Coolant boiling after shut off

K

KettleCarver

Gold forum user
Messages
262
A little background on the car:

260V8 freshly rebuilt with mild street performance cam. Shorty oil filter installed. Running stock exhaust manifold and Edelbrock F4B intake with a 4 barrel carb.
Has a new Sunbeam Specialties water pump.
6 blade flex fan.
Spal electric fan with Hayden fan controller.
160 degree thermostat
Horn holes blocked.
50/50 coolant mixture with 1 bottle of water-wetter added.
Stock shroud installed.
Stock hood
Rebuilt gauges, which are pretty accurate
13 lb radiator cap
Griffin Aluminum Radiator

The car overheated badly before the rebuild. I could not drive more than 2 miles before it would overheat and boil inside the radiator. The coolant passages had a lot of gunk in them.

After the rebuild the car runs much cooler. I am able to drive 35 - 40 miles and about 40 minutes, with the car reading mostly around 200 on the temp gauge, 210 at the highest. I have confirmed the temps at the thermostat after I stop at between 195 and 205 ( varies after several different drives) using an I/F gun. I have burped the system 3 times and got quite a bit of air out of it each time.


So the car runs at an acceptable temperature while driving and at a stop right after the drive. After a few minutes parked in the garage, I can hear the coolant boiling up in the over-flow tank. The electric fan comes on for short while to cool the radiator. However that is not doing anything to cool the fluid in the over-flow tank.

Anyone have ideas on why this thing boils on the overflow tank only after stopping the engine?

Thanks!
 
Ok... Here goes...

Quick question...in the rebuild...did you bire the 260 motor .. or do you know what the current bore is? Get back to that later....

As for the post shut down boiling... That's heat soak.. and given you have verified your temps with an infrared thermometer and they are around 200+.. what your reporting is no surprise.

The SBF in theory runs at its most efficient around 200 apparently...but that's not ideal for your average street drive... If your car on a normal drive in normal temps is running in the 200s ...when you shut it down the heat soak is going to easily take it over boiling point and you will get the resultant header tank kettle... And I'm assuming some loss of coolant.

The fan coming on won't do much as the water isn't flowing .. it's only cooling the water in the radiator.. the rest of the water is still slowly heating up by absorbing the engine heat.

Do you have a heater core? Mayne you have air trapped up in there?

Back to the bore size .. a 260 is very sensitive to over boring... If the bores are over 0.040 ...that may be the issue....
 
The engine was bored to .040 by a very experienced performance shop.

I do have a heater core installed that was pressure tested. Because the heater core is at such a high point, I used one of those funnels that you attach in place of the radiator cap. They are supposed to get the air bubbles out. And it did get a ton of air out of the system. I did it three times in fact and got air out each time. When that process was complete, I removed 1/2 of the coolant in the header tank. Maybe I need to do it a 4th time, and possibly take out more coolant from the tank?

The header tank kettle has happened about 3 times. The last time a small amount of coolant came out.

I should also state that on my test drive, I was going 45 -55 mph for the majority of the time. Very minimal stop and go driving. The engine now has about 550 miles on it.
 
My first thought is that one of the head gaskets might be on backwards.... These are labeled "FRONT" but it's easy to install it backwards. When the block was bored did the machine shop sonic test the wall thickness?
 
Austin Healer said:
My first thought is that one of the head gaskets might be on backwards.... These are labeled "FRONT" but it's easy to install it backwards. When the block was bored did the machine shop sonic test the wall thickness?
Click to expand...
A good thought. I was aware of the head gasket problem before we re-assembled the engine, so we triple checked the gaskets to make sure they went on correctly. I am not sure if the shop sonic tested the wall thickness.
 
LOTS of things to check here.

BTW, JUST internal Boiling on shut
off is Not a big problem, a symptom, yes.

It sounds like it's a bit soon to know
if you have a problem to be fixed.

Just Some cooling system notes

1) When filling the cooling system,
keep track of the amount of coolant.
If you don't come close to 3 gal,
odds are you have air in the system.
---Checking the system and finding
AIR 3 times is a BIG red light!---
It's best to TEST with only water.

2) Check the ignition timing curve,
from idle to max advance.
With and without any vacuum.

3) make sure the fan belt is tight.

4) Double check the Rad is not plugged!
even IF the rad is new, it can get plugged
quickly. IF you run an AL rad, you Should
have a top hose filter!
The only sure/quick way to check the AL rad
is to swap it out.

