Time To Replace Water Pump?

Thank you. I'll try that. Would you drive pressure through one of those flush kits? Or just gravity?

 

I think you nailed it! I disconnected lower hose and let it sit next to the radiator tank opening. After it all drained, I ran a hose through the radiator fill opening and sent a bunch of water through the radiator. Moments later water was exiting the lower hose profuesely and barely a trickle out of the lower tank. Obviously water was filling the upper tank and passing through the upper hose, engine, and lower hose. The tiny amount draining from the lower tank should have been at least a moderate flow, but when I say "trickle," that is being generous. So... sounds like the radiator is coming out and going to the doctor to get an enema! Thanks for your suggestion, and to all the othes who helped along the way.

 

Well, thanks to you and the gang, I think the immediate problem is identfied. I'll add another finding: with radiator completely removed and no cap on, I turned it upside down and filled the lower tank (now on top) with a hose and NOTHING drained by gravity to the upper (now lower) tank. I wiped it down and put my mouth over it to blow ait through and even air was not passing. I am going to have it professionally gone over. There is a good radiator guy in town... a vanishing breed in CA. I do have another from a 1963 that water flows through nicely but it belongs with the next project and I do no know it's full history. It might last but I think I will save the re-install effort for one that is known. Both are stamped with Modine, so I guess that is the maker? Thank you again for the help.

While I am waiting for the radiator, I will replace the thermostat while it's apart. I will leave the water pump alone for now. I might reconsider and put one in since the radiator is out of the way. Thoughts?

 

You must have good distance vision coupled with X-Ray vision! All the things I thought that indicated an opening thermostat were actually just the movment of hot water! I pulled the housing off and there was no thermostat! That's a good reminder to me to avoiod assumptions... or to let myself believe what I want the story to be. Good call!

 

A few decades ago I had a radiator shop install bungs in both tanks on my Chevy van's radiator, then installed 2 temp gauges. Result? 20º F drop across the radiator.

 

Just be sure and soak the t-stat housing bolts with a good penetrating solvent before you start cranking on em.
There's nothing like that sickening feeling when all of a sudden it turns really easy and you have a stub of a bolt in your socket..
If you're lucky, it'll be one of the two that are through holes.
If not, it'll be the one with a blind hole.

 

That's more of a drop than I would have expected! I won't be doing that, but you have my curiosity going... was there a performance reason you wanted to know by having both tanks monitored?

 

Thanks for the reminder. It truly is a sickening feeling! That has happened to me in other places that are not convenient... like the rear exhaust manifold bolt. It sits in that recessed area of the firewall so you can't get a drill in there to use an easy-out! Whole engine needs to come forward! Grrrrrr. But in the case of my thermostat housing, all three bolts are out (whew) and waiting for the new thermostat. Or did you mean the waterpump bolts? Either way, eh? Any snapped bolt is sickening.

 

Because of chronic overheating I had the cross flow radiator recored and wanted to monitor the results.

 

I drove it for several years while looking for an alternative to the belt driven thermo clutch fan. I tried a pair of early Honda Civic electric fans, a flex-a-lite fan, and a Ford direct drive (no clutch) fan. Ultimately I gave up and returned to the stock clutch fan and achieved a steady 20º temp drop. In the process I also reinstalled the factory "chin louver" panel, which directs air to the radiator (duh), removed a set of air horns from the air tunnel (double duh), and installed a front drive axle, which raised the rig about 5 inches. So, hard to say what actually solved the problem, but watching those temp gauges was very instructive.