FC Drifter

my T2 is showing 0 pressure at idle and only 30 at cruise. im not sure if its the gauge or if the car is actualy making that little of pressure. the wire on the sending unit is a litte screwed up but im pretty sure its making good contact. and also i have the mazdatrix oil thermo bypass thing. my question is....what could cause it and how do i fix it? thanks guys.

Icemark

Probably the sender, but you should check it with a mechanical gauge to make sure.

And please fix your signature. It should be no more than 10 lines, and your's is 17.

reamia

i had a rx 7 with the same oil presure and then it blew up. that sucked

CyborgRyu

iTrader: (8)

my NA recently started doing that in the winter, is it something to do with the weather? I also recently intalled new gauges on it. I get 60 when I start moving, but when I first start the car, its at like 0 and then after lil bit of driving it starts to idle at 30 again.

Black13B

iTrader: (1)

Follow Icemark's advice. Double check the sender wire. It has a tendancy to slip off or build resistance.

As for other possible causes, the thermo bypass oil valve may also fail. It's job is to keep oil pressure low when you first start the car so warm up is quicker. Once the oil warms up, the valve will allow full pressure.

A pellet is a popular replacement and allows full pressure all the time. Any RX7 website will have pellets for dirt cheap. Atkins, Mazdatrix, ebay, etc.

FC Drifter

its the 2nd sender ive put on it, all of them used off spare motors of mine that have been laying around. ive got a gauge i can use to check it laying around somewhere in my garage, i just have to find it.

the thermo pellet i put in it is a mazdatrix one that i just put in. however i did compromise it somewhat. the instructions that came with it were very vauge and i didnt realize there was more to take out than what it showed, so i kept cutting the spring thinking that was the problem. when i realized i hadnt taken it fully apart i stretched the spring back out with a pair of pliers to the length it originaly was. i can see this as a problem i need to fix, but dont see it as a part of my current problem, although i have been known to be completley wrong a lot of times.

and i will at some point fix the wire as well. its just finding the time to do it. i dont drive the T2 that much so im in no hurry.
and yeah ill fix the sig. is that some sort of new rule or something? its been a while since ive browsed these forums.

NZConvertible

That's not quite right. The thermal bypass stops the flow of oil to the squirters that cool the inside of the rotors until the oil gets to ~140degF, to get the engine up to temp faster.

Personally I'd rather replace a failed thermal pellet than perform a "hack" repair.

Black13B

iTrader: (1)

Hmm.. I thought it just dropped the pressure? Meh. Same idea basically..

Quote:

Personally I'd rather replace a failed thermal pellet than perform a "hack" repair.

Were you referring to FC_Drifter's experience or the bypass pellet mod in general? If you mean the pellet, I am curious as to your reasoning?

chuflay

dude im having the same problem my oil ps goes at 0 then all of the sudden goes to 30 when im going fast at 60 ps , but i think is the gauge any way is running fine ...im just waiting for him to blow up so when i build my other engine i'l make sure i put a new oil pump...
I also have a friend that has a turbo II ported (new oil pump) and it idles at 10 ps , if you dont wan to waste your time guessing just do a real oil p check up it should not be 5 or lower

skydivr73

when my 86 NA is at idle, it is usually between 15-30..15 when it is cold....but runs fine and pressure is around 60 at 3K....is that normal? BTW, idle is right around 1K and fairly smooth

NZConvertible

That's a result of bypassing the squirters, it's not the reason for doing it.
The reason for the thermal bypass is to bring the engine up to temp faster. To me that's a good thing, so if it fails it should be repaired, not disabled.

This is just like replacing a PD with a banjo bolt. People remove them because of a perceived risk of failure despite the fact that the original one lasted 15+ years.

CarmonColvin

I had simular problems with oil pressure on an old motor in my race car. Zero pressure at idle and around 30 psi at 8k rpm. It was the front cover o-ring. I pulled the motor and verified it was as described on Mazdatrix's website.

http://www.mazdatrix.com/faq/oring.htm

If this is your problem there is not an easy way to fix it in the car and your best bet is to pull the motor and fix it properly. But it is probably time for a rebuild anyway.