5) Verify system pressure And it Holds it.

If all seems good,

-remove the stat and test with a
restrictor plate W/ 3/4" hole.

-go to a GOOD Ridged 6 blade fan.

-go to a smaller water pump pulley.

DW
 
Last edited:
spmdr said:
LOTS of things to check here.

BTW, JUST internal Boiling on shut
off is Not a problem, a symptom, yes.

Just Some cooling system notes

1) When filling the cooling system,
keep track of the amount of coolant.
If you don't come close to 3 gal,
odds are you have air in the system.
---Checking the system and finding
AIR 3 times is a BIG red light!---
It's best to TEST with only water.

2) Check the ignition timing curve,
from idle to max advance.
With and without any vacuum.

3) make sure the fan belt is tight.

4) Double check the Rad is not plugged!
even IF the rad is new, it can get plugged
quickly. IF you run an AL rad, you Should
have a top hose filter!
The only sure/quick way to check the AL rad
is to swap it out.

5) Verify system pressure And it Holds it.

If all seems good,

-remove the stat and test with a
restrictor plate W/ 3/4" hole.

-go to a GOOD Ridged 6 blade fan.

-go to a smaller water pump pulley.

DW
Click to expand...
A few of my clients have fitted a bleed port on the RH top side tank. Pretty simple to do, they used a square headed 1/4 pipe plug. Sure fire way to bleed air out of the system.

I know there are those out there that swear by the Alloy radiators.... BUT, they cannot be cleaned nor repaired. The cost of a brass dimpled tube core being installed in stock tanks is roughly the same as an alloy radiator ($650) but you can service/repair it and it isn't susceptible to the corrosion issues of running with a cast iron block and heads.

I had a Tiger here a couple of years ago that would overheat inside a mile, even when the ambient temp was in the 60's F. Turned out it had a cracked cylinder wall.... not something I had expected to find. Did your machinist pressure test the block? Normally machine shops will crack and pressure test cylinder heads, not many are set up to pressure test blocks. I did an exhaust gas test on the cooling system that led to me having the block pressure tested once I had torn it to bits. Theoretically, I could have sleeved the bad "hole"... I sourced another block, in this case a 5 bolt 289.

Last thing to ask.... standard water pump? New small block Ford water pumps are designed to spin in the opposite direction from the engines built in the 60's and 70's... They have the same bolt pattern, the impeller is, obviously, reversed.
 
spmdr said:
LOTS of things to check here.

BTW, JUST internal Boiling on shut
off is Not a big problem, a symptom, yes.

It sounds like it's a bit soon to know
if you have a problem to be fixed.

Just Some cooling system notes

1) When filling the cooling system,
keep track of the amount of coolant.
If you don't come close to 3 gal,
odds are you have air in the system.
---Checking the system and finding
AIR 3 times is a BIG red light!---
It's best to TEST with only water.

2) Check the ignition timing curve,
from idle to max advance.
With and without any vacuum.

3) make sure the fan belt is tight.

4) Double check the Rad is not plugged!
even IF the rad is new, it can get plugged
quickly. IF you run an AL rad, you Should
have a top hose filter!
The only sure/quick way to check the AL rad
is to swap it out.

5) Verify system pressure And it Holds it.

If all seems good,

-remove the stat and test with a
restrictor plate W/ 3/4" hole.

-go to a GOOD Ridged 6 blade fan.

-go to a smaller water pump pulley.

DW
Click to expand...
Thanks for the check list. A couple of the things I can respond to now:

I forgot to list that the car has the Fairmont pulley.
I did add close to 3 gallons of coolant.

I never heard of a top hose filter. What does it look like, and where do I get one?
 
KettleCarver said:
Thanks for the check list. A couple of the things I can respond to now:

I forgot to list that the car has the Fairmont pulley.
I did add close to 3 gallons of coolant.

I never heard of a top hose filter. What does it look like, and where do I get one?
Click to expand...
CJ pony parts has a coolant filter kit for the 65-73 Mustang so it would be correctly sized. I imagine that summit would have them as well
 
Austin Healer said:
A few of my clients have fitted a bleed port on the RH top side tank. Pretty simple to do, they used a square headed 1/4 pipe plug. Sure fire way to bleed air out of the system.

I know there are those out there that swear by the Alloy radiators.... BUT, they cannot be cleaned nor repaired. The cost of a brass dimpled tube core being installed in stock tanks is roughly the same as an alloy radiator ($650) but you can service/repair it and it isn't susceptible to the corrosion issues of running with a cast iron block and heads.

