VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 1947 fleetline overheating

I have a 47 fleetline with overheating issues at redlights. As soon as I drive the temp gets back to normal. Its all original 216 6 cyl. A guy from work says I need a fan shroud. I'm not sure if there is a fan shroud? Any pointers?

You shouldn't need a shroud. I would look at the thermostat first, then your pump and then the Rad. The fan is so close to the rad I'm not sure a shroud would do a whole lot. With it overheating in a short time like that it must be running hot all the time. I run temp guage in my glove compartment.

Hello Cortezcrew and welcome to Chevy Chatter II. I had the same problem with my truck. I didn't know what to do. I reversed flushed my radiator, I don't know how many times. I had my radiator boiled out and nothing seemed to work. I found this site and asked for help and was told to check my petcock on the block. I did and when I unscrewed the petcock there was no water coming out of the block. I asked for more help and the tech's told me to take the petcock off and stick a wire in the hole and probe around. I did this and started getting little drips of water. I put the petcock back on and removed the thermostat. I ran a good flush through the motor. Make sure you follow the directions when flushing. Well I finished flushing and took the petcock off again and a lot more water was coming out. I decided to start the motor and when I did, the force of the motor blew all the crud out of the petcock hole and water was flowing out like a cow peeing on a flat rock. I resume flushing the motor with the water hose in the radiator and no thermostat and the petcock off for about a half an hour. I put a new petcock and thermostat and radiator cap plus new antifreeze. It runs now at about 175 and on very hot days it runs about 180. Think about joining this wonderful club. It was the best thing I ever did and the people are very friendly and are there to help when needed. I hope to chat with you in the future. Thanks and have a good day...Oscar

Your radiator is plugged with rust.The rust is comming from the bottom of the engine water jackets.Flush the radiator by removing to top and bottom hoses and placing the garden hose in the inlet and outlets to flush out the rust.The remove the thermostat and the pet cock as mentioned,Use the water pressure in all the hose openings to flush out the block and force water thru the pet cock opening.This will remove the loose rust.Then get a good heavy duty radiator cleaner and follow the directions on the can.May require two applications.May need to remove radiator and have it professionally cleaned....but be sure to clean the block to prevent future problems.

Hey guys thanks for the tips I'm gonna surely try these out, I'm off to a good start already!

It really is BEST to remove the radiator from the car, as you can flip it over, and at different angles to get as much of the rust out as possible with your hose. Also it is REALLY important to get the block as clean as possible as Gene stated. That is where most of your problem started. You may need a small dia. piece of wire to help unplug your petcock once the gunk starts flowing. You will be amazed what comes out of that block.

Alright guys I checked out the engine block looking for a petcock and the only petcock I see is on the end of a small pipe that is connected to the water pump. Is this the petcock I'm looking for?

The one you are looking for is on the drivers side, low on the block and near the cowl. It is a small valve and may have been replaced at some point with a plug.

The large petcock on the water pump pipe is your heater shut off valve. Its to keep the water from flowing to your heater in the summer months. The block drain, is a small petcock, and is located on the drivers side of the block about 6" up from the oil pan line, and to the very rear of the block. As Ray stated it may have been replaced at one time with a metal plug? Thats the one your looking for.

Thanks for the details- I found it! But now I have a question about the petcock on the water pump. I'm suppose to close it during the summer months? Any further details on what that helps by not sending water to the heater? Once again thanks for all help.

Closing off the flow to the heater helps keep heat out of the passenger compartment. It also reduces the amount of heat that can be removed as the heater core is another radiator. It can be used to help reduce overall cooling system temperature but is not too comfy in real hot weather.

Thanks for the info Chipper. It does get pretty warm in there I'll have to take a look and find out if it's open or closed.

The shut-off valve on the water pump prevents the hot water from flowing thru the heater core.It was an accessory and the water can be shut off when the heater is not needed.This eleminates the heat from radiating off the heater in hot weather.When flushng the cooling system open the valve so the heater core gets flushed out also.

