Runs TOOOO Hot for my Liking!

[Gerald Morris]

Greetings Moparians,

By now many of you have seen Gertrude, the 1968 convertible Newport that Chrysler apparently hastily cobbled together for export. Given how she came with a VERY OLD 115VAC plug-in coolant heater pump, I suspect this car saw duty at those latitudes above 45 degrees North. The following radiator came on the car:

This radiator lists as follows: 2898057 1968 C 22 383 MANL HTR
That's consistent with other quirks of this car; the starter relay meant for a manual transmission and the transmission cooler bolted in front of the radiator as an afterthought. Be that as it was, the hoses and clear age of the rust on the bolts all tell that these parts went off the assembly line as they now are.

Such a car wouldn't last a week in a Tucson June. Even now, after having just installed a capillary tube temperature gauge to supplement the idiot light switch in the water pump housing, I see a BAD temperature over-run up to 250 degrees Fahrenheit even when driving just 16 miles AT NIGHT with ambient temperature of just 74 degrees. This cruise should have rolled along at 190 F in Mathilda.

WHAT causes such a drastic heat-up?

I speculate that both the radiator and the on-AC water pump fail miserably to cool this engine in this environment. I flushed the coolant last week, and filled the radiator to the prescribed 1.25 inches below the filling neck with a 50% ethylene glycol mixture. I put a new (NOS) brass poppet thermostat in after suspecting at first that the Mr. Gasket Robert Shaw clone might have stuck. I've seen some flow after warming the engine up, so I figure the stat is opening, BUT....

Is the coolant flowing ENOUGH?

The water pump housing doesn't permit any extra temperature gauges, so I got clever and bored out a Dorman thermostat housing of this sort:

Its VERY EASY to drill and tap for 3/8 inch NPT into the flat spot facing diagonally out. I did so.

The capillary probe doesn't block or interfere with the thermostat. I made SURE of that before tightening down, taking some pains to rotate the thermostat to assure that it opens on the side opposite where the probe enters the housing. Admittedly, until the stat opens, the temperature reading from this arrangement might lag a LITTLE behind what the block coolant temperature is, but it doesn't lag much. This engine warms up to 180 F in under 5 minutes at fast idle.

My questions to the More Experienced Moparians are:

1.) Should I shop for a more voluminous 22 inch radiator? While I originally hoped to keep this one in service, I now suspect that even in brand new condition, this radiator will not cool well enough in Tucson traffic, even after sundown.

2.) Mathilda ALWAYS ran the higher volume water pumps! These were originally designated for use with air conditioning, but I suspect they got installed on anything which had to cool rigorously. Towing comes to mind aside from AC... I have the identical straight 6 blade fan Mathilda ran coolly with her first summer serving us. The radiator WAS a better model, meant for Hi Alt, AC and auto trans, despite being a 22 inch radiator. If THAT one didn't leak so much, I would never have opted for aluminum radiators. But it does leak.... Should I try a high volume water pump?

3.) The bottom hose is molded, lacking a spring to hold it open. I prefer sprung hoses. I can easily cannibalize Mathilda of her Gates Green Stripe right now, if warranted. How much could a partly collapsed lower hose contribute to heat runaway?

4.) While TIMING has occurred to me as a possible source of runaway overheating, right now, I'm at ~ 9 degrees BTC. This might cause detonation, but usually, RETARDED timing is more apt to cause overheating, right? This motor should be at 7.5 degrees BTC according to the FSM. I can bump it back to that easily enough.

I probably will start tomorrow with pulling the thermostat, and noting how long it takes this engine to reach various temperatures. I really don't expect this to have much impact, but want to eliminate the possibility ASAP, in order to then get to solving the more basic, inherent problem.

I suspect this will be a combination of undersized radiator and water pump, but if I AM missing something BASIC and CRUCIAL here, I would thank folks for telling me.

Just trying to Be Cool....

 

[detmatt]

If your lower radiator hose is collapsing it would definitely cause the issue. Does the current rad appear to be clean and free of ubstruction inside?

 

[CBODY67]

Might get an IR heat gun to check the block temps along the sides when it is "at temp" to see if any are significantly hotter than others OR if there is a trend toward hotter temps towards the rear (lowest) part of the block . . . due to accumulations back there which will restrict flow and heat the whole liquid mass to a hotter temp.

