I've opened it up, and it's like a little plastic capsule with flat rubber diaphram with a center stalk (that you can see in the drawing)... I somewhat destroyed it cutting the nozzle open. And, FWIW, I also tried replicating the larger inner diameter old nozzle by drilling out a new one.

I've got a set of home made nozzles with pneumatic grade check valves ready to go in, but if there's some kind of high pressure of oil or air that's enough to blow the OE nozzles, my concern is it creates a failure elsewhere... like blowing one of the plastic lines.

The one really interesting part is the diagram appears to show that thwere's also a check valve in the oil line itself too, right near the banjo fitting? I wasn't aware of that, and it seems too small for there to be one there... but I walked downstairs to the garage and looked, and there is a little brass fitting there.

 

 

Wouldn't like the chances of unscrewing the jet on an old housing, maybe a nitrogen spray to the brass might get them moving?

There's been instances of the oil injectors being defective new out of the box. I'm not too sure I'd take the air supply side of the injector doing much, there will be a small vacuum at the face of the compressor. A failure should still be supplying the engine with reduced apex seal lubrication....putting filters on the line and not plumbing them back to the intake is a mistake imho.

 

Dale, do you still sell those Viton check valves?

 

^^^^

If you're thinking what I think you're thinking, I installed a "supplemental" check valve in the line after the one in the nozzles blew, and it blew the line off and made a huge mess.

Also worth noting, I ordered some "new" brass jet inserts for the rotor housing last fall, just in case, and they are of the type pictured on page 2 with what looks like a flathead screwdriver head, but they aren't threaded. That must be the "new" style, or it was really old stock. Also, while the inlet hole is about the size of the one on the nozzle, the outlet into the rotor housing is tiny, like a pin hole... hard to believe much "boost" would be pushed back through that.

P

 

I'm so transparent... haha

I had a talk with Chris at Rotary Performance on this topic. It was an interesting discussion, here are some highlights for those interested..

• In their experience, people often times think a nozzle has failed when in fact it's just dirty. They have come across many that were leaking, cleaned them up, then regained normal function.
• However, he didn't refute their tendency to fail. Adding that higher and prolonged boost contribute to failure.

I asked the question about what potential consequences there might be to the relevant system components if a more robust check valve was installed in-line above the nozzle and before either a filter or line leading to the pre-filter intake. Interesting highlights from that discussion..

• If the nozzle is designed with a failure point in mind, it is not to protect the OMP (more below)
• The OMP is apparently designed such that oil cannot flow back through it, the other direction. This is also apparently not a hazard for the OMP itself because it takes its oil supply from the low pressure side of the engine, so if oil isn't flowing through the line, the OMP just won't take anymore from the front cover.
**Caveat** reflecting on everything else after the conversation I began to wonder about the newly discovered check valve in the banjo fitting.. why is it there if not to protect the OMP? Well, if the above bullet is true, then it must be to protect the oil line from rupturing, since the fitting can surely take more pressure than the line. **end caveat**
• The OMP has a maximum pressure that it is capable of generating (I don't know what, apparently pretty high, though), so if there is "too much" opposing pressure on the oil in the injector/line (from increased engine pressure), these appear to be the potential outcomes..
•• 1) Check valve in the injector nozzle will fail
•• 2) Check valve in the banjo fitting will fail
•• 3) Oil line will rupture (which would first require the banjo fitting check valve to fail
•• 4) Oil flow stops until the opposing pressure lowers

Combined, the above suggested to me that installing a more robust check valve above the nozzle and braided lines for the oil would yield a setup that should at best operate normally and at worst not leak..

The above comments are of my interpretation of the discussion with Chris, along with other research. It's easily possible I misinterpreted parts of our brief conversation so if I'm sharing info that is inaccurate, blame me, not Chris.

Thoughts?

Peter, your experience with the added check valve is disheartening. Part of me is curious as to if you might discover something that is allowing more pressure to build up in that area of your car than should normally occur. I'll be interested to hear about what you find when you go to replace the jet insert. Did you or did you not replace that part when you first installed the newer Mikuni pump and nozzles? There is also supposed to be a updated rubber seal installed with the updated nozzle, right?

