The RX

Right, so I've been with the forum for quite some time, and haven't ever really posted as I've become quite adept at the search feature over the years. However, at this point I have felt that I need to get some responses...

I own a very well kept, full records, 1987.5 RX7 GXL, 5 speed, Turbo driveline w/ GXL diff. I have meticulously maintained this car to the best of my abilities, and love it every bit as much as I did my first and second '87's that came before it.

To get down to the problem... I watch all my gauges religiously, and today noticed that my oil pressure, upon second start up of the day (paced 7 hours after the first), was nonexistent... Needless to say I was, and still am, quite concerned. I've ran it through the rev-range, I've checked under the hood for leaks of any sort (however my OMP, for reference, had a dribble leak sometime in the past that for whatever reason seemed to have sealed itself) and didn't find any whatsoever... There's no abnormal smells, vibrations, sounds, visuals, nothing. Only thing off is the reading oil pressure, which incidentally *does* in fact move slightly, just not above 15psi MAX.

Any insights would be more than welcome. I'll await patiently in the meantime.

misterstyx69

iTrader: (142)

you could have a bad connection to the Sender(located under the oil pedestal).It is a bell shaped looking thing.
Another guess would be that the sender went bad.
..and yet another guess,would be oil viscocity.What oil are you running?

The RX

I'm running 10w-30, in temperatures between 30 and 70 fahrenheit. Also, i replaced the sender roughly... Six months ago or so. I grounded the sender connection earlier and was able to get a strong reading out of the gauge, it quickly went up before i removed the ground. I'm trying to think of any other pertinent information... The car had 115700 on it. However, the records indicate a remanufactured engine was installed at roughly 65000. I'm running premix through the tank currently, and have been for about five months, or since first noticing the leak off the OMP, even after it ceased leaking. Interestingly it seems to be a bit more spritely in terms of it's revving and general sense of health.... Oh, i did check the condensor and it's still bolted down securely... I've noticed that during my areas current rain, that when the car gets sideways and i gold the drift, that the gauge will come up to roughly 30psi, however, i can't duplicate the results when merely taking the revs up without the force of the car moving laterally... So... That less credence to the idea of it being some sorry of connection issue (hopefully anyway), however, the fact that it won't do it at all unless I'm drifting is... Odd to say the least. If i can't figure this all out by the time my mechanic returns then I'm planning on taking it in, but this seems well within the scope of my abilities so.. I don't want to waste the money.

Aaron Cake

iTrader: (1)

Sounds just like a loose connection or dirty connector. Maybe the plug behind the cluster is loose.

If you EVER SO BRIEFLY touch the wire to the chassis, does the gauge respond?

The RX

Yes, as when i grounded the sender unit connector, it very quickly made it's way up the gauge. I didn't let it get above 45psi or so. Quick question, as to alleviate my worst fears, obviously no seal had catastrophically gone out, as I'd obviously be leaking or burning oil horrendously. But the same came could be said for the oil pump, yeah? That is to say, of it was bad/out, then i would most certainly notice it. I know that's am idiotic question, but just wanted to make sure.

jmike575

Sounds like wiring to me. Mine are very brittle and fall apart real easy. I've need able to use a female connector on the oil sending units before to make them work

The RX

Hm... I may give that a whirl. Admittedly this did all start during my areas current spot of rainy weather. Heh, I've fixed nearly every other electronic device in or on my car, so why not this too :P

Rhyno2050

I was wondering cuz it sounds like i might have the same problem, but my oil pressure needle works fine at start up but when the car has fully warmed to operating temp the needle is really sluggish and goes do to almost 0-15psi, and my car is a 86 n/a base model. Any suggestions or would it be the same fix as The RX problem?

Aaron Cake

iTrader: (1)

If you didn't have oil pressure, the engine would already be locked.

But, if you want to be sure, check it with a mechanical gauge.

Sounds like a bad sender if the gauge is working.

The RX

Quite right, well thanks for alleviating my concern of true loss of oil. However this is doubly annoying given the time frame between the last time I replaced the sending unit (the first time was due to a seeping leak). As a final bit of questions before moving on to the job at hand... Would anyone recommend an outlet better than MazdaTrix to go about finding a sending unit? Or should I just assume that I got the slightly more flawed than normal part? (Or perhaps repair mine..? I know that seems unorthodox, but I've rebuilt many things that were said to be impossible to reverse engineer and repair correctly.)

On a sentimental note, thank you all very much for the prompt assistance. As I stated in my first post here, I've been a member of the forums for quite some time, and have gone through three RX7's in the process. I've done nearly everything imaginable in that time aside from delving into turbos, engine management, or full on rebuilds; It all wouldn't have been as possible, nor "easy," if it hadn't been from the vast amount of information, support, and general services places like this provide. I've become a guru with my cars thanks to those here (and some credit should likely go to the years of schooling and projects I've taken on), and links made available. So, thanks.

Aaron Cake

iTrader: (1)

Mazdatrix is selling the same parts as the dealer, which by this time must be fairly old. So I guess one could expect a bad part now and again. That said it's still fairly annoying it failed. Just to be sure, if you can find one at a local wrecking yard you can swap senders without having to purchase a new one. There is still a possibility that there is intermittent wiring somewhere.

The RX

So, i have an update... Although it's not going to be very helpful. On the last off day i had (of which i have one per week), my gauge began working at full capacity again. So at idle i am reading between twenty and thirty PSI, and under steady load I've got fifty to sixty. Needless to say this knicked my plans for diagnosing and repairing for the moment, going by the adage of it not being broke... Yadda yadda. Obviously something is still awry almost certainly, and likely to happen again, but for the moment all is well. As a side note the weather has cleared in my region, and I'm largely attributing this to my former woes now given the time frame at which this all occurred. It also probably lends credence to the idea and distinct possibility of it being a wiring issue above all else. I had my clutch replaced with a higher performance unit just recently, and the loom going to my starter is as taught as can be (as i have a turbo driveline which obviously mounts the starter on the opposite end). So my thinking is that where the senders wire enters that loom something probably became problematic, and that's where all this stems from. This is all hearsay, but for anyone else whom may have had this particular issue... It might be a start on your investigation.

Thanks again for all the input guys/Mr Cake.