What does the build date on the data plate indicate? Early build or late build? Or even a "Monday build"?

Just some thoughts,
CBODY67

 

[Big_John]

While I have read that the lower hose spring is just there for filling the system on the production line, having seen hoses collapse in use, I still prefer using a spring. Some will tell you that there is a problem if you experience collapse and the hose is a band-aid. I don't know if that is true. The spring is cheap insurance. Buy one here... https://www.cjponyparts.com/lower-r...=1101206380003&utm_content=All Products Broad I think that's the right size. Some stainless wire wrapped around a mailing tube will get the same results.

What temperature thermostat? Yea, I know.... Time for the peanut gallery to pipe in on their opinions, but my personal experience with big block cars is that they do run a tad cooler with a 160 degree thermostat. Just for example, I knocked 10 degrees off the car I own now by switching from the 195 that was in it.

What about all the related rubber seals around the lower bumper/pans and hood seal. I've also experienced better cooling with those in place.

What about the fan? Lot's of opinions on this one...

I have a knowledgeable acquaintance that lives near Tucson that swears by the "water wetter" products to help cool off his old Chevys. While he doesn't claim it is a miracle cure, it is part of his cooling arsenal.

Page 8 of this thread has some interesting info on water pumps. Overheating issue resolved....interesting read !

 

[Toolmanmike]

Have you pressure tested the cap and cooling system?

 

[413]

Lots of good ideas in your head. Tell me about the “flush” what did you use, did you take the side pipe plugs out of the block?

You may need to remove freeze plugs and you may find a lot of debris on the block. This is so common. And manually cleaning it out works wonders.

Your coolant, was it rusty? Is it still rusty? Use Thermo cure by expvaporust. It does an amazing job of getting the rust out and the coolant clean again.

If you don’t know what thermostat is in there then find out and put in a 160, I agree with @Big_John they do help to lower the operating temps.

You could have a lean air fuel mixture at cruise speeds. This will make it run hot. I had this on a car once, everything was right and double checked, I swapped to a different carb and the cooling problem was gone instantly and it was cooling great with that one change. Can you swap on the carb from Matilda?

Lastly you could simply have a clogged radiator. Can you swap in the one from Matilda for a test?

I don’t believe your story of this car came with a manual starter relay and trans cooler from factory. It is now 52 years old, plenty of time to swap parts and fasteners to get rusted. And if it was out of he country they do what they have to do to make things work, they didn’t have parts and junkyards like we had here in the 70’s and 80’s.

this got long, sorry. Usually nobody reads long posts.

 

[BigblueC]

"water wetter"

I have seen "water wetter" work a few times. Funny, it's always been in small block Chevies. It's not a cure and shouldn't be used that way, but can be used as a band-aid.

Use Thermo cure by expvaporust. It does an amazing job of getting the rust out and the coolant clean again.

I've had great results using Thermocure.

 

[The Goose]

Being a Life Long Phoenix Arizonan I can tell you that you need to tackle this through a process of elimination. Keep it simple bud!

First get a temp gun and check your Delta T. The change in temp from inlet to outlet will let you know if the radiator is doing it’s part.

Next check your airflow - shroud and fan draw.

Then work down your list. Thermostat hoses cap etc etc etc.

Keep notes and as you go thru the list by process of elimination you will find the culprit.

I know you’d like to load every potential fix in a cannon and fire it at the engine bay but you’ll never figure out the problem area that way. Do the free stuff first and if parts need to be purchased you’ll be justifying the money spent towards your goal.

Good luck!!! make a plan, stick to it and keep notes. You’ll get it whipped and we are rooting for you.

 

[Gerald Morris]

If your lower radiator hose is collapsing it would definitely cause the issue. Does the current rad appear to be clean and free of ubstruction inside?

Thanks Matt! I changed that molded junk out with a good Gates Green Stripe hose, which has a good stiff coil spring from end to end. I had a learning experience with molded hoses w Mathilda this past Spring. For the night, I'll see what happens with the new hose and no thermostat. BTW, the coolant was CLEAR and CLEAN, indicating my flush job from the preceding week got all the loose **** out anyway.

