After lots of trials and parts, new carb, new plug wires, new heater and radiator hoses, and new reg. plates, I finally get the 64 running pretty smooth, and get to go for a nice ride on Sun. But after it warmed up it was a little hard starting, I suspect still has some timing issues to work out.
But after about an hour of easy cruising around, I stopped to talk to a friend and let it idle for about 5-10 mins, when I noticed the temp gauge was pinned and my friend said it was leaking lots of coolant.

Lucky it was just coming from the overflow in the expansion tank, and the whole system was gurgeling away when I shut it down.

So where do I start with the cooling system? I need some ideas on where to start or what needs attention, any help is appreciated.

Thanks in advance

 

Do you know for sure it was overheating?

If the system was overfilled, it would have belched coolant exactly as you described.

We know from numerous posts here that a pegged temp gauge could simply be a faulty gauge or sender.

If possible confirm the actual engine coolant temp with an IR temp gun before going further.

 

62 Jeff, thanks for your reply.....Well the gauge has always been right in the mid range after warming up on previous shorter runs.
I don't have access to an IR temp gun, but it's possible that it was over filled, it's easy to do when you can't see inside the radiator

 

I think Jeff was referring to the overflow tank. It should only be half full to allow for normal expansion. It does sound like you may have other problems though if the gauge is normally ok and it pegged. You may want to check and make sure you fan belt is tight and check your thermostat. Timing can also be a issue.

 

IR guns are very inexpensive at local parts stores. Well worth the $40 or so. You'll find yourself using it alot.

 

Can you feel air being drawn in from in front of the radiator? You said you were idle. Check your fan shroud and gaps involved.

 

First, overheats are no fun.
It is possible that you did not purge the air from the system as you refilled it, this can lead to overheat from air pockets in the cooling system. Fill the system with the front of the engine higher than the back. Parking on a driveway or up on ramps does this for you.
Fill slowly and listen for escaping air, you will hear it as air is escaping. Never continue filling when air is escaping to avoid trapping air.
it works best to fill the engine from the thermostat housing since it sits on top and in front, fill the engine first and then install the thermostat hook up your upper hose and fill the remainder of the radiator.
These engines really burp air easy so this should not be an issue but should be ruled out.

 

How old is your radiator, and is it OEM Aluminum or a copper replacement??? Pilot Dan

 

Yes, sorry for the ambiguity.

Agree.

 

I would look at the fan clutch......if you have a Harbour Freight near by, they sell an IR gun for about 25 dollars.

 

As previously stated, you must verify the actual coolant temp before jumping to conclusions. Aim the IR gun directly at the radiator hose as it exits the thermostat housing. Aiming at the shiny metal (aluminum or aluminum painted) tstat housing will give a false reading.

Next point: Temp gauges are not linear. As the indicated temp increases, the actual coolant temp is increasing at a slower rate. So, if the gauge is accurate at, say 210 degrees (it's only accurate at one and only one temperature!), then an indicated temp of 240 might mean an actual temp of 220. The IR reading becomes very important.

Next: I wish to hell that people would stop confusing "boilover" with "overheating". "Overheating" is another way of saying "overtemp"; neither of which is the same as "boilover". With the proper 70/30 mix of ethylene-glycol/water ratio, and a 15# cap, you should not experience boilover until about 245 degrees.

Next: All engines experience "heat soak" after shutdown. The stagnant water in the heads, near the exhaust ports heats up and "flashes" locally. If you overfill your reservoir tank ever so slightly above the "fill" line, then it will generally spill some coolant out the overflow tube.

Next: It's a very simple matter to hide a plastic expansion tank inside the right fender, thereby converting to a closed system. This will allow you to fill the reservoir tank to the neck, and never experience spillover.

