The Stovebolt Site Forums The Shop Area Engine Shop 49 blowing coolant at 180F

Took the 49 3800 on the road

Have no idea how long since it’s been on the road

New radiator

Drove 6 miles

Filled with gas

3 miles from home on the return trip stsrted blowing coolant out overflow steam

Jim Carter rebuilt temp gauge never went over 180

In fact didn’t go over 180 when I shut it off

Haven’t tested rad cap yet

Any thoughts

Thanks

Depending on the pressure rating of the cap, it might be doing what it should. I have a new radiator cap at the correct spec of 7 psi, I added an overflow bottle to the system, it keeps the radiator 100% full and the bottle takes care of expansion and contraction.

Turns out cap is not pressurized

What lb do you recommend?

The specified pressure of the cap will depend on the engine year and model, the type of radiator and heater core, and a non-leaking cooling system. Post the info and other members are sure to add suggestions.

49 3800 original engine

New radiator

Top tank looks more modern than I expected

Thanks

I use a 4 lb cap on my 1950 (51 engine) 216. 1941 Radiator.

I also have an overflow system that works perfectly.

You may have overfilled the radiator. Without an overflow tank the water should be about 2 inches below the bottom of the filler neck covering the tubes when cold.

What do tyhe numbers and words say on your radiator. It definitely looks like a replacement. Notice the placement of the inlet port. It should be in the center of the radiator..

On the back side of the upper tank it should say Harrison xxxxxxx

.

I ran into that till I got an over flow tank. Get an over flow tube to keep that over flow off the
engine and rad. Coolant will self level , leaving a lower level in the rad to 1st fin. The tank will keep
all that over flow and the return it back while cooling down.
Also will keep air from getting in the system.
I mounted mine as close to level to the top of rad.
7lb cap.

180° is the perfect operating temperature and I also run a 4lb. cap on my ‘59 235.

I agree with Otto, my fluid runs only about 1/4-1\2” above the core.

Mystery solved on the radiator

It’s a Chrysler unit

My 51 runs a 4lb cap and that cap fits the Chrysler radiator

Guess I’ll fine it a try

I still question why the antifreeze was blowing out not just running out with a non pressurized and engine temp at 180?

Thanks to all

You may have other issues along with the wrong radiator cap. If combustion gasses are getting into the cooling system it will purge coolant well before the system reaches operating temperature. Or it could be as simple as an air lock-not purging all of the air from the system as you are filling it.

Good point. I’ll run it and watch for bubbles with cap off. No water in oil thankfully.

My 49 3100 w/52 216 uses a 0lb radiator cap. Have had no overflow problems to date.

Thank you

My 235 with original '54 radiator 4lb cap runs 180 with coolant level "2 knuckles down" on my finger and no overflow tank. I never top off over 1" from full. That's the sweet spot. Nothing comes out of the overflow.

Coolant (especially a 50/50 mix of antifreeze and water) does a lot of expanding as it heats up. Unless you have a catch tank, it dribbles out of the overflow tube. There are lots of ways to catch and recycle the expanding coolant, depending on how "stock" you want things to appear under the hood.
Jerry

Make sure to consider the heater radiator pressure capacity!

Ed

What Ed said... I have a 75 year old heater core which I don't care to replace. 4 lb cap is all the pressure I dare use. No problems with engine cooling.

Don’t know that any of the plugs look like they’ve been steam cleaned

Going to change thermostat in case gauge is wrong and add copper block seal in case it is head or gasket

Please see pics

Probably not the T stat. But, take it out, put it in a pan of water withg a candy thermometer and watch when it opens and if it opens all the way.

When you say "copper block seal", do you mean the stuff you pour in your oil or coolant to fix leaks?

If so, do yourself a massive favor and don't. Most of those products do nothing, and the ones that do "work" gum up the engine and ruin your radiator.

Water doesn't boil at 180 degrees unless your truck is above 15000 feet above sea level and Belvidere is only about 800'. I'd say you have two problems. Your gauge is bad and your truck is running too hot.

