03 450 Engine Question

Oil system is not working after rebuild by local builder. Guy gave up. Anyways by what the drawings say, after removing the oil pump, I should be able to see through to the other side of the engine, where the line continues to the oil tank. I cant see a passage way, or fish anything through, or even blow air through. What are the chances that this guy either blocked the primary oil path somehow. Perhaps using a later year gasket kit or something?

Anyone who has torn down a 450 may have some knowlegde on this, please help.

You understand that there are actually two oil pumps in this engine, correct? They consist of two inner/outer trochoid rotor sets on the same shaft, and separated by a steel plate. The outer, thinner one is the feed pump, which draws oil in through the right crankcase cover from the feed line, then pumps it past the low pressure check ball in the RCC and up to the filter. From the filter, it flows through the cover to two passages, one leading to the crankshaft by way of a seal in the RCC, and the other to the crancase, where it is distributed to the trans and the cam box.

The inner, thicker pair of rotors is the return, or scavenging pump. The passageways here are very much simpler, and you should see them both at the "bottom" of the pocket the rotors ride in. One leads to the sump screen, which is bolted to the crankcase just on the other side of the bottom of the pump pocket. The other simply runs across to the left crankcase, wher the return line attaches to it. If you remove the ignition cover, you can see the screen, and if you pump oil through the passage from the pump side, you should be able to watch it run out through the screen. If you remove the return line, you should be able to take oil in a squirt bottle and pump it into the pump pocket.

What does the oil system not do?

You explained it much better than me. I have the pump out and I am talking about the path from the inner rotor to the other side of the engine. The drawings show it as a straight path through the engine. I can easily see the intake side that connects to the pump screen, but the other one seems to be blocked about where the two cases meet. Do you remember if that passage way is a straight shot that say a small zip tie should be able to fish through?

By the way, thanks for the responses, it what makes this sight great.

I would pull the line off and try to run oil through it. It is reasonable to think that the passage would be straight through, considering the location of either end, and the fact that they are bored, after all, with a drill. There is no gasket between the crankcases, and there is a dowel and O-ring at the point where the return oil passage bridges from one case to the other (#20 & 21 in the diagram here). If the builder got very sloppy with the sealant he used, and possibly left out the dowel, the passage may be blocked with sealer. Try rodding it through.


The blockage is definately metal. Im very afraid that the metal may be the dowel piece, and it flipped out and sideways and he crushed it. It seems like a long shot, but I cant figure how anything else could get in the way. I just really hate to split a newly rebuilt motor. But its looking like the only way to know for sure. Thanks a lot for your info.

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