Black13B

iTrader: (1)

Any drop in oil pressure wether it be disabling the squirters or not will heat up an engine quicker. But anyways, you win on a technicality, as usual.

Quote:

The reason for the thermal bypass is to bring the engine up to temp faster. To me that's a good thing, so if it fails it should be repaired, not disabled.

I see what you mean. I like your comparison on the banjo bolt.

To each his own though.

IMO, I would have to disagree with this. Perhaps if I was using this car in the cold weather, then I would be more concerned about it, but otherwise, I picture it's effectiveness being about as helpful in the summer as the cold start system is in the winter. And this is ruling out the worry of failure. I am aware a new replacement would last just as long (as you pointed about about the PD). But I am lacking in the experience department on contrast to yourself. If there is something you could point out to me to change my mind possibly on the matter? Going on what I have learned thus far (keep in mind my application is a summer only vehicle), I would rather use the bypass pellet.

NZConvertible

Yeah, but the heat would be generated by the friction damage being done to under-lubricated parts, which wouldn't be smart.

Disabling the squirters (which cool the insides of the rotors) means less heat is being removed from the engine, allowing it to warm up quicker. Same reason why both the radiator and oil cooler have thermostats that are closed until the engine warms up.
We're talking about the heat generated by combustion (many hundreds of degrees) and friction, so the ambient air temp is all but irrelevant.
I have no more experience with the thermal bypass than you, but the Mazda engineers who designed these engines probably have more knowledge and experience than everyone here put together. If there was no benefit to putting it there than they wouldn't have. I've yet to see any credible info posted here or anywhere that would convince me that I shouldn't replace a thermal bypass with anything other than a new one.

Black13B

iTrader: (1)

Well said.

How do you figure? We are talking about the engine warming up faster, right? The overall temperature? Why wouldn't this have to do with the ambient outside temperature?

What I was implying was the overall result of this is the engine is up to temperature faster? I was just saying I would be more concerned with an engine getting up to temperature faster when the engine itself is actually cold, not just the term "cold" for an engine that has been sitting turned off during a 30+ degree summer.

What I was trying to say is essentially to me it seems like this design was to help heat up the engine quicker in actual cold weather, not just a "cold" engine condition.

But I have not ingored what you already posted. I just wanted to clarify.

NZConvertible

Heat transfer is a function of temperature difference. The further apart the temperatures of two touching objects are, the faster heat will be transferred from the hot object to the cold object. (That's Thermo 101 for the day. )

So to make a simplification, if we assume shortly after start-up the temp of the inside of the rotor is rapidly climbing because of combustion, it's going to be far hotter than the engine's oil, which is still near ambient temperature. So whether ambient is 40degF during a winter night, or 80degF on a summer day, the inside of the rotors is going to be far hotter than that. So spraying oil into them is immediately going to start cooling the motor when we actually want it to be heating up.

So saying that ambient temp is irrelevant was overstating it a bit, but the thermal bypass is still performing the same task in summer as in winter. You still need a thermostat for the cooling system in summer for the same reason. Internal engine temps are far higher than ambient even when it's baking hot outside.

Black13B

iTrader: (1)

Learn something new everyday. I knew just as much but I would have never been able to put it into those words!

That said, I would like to change the direction of this...

What about the damage caused by the failed valve? The engine running constantly without the squirters? As stated before, the pressure reading drop is a result of no squirters. Does this mean the rest of the system is fully 'primed'? What could happen when running the engine without the rotors being cooled?

I would have (originally) imagined this would have caused engine damage?

NZConvertible

I'd guess there'd be potential for damage in you left it for long, particularly if the engine is worked hard. Not only is oil pressure low (so oil flow is reduced), but heat isn't being removed from the rotors (which have no water-cooling).

Whether you decide to replace the thermal bypass or disable it, it should be done ASAP.