On my last race, at Hallet, I lost oil pressure. Thankfully as I’m writing this, no major damage, and I’ll be able to reuse my motor. The cause was the oil pump gears let go.

I lost oil pressure hitting rev limiter for a split second just before I braked into the last corner. I was battling for 3rd place, and was fun till this happened. My first reaction was maybe my oil pressure sensor went out since my car felt fine. But my instinct told me to back off the battle, and ease into the pits. It not worth losing a motor if you can avoid more damage. I pulled into the pits still thinking its the sensor that went out. My sensor is electronic that goes to my ECU, and feeds that info to the AiM dash.

To make sure if it was a sensor issue, I have a accusump with a pressure gauge. This is a mechanical gauge, and was also reading zero. This told me I definitely lost oil pressure. I didn’t see any leaks or obvious damage, and the motor sounds good. No knocking or weird noises. This lead me to think maybe there is blockage in the oil passage or oil pump went out. My weekend was done, and I wasn’t going to get any points.

Back at the shop, I pulled the motor out because it’s easier to work on. Only took me 6hrs taking my time. If it wasn’t too hot, maybe 2hrs. I then started to undo the bottom end. The oil looked clean, and no metal flakes. So far so good.

Until I took off the oil pick up and heard some metallic sounds. That wasn’t normal. I’m not supposed to have big pieces of metal inside the pick up screen. I knew then, I had gear pump failure. Bummer.

Lucky I had a spare oil pump and there is some slight differences. The failed oil pump is the top, and the spare newer pump is on the bottom. I made a little youtube short on how you can tell: https://youtube.com/shorts/xZh-3WgHTcM?feature=share

I opened the pump, and sure enough it failed. This gear design is known to fail, and Toyota did update the design in the later 4age motors. It is actually rare to have this design, and I was just unlucky.

I have a spare 4age pump, and removed the back plate to verify it has the updated gears. This has latest design, with the 9.5mm thick gears.

If you want more info about the 4age oil pump design this youtube video is spot on:

Okay, that great, and its just oil pump failure. But I’m not out of the woods yet. Since the gear broke some pieces of metal could have made its way into the block, and I had to check the top part of the motor, aka the cam shafts.

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Checking out the cam shafts I was able to see the specs of the cams. No gouges or feeling any deep groves that my fingernail could catch.

The camshafts just showing normal wear, and clearances within factory spec. Next is to check the bottom end and clean it.

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Con rod bearings has the normal wear. Bearings felt smooth and nothing noted that can be concerning. Next is the crankshaft and main bearings.

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The main bearings looking brand new, and wearing in nicely. The crankshaft only has minor damage to the front where the oil pump gear rotates. Not bad where I have to replace it or take it to the machine shop. Thankfully the only major damage was the oil pump.

The bearings look good to reuse, but I figured to replace them. The reason is because its easier to replace while the motor is out, versus when its in the car. Refresh the motor a tiny bit.

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Checking the clearances with the new bearings, and within factory spec.

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I’m almost ready to put the motor back in the race car. I’m waiting on a new oil pick up tube I bought from Battle Garage, before I reseal the motor. In the meantime I’ll replacing the water pump, timing belt, and the front/rear main seal for maintenance.

If you want more info on how to tear down, and rebuild a 4age motor I made a youtube playlist.

The disassembly playlist.

Assembly playlist.

Thank for reading this far, and I hope to see y’all at the race track! I will be back racing again soon, my next points race is in September. But I plan to do a track day in next 3 weeks. Stay tuned.