sundeezy

I have an 85 GS with minimal modifications because I am trying to keep the car as stock as possible. Thus, I am currently in the process of replacing the OMP, instead of blocking it off and premixing. Is there anything I need to know as far as replacing it, or is it simply take the old one out and swap in the new one with a new gasket?

7aull

iTrader: (2)

It is a very straight forward swap… but, unless the unit is actually broken (pretty rare), why not rebuild it? Failure is usually bad gaskets or seals. Pineappleracing.com sells a rebuild kit WITH a DVD how-2 video for all of $30. These are really simple devices, so, unless you have deep pockets, rebuild.
Now - the OMP _lines_ that is another matter. If yours are the originals, they are waaaay past their replacement due-date and can be very fragile. Those I would replace with new.

Stu Aull
80GS
Alaska

Markjg

Where Can I find replacement oil lines?

Akagis_white_comet

iTrader: (4)

Unfortunately, only the front line is available now via Mazdatrix. However, you can make your own using some generic braided stainless 03AN or 04AN brake hose and the proper fitting adapters. The OMP has M8x1.25 threads, and I believe the intake manifold's ports are M8x1.25 as well (but it uses banjo fittings). Try threading one of the banjo bolts from the intake into the OMP's ports to doublecheck.

Brake hoses & fittings are cheap, so it won't dig too deep into your wallet. I did this on my 20B and expect them to last as long as the engine does, thanks to better materials for the purpose.

KansasCityREPU

iTrader: (9)

12A OMP lines are not threaded and don't use a bongo fitting. They just slip over the barb.

Jeff20B

iTrader: (13)

You don't want to use hoses that are too big of an ID. They need to be small for the "capillary action" to hold the oil in the hose up near the carb so it won't all drain back out through the OMP overflow and into the pan, thus leading to dry starts/dry running.

I wonder how many people with awesome aftermarket braided lines have created a situation where excessive apex seal wear can occur? It takes several minutes of idling or driving for the oil to move through the OMP lines. Even longer if the ID of the lines is bigger than stock.

Akagis_white_comet

iTrader: (4)

After re-checking Mazdatrix, you are indeed correct KansasCityREPU

Jeff20B, what I used are 03AN brake lines which are 3/16" OD, 1/8" ID. Stock lines are ~4.5mm OD, so it's close enough. I was concerned about them being too small and restricting flow. It seems that another person had the same idea on a First Gen here: https://www.rx7club.com/1st-generati...estion-879360/

I'm not a fan of hose barb fittings especially for something so vital. My general opinion is that hose barbs should only be used for vacuum lines while everything else gets proper threaded fittings.

What I would personally do is remove the barbs from the pump and tap it for threads in a suitable size in order to use threaded fittings on the OMP and retrofit the 84+ manifold injectors (Part# N318-14-6350) into the manifold.