201 runs hot

[Davidmccabe]

I have a 201 plymouth that runs hot. It will idle for days without  getting hot but once I try driving it it warms up I am afraid the distribution  tube is dirty anyone ever have any luck with chemicals  I don't know for sure that is problem just running out f options

[TodFitch]

What have you tried so far? The passages in the radiator are smaller than those in the engine so it is more likely to be come clogged than the engine. . . Have you done a flow test on the radiator? Have you back flushed the radiator? Etc.

[Sniper]

9 hours ago, Davidmccabe said:

I have a 201 plymouth that runs hot.

 

First, we need to define runs hot

[Bryan]

Try the simple stuff first.   If you sit in the car outside and hold the engine at a higher RPM, does it overheat?    How hot like Sniper said?  Pegging the gauge?   

 

Is this a gradual thing or did it start all of a sudden?  Simple things first - is fan/generator belt tight enough?    Does car roll easily down an incline in neutral - brakes not sticking?

 

Anything changed recently on the car like timing or mixture?

 

Bryan

[keithb7]

My laser thermometer has verified that my coolant temperature gauge is currently not accurate. It reads about 30F higher than actual.

 

Saying that, I have completed a fair bit of cooling system work over the past year on one of my cars. I found:

-My Block had about a 5” thick solid layer of scale and rust sitting on the entire floor of the block. Discovered when block would not drain at petcock. Cleaned it all out. 
-rad exterior partially gummed up with road grime. Limiting air flow. 

-old rad gummed up internally and leaking. Had it re-cored.  Rebuilt rad completely. It was limiting water flow. 
-water pump age unknown. Looked like they brought it up from the titanic. Replaced it with new. 
-Discovered a lack of a thermostat. None present. Installed 170F. 
-water only in block. No coolant additives to slow down rust and scale build up. 

-Questionable rad cap. Replaced with new. 

-Old rad hoses from the 70’s. Tossed them. All new installed. Clamps too. 
-Leaking block expansion plugs. New. 

-Absence of splash pans engine shrouds. Reinstalled. 
 

My cooling system was in a terrible state. There was no way it could do any decent amount of cooling. Its now healthy. Just the temp gauge is out as mentioned. I’ll looking into it. I need to learn if they are tweak-able. 

 

 

Edited June 2, 2022 by keithb7

[Davidmccabe]

So far I flushed the coolant system  and I removed the thermostat  I am going to try to bypass the heater core  water pump looks ok

[FarmerJon]

How hot is "Hot"? 180? 200? 250? 

How does it act when it is "Hot"?

We can't see what you are working with. A lot of good questions already asked, until they are answered, not much more help we can give.

 

Edited June 3, 2022 by FarmerJon

[Kilgore47]

One of the things I found on the 47 P15 was dirt dobber nests.  Many of the honey comb openings were plugged with dirt.  When replacing the water pump I removed the radiator and cleaned the dirt out of the honey combs.  There was a lot of dirt.  Used a light from behind to check that everything was clean.  I lucked out with this car.  One of the last things I did when I was looking at it was to remove the radiator cap and look inside.  I saw clean clear green fluid.  At that point I turned to the guy and said "I'll take it".  Pretty sure the dirt was the main problem on this car.  It was starting to get a little over 190.  Now with a NOS 180 thermostat it runs 180 to 185.

[MarcDeSoto]

Keith, excellent cooling restoration there!  Was that on the 38 Chrysler?  You said you had your radiator re-cored.  Did you have them put in an original type cellular, or honeycomb core, or a modern core with straight tubes?  Did you have the upper and lower hose outlets replaced with new?  I just just got a junkyard 48 DeSoto radiator that may need a re-core.  What did you pay for the re-core?  My radiator man is quoted me $1400 if I want a cellular core.  Also, should an old radiator be given a pressure test, if it doesn't use a pressure cap?  

 

[keithb7]

18 hours ago, MarcDeSoto said:

 You said you had your radiator re-cored.  Did you have them put in an original type cellular, or honeycomb core, or a modern core with straight tubes?  Did you have the upper and lower hose outlets replaced with new?  I just just got a junkyard 48 DeSoto radiator that may need a re-core.  What did you pay for the re-core?  My radiator man is quoted me $1400 if I want a cellular core.  Also, should an old radiator be given a pressure test, if it doesn't use a pressure cap?  

 

 

I dealt with the rad in my 1938 Plymouth. It was a non-stock rad. Slightly smaller and moved forward to accommodate a 25" long engine. It needed to be smaller so it could be wedged further ahead into the nose cone. It seems to be a 60's or early 70's rad. All alloy tanks and metal parts. I dropped it off a a local rad shop. The shop removed the upper and lower tanks and re-used them on a new core. It is a modern core straight tube. 2 or 3 row, I can't quite recall. I run a 7 psi cap. It was about $320 to have it rebuilt.