Didn't see Chips post on page 2........Turning the handle clockwise stops the water.After turning it several times it may leak around the shaft.If it does it will need a new stem packing-simple repair.

Where would I get a "stem packing repair kit ?" for the heater valve.

Mine does NOT leak when it's open, only leaks/drips when I close it.

Thanks
Michael41

The "waterpump" packing material for the early chevys works best.
Just unscrew the nut with the valve assm. in it, and put the packing material around the shaft, and re-tighten.

Go to your local plumbing store and purchase some of the white silicone rope. It comes in various deminsions. Get the small diameter stuff.

Here's a copy of a reply of a post on page 2 with the same issue. Via: "chevgene"
Subject: heater value

Remove the center stem.The valve screw will pull out with the handle.Wrap some faucet packing string (can be purchased Teflon coated) around the stem and reinstall.Tighten down snugly.The packing (or lack of it) is what is causing your leak.
_________________________
Chevgene

Don't believe anything that he tells you

Thanks Ray, Sarge & Gene.

Michael41

HI! I had the same over heating issue with my 48 a couple of years ago, but for me it was far worse. I couldn't go 4 miles without a boil over. The guys told me everything they told you, stressing that the 60 years of junk that has collected in the block needs to be cleaned out to really fix the issue. They also told me that lye drain cleaner could be used to really clean things up, but to be sure and use care in handling it. I was VERY reluctant to use the lye, but finally did. I added a few tablespoons or more into clean water in the rad and ran the engine for maybe an hour, driving it around the neighborhood. As I flushed and reflushed and reflushed again, I didn't see the coffee like material come out like I expected. When I stuck a garden hose in the upper rad hose and allowed it to drain under pressure out the drain cock hole I could feel bits of rust hitting my rubber gloves, and when the driveway dried, I could see the little rusty particulate that came out. I used the poke around technique discussed at the drain cock hole on the block. I did this probably 4 times and it worked for me. Each time around I could see the operating temp get better. Another thing that can get you a few (to maybe 20) degrees is that water wetter stuff at the parts store. It works too.

The use of lye was the accepted method years ago.In fact some brands of lye had the instructions for cleaning cooling systems right on the can.Some even had ads in magazines touting it for that use.I was reluctant to mention it here because the disposal of the solution is a bit of a problem.I would assume the EPA would frown on its use.

Thanks Gene - I was concerned that it might have a neg effect on other materials that it might come into contact with in the cooling system, but that stuff really did the trick for me. I would drive the same course every time I would do this, and every time I could see the temp get a little cooler. Proper disposal is always something we need to be concerned about these days. In my case I caught the water and it evaporated w/o getting into anywhere it shouldn't be. This is tough stuff and it demands that you use caution when using it. DON'T get it anywhere near your eyes or exposed skin. The neighborhood parts store makes it easy to recycle.

just don't let it flow into your local creek or pond...since many drain cleaners are granulated lye, putting the used fluids down a proper sanitary drain will clear your engine and your pipes...

epi

FYI: I did get my problem fixed yesterday. What we did was we flushed out the radiator separtely. Then with the thermostat removed we used a garden hose and tried to flush the block out with the petcock on the block removed while the engine was still off. We couldn't get it to flow through the opening so just like the tips that were posted we started the car up and that sure did the trick. It started flowing powerfully. One other thing we did was that we installed a new thermostat and gasket while we were there, then we buttoned it back up. The car now stays between 175 and 180 even stopped at redlights. It used to get to about 200 degrees. I definitely recommend this procedure, like a few guys posted you'll be amazed over how clogged it really is in there. Thanks for everyone's tips and pointers.

Question? I've heard that "boiling out" old heads and blocks has been replaced by baking at high temperatures causing the rust, old stop leak, grease, etc in the cooling passages to burn/oxidize and become dust. Then it may be blown out with air, glass beading or both....Any info appreciated....