FD OMP question
#1
FD OMP question
About how thick is the specialized copper crush gasket (i.e., piece of copper with 2 holes in it) on the FD oil metering pump? This would be the one that goes between the OMP banjo lines and the pump.
Long story short - My FD was purchased without an OMP, but the PO provided 2x good low mile OMP's for me when I bought the car. Along with my rewire of the Link G4+ ECU, I restored the factory OMP, with the RA OMP adapter & tank mod so I can run premix thru it. Since I had plenty of the correct size regular copper crush washers on hand, I figured I could use 1 of them on each side of the banjo fittings where the lines bolt up to the pump, thinking they would do the same job sealing up the lines as that funky Mazda copper gasket with the 2 holes would do. Apparently I was wrong - I can't get the damned fittings to not leak premix lube! Tried replacing the crush washers, and made sure the banjos were torqued to FSM specs with no joy. My only theory as to why it's still leaking is maybe the specialized Mazda copper gasket is significantly thicker or thinner than the regular crush washers I'm using.
Long story short - My FD was purchased without an OMP, but the PO provided 2x good low mile OMP's for me when I bought the car. Along with my rewire of the Link G4+ ECU, I restored the factory OMP, with the RA OMP adapter & tank mod so I can run premix thru it. Since I had plenty of the correct size regular copper crush washers on hand, I figured I could use 1 of them on each side of the banjo fittings where the lines bolt up to the pump, thinking they would do the same job sealing up the lines as that funky Mazda copper gasket with the 2 holes would do. Apparently I was wrong - I can't get the damned fittings to not leak premix lube! Tried replacing the crush washers, and made sure the banjos were torqued to FSM specs with no joy. My only theory as to why it's still leaking is maybe the specialized Mazda copper gasket is significantly thicker or thinner than the regular crush washers I'm using.
#2
Urban Combat Vet
iTrader: (16)
IIRC they are a bit thicker...a guess is maybe a millimeter. Gotta be someone that’s removed their OMP and has one lying around. Or see if Ray Crowe has them.
That said, are you sure it’s leaking at the hoses and not from that equally funky 'O' ring on the body of the OMP? They get pretty flat and stiff and will leak.
That said, are you sure it’s leaking at the hoses and not from that equally funky 'O' ring on the body of the OMP? They get pretty flat and stiff and will leak.
#5
Well I'm confident the source of the leak is the sealing surfaces between the banjo bolts and the pump - with a gravity fed tank full of pre-mix, it was easy enough to test. Just pinch off the oil supply hose, clean the mess in the OMP area, then un-pinch the hose and patiently wait with a bright flashlight shining on the OMP area. Didn't take too long for the oil to show up again as a bead right at that junction between the banjos & pump.
Anyway, all the mating surfaces were clean and flat, and the RA OMP kit came with a pair of the new oval O-rings, which I used a little Hymolar to keep in place while assembling the OMP/RA Adapter to the front cover, and I did this job with the motor out of the car on a stand, so all the usual PITA accessibility elements that would make it easy to F-up the job weren't there.
I'm thinking it's a thickness issue - might try doubling up on the crush washers on the OMP side, and if that doesn't work, I'll be calling Ray for the OEM parts.
Anyway, all the mating surfaces were clean and flat, and the RA OMP kit came with a pair of the new oval O-rings, which I used a little Hymolar to keep in place while assembling the OMP/RA Adapter to the front cover, and I did this job with the motor out of the car on a stand, so all the usual PITA accessibility elements that would make it easy to F-up the job weren't there.
I'm thinking it's a thickness issue - might try doubling up on the crush washers on the OMP side, and if that doesn't work, I'll be calling Ray for the OEM parts.
#8
RX-7 Bad Ass
iTrader: (55)
Doesn't seem like the stock double crush washer is that much thicker but that makes sense. You may be bottoming out the bolts without the washer fully crushing.
Also may be worth re-annealing the washers you've used as stated - heat with a torch to cherry red. That expands and "de-crushes" the washer.
Dale
Also may be worth re-annealing the washers you've used as stated - heat with a torch to cherry red. That expands and "de-crushes" the washer.