Unfortunately I have to agree with all of you

Have you used a laser gun or some other method of verifying the coolant temperature? Dash gauges can be notoriously inaccurate at times, and localized hot spots can happen that the gauge doesn't pick up right away. Pressurizing the cylinders one at a time with the brakes set and the transmission in gear can pinpoint head gasket leaks and other sources of combustion gases getting into the coolant, such as a cracked cylinder head. Be sure both valves are closed on each cylinder before putting air pressure into the spark plug hole. Look for bubbles in the radiator that indicate a leak from the cylinder to the water jacket.
Jerry

Thanks Jerry

That’s great advice

Need to do that testing before I pull the head

That's important, as it's possible to hide the evidence of a minor leak as you disassemble things. Pressurizing each cylinder individually can also isolate a problem to a specific location.
Jerry

Ok

New 160 F thermostat

I’d say within 5-10 minutes from cold had steam or at least bubbling coolant out of open rad cap

Pressurized each cylinder at 80 psi no air getting into coolant

Guess I’ll try a 4 lb cap and see if there’s any difference

And when it’s running before it starts spewing don’t see bubbles in coolant

Thanks again

Sounding more and more like you have a blockage in the water passages inside the engine. The waterpump cannot pump past the blockage so pressure builds until the cap cannot hold it back any longer. Out the overflow it comes.

All you've proved is that the old thermostat isn't the problem. Same for the new thermostat. I'm betting on exhaust gas in the coolant.

I'd say more like blocked radiator passages. The water pump sucks water from the bottom of the radiator, and then pushes it through the block and into the top of the radiator. If the radiator tubes are blocked, the water will have nowhere to go but the overflow when the thermostat opens.
[on edit] went back and saw that you have a new radiator. But the pic doesn't look that "new". Also just because the cap attaches at the top, doesn't mean it seals the section below the overflow tube. If you have a Chrysler radiator, then you need the appropriate Chrysler cap.

I tend to agree

Not knowing its history thought maybe a mouse nest was in block

Flushed block radiator heater core

Block flowed decently

Rad flowed decently but it sure looks crusty on cores

80 psi pressure check on each cylinder

No air into coolant so thinking head and gasket ok

Installed 4 lb cap it went longer before it boiled with 160 thermostat

Had bled air out of system by pulling heater hose at location under thermostat

Temp read lower about 160 than with old thermostat

Should have done earlier but checked heat where temp gauge goes into block over 200F when it boiled

Sooo thinking water pump or radiator

I’ll start with pump since it’s cheaper unless someone wiser thinks differently

Do you have a radiator shop near you? The one near me will boil one out the radiator and solder any leaks for $65.

If it looks crusty, it is crusty.

Throwing parts at it isn't the way to go. It's a rare thing to have a water pump not flowing coolant. The most common issue with them is the shaft seal goes bad and they leak.

Also, the T-stat doesn't regulate the engine temperature...the temperature marked on the T-stat is the temperature that it open to full flow to the radiator. Once the engine gets to the T-stat temperature set point it opens and stays open.

I'm with others, have the radiator looked at...

Mike B

Good advice and I do have a good radiator shop

Thanks all

Get the crud out of the water jacket for starters, followed by a good radiator repair. Various types of acid flush procedures work on the rust and scale, and a strong detergent such as Trisodium Phosphate will cut the greasy crud. Once the cooling system is clean, it can transfer heat efficiently from the engine to the radiator and the fan can blow it away.
Jerry

Radiator almost completely plugged. Hot tanking only increased flow by 15%. Core too poor looking to rod out per the shop I took it to. It's been repaired before. New core for the Chrysler radiator $800ish. Custom aluminum $525. Jim Carter $595 on back order. Anyone have any leads or other ideas. Would like to get an OEM look again but not necessary.

If you are not able to get a factory style unit then you might as well get one that will cool well and fit. I would measure the space, look at options, paint it black.

They're on eBay all the time for $200 or less. OEM style 49 to 53 pickup truck radiator. I just found one for $145 brand new on eBay