Well my base 87 NA seems to be losing its punch; my oil pressure now doesn't stay higher than about 31-32 constant (under acceleration it goes higher for a bit, but then comes back down). It seems fine when the engine's cold, but craps out when it finally warms up. I've gotten the sending unit replaced, but it didn't help.

Anyways, my question is this: I've heard of guys premixing their oil with their fuel (I think, anyways). Since I don't have a lot of $$ to spend fixing my car, I was wondering if it would help to do this, and also I was wondering how much, and what the method is to do this (add a quart and then fill up the tank?). Are there any downsides to this, like the injectors getting clogged, oil separating from the gas in the tank, etc?

Any help would be appreciated, I need this car to last me at least a few more months until I can graduate.

TIA

 

It won't hurt the apex seals but the real problem with low oil pressure in at the e-shaft bearings. Mixing oil won't do a thing to protect them. I guess the good news is that I haven't heard of too many shaft bearing seizing...though I haven't been around rotaries that long.

Chris

 

It may not be your oil pressure to start with. Do you have an aftermarket gauge? If not, and you are using the stock one, the senders go bad over time. Could just be a sender going bad. Be sure to verify the oil pressure with some sort of aftermarket gauge.

With premix, it won't hurt anything to use it. Just get some 2-stroke oil at the local parts store. Most people use an overdone 1oz/oil-1gal/gas ratio, but after figuring out how much oil is used by the OMP, it is a ratio of more likely 1oa/oil-4gal/gas.

I would go with the premix idea, and use it at a ratio of 1oz/oil-2gal/gas until you figure out what your oil pressure really is.

 

did you replace the sender with a new one?
if you did you need to check and make sure the engine has oil pressure. if the engine does not have oil pressure you will destroy every single piece of it. http://www.mazdatrix.com/faq/oring.htm
that might be the culprit, ive seen wht this does 1st hand and its not good.

mike

 

yes, the sender was a new one. argh, it sounds like the o-ring problem... pardon me for being mechanically retarded, but how would i make sure the engine is getting oil apart from using the dipstick?

 

tear the engine down.
there is an oil valve in the eccentric shaft. remove and clean it.
now put your engine back together. sounds simple, doesn't it.
sorry but thats the only way to know for sure. just run about 1/2 quart of twc 2-cycle with every tank of gas. put the oil in before you fill up so it mixes up. thats all you can do.

 

Again, I would verify your readings with an aftermarket gauge to make sure this is the problem. Maybe the gauge in the cluster is bad...who knows. Find out for sure, then go from there.

 

if you engine is stock then it's not the 0-ring. I've never heard of one of these giving out. only in rebuilt engines.

get an aftermarket gauge. pre mix isn't going to help with a low pressure problem. put some 20w50 oil in if not already that will raise the pressure too

 

Hmmm it was rebuilt about 90K ago, so who knows... Pressure probs happened after a little hard driving. All of a sudden the pressure went to zip (!!!) but I had it towed to the shop and it put out a little pressure after that. I had the sending unit replaced but it didn't seem to help too much.

btw, thanks for all your help so far

 

Oh yeah, are there any how-to's for installing a gauge? I've installed my own headers, which took an incredibly long time... how would that rate in comparison (difficulty-wise)?

 

Now that I think about it, the gauge should be fine.... I had it checked when the sender was replaced, and it shows plenty of pressure until my engine warms up.

 

Your engine sounds as though there is a problem with the oil circulation. Somewhere there is a leak in the oil passages and that is causing your oil pump to be unable to keep the pressure up because of the increased flow.

The oil pump in most cars is a constant volume pump. This means that for every revolution of the pump, there will be a given amount of oil moved. This is a finite value because of the spacing between the oil pump gears. More RPMs equal more pressure because of more volume trying to get through the various restrictions the engine poses to oil flow. If the pressure suddenly goes way below normal, then you have somehow created a less restrictive oil system.

On the rex, there are only two places this can happen. The most common on a rebuilt engine is the o ring between the front cover and the front side housing blowing out. This always happens when the engine is running at high rpm because this is a weak link and is the first to give way under high oil pressures. If your rebuilder used the front cover gasket this is almost a sure bet to be the problem.

The problem is that the gasket that is supplied with rebuild kits is substantially thicker than the original factory installed cover gasket. This has the effect of not compressing the o ring enough. The cure is to disassemble the front cover, clean everything up, and put it back together WITHOUT the gasket. Use Hylomar sealer instead. This will allow the front cover to compress the o ring properly. I have seen many of these o rings blow out. The result is always around 30 lbs max pressure. The fact that your enging has 90 K on it does not mean this could not be the problem. Do not use the teflon ring that comes with the gasket set either. Just install the o ring and use the Hylomar on the front cover. Be sure if you do this to keep the oil passage between the front cover gasket sureface and the side housing gasket surface from being plugged with sealer. If this happens, your OMP will not get any oil. You can make a short stand pipe out of steel tubing that will hand press into the side housing. The hole in the front cover is bigger, so it will slip fit there easily.

The other problem is the bypass valve located in the front of the eccentric shaft. The valve's purpose is to allow the rotors to warm up quicker by diverting their cooling oil supply. It simply allows the oil inside the e shaft to dump directly into the oil pan without going through the rotors first. If it sticks open then there will be much less restriction here and your e shaft will also be starving the bearings for oil. This valve is easily defeated by removing the actuating rod and reinstalling the valve with a spacer to keep the valve closed at all times. Check Atkins Rotary. They have a machined spacer that will do this. Hayes Rotary has one also.

Be very carefull when removing the front pulley hub for any reason. The end play flat needle bearings are prone to fall out of place when this is done and if you re-torque the pulley into place the bearings will be pinched between the lettered spacer and the frotn counter weight. This will quiclky lead to major problems. How do you know the bearings are in place? Simple. Check the distance from the front of the pulley bore to the eccentric shaft when you take the bolt out. Write this measurement down. When it comes time to reassemble, push the pulley hub back on firmly and measure again. If the distance has increased more than a very few thousandths, then the bearing has fallen out of place. This will require the front cover to be removed and the bearings to be realined again.

Mazdatrix has a good bit of info on all of these things I have spoken of. Just check out their web site.

Hope this helps. The short of it is that I do not think it is necessary to completely tear down the engine. Your problem can be repaired by the removal of the front cover which can be done with the engine in the car. At the very least tearing the engine down to this point while it is still in the car will allow you to know for sure what the problem is before going any further. If the o ring is blown it will be obvious to you upon seeing it.

 

wow, thanks a bunch... i will check this out pronto