Rebuild OMP LInes
 

I'm in process of installing a new engine. The old engine is on the bench and stripped and I am starting to build up the new engine.

Right away I need to install the OMP lines and OMP on the new engine and I realize that the original OMP lines have 100K and multiple very bad overheating episodes in them. They seem pretty delicate and I have read stories of them becoming brittle, so I don't want to reuse the lines (the metal connectors and oil injectors should be fine).

There is a DIY on the rx7 forum for a 2nd gen that sounds pretty good for replacing the lines with PFA tubing, but I can't find any reference to RX8 owners doing the same thing. Has anybody done it? Any problems?

Rebuilding the OMP oil injection lines - RX7Club.com

While I am at that level, is there any suggested maintenance for the OMP itself, or just leave it alone?

How about the fuel injectors from an engine with 100k and some overheating trauma? Take them apart and clean them, take them apart and install parts from a rebuild kit, or just leave them alone?

It looks intresting, but crimping the ends right might be some trouble.

I broke one of my lines and patched it with a larger hose and 2 clamps. IT works just fine with no problems. The patch is on the rearmost injector on top of the engine.

I haven't used ear clamps before, but they are made for that tubing and that is what the car currently has and they look pretty easy to set with pliers. Did you have trouble with the ear clamps, or were you using something else?

I've done it. works like a charm.. and the ear clams are not hard to lock..

Where to buy PFA tubing???
 

Where did you get your tubing and clamps, local or mail order?

The part number for the source listed in the RX7 forum is now PTFE not PFA, and their PFA only comes in 50 ft rolls. There is a source through amazon in 10 foot lengths, but they list it currently as back ordered. The other on-line sellers I have found also sell minimum 50 foot rolls and I only need 8-10 feet.

I live in San Diego and there have to be local suppliers for the scads of biotech and other engineering companies and research universities in town, but I have no idea who and where they are.

I used what was listed in the rx7 forum.. so to say it is the PTFE.. so far i dont see no ill effect. if you want to be safe you can buy new oem line which are 55$ each. and i bought it from that website that was listed. they ship one day. it came from navada to Washington and i was pretty impress.. at least got my 8 back on the road, cause one of the line snap when i was installing the sohn when i had to go over the rad hose. eventually i'll replace the last two but got lazy.. hahah

Thanks!

The heat and pressure numbers for the PTFE look very similar to the PFA (500 degrees, 300psi) so it seems close and both are way better than needed. I am not sure why the RX7 DIY recommended PFA explicitly, but I was surprised that the part number was PTFE instead.

I think I am going to order the PTFE.

yea that what i said too.. but i was like man i dont want to stress out the lines when i have the sohn.. so i was like what the hell.. buy extra!! for both the line and clamp i ordered 15 feet, and 12 clamps. if you are going to replace them i would replace all.. like i said i have two more left lol..

My engine is completely bare and sitting on my bench, so it is not question of whether I can reach them! I'll definitely replace them all.

My question is what else I should do just cuz I am in there and have the access.

other then your omp lines i would clean the ssv. but other than that i dont know what else.. i mean if your fixing your motor and not upgrade your cooling system such as the thermostat and water pump. that would be a good thing to do as well.. go with mazmart reremedy water pump and the thermo combo. :)

I'm flushing the omp nozzles and replacing the omp lines, flushing and rebuilding the fuel injectors (new screens, etc to make sure there is no gunk in them) and replacing the thermostat.

I'm not replacing the water pump because stock is supposed to be more than adequate for stock setup. I'm aiming for reliable stock rather than squeezing out more power.

Oil cooler lines all look very good. I'm replacing all the coolant hoses and I'm contemplating replacing at least some vacuum lines.

I'll take a look at the ssv and make sure it is clean and working well.

Thanks

Not true, I just ordered exactly how much I needed (in my case only 5 feet) price has doubled since that thread though on everything but no need to order 50 ft lengths. MSC was very helpful to me and I got my shipment in 1 day just got it this afternoon after ordering it yesterday morning. I am not doing the same thing as that old thread though, I'm doing a much better, more durable set up as the work involved and the critical nature of these lines is not worth the gamble not doing it right as far as I'm concerned.

I read some pretty sketchy shade tree engineering and materials being used on that thread and some are clearly outdated and highly risky IMO. The idea is to eliminate possible failures with certainty not add more uncertainty to a possible engine failure like several of those concepts will do.

Definately replace the vacuum lines on the oil injectors if no where else, they get really stiff and brittle and obviously are not replaceable or even able to be inspected with the engine assembled any more than the OMP lines are. Be very careful removing them however especially the back line because when you are removing them you're pulling directly off the injector but upward against the vacuum block and because they're so short it's really easy to snap off the vacuum connection as you have a lot leverage against an angle. I'm speaking with the engine in the car.

Over time the block gets quite brittle too it seems, I had to end up replacing the block I put very little pressure on it and it broke (the back vacuum fitting) which indicates to me it was likely decomposing from heat before I tried to remove the line. They're made of the same material they make any plastic pieces used for insulating in other heating appliances like toaster ovens or space heaters and it still gets brittle over time and if they fracture you now have a vacuum leak and the oil injector won't work properly either giving you a double jeopardy situation and performance issue it'd be very hard to know it even happened until dis-assembly after the damage has already been done and even then maybe not, if not paying really close attention. Because of the material they can crack partly through without fully fracturing and you'd think it's ok but it could still be leaking vacuum, I've seen it before.