Dale
#9
Well the doubled-up washer idea is working so far - been on there for almost 2 hours with zero signs of leakage. With the single washer, it would show signs of leakage within 15 minutes. So I'm going to just leave the car untouched on the lift overnight - if it's still dry tomorrow morning I'll call it done.
#11
#12
An update to this annoying damned leak.... After getting the oddball Mazda OEM copper double washer & regular crush washers, it still leaks premix from the same place - looks like its coming from the joint where the lines mate up with the pump.
One thing I noticed is it leaks worse when the external pre-mix tank is full; if I fill it less than half, it barely leaks at all, and the rate of leakage is worse when driving. Don't worry, I'm running pre-mix with the gas.
So at this point I'm left with 2 theories that might explain the leakage:
1. There may be a hairline crack in the OMP machined casting under where the banjo bolts mate up to it
2. Longshot - the SS lines that came with the car may be blocked, and oil flow is taking the path of least resistance out.
I have a 2nd spare OMP, so plan is to pull and inspect the one that's on there now, and if necessary, replace it with OMP #2. The one that's on there now is a lower mileage part, and appeared to be in much better shape than used OMP #2, hence why I used it. Also, I've gone thru the drill of calibrating it and electrically testing it with my Link G4+ ECU, so I know it functions properly.
One thing I noticed is it leaks worse when the external pre-mix tank is full; if I fill it less than half, it barely leaks at all, and the rate of leakage is worse when driving. Don't worry, I'm running pre-mix with the gas.
So at this point I'm left with 2 theories that might explain the leakage:
1. There may be a hairline crack in the OMP machined casting under where the banjo bolts mate up to it
2. Longshot - the SS lines that came with the car may be blocked, and oil flow is taking the path of least resistance out.
I have a 2nd spare OMP, so plan is to pull and inspect the one that's on there now, and if necessary, replace it with OMP #2. The one that's on there now is a lower mileage part, and appeared to be in much better shape than used OMP #2, hence why I used it. Also, I've gone thru the drill of calibrating it and electrically testing it with my Link G4+ ECU, so I know it functions properly.
#16
The RA OMP adapter seals up to the front cover with the same oval O-rings Mazda uses to seal the pump to the front cover, and the RA adapter has a groove in it for the ring to seat in for where it mates to the front cover. The other side of the adapter is flat where it mates up with the OMP (OMP has a seating groove for that O ring). The kit comes with 2x of those oval O-rings and longer M6 mounting bolts for the install. There's zero signs of it leaking from either of those points though, and when I installed it I had no issues with the rings walking out of their grooves - used some Hylomar sealant to keep them in place.
#18
You know, the only reason I'm using the SS lines is because they came with the car and I assumed they were good - passed visual inspection at least. I actually would prefer a new set of OEM lines, as they last a long time and I can see my pre-mix oil flowing thru them.
Last edited by Pete_89T2; 10-02-20 at 04:34 PM.
#19
RX-7 Bad Ass
iTrader: (55)
It may be worth doing that, but changing lines can be a pain. If you are single turbo without all the rat's nest it's not as bad.
I prefer the OEM lines, they fit awesome and really have zero problems for 100,000+ miles, especially if you don't touch them.
I had a writeup ages ago on how to pre-fill new lines with oil, may want to look for that.
Dale
I prefer the OEM lines, they fit awesome and really have zero problems for 100,000+ miles, especially if you don't touch them.
I had a writeup ages ago on how to pre-fill new lines with oil, may want to look for that.
Dale
#20
So for those of you who guessed it was the banjo fitting/SS line, you were right. I rigged up my Motive pressure bleeder to create a controllable source of low pressure air, and used it plus some tubing and a small reservoir (from my Mity-vac kit) to supply a some pressurized pre-mix oil to the RA OMP adapter's oil inlet port. At about 7~10psi, oil became visible on one of the two lines, coming from just below where the SS line is crimped onto the banjo fitting.
Time to give Ray a shout and get me some new lines!
Time to give Ray a shout and get me some new lines!
#22
No worries - Single turbo here, takes me about 10 minutes to pull the UIM off with no rats nest to deal with. And with the Staubli leak free fuel line couplers the PO was smart enough to put in, I can have the fuel rails & injectors out of the way in another 5 minutes without stinking of gas
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