Ummm my oil pressure seems to be a bit low in my 89 GXL. It reads around 30 when it is warmed up, could this be due to a bad fitting oil filter? Since it looks like it is leaking around the filter. After this weekend I am going to take it in and put it on jacks and start working on it. If this isn't the reason than could it be a bad oil pressure sending unit? I don't mainly care where this is because I have both haynes and factory so I can just look it up. When these go bad do they just read 0 or do they read some funky stuff? Thanks for the help and any response is a good one in my book.

 

Oil pressure should be around 30psi at idle and 60psi at 3000rpm. Check it with a mechanical gauge to see if it's just a dud gauge. I wouldn't guarantee the stock gauge's accuracy even if it is OK.

 

Aight, bumpity bump, anyone else?

 

what grade/brand of oil are you using?

 

60 psi @ 3000 rpm? WOW, I run like 80-90 at that rpm. I use castrol 10w-40.

'86 rex luxury
single turbo
100% stock

 

The 30 PSI figure at idle is what most 13B engines run unless the e-shaft oil jets have been modified.

The 60PSI at 3000 RPM is from the Mazda factory manual and is a minimum figure. 80 to 90 PSI with 10W 40 oil sounds to me like your gauge is screwed. There is a regulating valve in the engine that opens up and dumps oil back into the pan at anything over 71 PSI. You might be able to get more pressure with a cold engine but I doubt anything over 71 PSI is possible when the oil is hot, assuming the regulating valve is stock.

 

What oil pressures do you get with what weights of oil; i.e. 10w-30, 10w-40, 20w-50?

 

At higher engine speeds the oil pressure will be the same or nearly so with any weight oil. This is because the oil pump puts out more volume than the engine can use. The regulating valve simply dumps the excess into the oil pan. At idle there might be a few PSI difference, but not much. I thing most everyone on this forum uses 20W-50. It is good for anyhing above zero degrees.

 

I was under the impression that a lighter weight oil would reduce the oil pressure slightly. I swear there was a thread on this topic at one point.

I use Castrol GT-X 20W-50.

 

If the connector on the sending unit is dirty or corroded, your gauge will show lower readings.

The easiest way to verify your still running good pressure is to have someone rev the motor to about 3K while you try to squeeze an oil cooler line. It should be real firm. If it feels soft or flimsy, then you have a problem.

A leaky seal won't change your oil pressure by anything noticeable until you've jetisonned almost all your oil.

 

Do aftermarket oil guages connect to the same location as the stock guage? I really want to get one, but I don't know where I would put it. I like the stock interior look; but a good guage could save your motor and if nothing else, at least give you peace of mind while driving.

 

Using 14.7 psi as 1 bar, a metric oil pressure guage should read about 4 bar at 3000 rpms, correct?

 

Installing an aftermarket mechanical gauge is a fairly good idea. I am running Stewart-Warner gauges for oil pressure and oil temp. I have them mounted where the ash tray would normally be.

As for the place to connect them, the stock gauge sending unit location can be used. If you desire to keep the electrical gauge as well then all you need do is tee off the fitting and put the sending unit on one side and the mechanical line on the other. Auto Zone or a racing specialty shop will have the metric adapter that needs to be screwed into the block first. I used an old stock sending unit to obtain the brass fitting. I simply sawed off the sender part and drilled and tapped the brass pipe that was left. I am not running my stock oil pressure gauge.

For the oil temp I machined a fitting and then welded it to the oil cooler line banjo bolt after first boring a hole through the head (of the banjo bolt). The thermocouple (gauge probe) fits into the banjo bolt directly in the oil stream.

If anyone is interested I can post a photo or two of the gauges sitting where the ash tray was. All I did was hand form a thin piece of aluminum to cover the opening, cut two holes in this piece, then epoxy two pieces of aluminum pipe to it. They are angled towards the driver for easy viewing. It is not nearly as complicated as it sounds to do.

 

Just a minor correction...

1 atmosphere = 14.7psi
1 bar = 14.5psi
1 kg/cm^2 = 14.2psi

Watch it, a lot of times these units are interchangably used.&nbsp Japan boost gauges usually are graduated in kg/cm^2 units!



-Ted

 

When I start up my gauge reads about 30, but after it is warmed up it reads pretty low. When Im at 3000 rpms it reads 60. Does that seem right. I think that my oil system was upgraded when Hayes rebuilt my motor though. I use 20w50 oil

 

my oil cooler lines are leaking
where can i get stainless steel direct replacements??
how much will it cost me about??
thanx