Zmanco Posted December 24, 2009 Share Posted December 24, 2009 For those of you with S30 cars, you should know that the stock oil pressure gauge can often be inaccurate. While tracking down an oil pressure issue I temporarily attached a mechanical gauge and found that the stock gauge was wildly inaccurate. The pressure read much higher than it really was across the rev range. I only had 50 psi max, even at 7k rpm even though the gauge was reading 80 psi. After solving the oil pressure issue I looked at installing an aftermarket gauge and sender, but I like keeping things as stock as possible in the cabin, so didn't want to go that route. I already had a sending unit from an '80 280zx that came with an engine I had bought so decided to try it. The main difference is that the newer sending unit has 2 connectors - instead of relying on the case connecting it to the block it has a separate connector for ground. So I installed the new sender and made a simple 2" adapter wire between the bullet connector on the car's harness and the spade lug on the sender and ran a separate wire from the other connector to the case of the alternator. This worked pretty well, but the gauge was still reading a little high across the rpm range. After some trial and error, I found that 3 ohms of resistance between the sender and the harness got me close enough to the mechanical gauge. So I picked up a pack of 10 ohm 1/2 watt resistors at Radio Shack and fabbed a 2" adapter cable with 3 of them in parallel. The result is that I still have the stock gauge in the cabin and it's accurate within 5 psi across the rev range. Plus I didn't have to cut the stock harness. If you're running your engine above 5k rpm regularly, I'd strongly suggest verifying that the gauge is accurate and there's enough oil pressure. Quote Link to comment Share on other sites More sharing options...
at-jefft Posted December 24, 2009 Share Posted December 24, 2009 Nice Work! Quote Link to comment Share on other sites More sharing options...
zcline Posted May 6, 2010 Share Posted May 6, 2010 Hi. So I just tried to do this mod on my recently acquired 1977 280Z. On my car, i loosened the stock oil pressure switch, but after twisting for what felt like ever, the thing never came off. Thats when I noticed that compared to your car, Zmanco, it seems like my oil pressure switch is threaded into a bolt/adapter of some kind. Is this normal? Should the S130 oil pressure switch just bolt right into the block? On your car, at least on the picture you posted, it seems like its screwed into something else, on mine its definitely going right into the block ... although I see you have a 240Z, so maybe that's the difference? Any help would be appreciated, maybe I need to get in there with an open ended wrench and see if that bolt loosens things up ... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 7, 2010 Share Posted May 7, 2010 N/A motors have the sender directly in the block. Â Turbo motors have a dual outlet fitting that feeds oil to the turbo AND to pressurize sender. Quote Link to comment Share on other sites More sharing options...
zcline Posted May 7, 2010 Share Posted May 7, 2010 i'm an idiot. The bolt I was talking about WAS the sender. Or at least part of it. I had just gripped onto the metal part and twisted and thought that would unlatch it. I got a 14MM wrench on there and it popped right off. Now I have the new sensor installed as Zmanco described, and am ready for a ride! Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 7, 2010 Share Posted May 7, 2010 Awesome write up!! I would like to run tWo oil pressure gauges in the cabin, just to be safe. Do you know what fittings I would need to do this??? Thanks! Quote Link to comment Share on other sites More sharing options...
Zmanco Posted May 7, 2010 Author Share Posted May 7, 2010 jacob80, you're in luck. Since I posted this I decided to install the mechanical gauge as well - the stock gauge is so slow to change. Here's a picture of how I did it. Basically I mounted a 2nd T into the turbo T. The copper adapter is from McMaster 4978k121. Then there is 4860k631 also from McMaster to adapt the female copper T to the female turbo T. The last adapter came from Summit. It's a 1/8" NPT to BPT adapter ATM-2269. It's a bit of a Rube Goldberg setup, but I couldn't find a better way given the mix of BPT and NPT. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.