The Stovebolt Site Forums The Shop Area Engine Shop Back flushing a rad

Having to flush out my 53....3600 rad. Will be installing a new water pump.....Can I just switch the flush tee (on the heater hose now)and put it on the bottom one now?? I am using Flush also.....Thanks, Paul

I don't know what engine you have, but since most babbit engines are in "engine heaven", I will take a stab at this. If I had the water pump off of an unknown 55+ 235, I would try to scrape the accumulated sediment out of the rear of the block water jacket. With the water pump removed, the later engines have enough space enabling you to stick a pressure washer wand in the water jacket. There seems to be a recurring trend of folks having overheating issues that trace back to clogged water jackets in and around the number 6 cylinder.

In a previous post there was mention of "Going to replace the 216 in my 3600, 53 pu. with a 54', 235."

If you did get that 54 235 (from a Powerglide car, I think you posted), it is a little more difficult getting to the rear of the block water-jacket from the water-pump holes. Nonetheless, Paul WNC's advice is excellent.

It's a 216ci. in a 53,...3/4 ton, 3600. Going to keep flushing, and reverse the heater hoses, and try to get it as clean as possible.Will try the power washer in the water pump before replacement and also use washing soda before finale rad cleaner flush....Thanks for your reply....Paul

A good back flush uses air pressure as well as water. Adapt a garden hose to the lower radiator hose, with a small piece of fuel hose teed into the adapter. I use a piece of exhaust pipe with a 3/8" copper tube soldered into the side.

IMPORTANT! Extend the top radiator hose away from the engine compartment so you don't flood yourself and everything under the hood. Fill the radiator from the bottom with the garden hose and then goose a quick shot of air pressure into the small pipe. The shock effect of the air will dislodge debris in the radiator and flush it out the top hose. Refill and repeat several times.

Cleaning out the block is almost always a manual job with a probe through the freeze plug holes. Using a pressure washer wand to flush out the dislodged crud is a good idea, but it's usually necessary to start the process by digging at the accumulated crud.
Jerry

Thanks Jerry, was also thinking about dishwasher soap???Going to make sure I give it 100% 0f my trying to get it the cleanest......

On the badly clogged ones I circulate a weak solution of Muriatic acid (technical-grade hydrochloric acid used for masonry cleanup) followed by a flush with clear water and baking soda to neutralize the acid. About 3-4 ounces of acid to a full fill of water, run it for 15-20 minutes with the thermostat removed, drain and refill with water and 1/2 box of soda- - - -run for 10 minutes and flush with clear water. After the acid/soda treatment, then do the back flush to dislodge the remaining deposits. Then use a 50/50 antifreeze/water mix for -37 degree F. freeze protection.
Jerry

My 48 3100 was not getting even warm. I opened the thermostat compartment I found no thermostat. I drained the radiator and added 180 thermostat. Add new fluid and started up. The temp went to 220 and I shut it off. Notice the top hose was HOT and the bottom hose was COLD. Cab heater was producing good heat now... Drained radiator via peacock valve.... Thoughts? really appreciate.

Did you test the thermostat in hot water before installing it?

If your engine was not warming up without a thermostat, and your engine overheats after installing the thermostat, the thermostat is a prime culprit.

Also, after testing a thermostat and assuring that it works, it is a good idea to drill a 1/8" hole in the thermostat to allow a little coolant to flow through it all times. It is possible that you do not have coolant in the head - where the temperature gauge sender is located?

Well... I did not test it first. New in the box.

I did drill a 3/16" hole in the rim.

How can check if coolant is in the head?

Thanks...

Wait to hear from someone else.

I have taken out the coolant temperature sensor (at the driver's side rear of the head) to see if coolant is at the rear of the head.

Leave the thermostat housing top off and fill the cooling system through that hole until the coolant is almost level with the top of the head casting, then install the thermostat and finish filling the radiator. It's the simplest way to avoid an air lock caused by a closed thermostat.
Jerry