 

I heard of an easy way to test a rad for leaks. Seal-off all openings of rad. Full up the bath tub or take it to lake. Submerge it. Bubbles will come out of any leaking areas. Cheap and easy! Originally the car had a non-pressurized system with the 201 engine. Now it has a 237ci 25" engine with pressurized rad. No ill effects that I know of.

 

 

Edited June 5, 2022 by keithb7

[keithb7]

My story seen here:

 

[1949 p17]

we have cleaned heavy scale and deposits in engine blocks and radiators just by draining them and refilling with vinegar. let it sit a week and flush it out. you won't believe how much scale comes out and how clean the radiator will be. a 50/50 mixture works great.

[FarmerJon]

28 minutes ago, 1949 p17 said:

we have cleaned heavy scale and deposits in engine blocks and radiators just by draining them and refilling with vinegar. let it sit a week and flush it out. you won't believe how much scale comes out and how clean the radiator will be. a 50/50 mixture works great.

Do you do anything special to neutralize the vinegar when you flush it out?

[1949 p17]

remove a heater hose and connect it to the garden hose and start the car. let it run till clear clean water comes out of the heater hose fitting and radiator drain. after its empty you can look with a flash light and decide if you want to refill it with vinegar for another week or if its clean refill with 50/50 antifreeze mix. we had to repeat it twice on one car. finally it was clean.

[MarcDeSoto]

Boy, that sure sounds better than paying $1400 for a new core!  They also make a radiator cleaner that you put in the radiator to loosen the scale before back flushing it.  But the vinegar sounds good if it really works!  

 

[capt den]

the vinegar flush.  do you remove the thermostat as i think you would have to?  how about a core plug when flushing? which heater hose do you connect to? the one in the front or back.  i have a new heater core so i do not want to flush anything through there. i guess you do not run the car for the week you let it sit with the vinegar? distilled white vinegar?  alot of questions but i did all the things keith has done and i still have a problem at idle and at high speed.  i think there are blockages in the block somewhere.  i will be at home depot today, so i might get a laser thermometer if they sell them.    capt den

[Los_Control]

On 6/1/2022 at 11:13 PM, Davidmccabe said:

I have a 201 plymouth that runs hot. It will idle for days without  getting hot but once I try driving it it warms up I am afraid the distribution  tube is dirty anyone ever have any luck with chemicals  I don't know for sure that is problem just running out f options

Taking a shot in the dark here .... Chemicals will not clear the tube.

 

When I bought my truck I'm certain overheating was the reason it was parked 20 years ago.  .... Along with the owner physically unable to repair it.

When I got it running for the first time, as it warmed up it ran good but as it warmed up it simply went straight to overheating ... It had no coolant flow.

 

Was obvious previous owner went to check the Thermostat, broke a bolt off & walked away.     It had the original Brass T-stat installed from 1949.

 

The water distribution tube was completely packed with minerals. ....

I used a piece of flat bar 3/16" x 3/4" and a hammer to drive the bar through the tube .... it was clogged solid with minerals.

I had to pound hard at it ... Then I had to drill a hole in the end of the flat bar to connect a chain & slide hammer to to pull the bar back out.

I spent a few days at it using the flat bar like a chisel  to clean the hard minerals off of the sides and open up the distribution tube.

 

I then started the engine & let it warm up, it seemed ok after this. I then filled the cooling system up with cheap vinegar from the grocery store. I would start and run the engine through several heat cycles ... for a couple weeks while letting it sit in-between ... I even drained it at one point & re-filled it with fresh vinegar ... kept going.

 

Later I yanked all the soft plugs out and again with the water pump off I ran a hose through the distribution tube and flushed all the sand out of the block.

Amazing how much casting sand from the manufacturing process is left over in the block and it all collects at this point in the block <---- this needs cleaned out.

 

Since then I have let it idle in the driveway for up to 2 hours with no T-stat installed  .... it would run about 160 ... eventually it would creep up to 180 .... give it some gas off of idle and would drop right back to 160 again. With a 180 T-stat installed it stays at 180.

 

I'm only suggesting there are a few ways to clean out these old enginines

[Los_Control]

Just now, capt den said:

the vinegar flush.  do you remove the thermostat as i think you would have to?

The vinegar is a pretty mild acid, you can just disconnect your heater core and run the strait vinegar for a couple days then flush it out.

