Could anything other than the oil pump or main bearings cause the oil pressure light to come on when at low rpm's? Im going to put a Mech. gauge on it soon right now I dont have the spare cash.
 I am NOT driving it until I find out the problem!




FORGOT TO MENTION: 88 Samurai 1.3L

Ya, a stuck open pressure relief valve,
I blew a turbo because of one of those.

Keep in mind that the light comes on at like 5-7 PSI
so it doesn't take much to keep it off

Wild

Ok Im a noob. What and where is the pressure relief valve?

A defective oil pressure sender/switch is another possibility.

The pressure relief valve is a spring loaded valve that is a part of the oil pump (on this engine) - it will lift off of it's seat and allow oil to return to the oil pan without flowing through the engine from around ~65 psi - the idea is to prevent excessive pressure, possibly from too thick an oil on a cold day, from causing damage.

What He Said

I have heard that if some of the screws are missing out of the rocker arm shafts that can cause the oil pressure to run low.  You can check them by pulling the valve cover and looking to make sure they are all there.  I would also check to make sure they are all tight too.

Just had the head reworked so everything should be tight but i will check them this weekend. Going to buy a mechanical gauge also.

Suzuki uses a 1/8" BSPT fitting for the oil pressure switch, most gauges come with 1/8" NPT - you'll need to get an adapter.

I pulled one of the plugs as well as moved the sender for the turbo
install, but I used a NPT thread adapter compression fitting, I didn't
have any trouble, what is the difference in the two???

Wild

Both are tapered pipe threads, with the same taper (1/16" in an inch) but 1/8" NPT is 27 tpi, with a major diameter of 0.405", whilst 1/8" BSPT is 28 tpi, with a major diameter of 0.383" - note those diameters carefully, the NPT fitting is a hair larger than the BSPT one.

They are almost indistinguisable to the naked eye, but if you try to screw a 1/8" NPT fitting into a hole meant for 1/8" BSPT you'll typically get it about 1/2~1 turn in before it jams, on the other hand, you can screw a 1/8" BSPT fitting into a 1/8" NPT hole without ever realising they are not meant for one another.

I've heard of folks "re-tapping" the 1/8" BSPT hole to take the 1/8" NPT fitting, and also of them just forcing the fitting and letting them cut their own threads (more likey deforming the fitting slightly).

What I do is buy 1/8 BSPT to 4mm compression fittings on the UK ebay site, and swap the 4mm ferrule (or olive) for a 1/8" one.

I guess the oil hose from the Mazda that I used was a BSPT and I never
realized that it wasn't NPT   

Wild

That may have been it - I believe they are fairly common on Japanese cars.