I've started to clean the 13B that I got out of junk yard car some 7 years ago.

I'm amazed at the amount of crud (scale, rust, etc.) there are in the water passages.

When I overhauled my first junkyard engine, I didn't pay much attention to the water passages in the end and center housings. They are not all that easy to get to as they pass beneath the side surfaces.

For quite a while now I've been puzzled why my left radiator only flows 1/10th of the right radiator, and thus runs very cold. But when I first ran the engine it was just a hot as the right rad. So, I think it's possible that some scale or flakes broke loose from the water passages and jammed in the small pasasages in the radiator.

Of course I'm going to try to clean the current engine as best I can (any suggestions on how to get to those passages are welcome), and I might just run the engine for some time without the rads - simply connecting a hose from a water post to the pump inlet and thus flush it while it runs.

But I'd like any suggestions of suitable filters to put in line with the hoses from the engine to the rads. Does not have to be very fine - just enougth to stop particles that could get caught in my new rads.

Finn