How to get an oil pressure gauge to work (almost)
How to get an oil pressure gauge to work
I've been trying to get an oil pressure gauge to work on my Cobalt (2.4L -- 2.2L and 2.0L same). I installed an electric oil pressure gauge into an SS/SC pillar post and installed the sending unit in the back (driver's side of the cylinder head) but found that the oil pressure to the cylinder head is restricted so the gauge does not read what the block's oil pressure is (13 PSI at idle, 37 PSI at 6000RPM - engine at operating temperature) . After trying to come up with some sort of adapter or tee fitting, I realized that the original sending unit can be mounted on the back of the cylinder head -- since the factory oil pressure sending unit is an off-on switch only there is enough pressure to keep it working. After repositioning the original sending unit and splicing in wire so that the original connector is used I positioned the Autometer gauge's sending unit where the original factory sending unit goes. The pressure reads correct now (50PSI at 1000RPM, 75 PSI at 6000RPM) BUT after looking over my installation (final QC) I see the darn intake manifold is wedged against the Autometer sending unit. Looks like I'm either going to have to find a smaller sending unit or go with a mechanical gauge after all.
Here's where my original oil pressure sending unit is now:
https://www.cobaltss.net/gallery/fil...ing_unit_2.jpg

Here's where I positioned the Autometer sending unit -- But I just found out that it is wedged against the intake manifold -- too little room. (blue arrow shows the hole for the Knock Sensor -- I removed it to aid in installing the sending unit)
https://www.cobaltss.net/gallery/fil...nding_unit.jpg

More on this as I get it right!!!!
Here's where my original oil pressure sending unit is now:
https://www.cobaltss.net/gallery/fil...ing_unit_2.jpg
Here's where I positioned the Autometer sending unit -- But I just found out that it is wedged against the intake manifold -- too little room. (blue arrow shows the hole for the Knock Sensor -- I removed it to aid in installing the sending unit)
https://www.cobaltss.net/gallery/fil...nding_unit.jpg
More on this as I get it right!!!!
Last edited by Red07SSNA; Apr 20, 2008 at 05:57 PM.
In order to get an oil sending unit to fit you have to remote-position it (on the 2.2 and 2.4 -- I don't know if there is a clearance problem with the 2.0). I used an Autometer adapter #2278 and inserted it into the block where the Factory Oil Sending Unit goes and then bought a copper tube kit and used the adapters that came with the kit and positioned the Autometer electric sending unit next to the cylinder head on the driver side where there is an unused bolt hole. I kept the Factory Oil Sending Unit in the cylinder head (^^^post above) so that it still tells the ECM I have oil pressure. Put 30 miles on the car and everything is working. Oil Pressure at speed is 75 PSI, Idle it is 25 PSI, and as soon as I touch the throttle it jumps to 50 PSI by 1000 RPM -- right where the factory service manual says it should be. I also bought an A-Pillar with the boost gauge from CED and positioned an AutoMeter Electric Gauge #1927 in it.
https://www.cobaltss.net/gallery/fil...il_gauge_2.jpg
https://www.cobaltss.net/gallery/fil...il_gauge_2.jpg
Have to remove the intake manifold -- no other way to adequately get to the sending unit. Plus it gives you the room needed to bend and position the copper tube. You could use the plastic tube but it won't stay in a pre-bent position. I routed my copper tube under the oil filter housing and then straight up to the sending unit. Once I installed my copper tube I covered it with a 3/8" black plastic wire loom so it can't be seen.
Note that my original factory sending unit is in my cylinder head (picture in first post) there is enough oil pressure there to make it work in that position. I also soldered in a piece of wire by splicing the original wire -- so that the factory connector attaches to the factory sending unit.
Autometer recommends their 3' steel braided hose but this too doesn't stay in a pre-bent condition and is >$50.
I'll get some more pictures up soon.
All complete and working like factory!
The tube is routed under the oil filter housing:
https://www.cobaltss.net/gallery/fil...t_at_block.jpg

Electric oil sending unit positioned with a homemade braket -- bracket is turned 90 degrees at the end and a hose clamp is holding the sending unit to the bracket. Also the ground wire for the gauge is attached at the cylinder head bolt -- this is an unused bolt hole in the cylider head:
https://www.cobaltss.net/gallery/fil...inder_head.jpg

Clean look -- not noticable by the average car nut:
https://www.cobaltss.net/gallery/fil...der_head_1.jpg

