Blocked drain plugs

[ezettler]

I am trying to clean my cooling system on a 1969 raw water cooled engine that has been running hot. I tried the acid soak and high pressure flush but for the flush could not get any water to flow into the rear drain plug (under the distributor). I can only reach about 1 inch into that hole with a coat hanger. I get just a trickle from the forward drain plug (above the starter) and can reach about 2 and 3/8 inches into that hole. Since I couldn't get water into these openings I used the T-connector on the cooling water inlet plate and the fitting on the thermostat to pump acid in with a hand pump and then flush with a hose. Water flow in either direction was strong so I think the cooling jacked itself is now relatively clean.
My question is how much effort should I expend to clear these drain plugs and how I would go about doing it if I have to? I already sheared off one bolt on the inlet plate trying to open that and have a slow leak there (when charged with full city water pressure) so will probably have to remove that and replace the bolts with studs.
Thanks for any advice.
Erik

[ILikeRust]

Sounds like you need to go ahead and remove the side plate. That will open up the water jacket and give you access to the area behind the plugs.

Then you can dig around in there with a coat hanger until your heart's content. You might be surprised how much crud you'll find packed in there. I know I was!

[ezettler]

Thanks Bill. Can you tell me what the configuration of those drain channels are? Do they just go right into the cooling jacket as a straight shot or are there some angles or bends? Do I risk damaging anything such as the cylinder walls if I poke HARD (such as scraping with a screwdriver) to try to remove the crud?
Erik

[hanleyclifford]

They do go straight into the cooling acket and there is a danger of damage to the cylinder. Better to remove the side plate. Moyer Marine has stud kits for repairs when you break off capscrews.

[ILikeRust]

There's not really much of a "configuration" or passages. The water jacket basically is a box around the cylinders, and the drain holes are just holes through that box.

As far as whether you could damage the cylinders, that depends on how corroded they already are and how crazy you get with the screwdriver. It theoretically is possible, if the cylinder walls are heavily corroded and thinned down, that if you jam a screwdriver in there, you could go through a cylinder wall.

I wouldn't go digging around in there aggressively with a screwdriver. Take that side plate off, which is easy and no big deal, and then you'll see what's gunked up in there. I would use a wire hanger straightened out, because it's stiff enough to dig out the crud, but not so hard that you can really do any damage in there, and poke it all around to loosen up what you'll find in there.

[Baltimore Sailor]

A trick that's worked for me is to get a drill bit that fits the hole, and using just your fingers, GENTLY turn the bit back and forth with a little pressure and see if you can clear the passage.

If you punch a hole in the side of a cylinder doing that... well, it was probably about to go anyway.

[ezettler]

Thanks to all for the advice. I'll try these ideas this weekend and let you know how it goes. In the meantime, I'll order the stud kit!
Erik