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OMP Questions (Rebuild kit and dangers if wasn't working)

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Old 05-05-09, 09:26 PM
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OMP Questions (Rebuild kit and dangers if wasn't working)

Hey guys -

I had a few days to myself around my birthday, and decided I need to paint my engine compartment so I can open my hood at shows, haha...

While taking the engine out (which is stupid easy compared to the Jeep we did last month), I started doing some inspections and research.

I thank everyone who has contributed to this forum in the past 8 or 9 years or whatever is has been. I have learned a great amount of information.

Now to the questions!

I noticed oil ALL around my OMP. I did research, and I now know what it does completely. It would have been nice if I knew about it before this. :/

The lines are bone dry, I'm guessing the oil leaked out at the rubber connectors attached to the OMP.

What damage could have been done if this was not functioning properly? I was not running pre-mix (which now I will do for a safety sake)

Where can the rebuild kit be purchased? I read in numerous threads there is one out there. I couldn't find a link to anything.

Info on my engine:

12A, 84 GS
104,000 miles exactly (when pulled into the shop)
No problems other than running very rich (couldn't lean it out, wouldn't run correctly)

Eventually I would like to rebuild. I'm still in the research stage, so my engine is going back in as it is, minus a cleaning, intake gasket, exhaust gasket, and other gaskets as I go on. (oil pan)

Thanks!
Chris
Old 05-06-09, 03:04 AM
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Chris - go to Pineappleracing.com's site and order their rebuild kit. They have an on-line video that shows you how to rebuild, which is actually pretty simple (and I am NO mechanic). Might want to clean out your metering lines at the same time. make a note of the ROUTE they run up the block before you pull these!!! (digi pic is best). As to the lack of oil to the engine... what can you do now?
I mean, really - just get it functioning again ASAP and don't fret it...
Stu Aull
80GS
Alaska
Old 05-06-09, 07:10 AM
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Yea, I was looking at mine the other day while messing with the belts and I never saw anything. My lines look good, as well as the rubber connects, just did not see oil. From what I have read here, its actually hard to see the oil in the lines, would that be correct?
Old 05-06-09, 09:13 AM
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^ yes, but no, what happens is the lines get old and they get yellowish so it makes it hard to see, but if you take a rag and clean any dirt or anything from it and look closely you should be able to see some in there, if not, then you better premix meanwhile you find what's wrong. or just give into premixing and block off the OMP
Old 05-06-09, 09:30 AM
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I got my kit from http://www.loweperformance.com/ They use Viton o rings as well. I don't know if that pineapple racing kit works for 12A. They are a different pump than the 2nd gen mechanical.
Old 05-06-09, 10:08 AM
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Even with really clean lines, if your oil is fresh and clean, it can be hard to see in the lines; the bore is very small. Dirty oil shows up better.

Easiest time to spot flow visually is just after startup after a long off spell, as most cars' lines bleed down some. You can see the oil pushing bubbles along the lines. Movement speed through the lines at choke-out-fast-idle (2000 rpm) is only an inch or two every couple seconds; it pulses, first one line, then the other.

Since flow rate is based on engine speed, at normal idle, it's quite slow, and if there's no air in the lines, you can't really see any visible movement.

The FSM flow test is the only for-sure way to test the pump.
Old 05-06-09, 10:29 AM
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So how do you test it? Im guessing if its not working, you would know it at some point. Cant you pull the line where it goes into the carb and see if any oil is coming out?
Old 05-06-09, 10:36 AM
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well that will let you know for sure lol, unless your line is somewhat dry it will take a while, but i guess even easier to check would be to take it off at the OMP
Old 05-06-09, 02:06 PM
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There is a volume test in the FSM to gauge how well the MOP is pumping. Section 2 p. 8 of the 85 FSM.
Old 05-06-09, 07:00 PM
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I thought the carb vacuum was what pulled the oil in. The throttle rod just opens the OMP up to increase volume.

You can at least tell if its pumping anything at all after it's been warmed up and driven test by pulling the vacuum line off at the carb and see if there's any oil residue at all. If it's dry you have a problem. If there's some oil in the nipple or on the tip of the line then you know it's at least pumping something.

Something else you could do is splice a fatter line in the center of the existing line. It will act like a little storage tank and you can see if oil builds up, how much, and how fast.
Old 05-06-09, 08:32 PM
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The MOP works like an old style counter top mounted sausage grinder. There's pressure pushing the oil and as the MOP turns, it 'slices' off a little chunk of oil with each pass. Each chunk then pushes the preceding one up the MOP tubes. Once the oil enters the carb throat, then the vacuum pulls it into the engine. One reason it's set up this way is it makes the oil supply rpm based instead of vacuum based.
Old 05-07-09, 09:54 AM
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^^yep...and the pump is "double-acting;" it burmps oil from one side of the "slicer" for half a stroke into one feed line, and then burps oil from the other chamber on the other half stroke, into the other feed line.

Kind of like an old double-expansion steam engine, but in reverse.
Old 05-07-09, 11:35 AM
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I have bought 2 kits from Lowes Performance. Great quality, communication, and fast shipping. They include directions on how to do it. Very easy.

I just rebuilt my last one and installed it with the RA OMP adapter to run Indemitsu premix. After I got it installed I just let the car run, with premix in the tank, and let the lines fill back up with Indemitsu before I drove it. It takes a while for the lines to refill though. I sped up the process by manually lifting the OMP lever to similate full throttle.
Old 05-07-09, 12:11 PM
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Originally Posted by 7aull
Chris - go to Pineappleracing.com's site and order their rebuild kit. They have an on-line video that shows you how to rebuild, which is actually pretty simple (and I am NO mechanic). Might want to clean out your metering lines at the same time. make a note of the ROUTE they run up the block before you pull these!!! (digi pic is best). As to the lack of oil to the engine... what can you do now?
I mean, really - just get it functioning again ASAP and don't fret it...
Stu Aull
80GS
Alaska
Where is the video on there site?
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