-fitting at the factory location...never tried to source anything.
I was going to try that plug on the filter housing....and not to invoke any karma, but if I cracked the housing trying to remove it....then we would be talking a huge undertaking....didn't even want to go down that road.
You don't need the dual gauge...you could source just the pressure gauge with the sandwich adapter. Then place the gauge anywhere you want in a more non-permanent location.
I was going to try that plug on the filter housing....and not to invoke any karma, but if I cracked the housing trying to remove it....then we would be talking a huge undertaking....didn't even want to go down that road.
You don't need the dual gauge...you could source just the pressure gauge with the sandwich adapter. Then place the gauge anywhere you want in a more non-permanent location.
Mooseman
Moderator
Those are located along the right side of the block along the oil gallery under the exhaust manifold.
I forgot to update the progress of the project.
When I removed the PS pump (for an unrelated issue) and belt tensioner there was much better access to the oil galley plug. For a few days I sprayed it every few hours with various penetrating oils. Also tapped it with a hammer. I cut a different piece of 8mm hex which I think was stronger than the one that twisted previously.
This time there was a loud cracking sound and to my surprise instead of broken metal the plug started to turn for the first time in 19 years
here's what the sensor looks like:
Only a single wire is needed.
Inside the cab:
Less than $20 all in. Curiously, mounted in this location the display reflects on the top of the windshield and is almost readable.
When I removed the PS pump (for an unrelated issue) and belt tensioner there was much better access to the oil galley plug. For a few days I sprayed it every few hours with various penetrating oils. Also tapped it with a hammer. I cut a different piece of 8mm hex which I think was stronger than the one that twisted previously.
This time there was a loud cracking sound and to my surprise instead of broken metal the plug started to turn for the first time in 19 years
here's what the sensor looks like:
Only a single wire is needed.
Inside the cab:
Less than $20 all in. Curiously, mounted in this location the display reflects on the top of the windshield and is almost readable.
Mooseman
Moderator
I might consider locating a right angle spade terminal at a local supply house.
As you can see from the photo, only when the engine is not running do the real and fake gauges agree 
I was thinking of insulting the GM engineers by removing the decorative stock gauge and installing the real one in its place. There is enough room in the instrument panel to do that.
Others have speculated on using an arduino to drive the stock stepper motor - kudos to anyone who can pull that off.
I get a reading that jumps from 8-12 at hot idle and 65-66 after a cold start. 45 mph cruise with a hot engine gives 36-40. I'm planning to try 10w30 oil next time and see if it changes the readings.
In my case, a chemdip soak of the oil pan had no effect.
I was thinking of insulting the GM engineers by removing the decorative stock gauge and installing the real one in its place. There is enough room in the instrument panel to do that.
Others have speculated on using an arduino to drive the stock stepper motor - kudos to anyone who can pull that off.
I get a reading that jumps from 8-12 at hot idle and 65-66 after a cold start. 45 mph cruise with a hot engine gives 36-40. I'm planning to try 10w30 oil next time and see if it changes the readings.
In my case, a chemdip soak of the oil pan had no effect.
Last edited:
Mooseman
Moderator
Just speculation on my part... It appears this engine is OK with a low pressure at idle and that it depends more on flow than pressure. If a higher pressure was needed why then does the oil pressure switch flip at around only 3 or 4 psi? With this in mind how many owners of a newly purchased vehicle would be content seeing their oil pressure gauge reading say less that 20 psi at idle??
I would love to know what these engines had for true oil pressure at idle when new with oil temps above 195° F. I have over 287000 miles on mine so I expect to see low oil pressures at idle.
My guess would be one of two choices:
1) a bean counter discovered they could save 39 cents per vehicle off the line
and/or
2) Have an oil gauge that fluctuated around is not a good look and would generate service calls to the dealer
Mooseman
Moderator
I should install one on mine as the pressures would be close to original. It has only 115k km (72k miles). Most of its life it ran on new oil as it wasn't driven enough to get oil changes on mileage or the OLM but annually. Only since I've owned it at 87k km that I have been using the OLM. In fact, it's at 12% life now so I should do this at the same time.
gmcman
Member
- Dec 12, 2011
- 4,656
You can sort through this thread, I added pics of my Glowshift gauge install using a sandwich adapter....works very well.
gmtnation.com
Oil Pressure Gage
Has anyone permanently installed a real oil pressure gage in the I6? I'm thinking of welding on a steel tee to to the old pressure switch with fittings for the switch and sensor. Is there an easier way?
gmtnation.com