I first flushed mine with the water pump removed and put a garden hose in the water distribution tube.

Later I added a flushing T to the heater hose and remove the radiator cap and back flush the system out of the cap.

 

Modern chemicals may be to harsh for our old radiators but still wont touch the hardened minerals in the distribution tube.

 

Sorry for double post, I wrote above post yesterday and walked away without hitting send 

 

[Sniper]

The OP still hasn't clarified what he means by runs hot.

[Los_Control]

Just now, Sniper said:

The OP still hasn't clarified what he means by runs hot.

Gotcha .... that would be nice to know what temps they are seeing. How fast do they see them.

 

 

 

[Sniper]

It also helps to narrow down where the issue may lie if we know when it's running hot.  Highway speeds?  In the driveway?  low road speed driving?

 

Heck it might even be a case of thinking you have a problem when it isn't one.  Keith pointed out his gauge read way high in his testing.

 

Is it puking coolant? 

[Los_Control]

Understood ... I bet @Sniperis just about as anal about cooling systems as I am. Today temps will be 108 and do not see any days below 100 in the near future.

Is very important to keep our vehicles cooling system .... along with the vehicle in good condition .... nobody wants to be sitting on the side of the road in 108 temps waiting 1 hour for a tow truck. For some in poor health it could be deadly.

 

For me a cooling system is very important and worth extra effort to be sure it is working properly. If I had any concerns about it I would not hesitate to go completely through it. I have done so with my Wife caravan, my chubby & my 1949 truck. I go through the complete system so I know what condition everything is in.

 

So for me, if I was not comfortable with the cooling system, I knew nothing about past maintenance I would not hesitate to go through it.

Simply mandatory first steps on a new to me vehicle. ..... Yes I'm talking the shotgun approach. Not troubleshooting the exact issue.

Just simply the only way I would feel comfortable with going out of town.

 

Pull off the hood then remove the radiator & the water pump. ..... @Davidmccabe original concern was using chemicals to clean the distribution tube.

If you can snake a piece of rebar used for concrete through the grill and into the distribution tube ... if it goes through ... no longer guessing if the tube is clogged or not.

You just mechanically confirmed it is not clogged.

Now you can insert the garden hose in the tube & flush that part ... the water will circle around and run it til it comes out clean.

 

Then pull the freeze plugs out and flush it some more ..... simply amazing how much casting sand from the day the engine was poured is still in the engine.

The sand collects down in the side of the engine and prevents coolant capacity and cooling in those areas of the engine .... freeze plugs are cheap and you now know your block is clean and will not have one rust out on you your next trip for ice cream.

 

What water pump is installed? is it the original with a zirk fitting to pump grease into it? They have been known to have the impeller blades rust away and no longer move water. Open it up and inspect it. .... A new water pump is cheap .... automagically we are going to replace the T-stat, hoses, belt.

 

Just saying this is the shotgun approach, now I feel comfortable my cooling system will not leave me sitting on the side of the road and will have many miles of summer cruising ahead.  .... The $$$ is minimal if you do the labor yourself, If I was 20 years old this would be a long weekend .... with my body it might take a week or 3.

 

I did the exact same thing on my daily driver when I had a ignition miss at high speeds. I replaced the complete ignition system on the sbc. I knew nothing about it's history. I changed it all. Distributor, coil, wires, plugs .... the dizzy was the culprit, I now have peace of mind & spare parts.

[Sniper]

11 minutes ago, Los_Control said:

Just saying this is the shotgun approach, now I feel comfortable my cooling system will not leave me sitting on the side of the road and will have many miles of summer cruising ahead.

 

Very good advice, especially on a new to you used vehicle.  Who knows what sort of issues you may have.  Might be overkill to do all that LC recommends, but then you'd know everything was good.

[1949 p17]

5 hours ago, capt den said:

the vinegar flush.  do you remove the thermostat as i think you would have to?  how about a core plug when flushing? which heater hose do you connect to? the one in the front or back.  i have a new heater core so i do not want to flush anything through there. i guess you do not run the car for the week you let it sit with the vinegar? distilled white vinegar?  alot of questions but i did all the things keith has done and i still have a problem at idle and at high speed.  i think there are blockages in the block somewhere.  i will be at home depot today, so i might get a laser thermometer if they sell them.    capt den

yes take the thermostat out. doesn't matter which heater hose, don't run the car with the vinegar mix, distilled white vinegar. a neat vinegar cleaning trick is to fill your kettle with 50/50 mix and let it sit for a few hours. it will look brand new inside. 

[Sniper]

Yes, we used to clean coffee makers that way, run a pot of vinegar thru it.  Do it outside though, the smell, lol