Author Topic: Omp rebuild  (Read 1318 times)

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Offline FCwidman

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Omp rebuild
« on: July 26, 2014, 01:40:36 PM »
Has any one done this to an s4? im dripping oil all over my driveway and need it done. I read up on how to do it and have to O-rings bookmarked to buy. Was wondering how long it took someone, shes my only ride and cant be out of commission for more than a day  :-\

Offline toplessFC3Sman

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Re: Omp rebuild
« Reply #1 on: July 27, 2014, 11:28:03 AM »
The whole thing took me a couple hours the first time.  Pulling the OMP isn't difficult if you get the airbox out of the way.  If you remove the radiator shroud & fan, that makes it even easier (although the time spent removing those may not make it worthwhile unless you're taking them off for another reason too).  Remember to add some 2-stroke oil to your gas in the tank before doing the rebuild, since when you take the OMP apart & drain all the oil out of the lines, it can take 15 min to a half-hour of running (even with the control shaft held up) for it to fill up and start injecting oil again.

Are you rebuilding the lines too?  There had been a thread on RX7club about doing them, and the supplies were all pretty cheap from McMaster.com.  Its a good idea to make sure the check-valves in the oil injector nozzles are working properly too (you should be able to blow through the vacuum nipple, but not the other way).

The oil may be leaking from the front cover gasket, front main seal, or one of the connections for the oil cooler, or the oil return from the turbo if you have one, and all look like its coming from the same place too, so that's something to check while you're in there as well

Offline FCwidman

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Re: Omp rebuild
« Reply #2 on: July 27, 2014, 01:08:25 PM »
Thanks for the info, I didn't plan on doing the oil lines cause I don't wanna take my intake off. how often do the oil injectors go bad?

Offline toplessFC3Sman

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Re: Omp rebuild
« Reply #3 on: July 28, 2014, 09:35:48 AM »
I'm not sure how often they go bad, but all the check valves had failed on my engine when I had everything apart last summer.  I don't know the history of them, since they were on the turbo engine when it was bought out of a field in VA

Offline ITSWILL

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Re: Omp rebuild
« Reply #4 on: July 31, 2014, 06:59:07 PM »
I have had oil injectors go bad as well, I dont think they stopped injecting oild but the check valves were definately bad.
86 Base LS1 w/100 shot
88 TII 20B T70 turbo

Offline toplessFC3Sman

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Re: Omp rebuild
« Reply #5 on: August 01, 2014, 09:44:21 AM »
Yea, oil will still get pushed through them, but the air from the vacuum lines attached to the top probably won't atomize the oil as well, resulting in more of a drip than a spray or mist.  Also, if the check valve isn't working, the oil could get pushed up the vacuum line instead of down into the housing or runner when intake pulsations are high or if you quickly shut the throttle, causing inconsistent oil delivery (at least for a couple seconds)

Offline FCwidman

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Re: Omp rebuild
« Reply #6 on: August 07, 2014, 05:50:18 AM »
thanks for all the info guys, still havnt gotten around to it yet and i leave for school tomorrow :( think im just gonna run pre mix to be on the safe side for now.