nrt69

my 64 has ALWAYS run cool. surprisingly cool in fact even in the middle of summer.
just recently it just started overheating while driving and/or boiling over when parking it. Need some help narrowing down the problem.

it has the stock radiator thats been in the car since ive owned it - 15 yrs. I put some radiator flush through it a couple of months ago to see if that would work.
stock water pump. I think I replaced it in 2003 when I built the motor.
180 thermostat which works because I can watch it open up on my autometer gauge.
fan clutch is good. I compared its ability to spin against a new one. same resistance in both.
its got a new overflow tank cap on it. I THINK I replaced it when I did the radiator flush. I think its a 13. don't remember what the old one was.
car used to run no more than 200 in the summer. now its running 220-230 if I take out on the highway. around town it does ok still. oil temp is 230-240. the car have never come close to overheating in the past 15 yrs and now all of a sudden its doing it.

suggestions?

claysmoker

Did you check to see if the vacuum advance is working? Put a timing light on it and check to see if the timing is per specs..

jtranger

Brian,

I have been through this with my '65 and '61 copper brass radiators.

Get a Dewitt's direct fit radiator and you will lower your temps by 30* plus.

All the parts houses have them and they are running sales right now.

I wish I had taken advice from folks on here sooner. I can now drive my cars in the summer and they stay cool at even at idle. Best money I have ever spent!

nrt69

didn't check vac advance....but then I haven't touched the timing since the motor was built in 2003. the electronic ignition and distributor was replaced at the same time.

I don't mind replacing the rad with an aluminum one but id like to diagnose the problem first. my brass radiator has worked more than perfectly for the past 15 yrs. this is a new, sudden, problem.

jtranger

I thought mine was working for the past 15 yrs also until I replaced it! If the obvious checks out you probably need one. Use a IR temp gun to check the temp of the radiator to see if it is cooling properly.

EDinPA

Was this done cold? How do you know that it is still engaging when it gets hot? This would be what I would first think of with your description. That or air in the system.

65GGvert

If it does ok in town and heats up on the road, it's not the clutch fan. Air flow through the radiator at speed should be controlled by the vehicle speed and not the fan. If nothing changed in the shroud or air flow through the radiator, you may have a clogged or corroded radiator.

mikelj

I would definitely check the vacuum advance, and the timing, make sure it is advanced at idle to max vacuum. I usually make sure the vacuum advance is on full time manifold vacuum, not ported off the carb. Good luck.

VeroWing

Another thing you may want to check are the radiator hoses. Sometimes when they get older and weaker, they will collapse under acceleration impeding flow.

Mike67nv

Like others have said, first check you timing to make sure your vacuum advance is kicking in at idle and cruise. A bad vacuum advance pot can cause over heating.

You say it’s the “stock” radiator. Is it an original aluminum stacked core without side tanks? Just trying to determine the type and age of the radiator. If it’s 49 years old, it could be problematic due to age.

It’s also not clear from your post whether your problem started before or after you flushed the radiator? Also, please define what you mean by “flush.” Did you add a chemical flush solution and flush it under pressure? Depending on how it was done, you may have dislodged rust and gunk that didn’t get totally removed from the system, clogging the radiator. You might try a professional flush (radiator shop) including removal of the block drain plugs.

If everything else fails, a new DeWitts restoration radiator is a work of art.

nrt69

fan clutch was checked cold.

nothing changed with the timing.

hoses aren't old, but aren't new either. the lower rad hose has always had a slight kink in it but again, the car has always run low temps until recently.

started before. the rad flush was with an off the shelf product to see if that would help the overheating. flush, drain, and new coolant, done in my driveway. no significant change.

stock rad. It looks like it has side tanks.

Mike67nv

To check your vacuum advance, hook up a timing light. Check the timing with the vacuum hose to the distributor disconnected and plugged. Then connect the vacuum hose to the distributor and compare readings. You should see a jump of about 8-12 degrees depending on the vacuum canister.

The original lower hose and correct reproductions have a coiled spring inside to prevent them from collapsing. Modern hoses are more rigid and don’t need a spring. May or may not be a problem.

Again, a profession flush including removal of the block drain plugs may help.

If it has side tanks, it’s not an original aluminum stacked core radiator. Even a new copper/brass side tank radiator will have 20-40% less cooling capacity than a new aluminum stacked core radiator. There is a pic of a new DeWitts aluminum reproduction radiator (like the original) in my album if you’re not sure what to look for. I suspect you may have a 20+ year old copper/brass replacement radiator that has reached the end of its life cycle.

Good luck!

rongold

If it runs hot at speed and cool around town, that's an indication that the radiator is clogged. After it has been running for a while, open the hood, put your hand between the hood and the nose panel, (put a bolt through the hood support so the hood doesn't close on you), and feel different areas of the front of the radiator core. It should have a uniformly hot temperature to it. If you feel any cool spots, the radiator is clogged.

DSR

Hi: I had the same thing with my '65. It ran at 180 degrees all the time, then all of a sudden it started running at 200 to 220*. I did the basic checks as you are doing now, the rad looked good and clean inside when looking in the top. The fix was a new Dewitt’s reproduction stack plate type rad. It looks stock and with a 160* thermostat the car would not get over 150*. I installed a 180* thermostat and it runs at 160*(using an IR gun to check temp at thermostat housing). On a 90*F day in stop & go traffic it might climb to 170*. You can't go wrong with a Dewitt’s rad. Dave

AZDoug

I would suggest T-stat. When you say you can see it open up on your autometer gauge, I assume you mean while driving, temp rises, then cools a bit at Tstat temp, but then srtarts rising again. T stat may not be opening up fully.

Doug

DSR

Good point! I had a t-stat sticking in my truck one time, a cheap and easy part to replace.
Dave

0Tom@Dewitt

Highway overheating is usually the end of the radiator. It probably doesn't help that it's been 100f in Texas.

10% hotter outside means 10% hotter motor 200=220