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-   -   Repair/replace 12a long OMP line to carb (https://www.rx7club.com/1st-generation-specific-1979-1985-18/repair-replace-12a-long-omp-line-carb-1085736/)

TimWilbers 06-27-15 03:57 PM

Repair/replace 12a long OMP line to carb
 
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During the 12a rebuild last year, I broke the long plastic OMP line to the carb. (Late night, involved a hammer.) I noticed the vacuum line I was rehabing the rats nest with was just the right size and a tight fit. Held pressure and vacuum. But, after 1600 miles, it did not hold hot oil.

I may have 15 city miles (3-4,000 rpm) before discovering the oil leak.

First question: Any estimate of damage done? (Probably impossible to determine.)

I clamped the hose back in place with twisted paper-clips, got to the closest stop-n-shop, picked up 8oz of 2-cycle oil, and filled up the tank. The paper-clips got me home, no leaks.

I checked and only the short lines are still available (Mazdatrix).

I also rebuilt the OMP last year with the Lowes kit. It came with two connecting hoses which I did not use as I could not easily get the OEM hoses off the lines. I installed one of the Lowes hoses on the OMP line break and clamped it in place. (image)

As the Lowes hose will come in contact with the same hot oil, be it at the OMP or half-way to the carb, my thinking is it will hold. (I'll be premixing for awhile for insurance, and checking the condition of the hose and for leaks.)

Second question: Is my thinking rational/sound in that the Lowes hose will be a sufficient repair?

If not, I'm open to suggestions.

Thanks.

Jeff20B 06-27-15 05:12 PM

The fabric covered line absorbs oil on the outside and is gross to deal with. But use it as long as you need to.

I don't think any damage was done to your engine. They can go for hundreds of miles with limited or no OMP oil before any real damage begins to show.

The stock nylon tubing is best because it has capillary action (tiny ID) to hold oil in the line after shutdown. All other aftermarket lines are too big and oil always drains back down into the engine after shutdown. It takes longer to fill large ID lines than small stock lines as well. This leads to more engine wear over the time. Something to be aware of.

TimWilbers 06-27-15 05:30 PM

Thanks Jeff.
I was really more concerned about potential damage.

I know the OMP works as there was a puddle at the top of the intake manifold, and the plate under the carb.

Understood about the stock tubing ID.

First leak of anything after the re-rebuild last Nov.
And now that I know what's inside the engine, I've been driving it harder than before.

Jeff20B 06-27-15 08:51 PM

Me too! And I know if I break it, I can build another!

MIKE-P-28 06-30-15 03:45 AM

I got several used ones in good shape. Been sitting on a shelf for YEARS! Wonder if they worth money now? Lol


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