See the bottom of the bucket? No rust or particulate debris in this coolant!

 

[Gerald Morris]

Being a Life Long Phoenix Arizonan I can tell you that you need to tackle this through a process of elimination. Keep it simple bud!

First get a temp gun and check your Delta T. The change in temp from inlet to outlet will let you know if the radiator is doing it’s part.

Next check your airflow - shroud and fan draw.

Then work down your list. Thermostat hoses cap etc etc etc.

Keep notes and as you go thru the list by process of elimination you will find the culprit.

I know you’d like to load every potential fix in a cannon and fire it at the engine bay but you’ll never figure out the problem area that way. Do the free stuff first and if parts need to be purchased you’ll be justifying the money spent towards your goal.

Good luck!!! make a plan, stick to it and keep notes. You’ll get it whipped and we are rooting for you.

I've HAD the temp gun for over a year. There is NO SHROUD on the machine yet. Note, Mathilda did fine without any shroud her first 2 years in my care. The first summer, 2016, I worked a crew of 4-5 other adults out of her as political canvassers, hauling them all over both Pima and Maricopa Counties. I used the exact same 6 blade rigid fan this car came with. The DIFFERENCE in that case was THE RADIATOR! I had a 1965 #2524984 22 inch radiator meant for high altitude, AC and automatic transmissions. I've seen exactly TWO MORE aside from mine since then. I still have this radiator, but by 2017, the leaks became too severe to continue using it another summer. I bought the Cold Case MOP753A Spring, 2018....

Rest assured. I WILL test each component of the cooling system, and every variable. Timing and fuel mixture will be addressed in the next day or 2, regardless of other findings. Now, I'm going to see what no thermostat and the Gates Green Stripe do.....

 

[Gerald Morris]

Have you pressure tested the cap and cooling system?

THANK YOU FOR THE ONE IDEA WHICH HADN'T OCCURRED TO ME TODAY!!! I thought of this in passing last week, before I put the gauge on, relying on prayer and the idiot light. It came on TWICE since then, once pre-gauge, and briefly, post gauge, BOTH times as I was parking in my driveway. This maneuver requires some backing and turning. I saw ~245 F the second time I saw the RED liught flicker on briefly. I goosed the gas, spun up fan and water pump, and cooled the motor just enough for then.

BTW, the pump DOES move the coolant, as I verified after pulling the T-stat this afternoon. Had to be sure of that. I'd seen SOME motion with the T-stats before, but was happy to see PLENTY without them.

I'll order a pressure test kit tonight. Been meaning to get one.....

BIG THANKS AGAIN!

 

[Gerald Morris]

Lots of good ideas in your head. Tell me about the “flush” what did you use, did you take the side pipe plugs out of the block?

You may need to remove freeze plugs and you may find a lot of debris on the block. This is so common. And manually cleaning it out works wonders.

Your coolant, was it rusty? Is it still rusty? Use Thermo cure by expvaporust. It does an amazing job of getting the rust out and the coolant clean again.

If you don’t know what thermostat is in there then find out and put in a 160, I agree with @Big_John they do help to lower the operating temps.

You could have a lean air fuel mixture at cruise speeds. This will make it run hot. I had this on a car once, everything was right and double checked, I swapped to a different carb and the cooling problem was gone instantly and it was cooling great with that one change. Can you swap on the carb from Matilda?

Lastly you could simply have a clogged radiator. Can you swap in the one from Matilda for a test?

I don’t believe your story of this car came with a manual starter relay and trans cooler from factory. It is now 52 years old, plenty of time to swap parts and fasteners to get rusted. And if it was out of he country they do what they have to do to make things work, they didn’t have parts and junkyards like we had here in the 70’s and 80’s.

this got long, sorry. Usually nobody reads long posts.

I do! Speed Reader, high IQ and all that. Will reply at length later tonight.

