novaboy009

'85 GS, all stock, 105k miles. Daily driver. The last 200 miles or so my oil pressure has dropped from 25 at idle and 60 cruising to 5 or 10 (almost 0) at idle and only 30-40 (sometimes less) while cruising.

I'm going to hook a mechanical gauge to it, but if the readings are correct, what's next on the list?

I searched and saw info on a front cover o-ring blow out. Is that your guys next guess? How difficult of a job is it? I've guessing I wouldn't have hurt the bearings with only a few miles with low pressure?

The oil cooler beehive is leaking too. Would that cause low pressure?

Kev

trochoid

iTrader: (6)

Check/clean the wire connection on the sending unit, backup your reading with a 2nd gauge. Leaking o-rings would soon deplete the engine of oil to make much difference in oil pressure readings.

Hyper4mance2k

iTrader: (40)

you can never trust a stock oil pressure sendor asfar as you can stuff it in your bum. I went through 3 sendors and two dashes before i learned to just buy a mechanical one and realise that there in fact is no oil pressure problem...

novaboy009

Is there an easy way to T or plug into the mechanical gauge for a quick check? I searched but couldn't find anything real useful.

Kev

peejay

Change the oil.

If that doesn't do anything, clean the electrical connection at the pressure sender.

If that doesn't do anything.... don't worry about it. It's still plenty of pressure.

SPERRYsan

iTrader: (1)

gauge failure is more likely unless the motor was mistreated

Hyper4mance2k

iTrader: (40)

99% of all rx-7 gauges are wrong. Mazda used the same sensor from 81-92 and when the gauge sendor starts to go bad it takes the display on the dash with it. So, when you replace the sendor your dash is still going to be off. Just get a mechanical gauge then ask about oil. I'm not trying to be an ******* but I had about 3 "Low oil pressure" posts around the forums. And that's what everyone told, but me being the stuburn ******* that I am ignored them only to find the only answer was a mechanical gauge that told me I didn't have a problem after all...

novaboy009

Better safe then sorry. Don't want to hurt the Daily Driver if yah know what I mean.

One more time, any thoughts on how to temporarily check the oil pressure with a mechanical gauge? I just want to plug in the mech gauge and test it real quick.

Kev

Rx-7Doctor

iTrader: (13)

No quick test unless you get the proper fitting for the block. The fitting size in the block is
1/8-28 B.S.P. and the standard gauges or test gauges are generally 1/8 NPTF. Yiu can buy this adapter fitting at most Napas. Part # is 701-1550.

novaboy009

I've never heard of a BSF fitting, but I used the part number to order from Napa today. Should be in tomorrow morning. We'll see what's going on then.

Kev

Rx-7Doctor

iTrader: (13)

B.S.P. British Standard Pipe, not BSF..

speedturn

iTrader: (1)

Did you put a fresh oil filter on it?

novaboy009

SOB!!!! That sensor is in the worst location ever! Couldn't get it from the bottom (coolant hoses to beehive in the way) and could barely get it from the top (beehive, lot's of random hoses, spark plugs, brackets, etc). I turned it 3 mm a turn with a crescent wrench until it was pretty loose and then spun it out by beating counterclockwise on the nubs of the mushroom with a hammer and screwdriver.

Thanks for the PN Rotary Doc, worked like a charm. By the time I got the f-ing thing out of there, I decided to just mount a mechanical gauge and be done with it. Pep Boys carries a relatively inexpensive sunpro 2" oil pressure gauge in black with orange pointer, fits right in with the dash.

Stuck it next to the dimmer and side mirror auto mover. Looks pretty nifty.

Oil pressure is now showing at 65 psi fast idle, 40 normal idle and 75 cruising. That's more like it

Thanks for the help guys!

Kev

trochoid

iTrader: (6)

Fwiw, if you trashed the sender, cut the 'button' off of the 'mushroom', then tap the 'stem' for 1/8" NPT. Don't even need to drill a pilot hole. Screw in the sender for the new gauge, run the line, mount the gauge, you're done. The 'stem' takes a 14 mm open end wrench.

Hyper4mance2k

iTrader: (40)

told you so LOL!

Frostycrowd

iTrader: (9)

Would replacing the gauge with an aftermarket electronic one be ok?

Siraniko

iTrader: (13)

IMHO, mechanical is best for second opinion.