Trevrxuk

Any advice appreciated, I've searched hundreds of posts so far.

Engine was re-built 6K ago by RX motors (good reputation) so I'm assuming the rear engine oil seal is good. I've replaced the two rubber 'O' rings in the oil filter housing.

Still have a slight leak, must be nothing more than a tiny drip but after a high speed run it smokes slightly from oil burning on the exhaust. Seems to be wet around the passenger side (R/H drive car) near the bulkhead mainly. In the pic you can see the rear rotor housing wet. Fuel pipes and oil pressure sender also wet.

Would replacing the re-breathe valve (pcv valve?) do any good?

Thanks.

Trevrxuk

Anyone ? Any ideas please?

FDjunkie

First be sure that you're seeing oil and not fuel. Some have reported problems with leaking fuel pressure regulators and/or the pulsation dampers, plus there are the fuel lines and injector plumbing. We don't want to loose another FD to a preventable engine fire!



Your description says that you have oil on the top of the engine. I can think of only a few possible sources that high on the rotary:

1. Spilled oil during re-filling operation.
2. The oil filter’s base seal.
3. Leaking seam on the filter's metal housing.
4. O-rings on the oil filter pedestal where it attaches to the engine - the o-rings you've already replaced.
5. The o-ring on the oil fill pipe where it attaches to the engine.
6. The OMP lines that go across the top of the engine.

You've probably already done this, but a serious eninge-top washing followed by close/frequent inspection should help narrow your search.

rx7raca

If I was living in England I would have cleaned that motor up a long time ago.

First thing I would do is take off the intake manifold. Get rid of the rats nest and check out all the rubber lines(fuel, oil, coolent).

Also to add, it looks like the "oil stain" is after the oil filler. Which could mean when moving oil comes out of that moving backwards on the motor. The oil filler is made of plastic, so it might have a small crack or maybe even the seal is gone.

Whats even more important is that, like you said the motor was just rebuilt!? Those oil filter O-rings should not be leaking after only 6k miles. So maybe you should give those people a call.

Mr rx-7 tt

iTrader: (5)

The oil filter’s base seal. (It's a big O-ring)

DamonB

You have a crankcase venting problem, not an oil leak.

There are two lines that vent the pan. One is a short one from the oil filler to the UIM and has the pcv in it. The other is a line from the oil filler to the primary turbo inlet. If either line is not functioning properly you can have the problems you are.

If the pcv is sticking open (or installed backwards) then boost can enter the crankcase and pressurize the oil pan, pushing oil out from the path of least resistance. The easiest places for the oil to be pushed out are the oil filler tube and the dipstick since they do not have strong gasket seals. Alternatively if the pcv valve is working correctly but the second line is plugged then while under boost there is no place for the crankcase to vent and blowby gases will pressurize the pan. This will only happen while under boost for extended periods.

My car had this same oil problem only after very high rpm and boost (racing). Oil would be all over the oil filter and the dipstick area. In my case a shop had removed and plugged the second vent line that goes from the oil filler to the intake, leaving only the short pcv line. In my case blowby gases were pressurizing the crankcase and pushing oil out from the dipstick and onto the fuel lines, oil filter and power brake booster. It really had me puzzled until I troubleshot the pcv system as the car would not leak one drop until I was racing; it was perfect on the street.

It's my understanding that the later model FD's only had one vent line and that's the short one with the pcv in it. That makes no sense to me because as soon as there is boost present the pcv must shut, otherwise boost leaks into the pan and pressurizes it. With the pcv shut and the second line removed there is now no venting for the crankcase Once I re-installed the second line on my car all was perfect again.

rx7raca

Would you be able to take pics or find some pics of what you are exactly talking about?

If its what I think your talking about its under the motor in the oil pan, maybe?


I am interested in this because I had a friend with this problem, with the oil coming from the filler, which later led to his motor blowing becuase of oil starvation. This is just a guess.

Get back to this thread if you can.

Trevrxuk

Thanks for the replies guys, much appreciated

After reading this I'm thinking :

1 : Oil filter 'O' ring, but surely not! That would be too easy, but I'll change the filter this weekend and check it out.

2 : OMP lines, but I dont know where they are exactly, gonna have to search for some info there.

3 : PCV valve, gonna check it and the other line, should I be able to blow thru the valve one way?

Thanks again

Trevrxuk

I've looked at the filler neck and it didn't appear to be leaking anywhere, but I'll check it more thoroughly again. The main leaky area is as DamonB described - fuel lines, oil filter/housing/pressure sender, and the bulkhead (no brake servo as R/H drive car).

Also the wet rotor housing and spray-back onto the exhaust and under panels, but that's just from going too fast!

Sorry , dont know what you mean about the oil pan?

rx7raca

no i was referring to what was said earlier about the pcv. I dont remember where it is.

honestly you will never know the answer to this leak until you take off some things an do your own experimenting. Its hard for us to figure it out without being there.

Good luck.

Trevrxuk

rx7raca.... the pcv valve is in the pipe from the top of filler neck, about 4" along.
I checked mine today and it's fine.

Also checked the filler neck, I didn't realise it was so long before, kind of swan neck shape. When I held the filler cap and pushed the filler back and forth I could see slight oil/air bubbles being squeezed out wher the filler neck joins the block. I'm assuming it's held on with two bolts but I could only see the near one, other one looks a pain to get to.
I loosened the bolt and there is no visible gasket on the join, do you know if there should be, or an O ring ?
Would oil spray out here, even though the pcv / breather system is good?
How would it get pressurized that much?

Thanks for help.