I have to add a quart of oil about every 4th tank of gas. At this rate I'll never have to change the oil - just the filter. I understand that the rotary engines use some oil, but this seems too much - or is it?

 

the more the better.

cuz if it stops your in trouble.

your new, let me be the first to say welcome.

you do have to change your oil but not as much as a boinger (piston) engine.

i would only change mine about every 10k longer sometimes. I never had a problem and the oil was pretty clean when it came out. But all engines are different. a good rule of thumb is that the more power you make with the engine, like when you add headers and such, you should start changing it more often.


The seals on the rotors need lubrication. they cannot be directly oiled from the eccentric shaft, so there is whats called a oil metering pump on the front of the engine. You can find it by the clear plastic lines coming from it.
that injects a certain amount of oil into the engine based on rpm.

again welcome to the club.

What year and model do you have.

 

I guess I'm relatively new to this forum. I've owned this 1985 GS with 220,000 miles for about four months now. It is my first RX-7. The previous owner put in a rebuilt engine about a year ago, but otherwise didn't take care of the car.

First thing I did was replace the A/C compressor and the fuel pump. Next I replaced the radio and two of the speakers. I sanded it down and repainted it the original color. It doesn't look half bad now. Within the last week I replaced the pinon seal on the differential and changed the fluid. Yesterday I changed the fluid in the manual transmission. Right now I'm refinishing the black plastic trim all around the car. Next project is to find someone to reupholster the inside door panels.

 

Every 4th tank is what..... 1100 miles or so? That's a little on the high side IMO. Have you checked for oil leaks? These engines when unattended have been known to develop oil leaks. Two main spots are just under the oil filter and around the OMP (Oil Metering Pump). Also, although it doesn't happen often, sometimes the OMP (Oil Metering Pump) can get stuck in an open position. This device as 82streetracer has said, is designed to pump oil into the rotor chamber. If it's stuck open it'll be dumping more oil than needed. Just a thought.

Good luck and welcome to the forum!

--Bob

 

I believe there are OMP rebuild kits available, check it out.

 

Provided everything is working right and properly adjusted/tuned, the excessive oil consumption can be a sign of a high mileage and worn engine...how many miles are on yours?

 

A quart is a quarter of a gallon, so that makes the mixture ratio for the OMP about 240, which I think is in the expected range.

B

 

Yeah, one pint per 650 miles is in the normal range.

 

Not only are they available, they're DAMN EASY to rebuild, and very important to rebuild as well. The oil metering pump is an essential part of keeping your rotary engine running properly. Without the OMP, your engine's seals will not get lubrication and your engine will sieze up, or even worse, break a seal requiring a rebuild.

The kits are available for $20 for a 12a here:
http://www.loweperformance.com/
it's much better to call them though, they don't check their e-mail as often:
(941)-924-8597

They'll mail you the kit, very easy to install.. Here are two pages that outline rebuilding the OMP:

http://www.godofredo.com/mound/3-11-03.html
and
http://www.mazspeed.com/oilmeteringpump.htm

Once the OMP is rebuilt, check the o-rings under the oil cooler (the bee-hive like thing that sits under the oil filter). These are known to leak oil, and at 220,000mi, yeah, every piece of rubber on your car probably needs some help!

If the O-rings and OMP restoration are done properly, your car will still burn oil (obviously) because it IS designed to. I don't know your funny american measurements very well, so I don't know if what you're burning is more that what you're s'posed to, but it's a good idea to check those two things.

Also, expect a *little* blue smoke. All rotaries give off a little blue smoke. If you're getting ALOT of blue smoke, then you can worry.

Jon

 

I'l try and answer several of your questions in this one reply.

The engine itself is a professionally rebuilt unit - installed by the previous owner. It has been in this car about a year. I really don't know how many miles are on it. Probably not more than 20,000.

One thing it is not doing is leaking any oil from the engine. All the oil consumption is definitely going out the tail pipe.

A few days ago I changed the spark plugs. The old ones were not black with soot. They did have some crusty gray build up. In olden days I would have called that lead fouling, but since we can't get leaded gas any more it may be ash from the burnt oil.

The inside of the tail pipe is sooty black. With an ordinary boinger, I like to see a gray tail pipe. I've assumed that this is from all the oil it burns and have not worried about the black tail pipe since I know this engine is supposed to burn oil.

Your comment about 1100 miles on 4 tanks of gas sounds a bit high to me. I'm getting anywhere from 20 to 22 miles per gallon. Four fill-ups of 15 gallons each would get me 900 miles at most.

I never thought of this in terms of the oil mix ratio. 1 quart in 45 gallons is 180:1 mixture. That actually sounds pretty good compared with the 50:1 mixture that many 2-stroke engines use.

The consensus of opinions above is that my oil consumption is within the normal range to maybe a little high. It is good to know about the omp rebuilding kit. I'll order one. Wouldn't worn out seals in any pump deliver LESS rather than MORE product?

 

Just curious, what kind and weight oil are you running? I use Castrol GTX 20w50 and my 90k engine burns about a quart every 3,000 miles or so.

 

Holy ****. Not saying you are wrong by doing so... But my FC gets it every 3k.

 

Eric and I have ours scheduled for every 4,000km, this seems to work for us.

Jon

 

The guy a bought my GSL-SE from (someone who also races Rx-7's) said to change the oil ~2000miles to keep the oil nice and fresh for the OMP.

 

Hey this is pretty unrelated, but i have an oil leak on my car. It looks like is directly under the oil pan in which case should i just change the gasket? Or is it more likely probably what inittab stated as being under the oil filter. If so how should i tackle it?

Zachstylez

 

<~~~~~my 7 like it????



just save up for a rebuilt...go BIG STREET !