Finally: You already suspect a timing issue. How long have you owned this car, and did this situation ever occur before? You have made a lot of changes, and it is probably a timing issue as you suspect. Base timing with a 250 and 300 HP engine should be 8 BTDC, 12 BTDC with the 365/375 engine. In addition, set your timing as follows:



These are 1965 specs. 1964 specs are the same except for the deletion of the 350 entries.

 

With the correct 50/50 water/coolant mix and a 15# cap, it won't boil until 265*F.

 

It's a good thing that we have each other to check up on each other.

http://www.engineeringtoolbox.com/et...col-d_146.html


Boiling Points Ethylene Glycol Solutions
Boiling Point
Ethylene Glycol Solution
(% by volume) 0 10 20 30 40 50 60 70 80 90 100
Temperature (oF) 212 214 216 220 220 225 232 245 260 288 386
(oC) 100 101.1 102.2 104.4 104.4 107.2 111.1 118 127 142 197

 

Overheating at idle is usually a bad fan clutch. I have had lots of bad aftermarket fan clutches they lockup at wrong temp. If the rad is bad it will overheat at highway speeds. But you have to check the actual temp first as stated above
Mark

 

15# cap not specified in your chart for 50/50

h2o boiling point rises 3° per pound of cap pressure

plain h2o will hold till 212° + 45° with a 15# cap, and I will assume it will be higher with 50/50

PS from Arrow Radiator site:

A 50/50 mixture of water and ethylene glycol antifreeze in the cooling system will boil at 225 degrees if the cap is open. But as long as the system is sealed and holds pressure, a radiator cap rated at 15 psi will increase the boiling temperature of a 50/50 coolant blend up to 265 degrees. If the concentration of antifreeze to water is upped to 70/30 (the maximum recommended), the boiling temperature under 15 psi of pressure goes up to 276 degrees.

 

Wow, thanks guys you all gave me lots to go on.

I will try to answer all the questions:

First I will look for an IR gun, they apperantly aren"t as expensive as I thought.

Yes I believe it is the original radiator, but I have only owned the car since Mar. 2011. It was originally a fuel injected car but the PO removed it, and a few other mods here and there. (I find them as I go)

The shroud appears to be in good shape, exept the flap is missing at the bottom.

65tripleback, thank you for the timing advice, I am going to try and work on that this weekend, (supposed to be near 60) so might be a good time to work on it.
It is a 300hp 327, so I will use your notes.

As far as the fan clutch goes, is there a way to test it, or what do I look for to check it's functioning? It seems ok as far as I know??

Thanks again for all the input.....that's why I love this forum!!

 

Fan Clutch Test, Providing you do have a Thermal Fan Clutch on this car. A Thermal clutch has a spring on the front that engages the clutch when the air moving through the radiator is hot. Usually they engage between 200 and 225 degree's. There are pictures on this forum that show both a Thermal and Non Thermal clutch, use a Thermal Clutch they work to keep you cool and avoid excess power loss and noise when not hot. When your car is hot and overheating the fan clutch should be at full engagement. Shut the engine off, turn the blade by hand. On the first touch to turn the blade it should have significant drag, if you continue to rotate it will dis engage quickly. This is normal. Fully engaged the fan clutch should spin at 90% of engine speed. Dis Engaged it will spin 10 to 15 % of engine speed. This is what saves you power and fuel waste when the clutch is not needed. Fully engaged the fan should pull a ton of air past the radiator into the engine compartment. The air should blow harder with engine RPM increase if the clutch is engaged. If it was not blowing air when your car overheated your clutch is shot.
There are also notes on this forum showing how to re clock your Fan Clutch spring to make it engage at a lower temp to help avoid overheating.

 

Westlotorn, Thanks for the great explanation. I will run through all that this weekend, and report back with the verdict.

regards,
Mark

 

Yeppers, http://forums.corvetteforum.com/c1-a...tml?highlight=

 

I replaced the heater hose and didn't elevate the front of the '56 when refilling the system. I'm thinking air is trapped in the mix ,causing overheating. Could this be?