I had a Tiger here a couple of years ago that would overheat inside a mile, even when the ambient temp was in the 60's F. Turned out it had a cracked cylinder wall.... not something I had expected to find. Did your machinist pressure test the block? Normally machine shops will crack and pressure test cylinder heads, not many are set up to pressure test blocks. I did an exhaust gas test on the cooling system that led to me having the block pressure tested once I had torn it to bits. Theoretically, I could have sleeved the bad "hole"... I sourced another block, in this case a 5 bolt 289.

Last thing to ask.... standard water pump? New small block Ford water pumps are designed to spin in the opposite direction from the engines built in the 60's and 70's... They have the same bolt pattern, the impeller is, obviously, reversed.
Click to expand...
My car came with the aluminum radiator, so I don't have a stock one that I could have the dimpled tube cores installed into.

I will have to check the invoice from the shop to see what tests were done.

I bought a stock water pump from Sunbeam Specialties for a 260 V8. I would sure hope they sold me the correct one.

For the bleed port, do you need to weld a bung onto the top of the tank? Do you have a picture of one?
 
KettleCarver said:
My car came with the aluminum radiator, so I don't have a stock one that I could have the dimpled tube cores installed into.

I will have to check the invoice from the shop to see what tests were done.

I bought a stock water pump from Sunbeam Specialties for a 260 V8. I would sure hope they sold me the correct one.

For the bleed port, do you need to weld a bung onto the top of the tank? Do you have a picture of one?
Click to expand...
on the alloy radiator the tank material is probably thick enough so you wouldn't have to weld on a bung... I'll dig through my pics and see what I can find
 
KettleCarver said:
My car came with the aluminum radiator, so I don't have a stock one that I could have the dimpled tube cores installed into.

I will have to check the invoice from the shop to see what tests were done.

I bought a stock water pump from Sunbeam Specialties for a 260 V8. I would sure hope they sold me the correct one.

For the bleed port, do you need to weld a bung onto the top of the tank? Do you have a picture of one?
Click to expand...

Here you go! Even better than just a plug, this one has a drain tap mounted on the top of the RH tank. Bleeding the system would be a breeze!

P6242195.JPG
 
KettleCarver said:
Ha, ha, that's funny! When you mentioned adding a bleed screw, that's the first thing that came to my mind.
Click to expand...
Glad I could amuse!

Seriously, the very next step I would take would be an exhaust gas test of the cooling system. It doesn't require any dismantling of anything and just takes a minute or two... A crack in the cylinder wall will pump an amazing amount of exhaust gas into the cooling system.... which looks just like air if you're trying to bleed the system.

In the 40 years I have been restoring Brit cars I have never had to "burp" a cooling system on a Tiger. I own and drive Tigers... My Mk2, 5000 miles a year. In the summer here it's triple digits for a couple of months and my temps are nowhere near what you are experiencing.

Mixtures and timing are also very important to operating temp. I have a 302, but I'm running stock exhaust manifolds, like you. (albeit, with 2" pipes). I am also using an F4B intake with a Holley 600CFM 4bbl. (vacuum secondaries). The engine has a mild cam. I am running a stock dizzy (points) and OE vacuum advance unit. I have set my timing at idle (vacuum disconnected and plugged) at 10 degrees BTDC. The idle mixture is set slightly on the rich side. On an O2 gauge it's about 12:1. Mixtures too lean and timing too far advanced will cause hot running.

The vacuum port for advance is on the throttle plate, not the side of the carbie.... The side port has NO vacuum signal.

I know I've beaten the electric fan thing with a dead horse, but these are only effective at idle... Anything over 10 MPH and the airflow through the rad is greater than the fan can provide. (mechanical as well). This is why Shelby told people to remove the fans from their 289 Cobras after engine break-in.... Micheal King is quite correct... the fan coming on with the engine stopped doesn't provide any benefit at all.... as there is no flow of coolant... Incidentally, 75-80 MGB's had the same feature... and they ended up with cracked intake/exhaust manifolds due to inadequate cooling....
 
Austin Healer said:
Glad I could amuse!

Seriously, the very next step I would take would be an exhaust gas test of the cooling system. It doesn't require any dismantling of anything and just takes a minute or two... A crack in the cylinder wall will pump an amazing amount of exhaust gas into the cooling system.... which looks just like air if you're trying to bleed the system.