Only area I'm not happy with -- Chevy did not provide a power source for aftermarket accessories -- I ran the power wire to the fuse box location here -- have a 4 amp fuse in line:
https://www.cobaltss.net/gallery/fil...wer_source.jpg
Note that my original factory sending unit is in my cylinder head (picture in first post) there is enough oil pressure there to make it work in that position. I also soldered in a piece of wire by splicing the original wire -- so that the factory connector attaches to the factory sending unit.
Autometer recommends their 3' steel braided hose but this too doesn't stay in a pre-bent condition and is >$50.
I'll get some more pictures up soon.
All complete and working like factory!
The tube is routed under the oil filter housing:
https://www.cobaltss.net/gallery/fil...t_at_block.jpg
Electric oil sending unit positioned with a homemade braket -- bracket is turned 90 degrees at the end and a hose clamp is holding the sending unit to the bracket. Also the ground wire for the gauge is attached at the cylinder head bolt -- this is an unused bolt hole in the cylider head:
https://www.cobaltss.net/gallery/fil...inder_head.jpg
Clean look -- not noticable by the average car nut:
https://www.cobaltss.net/gallery/fil...der_head_1.jpg
Only area I'm not happy with -- Chevy did not provide a power source for aftermarket accessories -- I ran the power wire to the fuse box location here -- have a 4 amp fuse in line:
https://www.cobaltss.net/gallery/fil...wer_source.jpg
Last edited by Red07SSNA; Jan 13, 2009 at 11:32 PM. Reason: spell check
There is not enough room to mount the sending unit in the front of the block -- the manifold butts against it. I tried to find a thinner sending unit too -- with no luck -- even called Autometer to check if they had anything that would make it work.
You can install the sending unit in the cylinder head but you will not read block pressure. The oil to the cylinder head has a restrictor orifice that cuts the pressure.
Head pressure (Hot)...Idle: 15-17PSI, max pressure: (WOT) 37 PSI; ~20 PSI at 1000RPM
Block pressure (Hot)...Idle: 25-27PSI, Max pressure: (WOT) 75 PSI; 50 PSI at 1000RPM (factory spec)
I installed an autometer #2278 adapter in the front of the block, ran a brass tube (kit) and remote mounted an Autometer electric sending unit on a home-made clamp bolted to the head. The original factory sending unit is in the middle of three oil galley plugs in the cylinder head (driver's side of block -- over the tranny).
There is not enough room to mount the sending unit in the front of the block -- the manifold butts against it. I tried to find a thinner sending unit too -- with no luck -- even called Autometer to check if they had anything that would make it work.
You can install the sending unit in the cylinder head but you will not read block pressure. The oil to the cylinder head has a restrictor orifice that cuts the pressure.
Head pressure (Hot)...Idle: 15-17PSI, max pressure: (WOT) 37 PSI; ~20 PSI at 1000RPM
Block pressure (Hot)...Idle: 25-27PSI, Max pressure: (WOT) 75 PSI; 50 PSI at 1000RPM (factory spec)
There is not enough room to mount the sending unit in the front of the block -- the manifold butts against it. I tried to find a thinner sending unit too -- with no luck -- even called Autometer to check if they had anything that would make it work.
You can install the sending unit in the cylinder head but you will not read block pressure. The oil to the cylinder head has a restrictor orifice that cuts the pressure.
Head pressure (Hot)...Idle: 15-17PSI, max pressure: (WOT) 37 PSI; ~20 PSI at 1000RPM
Block pressure (Hot)...Idle: 25-27PSI, Max pressure: (WOT) 75 PSI; 50 PSI at 1000RPM (factory spec)
im referring to the electrical sending unit for the oil gauges, not the mechanical one....also did it ever hit you that you could install them in one of the three plugs on the back of the motor that are in the block and not the head? youd have enough room
there are 3 galley plugs on the bak??????? never occured to me... just thought there were 5 on the drivers side then a knock sensor and stock sensor guage on the front. edit-the botom ones on the drivers side are coolant
There are three oil galley plugs on each side of the block (with the original sending unit position there are 7 oil galley plugs). Three are nicely positioned under the intake manifold and three under the exhaust manifold. I looked at possibly using a mechanical guage setup in these positions but all 6 have minimum space! I'd hate to run oil lines so close to the exhaust manifold too!

the blue circle and then the two to the left
There are three oil galley plugs on each side of the block (with the original sending unit position there are 7 oil galley plugs). Three are nicely positioned under the intake manifold and three under the exhaust manifold. I looked at possibly using a mechanical guage setup in these positions but all 6 have minimum space! I'd hate to run oil lines so close to the exhaust manifold too!
Last edited by mike25; May 24, 2008 at 06:16 PM. Reason: Automerged Doublepost
That shows how little the Autometer Techs know about their products! I sent several e-mails to the contact address on their site and after several e-mails discussing the mount positions the best they could do was tell me to remote-mount the sending unit.
the bitch of it all is that thing goes for 100 dollars
Last edited by mike25; May 24, 2008 at 06:46 PM. Reason: Automerged Doublepost
Actually the real PITA is that the full sweep gauges that look good in the pillar cost around $200!
its not that i wouldnt trust my work...i just wouldnt want hot ass oil in the car if i have a wreck or something...could get messy....and also i can pick up the full sweep electrical for about 150
alright, i think u may have just convinced me to switch... completely slipped my mind... and i have gotten into a crash before....looks like i will be replacing mine with an electric... better safe than sorry
yep youll definately want a full sweep...i mean i got the vacuum in mech. but theres no harm in that...i just dont feel comfortable with a mech oil gauge....check out ihavethebestprice on ebay, hes a great seller and has some awesome prices on gauges