Out of curiosity by any chance, has anyone here ever taken a heat gun reading in this area after they've run their engine a bit hard to see what the temps in there are? I haven't seen any info on that, I'm certain it's quite hot by all of the evidence but how hot I'm wondering? I don't think the engine cover is at all helpful with extracting heat out of the engine either it's just a big low cover the hold it in and intensify it so, I remove it for daily use, I'll put it back on for dressing when I sell the car later and pass on my advice to the next owner.

Wondering if silicone tubing would be a good alternative? Silicone handles heat pretty well, as far as pressure the OMP system isn't pressurized or at least not much pressure running in those lines, so I'm sure silicone would be more than adequate for that.

I have shot my engine with a Flir using different emissitivity settings and pretty much everything metal aside from my turbo and manifold is around 200-250F.

And not all silicone is the same and the idea of making your own OMP lines is not a good one. The stock OMP lines typically last 10 years or longer so the stock ones are just fine. Not everything lasts forever, when they fail just replace them with new stock lines. There is too much room for error in making your own.

I'm curious why you say this? The process of cutting, replacing and crimping a new line seems pretty straightforward to me (maybe it's just me), but is there something else I'm missing? Maybe you're worried about routing them badly and kinking it or something?

I dunno, I just ordered some PTFE and some clamps from a local place for less than the cost of one new line, looking forward to replacing them all while the engine's out over the winter..

Well it depends on the type of clamps, the hose used, how you route them, etc.

200 to 250 you say? I hope that's right that's what I was thinking given oil temps are very close to that as well. That'd be good but I'm wondering what the injector is seeing directly? I believe it to be hotter, it is directly installed in the combustion chamber but the engine is water cooled and the oil, though it doesn't really "flow" in a sense through the injector or lines is also there for some heat resistance and cooling effect. I will be getting a laser heat gun myself soon and that's something I'm going to confirm for my own info.

Soon I'm going to be posting up the lines we'll be offering aftermarket, as these cars age the need is increased exponentially. ONE of the critical problems with the OEM lines is they are not in a place where they can be regularly inspected or easily replaced while the engine is in the car and the critical nature of both them and the fragility of the motor already, which was never planned in the first place, makes them failing a real losing proposition I'd not want to gamble with. The price of being wrong is simply too high and if you're going to replace them anyway why not for the sake of piece of mind, reliability and at nearly similar cost (possibly cheaper) go to a quality aftermarket product instead of the same o same o and never worry about them being a problem again.....Ever?

There is also the other theory (unproven no doubt as are many of the theories surrounding the engine failures that seem to be more of a pile of unique factors over just one or 2) that the plastic fuel lines are breaking down chemically over time due to the methanol in the fuel which leaves deposits in the oil which then turn into ash and carbon deposits once burned being a contributing factor to engine failures as well. Again probably not working alone or the same in EVERY case but several factors working all together. Given that, the more of these factors that can be reduced or eliminated altogether the less likely of future problems being so eminent.

When you have reliability issues on so many levels as these engines do any issues you can sideline is a step in the right direction and these will eliminate several potential issues.

Checkout RotorSports Racing Mazda RX-7 rotary engines and performance modifications shop

Bryan there hooked me up with some very nice SS OMP lines.

SS lines would be a good option but for that price I think SS is a bit overkill for OMP lines. I can make my own set of silicone or ptfe lines for less than $40 re using the old banjos. Making your own lines is as easy as finding capable teflon/PFA/silicone tubing and pushing the hose onto the banjo fitting nipple. Theres not much you can screw up there.

You can buy new ear clamps which are easy as pie to clamp on, or on 7club I've read of people even re using the old ear clamps so long as you can spread them apart and slide them off without damaging. But new ones are dirt cheap so why not replace. But I can see in a pinch having to spread them apart and re use them.

Sure you can make a quality hose but to say it's better is just silly when you have done no R&D to prove that. The factory lines don't fail often at all, it's typically the oil injector that fails first. The lines typically last well over 10 years. I had mine fail, but I can't blame the line itself as my car is over 12 years old.

Now if someone wants to assemble their own that is fine, but not everyone can do that and so installing new OEM OMP lines is the smart choice.

If your going to do that spend the little extra money and go to a parker shop. Get 919n hose it's ptfe with a stainless braid. If memory serves me it's good for 1000 psi at 400f. You can probably find some jic banjo's and have parker put on the correct crimp on stainless ends.

Yeah the factory banjos have a check ball in them though.

Adding to 9krpm's comment above, the check ball is in the OEM banjo bolt that goes through the banjo hose fitting. I.e. it's not in the circular banjo fitting that the oil line is crimped to. The OEM bolt can be re-used (after cleaning) with original or compatible banjo surrounds, though you will need to test the check valve mechanism to ensure it holds 9psi of vacuum per workshop manual. If it can't hold this vacuum, buy a new banjo bolt.

Thanks for the info. Does anyone know the thread pitch and dimension of the bolts? Before I take mine out I'd like to have replacements. Otherwise I'll have to take them out and measure them up and then get replacements.