 

[Gerald Morris]

While I have read that the lower hose spring is just there for filling the system on the production line, having seen hoses collapse in use, I still prefer using a spring. Some will tell you that there is a problem if you experience collapse and the hose is a band-aid. I don't know if that is true. The spring is cheap insurance. Buy one here... https://www.cjponyparts.com/lower-radiator-hose-spring-stainless-steel-small-block-mustang-1965-1973/p/HW769/?year=1965&msclkid=31f4b38ceef51670965fd2e997bedf02&utm_source=bing&utm_medium=cpc&utm_campaign=New Bing Shopping Ads Broad&utm_term=1101206380003&utm_content=All Products Broad I think that's the right size. Some stainless wire wrapped around a mailing tube will get the same results.

What temperature thermostat? Yea, I know.... Time for the peanut gallery to pipe in on their opinions, but my personal experience with big block cars is that they do run a tad cooler with a 160 degree thermostat. Just for example, I knocked 10 degrees off the car I own now by switching from the 195 that was in it.

What about all the related rubber seals around the lower bumper/pans and hood seal. I've also experienced better cooling with those in place.

What about the fan? Lot's of opinions on this one...

I have a knowledgeable acquaintance that lives near Tucson that swears by the "water wetter" products to help cool off his old Chevys. While he doesn't claim it is a miracle cure, it is part of his cooling arsenal.

Page 8 of this thread has some interesting info on water pumps. Overheating issue resolved....interesting read !

Gotta go get brats pizza NOW. Will reply to you w Due Respect later bro. Thx.

 

[Gerald Morris]

All,

Gotta feed my spawn and breeder now. Will get back 2 U all L8r. Thx BIG!

 

[The Goose]

I've HAD the temp gun for over a year. There is NO SHROUD on the machine yet. Note, Mathilda did fine without any shroud her first 2 years in my care. The first summer, 2016, I worked a crew of 4-5 other adults out of her as political canvassers, hauling them all over both Pima and Maricopa Counties. I used the exact same 6 blade rigid fan this car came with. The DIFFERENCE in that case was THE RADIATOR! I had a 1965 #2524984 22 inch radiator meant for high altitude, AC and automatic transmissions. I've seen exactly TWO MORE aside from mine since then. I still have this radiator, but by 2017, the leaks became too severe to continue using it another summer. I bought the Cold Case MOP753A Spring, 2018....

Rest assured. I WILL test each component of the cooling system, and every variable. Timing and fuel mixture will be addressed in the next day or 2, regardless of other findings. Now, I'm going to see what no thermostat and the Gates Green Stripe do.....

I’ve never run shrouds on any of my stuff except for one cbody that came with one. The one car that I did a big fan a shrould and a big four core was the AAR with its W2 340. That beast never wanted to run cool in the summer LoL. All my stuff back then were daily drivers.

 

[Gerald Morris]

I’ve never run shrouds on any of my stuff except for one cbody that came with one. The one car that I did a big fan a shrould and a big four core was the AAR with its W2 340. That beast never wanted to run cool in the summer LoL. All my stuff back then were daily drivers.

Thanks and Good to Know! I only started shrouding my cooling system in earnest with Mathilda, back in 2020/ I made a VERY EFFECTIVE shroud from aluminum flashing. I cut long strips of it 3" wide, used aluminum L brackets to mount to my Al Cold Case MOP753A radiator, and made a rectangular box to direct the relative vacuum made by the 18 inch 6 blade DeRale clutch fan w Haydn thermal clutch, and yes, that box shroud enhanced cooling by at least a factor of 2.

Even with that, I was glad I had the A-Team 16" pusher fan for heavy, stop and start traffic. I'm going to install one of those on Gertrude ASAP.*

*This case that means when the CHARGING SYSTEM IS BROUGHT UP TO SUPPORTING THE LOAD OF A 20A DUTY CYCLE MOTOR. I ordered the 95A PowerMaster last week, and expect it here by this Thursday. I got the 8 gauge wire, sundry connectors, breakers, fuse blocks et al to insure overcurrent protection AND efficient, SAFE power distribution. The cooling system had not even come into consideration when I decided on this; I just wanted to upgrade from the 35-55Amp paradigm in force when the car was built.

BUT, I DAMNED SURE WANT TO CORRECT THIS HEAT OVER-RUN BEFORE ADDING SO MUCH AS A 2 INCH WALFART USB FAN! Read my Evening Report, follow-up.

 

[Gerald Morris]

While I have read that the lower hose .... results.

