Blocked cooling passages?

[Tristan]

So by this point I'm convinced that I have some blocked passages in my block. It gets way too warm sitting at idle or in traffic unless both the electric and mechanic fan are running. Does fine otherwise. It seems to be vapor locking really fast and I believe that the intake manifold is much hotter than it should be. I haven't the slightest idea on how to confirm or clear this up. I flushed it with the hose before I put it back together during the build but maybe that wasn't enough.

[Flintlock]

Drain your system and then flush it with a commercial radiator/cooling system cleaner available at your local auto parts. Follow directions exactly as given. You will be surprised at what all will come out of there when you are done doing this. When you refill make sure to get all the air out of the system as trapped air can cause problems. Parking on a hill at an angle when refilling can help force the air out. If that doesn't fix it you may need to replace the thermostat with a cooler version. Good luck!

Mark

[comethead]

Even if you get a bunch of debris out of it during the flush you should run a coolant filter for your new radiator. It'll catch the rest of the junk before it clogs up the radiator.

Joe

[CALIFORNIA CALIENTE]

X2 on what Joe stated!!! You will not believe how much crud will come out!!! ROY.

[Tbart]

I believe one of your head gaskets could be installed wrong. It is an easy mistake to make on SBF. Or the radiator is plugged, or the tstat stuck. New head gaskets are marked FRONT though its some times hard to see.[or know] The gaskets are identical and so are the heads. Since they are opposite each other, one major passage is at the front on one side and the rear on the other. The gasket MUST be right! Old 2 core rads were not very good when new. 50 years didn't help. $180 got me a nice, new 3 core.[Mustang] If you suspect it [the engine] is "blocked" it has to come apart anyway. Did you try running it with no Tstat? If it heats up fast you have blockage. Good luck.

[Tristan]

I believe one of your head gaskets could be installed wrong. It is an easy mistake to make on SBF. Or the radiator is plugged, or the tstat stuck. New head gaskets are marked FRONT though its some times hard to see.[or know] The gaskets are identical and so are the heads. Since they are opposite each other, one major passage is at the front on one side and the rear on the other. The gasket MUST be right! Old 2 core rads were not very good when new. 50 years didn't help. $180 got me a nice, new 3 core.[Mustang] If you suspect it [the engine] is "blocked" it has to come apart anyway. Did you try running it with no Tstat? If it heats up fast you have blockage. Good luck.

I actually went through the head gasket thing when I did the build and had to swap both of them. My new radiator is a three row large core aluminum racing radiator and warmed up a lot sitting in traffic or at a drive through with the old 160 thermostat and the new 185 i just put in for the winter so that I could have decent heat. of course, its much quicker with the 185.

[Rocket989]

You can try flushing w/ the galley plugs out!

[loman]

I remember when I removed the drain plugs on my big block there was no water coming out. I used an old screwdriver and a stiff piece of wire to get through all the crud blocking the drain whole. It was clogged up pretty good, but after a little bit I got it cleaned out. I had to do that to both sides. I don't know if that would be enough of a restriction but it might be something to check since you are still having problems.