Plumbing; mostly oil

Sep 14, 2009 update on ae86andkp61's Toyota Corolla GT-S

A lot of the rest of my work lately has been on plumbing. Thankfully, a friend working on a similar build has been paving the way for a lot of this, and I have benefitted from his updates and his trial-and-error…always good to have someone to bounce ideas off of. :)

First up is the fuel pressure sensor for the management system…it needs a place to go. Our new setups won’t require (nor use) a cold start injector, so the lack of a fifth injector leaves a hole in the fuel rail. All it took to make it work was a bit of drilling at my workplace and an NPT tap.

All of this plumbing work has lead me down an interesting side road I didn’t ever imagine, but one which has been an interesting learning experience. I’ve had to bone up on threads, sizes, and standards for plumbing and fittings, learning about what types of threads are out there, and what does and doesn’t work together. It seems that Toyota uses British pipe threads on the block, and not only that, but they are tapered British pipe threads (BSPT.) The most common threads around these parts (and therefore on many of the sensors) are North American pipe threads (NPT) which are often the same diameter, and similar, but not identical, in thread pitch, thread type/angle, and taper. The Mocal oil cooler sandwich plate uses BSPP, the parallel version of British pipe threads, and the oil cooler and lines use AN (also known as JIC) or Army-Navy fittings, which are pretty much the standard for the race/high performance automotive aftermarket.

So, let’s start with the oil pressure sensor, which needs a home. The sensor is 1/8” NPT so it won’t just thread right into anything on the engine. My friend Dan had the brilliant idea of putting it in the plug on the side of the oil pump. The resulting hole is 3/8” BSPT, which is close enough to 3/8” NPT that you can start threading a North American fitting in, but to be on the safe side, I ordered a reducing adapter.

Now on to the oil cooler setup. Trying to put it on, we found that clearances are too tight. Before I even got the lines on to the fittings, the fittings are hitting both the coolant drain petcock and pointing straight at the stock oil pressure sensor! So I ordered up a 1/4” BSPT plug for the coolant drain. Sure, it will be messier when I have to drain the coolant, but with new red coolant that won’t be for years, and the plug created a lot of room. I also ordered up some BSPP to AN adapters in a 45 degree angle to replace the straight fittings coming out of the sandwich plate. You can see in the pic that it all works a bit better. Still tight, but it all fits now. Also note the adapter in the oil pump:

I also pulled the stock sensors from the coolant necks, and have to get more plugs for some of those because the new management won’t need all the holes. I will probably do an oil temp sensor setup like Dan’s-in a tee which is in the middle of the oil cooler line, mounted to the inner fender or the inside of the front frame rail. I thought about trying to mount it onto the sandwich plate directly, but I don’t think I will because I am concerned about the weight of the fittings and that the assembly will be prone to fatigue/cracking with time and vibration.


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