My overheating senario….

[koosh]

Ok guys….. here’s my issue…. Looking for a starting point to remedy.
69 Super Bee, 440, a/t ….
Take car for cruise, at least 30 minutes or more. Checking temp gage, it gets to 200 really fast, but stays there while cruising back roads around 45-50 mph.
Once stopped at traffic light, goes to 210-220. Upon resuming cruising, back down to 200 degrees. Has 195 t stat, standard no clutch 6 blade fan, no shroud.
NOW- return home park car, wait about a minute , then coolant peeing out the radiator cap, and the overflow tank!
Open for suggestions where to start!!!!

 

[fine69]

180 degree thermostat, fan shroud, get rad cleaned and/or 4 cored. Flush block

 

[hunt2elk]

How full did you fill the radiator. Should be about an inch low from the top of the tank. It will find its own level by pissing out the excess. Add a shroud and maybe think about running a 180* stat? Also, if you are running lean or not enough timing, that could contribute to higher temps.

 

[PurpleBeeper]

Poor air flow at low speed…..shroud

 

[66 Sat]

How long has this been an issue?

How long have you had the car?

Have you made any recent modifications e.g. new thermostat, new hoses, changed timing etc?

 

[koosh]

How full did you fill the radiator. Should be about an inch low from the top of the tank. It will find its own level by pissing out the excess. Add a shroud and maybe think about running a 180* stat? Also, if you are running lean or not enough timing, that could contribute to higher temps.

Coolant level barely covering the inside tank, so about 1-1 1/2 below neck fill?

 

[koosh]

How long has this been an issue?

How long have you had the car?

Have you made any recent modifications e.g. new thermostat, new hoses, changed timing etc?

Definitely been playing with timing, unfortunately my antique timing light bit the dust, so been adjusting by “ear” and test driving . Have to bring to a knowledgeable technician to get it timed right. I thought maybe since leaking from rad cap, that cap was bad ?

 

[R413]

Had one that was all fresh and it would do exactly what you describe. I found the right numbered carb for it, put it on and the overheating was gone with that carb swap.

Odd thing is that it ran just fine with other carb, no surging and plenty of power.

A 6 blade fan is not stock for a 69 B body
Get a shroud on it.
And swap that 195 t Stat.

What camshaft?
What carb?
Any vacuum leaks?

 

[koosh]

Definitely been playing with timing, unfortunately my antique timing light bit the dust, so been adjusting by “ear” and test driving . Have to bring to a knowledgeable technician to get it timed right. I thought maybe dince lesking from rad cap, that cap was bad ?

Had one that was all fresh and it would do exactly what you describe. I found the right numbered carb for it, put it on and the overheating was gone with that carb swap.

Odd thing is that it ran just fine with other carb, no surging and plenty of power.

A 6 blade fan is not stock for a 69 B body
Get a shroud on it.
And swap that 195 t Stat.

What camshaft?
What carb?
Any vacuum leaks?

No vac leaks that i could find. Edelbrock carb (hate it)…picking up shroud this week.
Ive never seen a temp go up to 200 so fast from cold start. Maybe thats what bad timing does?

 

[Orig69]

Have you drained the cooling system recently?

 

[bobsgtx]

Most new cars with 195 t stat will run 200. High temp t stats are for emissions. Seal shroud to radiator with foam weatherstrip. Large trucks and construction equip. do it to maximize air flow.

 

[oldbee]

You could be right. Also, all the above recommendations. I run a 160* t-stat with clutch fan & shroud. Noticed almost 190* while getting into a car show recently (upper 80’s outside temp). Mine runs just a tad over 170* normally. Clutch fan is at least 20yr old, may have to replace. And 26”radiator.

 

[Ron H]

I’d suggest getting another cap as it ‘might’ be part of the hassle. Had one that was bad, but it resulted in serious overheating due to pressure failure and spit all over…and parked on the interstate for a tow. Cap may not be bad, but if I even suspect it, it’s a cheap replacement. I did notice that bad cap didn’t seem to fit tightly before it happened and kicked myself for not checking it further.

If your ride ran fine before, what if any work did you do on it? If you had drained the coolant and refilled, there could be air pockets needing to be purged. How are the hoses on it, especially the lower rad hose? As posted, good tips, though if your rad spit out that’s more than a 220 problem. Since I don’t drive mine in colder weather, have a 165 t-stat, not needing to get heat or defrost ‘quicker’ this was my choice, many do run a 180. Just MO, get a cap, refill and bleed out possible air pockets and see what you get. If the lower hose can be squeezed shut w/o much effort maybe not having an internal spring or not a formed one for the car, replace it before refilling with new coolant.

 

[koosh]

Have you drained the cooling system recently?

No

 

[oldbee]

Routine maintenance, I’m lax also.

 

[Ron H]

Given your hassle ya will need to refill and if that lower hose should come off, refill more as it will drain the block. Take your time either way to assure air pockets are purged. For some it may be a one and done; but I've had to do it more than once. Air pockets can be sneaky to get rid of.

 

[snakeoil24]

Two items clutch fan with shroud and dovthe head gasket test with carbon monoxide tester in radiator

 

[YY1]

Why is anyone shocked a car with a 195* thermostat runs 200 degrees?
That's the design spec.


How big is the recovery tank?
Does it work?

Agree on-

180 stat
shroud
clutch fan

 

[koosh]

Why is anyone shocked a car with a 195* thermostat runs 200 degrees?
That's the design spec.


How big is the recovery tank?
Does it work?

Agree on-

180 stat
shroud
clutch fan

Recovery tank is one of those chrome long tubular style, probably about 2” diameter by about 20” long?
Not sure how to tell if it works, its about 1/2 full every time i check it cold

 

[66 Sat]

Definitely been playing with timing, unfortunately my antique timing light bit the dust, so been adjusting by “ear” and test driving . Have to bring to a knowledgeable technician to get it timed right. I thought maybe since leaking from rad cap, that cap was bad ?

So you answered part of my questions. Radiator cap is leaking? Definitely could be the cause as system won't be pressurizing properly.

How long have you had the car? Has it just started doing this?

The reason I ask is that if you've had the car for many years and it's ran fine previously but there's suddenly an issue, then the suggestions of a fan shroud is just a band-aid fix to the real problem.

Radiator cap and thermostat are quick and cheap and it's likely that one of these is failing. Maybe your radiator is partially blocked - how clean do the tubes look when you look down the filler neck? If you can see crap in there then it's likely the tubes need rodding or you need a re-core. Maybe back-flush the radiator and as much of the block as you can.

If it's a new build then yes I agree with the fan shroud, but you still need to address that leaking cap.