In the 40 years I have been restoring Brit cars I have never had to "burp" a cooling system on a Tiger. I own and drive Tigers... My Mk2, 5000 miles a year. In the summer here it's triple digits for a couple of months and my temps are nowhere near what you are experiencing.

Mixtures and timing are also very important to operating temp. I have a 302, but I'm running stock exhaust manifolds, like you. (albeit, with 2" pipes). I am also using an F4B intake with a Holley 600CFM 4bbl. (vacuum secondaries). The engine has a mild cam. I am running a stock dizzy (points) and OE vacuum advance unit. I have set my timing at idle (vacuum disconnected and plugged) at 10 degrees BTDC. The idle mixture is set slightly on the rich side. On an O2 gauge it's about 12:1. Mixtures too lean and timing too far advanced will cause hot running.

The vacuum port for advance is on the throttle plate, not the side of the carbie.... The side port has NO vacuum signal.

I know I've beaten the electric fan thing with a dead horse, but these are only effective at idle... Anything over 10 MPH and the airflow through the rad is greater than the fan can provide. (mechanical as well). This is why Shelby told people to remove the fans from their 289 Cobras after engine break-in.... Micheal King is quite correct... the fan coming on with the engine stopped doesn't provide any benefit at all.... as there is no flow of coolant... Incidentally, 75-80 MGB's had the same feature... and they ended up with cracked intake/exhaust manifolds due to inadequate cooling....
Click to expand...
Thanks for all the great information!

How do you do an exhaust gas test?
 
KettleCarver said:
Thanks for all the great information!

How do you do an exhaust gas test?
Click to expand...
Kits are sold by a lot of the parts houses... (autozone etc) Or you can take it to a radiator shop. Basically there is a dye component and then a fixture that mounts where the radiator cap goes... If the coolant turns a specific color, it contains exhaust gases. I had my local radiator guy swing by, the test took less than 5 minutes...
 
Austin Healer said:
Kits are sold by a lot of the parts houses... (autozone etc) Or you can take it to a radiator shop. Basically there is a dye component and then a fixture that mounts where the radiator cap goes... If the coolant turns a specific color, it contains exhaust gases. I had my local radiator guy swing by, the test took less than 5 minutes...
Click to expand...
Got it, thanks!
 
Autozone may also have the pressure test/bleed tools for loan. I ended up getting a kit from Amazon as my kid has a 2003 Land Rover discovery with the always blown head gaskets. It can pressure test, but it can also to a bleed the air out of the system. If you are in the Los Angeles area you are welcome to use the test kit I have, I think it has adapters for all types of Radiator caps.

I had an old stock 65 mustang with a 289 that had the same issues, changed pretty much everything in the cooling system at one point but in the summer could never get it to not boil over when stopped. Chalked it up to engine issue, timing, head gaskets, never could nail it down but was not the cooling system parts. Motor had been rebuilt at least once.

Last comment is the Griffin radiator is likely the least effective radiator for the Tiger IMO, I had one and it worked in my stock 260 but only got it because my original was in really bad shape and didn't know better to fix that at the time, it was the new aluminum radiator syndrome :) The Fluidyne is a different story, I'll find out soon enough I guess.

Also water wetter in Antifreeze doesn't do much, not sure if it actually drops the boiling point, but with antifreeze I never noticed a difference adding WW until I just used it alone, and was not much going that way either. And if you did run WW alone need to make sure it's one that has a rust preventative.

QUESTION FOR OTHERS : I thought the purpose of the tank was to collect the air (Like my diesel has an outgas tank) to ensure things are full. The way the Dale/Fluidyne radiator are plumbed I think that is how it works, but can't remember how the Griffin or Stock one does it. Pic attached of the Fluidyne with the bleed at the top left back to my tank.

Good luck with this, it's a never ending chase!

Sandy

20241109_151626.jpg
 
sandy said:
QUESTION FOR OTHERS : I thought the purpose of the tank was to collect the air (Like my diesel has an outgas tank) to ensure things are full. The way the Dale/Fluidyne radiator are plumbed I think that is how it works, but can't remember how the Griffin or Stock one does it.
Click to expand...
I had the Griffin before switching to the Fluidyne. The Griffin has a "bleed" at the top like the Fluidyne.

Screenshot 2025-06-26 at 9.42.00 AM.jpg
 
You must log in or register to reply here.
Back
Top