What temperature thermostat? Yea, I know.... Time for the peanut gallery to pipe in on their opinions, but my personal experience with big block cars is that they do run a tad cooler with a 160 degree thermostat. Just for example, I knocked 10 degrees off the car I own now by switching from the 195 that was in it.

What about all the related rubber seals around the lower bumper/pans and hood seal. I've also experienced better cooling with those in place.

What about the fan? Lot's of opinions on this one...

I have a knowledgeable acquaintance that lives near Tucson that swears by the "water wetter" products to help cool off his old Chevys. While he doesn't claim it is a miracle cure, it is part of his cooling arsenal.

Page 8 of this thread has some interesting info on water pumps. Overheating issue resolved....interesting read !

John, as promised, an in depth reply now id due. I replaced the lower, 1.75" molded hose with a Gates Green Stripe, a corrugated, "universal" flex type hose with spring molded into the corrugation. I'd actually tried a molded hose about a year ago on Mathilda, but, sure enough, the hose would collapse at the bend, constricting coolant flow and raising temperature. I replaced that after 4 months with the tried and true Green Stripe. That, in turn, now serves Gertrude. It seems to have helped this evening, as I never got the "Hot" idiot light to come on, even when parking at the end of my run back home! That's normally the hottest point in any trip I take, given the nature of our driveway and neighbors.

I pulled the thermostat for this evening's experiment. It seems to have both helped to SLOW the overheating runaway, but also showed that something ELSE is the ROOT CAUSE. I expected as much. I still am afflicted by backfiring when attempting any WOT acceleration, despite having swapped in a CLEAN gas tank, and double inline filters, one before the pump, the other in the spec spot above fuel pump feeding carburetor. I'll change the see-through filter before the fuel pump tomorrow morning, then adjust the timing back to 7.5 degrees BTC, as the FSM calls for for this year. I heard very slight, but unmistakable pre-detonation chatter i the heads this evening. I want NONE of THAT!

The main hood seal down front is supple and seals well. A second weatherstrip i the back, by the wiper motor has nigh disintegrated. In time, I'll replace that, but don't expect this to cause the overheating I'm getting right now.

I've used "wetters" before. They don't hurt. Will get some tomorrow.

I've READ ALL the "Overheating issue resolved" thread several times these past 5 years. If I opt for a pump upgrade, I'll probably go with the Tuff Stuff iron one depicted in the thread. It gets good reviews, and is modestly priced. I'm running the stock 1967-69 Mopar water pump housing, and have a spare. Perhaps I should swap in the nice clean one I prepped earlier this summer, before realizing it won't work on a 1966 accessory setup. Mine is clean, smooth, ready for duty. What I saw inside what Gertrude is running showed a lot of internal rust, though at present, NONE of that has gone into the coolant. There's an old non-AC pump in that housing. I have a spare one of those too, rebuilt about 40 yrs ago. I can try THAT, and if it works, swell, or, if NOT, then the Tuff Stuff pump can be tried. I KNOW Mathilda ALWAYS ran the w AC/'towing pump. THIS might be CRUCIAL!

But first, let me twiddle that timing, and maybe enrich the fuel mixture before I dirty my manicure on that water pump.

Again, I thank you for a thoughtful contribution to this problem's solution.

 

[saforwardlook]

All I can add is that you appear to have a B engine and in Los Angeles temperatures in the summer, no 22" Chrysler radiator will adequately cool that engine in Los Angeles , much less in Tucson temperatures in the summer that are usually significantly higher than Los Angeles temperatures. Those 22" radiators aren't adequate for Los Angeles even with everything working properly and a clean system especially in slow moving traffic.

I personally have never had a 160F thermostat make any difference in temperatures in the 90F and above temperature range nor do I see why they should unless one is driving at freeway speeds with everything else working well. In traffic where these under-designed 22" radiator systems are weakest, such a thermostat shouldn't make any difference when equilibrium is achieved.

 

[detmatt]

Removing the stat all together is not a good idea. It is there to keep the fluid in the radiator so it can be cooled. If it’s not there the pump will just keep circulating the hot fluid and it will just get increasingly hotter with every lap through the system.

 

[67Monaco]

It's the head gaskets.