 

Well, the issue with the supplemental check valve blowing off was in part due to the fact that vacuum fitting atop the nozzles isn't barbed, so if you add oil to the equation they can slip right off. That's what led me to creating higher-quality versions with more robust valves and barbed fittings... I'd even thought about -3AN fittings on top. These pnuematic check valves are supposedly good to 125 psi... I'm interested to see how they do with oil and heat, but they were the best thing I could find to try. Maybe someone else knows of a better type.

I've had the Mikuni in since my previous motor, when the car was TT and I don't think it was a problem (ray even had the pump turned up in the PFC), and it didn't seem to be an issue when I first went single turbo with the old motor... this latest rebuild is when it started to show on the dyno, and then on the track, but I never really tracked the old motor w/ single turbo. This motor re-used one housing (both were new from Mazda last time around), and one new/used housing, and both nozzles blow when it happens, so its unlikely they are both messed up somehow. It's very strange. I guess there's probably not much to do but try these. It makes me wish I'd gone with an aftermarket primary fuel rail and injectors though, because pulling the rail to get to them is a major PITA and barrier to testing things.

ALSO: Can anyone tell me why the F every picture from a phone comes in upside down on this forum?!

 

 

I think they just run to a metal hard line in the rats nest, that eventually runs to the primary turbo inlet. The check valve in the nozzle definitely is oriented to flow air IN to the nozzle, so I'm not sure what applying vacuum to it would accomplish. I COULD see applying boost to it, to equalize aqainst boost in the motor.

 

Also, here are the oil jet inserts I got brand new from Atkins. I can only assume that these are what are in my motor now. Take particular note of how ridiculously small the oil outlet is. I can't imagine much oil going through there, and I could definitely see them clogging easily since the inlet is larger, and at some point it must take a 90 degree turn.

Another aspect to consider is the fact that I run 20/50 motor oil, which is thicker as well.

 

That hole is incredibly tiny, very interesting. I could see it getting clogged too, but yours must not be, since engine pressure seems to be forcing fluid out the nozzle check valve.

So do I have it right in this annotated drawing: the oil jet rests in the housing, but instead of seating against the opening, it stop just before, leaving a cavity that is presumably filled and drips into the rotor housing?

If so, perhaps it's possible the engine could build up pressure in that cavity faster that the OMP could fill it with oil??

 

Also, by the drawing I provided on page two, it appears that the oil jet you have is of the old design. If the drawing uses grey coloring for cavity space, the old oil jet's horizontal cavity appears to be shown. The new design shows a seal in that space, and no grey coloring; indicating no horizontal cavity.

 

Confirming this is the "new" style, same part number as Ray had:

https://www.atkinsrotary.com/store/8...26-14-633.html

Also, I just ordered the last rubber o-ring spacer in the country.

 

Cool, that's good news.

Do you have a link to the o-ring spacer? Curious what it looks like. You mentioned it's the last one in the country; is it NLA?

 

Here are some images of them. And no, Ray didn't see that they were NLA, so he figured there's an order in from Japan.

P

 

Thank you!

So you have this o-ring spacer installed in the housing currently, and you ordered replacement ones? Or you're unsure if they're in there so you ordered the spacer? Just trying to clarify if/how you believe this piece might be contributing to your issue.

 

I'm going to pull the existing ones out, spray cleaner in there, look for problems... but the only way i can think to get them out is with a dental tool/pick, and I'd bet there's a good chance I damage or lose at least one of them.

 

Good point.

Had another thought (which you may have already had). If your currently installed oil jet/s is/are clogged, do you think maybe it's not the increased chamber pressure but rather the OMP that is blowing your nozzle check valve?

