Can anyone think of a way to pressurize the oil system without starting the engine? I have the tranny out and trying to see if I have a rear main leak or a pan leak. They both look pretty sketchy. My idea is to weld a bolt or nut to a bar, that I in turn bolt to the rear crank, then use my impact gun to turn the engine over (from the rear I'd turn it ccw, looking from the front it would be cw). The plugs would be removed of course. Does anyone have any other ideas? I briefly searched posts for people trying to test their oil system, but hadn't seen anyone trying to do it with the tranny out.

I'd rather not pull the engine, but my have to if I can't figure out which seal, if it's only one, that's leaking. Any help would be appreciated. Thanks!

 

https://www.miataturbo.net/forum/t33197/
This I don't know has been replicated but seemed to get a rise of some us.
***Edit**** I see you don't want to crank the motor?

 

Any reason why you couldn't just start the engine anyways? If the flywheel is still on, it should idle fine... just don't rev it.

I genuinely can't think of a reason not to start it... but there may be a good reason I'm missing.

 

There is no exhaust on the engine (though I could put it back on), and I was hoping to avoid running it because once I run it for a while, I'd have to (possibly) quickly take off the flywheel and look for leaks (assuming the oil wasn't shot everywhere by the flywheel). Also, I'd have to make a bracket to mount the starter. That's not an issue, it just seems like it's more work than welding a bolt to a bar with 2 holes in it. Also, would I have to support the engine more than just the 2 mounts? It seems pretty stable, though I put some wood under the pan just for support incase.


I'll read that Real Men Of Genius post soon. Though I quickly searched thru it and it looks like they are pulling a vacuum, I want to pressurize the system. That may not have been what they were doing, that's just what I got from a 5 second skim of the post.

 

pull plugs
disable fuel pump

crank starter.

 

starter not mounted



OP, I kinda like your idea, and the mazda pump should build a good bit of pressure with minimal pumping.

btw, unless the pan has been removed previously in it's life, I doubt it's leaking.


Not only remove the plugs, but take you belts off as well. Another idea would be to use a belt to drive the crank pulley, just don't put too much lateral force on it.

 

oh, duh.

grinder motor belt drive to the crank pulley!

 

I do not think an impact gun will spin it fast enough to get much pressure. The real men of genius approach (mine) would not work either since that creates a vacuum just to help prime the pump. It will pull a vacuum on your system which is the opposite of what you want.

If you really want to do this, you could rig up a pressurized oil reservoir and feed it into the hole where the oil sending unit goes. Pressurize it to 20 psi with a shop compressor. Never done this myself, but it should work, though the setup could be a PIA, and the execution could be messy.

The stuff they use to put the oil pan on at the factory is like glue so I agree, it is less likely to be the source of the leak if your pan was last factory (or competently) installed. Based on that, you could just gamble and replace the rear main seal and reassemble. The rear main seal is easy to do when the flywheel is off. I did one successfully (no leaks) during a clutch swap.

Check the CAS seal (if you have a rear CAS, add your car details in your sig) and the valve cover gasket too.

 

Thanks guys. I was thinking of doing the CAS seal and the valve cover gasket as well. I had also heard that the back corner of the head gasket can leak as well.

My oil pan gasket looks like it's been replaced as there is red silicone in there, and either black silicone or the gasket has extruded out (it feels harder than silicone to me, which is why I think it's the gasket). Which is why I'm hesitant to just replace the rear main.

A pressurized oil reservoir is an interesting idea. I already have a pressure vessel I made for vacuum bleeding brakes that I could use. It would also be interesting to see if 20 psi will shatter a tomato sauce jar!! Safety glasses required. Or beer and some gulliable friends.

Although I'm starting to be convinced that the best thing to do is say f' it all and pull the engine to replace all the freakin' gaskets (rear main, oil pan, head, valve cover, CAS, etc.) Much more work that I was planning, but less than doing the job twice.

 

lol just thinking about that. Unless you love oil, I'd hold off on this approach. It could be done, but the time spent constructing a dependable setup for this could better be spent pulling the motor...which is what you'll have to do anyways if it is the oil pan.


I agree with ZXTex, change rear main, put on tranny. If problem isn't fixed, you HAVE to pull motor anyhow. Many argue it's easier to pull motor and tranny as a unit than it is to actually pull the tranny. I personally don't agree, but this is a GOOD game plan that means you either fix it cheap and easy with work you're already doing, or you have to do a lot of work anyhow and you didn't have to build a pressurized oil system/grinder motor belt drive/impact wrench adapter to do it.

 

As you can see, the oil pan gasket has clearly been messed with before, and you might be able to see how the rear main doesn't look right either (part of the bottom is missing, though that isn't the spring energized portion, and there seems to be more of a gap at the top, but again, that isn't the spring energized portion). Since the tranny is already out, I'm thinking it might be easier to just pull the motor, change the gaskets, then bolt the tranny to the engine and put the whole thing back together.

 

it works on SBCs.

 

SBCs?

 

Small Block Chevy's .... like my 417 (Stroked 400) in my Nova.....

 

Ahh OK, got it. Well both oil pumps (SBCs and BPs) are positive displacement pumps so once they are primed I suppose they would move enough oil to work even at low speeds.

 

Why not just pressure up the crankcase with some shop air? It doesnt take a lot of pressure to find the leaks. I use a smoke machine, it will build only about 3 psi with everything plugged and the machine pumping in smoke. Less than 10 psi will show up the leaks fast. I put the smoke hose on the dipstick tube and plug the breather and vent, then look for the smoke, same would apply with some air pressure, you just have to look harder.

Ron

 

Looks like the leak is from the pan gasket. I let it sit for a few days and checked it out tonight, oil was running down the pan from the gasket. Looks like it's coming out this weekend! Gotta order a seal kit tomorrow then take that bad larry out. Figured I could drill and tap the oil pan for a return line while I have it apart and just plug it. Thanks for all your comments.