Since the OMP is a positive displacement pump and it's flow is determined by engine rpm and the sector valve needle position, perhaps at lower rpm and lower throttle, the sector valve needle isn't as open, so it's not taking as much oil and not building up much pressure in the line. At prolonged higher rpm and higher throttle the stepper valve needle is more open, allowing the OMP to take and flow more oil into the lines/nozzles and increasing the pressure. Once in the nozzle and not able to go down (due to the clog) the pressure eventually breaks the check valve and goes up.

Sorry if my rambles aren't helpful, I can already tell there's holes all over this theory.. I've basically reached a point where I am thinking/typing out loud.. Will be curious to read your report after you've had a chance to get inside there.

 

Well, on a down note, I removed the o-ring/spacer from the rear housing. It was a bitch to dig it out of there, and it was destroyed in the process. But one out, I noticed that the "screwdriver slot" in the brass fitting was filled with black rubber/plastic debris. It was even more of a bitch to dig that out, but the hole itself is clogged.

I devised a way to test it by using a broken nozzle, and a bolt to fill the space that the banjo would havem bolting it in, then applying vacuum with the mityvac. It'll draw over 25 psi of vacuum and then slowly bleed down. I tried the same on the front rotor, and it just pulls air and builds no vacuum.

So, I either clogged it up digging that stupid thing out of there, or the oil/heat had deteriorated the rubber and it was clogged in there. I'd actually guess the latter, given how hard it was to dig out of there, and the consistency of the rubber. The question is, where to go from here. I don't think there's a prayer of unclogging it without disassembling the motor. Really shitty design on Mazdas part. I could remove the OMP entirely, but even that would require pulling the whole turbo.

 

That sounds really obnoxious.

I don't know about removing just the rubber spacer, but if you can access the oil jet below, you may be able to pull that out (and all the remaining rubber bits above it). Here is a permalink to a thread where a guy talks about how to do that. *method requires new oil jets*

https://www.rx7club.com/3rd-generati.../#post10754562

Do you have any photos you can share of all you saw and tried?

 

Disaster narrowly averted.

I managed to dig it out by using a 1/16" hex shank drill bit and finger turn attachment to slowly thread in there and remove the debris. It was quite a bit, so I'd really be surprised if this was a result of my digging in there to remove the spacer. I think it was deteriorated from the start. Here are pics of the "test rig" of broken oil nozzle and bolt to seal it up, and the clearing tool, and the remnants of the spacer.

 

Wow Peter that's wild. Creative thinking with the drill bit and well played.

So if that rubber spacer deteriorated from heat cycles and clogged up your nozzle pathway, do you believe it was actually your OMP that was blowing the nozzle check-valve?

And what do you suppose the implications are for those of us that would prefer to continue running the OMP (combined with pre-mix)? Options I can see are...
• Using old injector that are longer and extend down to the oil jet (hard to come by)
-- But, if they could be found, it wouldn't matter if the check-valve was blown because it could be backed up with a more robust check-valve.
• Finding some 3rd party to make new spacers out of something more durable (obvious challenges)
• Don't use the spacer and see what happens
• Hope replacements last..

Thoughts?

 

 

 

I've no idea what the OE spacer is made of, it might be viton who knows. Once I receive the brand new one, I can compare the consistency. What came out felt pretty hard and plasticky, and what was in the slot at hole of the brass insert was almost like it was melted in there. It would be hard to believe I did that getting it out, but it's possible. I think the only thing to do, its install my home-brewed nozzles, and see how that works. I think if they don't work, I'm likely ditching the OMP.

As I've researched this, I've found a lot of people complaining of bad nozzles right from Mazda, brand new... like probably 2 out of 4 or 1 out of four are just junk, but I suspect not many people notice because it's really only going to be noticeable on single turbo track cars (of which there really aren't that many. I've heard from regular mechanics/tuners that they've seen this with other OE parts that don't seem to be of the same quality as what cam on the car originally, possibly due to changed specifications or changed suppliers. Mikuni pumping more oil at a given setting probably exacerbates the issue. It's possible that both boost and oil flow contribute, but having seen into the check valve, I could see how a bunch of oil could get in there and stick it open.