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So, I've got a new-to-me 65 convertible, so naturally, I have an overheating question.
Taking it out, either city or highway speeds, and the temp is stable at 180. But when I find myself at idle after some driving (whether on highway at 60 or in city at 20-50), the temp immediately spikes over 220. After reading the FAQ threads, I bought an IR gun and confirmed that the thermostat housing read 225 after coming home in traffic and idling. What's more, I've got receipts from the previous owner confirming a new Dewitts radiator installed 2008, along with new hoses. Fan shroud looks to be well sealed.
What do you think? Ignition timing? Could deposits have killed the radiator so soon?
Check and tried everything. If you can live with a non-factory change just put an electric fan inside the radiator. You have to bend over and look inside the shroud to see it. Has it's own thermostat, I don't have to touch anthing, no switches inside the car. Deal done, problem solved. No a seven blade fan did not help. Yes, I have a (1967) small block with factory AC.
So, I've got a new-to-me 65 convertible, so naturally, I have an overheating question.
Taking it out, either city or highway speeds, and the temp is stable at 180. But when I find myself at idle after some driving (whether on highway at 60 or in city at 20-50), the temp immediately spikes over 220. After reading the FAQ threads, I bought an IR gun and confirmed that the thermostat housing read 225 after coming home in traffic and idling. What's more, I've got receipts from the previous owner confirming a new Dewitts radiator installed 2008, along with new hoses. Fan shroud looks to be well sealed.
What do you think? Ignition timing? Could deposits have killed the radiator so soon?
JohnZ wrote an excellent paper on C2 Cooling. It is in the archives. Look for it. Perhaps someone will post a link.
For starters:
1. BB or SB?? Auto or manual trans?? Modified??
2. Check initial advance, centrifugal advance, and vacuum advance. Vac advance should be full manifold vacuum and not ported.....probably around 12-16 degrees at idle. Initial advance should be around 6-12 degrees. Total mechanical advance (initial and centrifugal) should be around 36-38 degrees total. Total idle advance should be 20-25 degrees or so.
3. Radiator should have a rear shroud. Adding an AC extension and AC seal strips will also help. Archives has "how to do".
4. Fan clutch may be bad and/or not fully engaging at normal idle temperatures (180 F or so)
5. The fan blades should be about 1/2 or more within the radiator shrouded area.
6. Check radiator inlet and outlet temperatures with IR gun to see what the differential is. Some examples are in the archives and the JohnZ article
"A typical 10-year-old radiator that hasn’t seen regular coolant changes has lost anywhere from 20% to 40% of its heat transfer capability, although it may look good. "
May be the fan clutch. My original took a crap on a road trip, and bought a GM one recommended by JohnZ. Clocked the spring so it would engage at a lower temp, etc. same problem. Car use to idle at 180, maybe 200 in the heat of August in traffic. Now it's 210-220.
Put a solid mount flex fan on for a idle test, and solid 180.
Going to send my original out and have it rebuilt.....
JohnZ wrote an excellent paper on C2 Cooling. It is in the archives. Look for it. Perhaps someone will post a link.
For starters:
1. BB or SB?? Auto or manual trans?? Modified??
2. Check initial advance, centrifugal advance, and vacuum advance. Vac advance should be full manifold vacuum and not ported.....probably around 12-16 degrees at idle. Initial advance should be around 6-12 degrees. Total mechanical advance (initial and centrifugal) should be around 36-38 degrees total. Total idle advance should be 20-25 degrees or so.
3. Radiator should have a rear shroud. Adding an AC extension and AC seal strips will also help. Archives has "how to do".
4. Fan clutch may be bad and/or not fully engaging at normal idle temperatures (180 F or so)
5. The fan blades should be about 1/2 or more within the radiator shrouded area.
6. Check radiator inlet and outlet temperatures with IR gun to see what the differential is. Some examples are in the archives and the JohnZ article
Get and read JohnZ's article.
Larry
All good information, but after doing and confirming all that it didn't help my 1962 at all.
This did, though. I installed a SPAL 16" electric fan hidden behind the fan clutch and fan. Mine ran up to 235-240 even with a brand new Dewitts restoration radiator which is rated highest for BTU dispersion. Now it never gets over 185 even when stuck in parade like traffic.
Before:
After:
Installation in process. I made straps to support the fan:
Installation done. Shroud back on with fan and fan clutch back on. No one sees it unless you point it out:
Stuck in gridlock New Years Day on Pacific Coast Hwy in Laguna Beach. Took 30 minutes to go 2 blocks. Sure took the worry out of having fun in the car:
Didn't get hotter than 180*. Notice the speed on the speedo. Parked watching the signal light go green/yellow/red/green/yellow/red.
I added a Powermaster 90 amp alternator that looks and mounts like an original generator. I have a digital voltmeter that plugs into the cigarette lighter. At idle, headlights on, fan running it holds at 13.6 volts +.
383 CID Blueprint crate motor, 700R4 4 speed overdrive automatic transmission, 2,200 RPM stall speed lock up converter. Life is good. I could daily drive this thing.
65 miles per hour (GPS speed confirmed), 1,990 RPM, 185* and holding. It actually runs cooler in traffic.
Last edited by Randy G.; Jan 27, 2016 at 03:19 AM.
It's your fan clutch. Most replacements are set for Over 200 degrees to begin to engage.
My car never over heated, ever. My original radiator began to weep in 2008, 43 yrs! With the OEM fan clutch, and spec timing, never had an issue.
Put new Dewitt's repo radiator in in 2008, no change in temp behavior.
Did a SD to Phoeniz AZ trip in 2009, and my OEM fan clutch gave up. The bearing was fine, but showed signs of fluid being slung. Bought a Napa replacement so I would have a spare for the trip home.
Bought a reproduction OEM type, installed it and immediately ran 20* warmer at idle. (Rebuilt engine in 06, new hoses, pump, etc) so the only factor was the fan clutch. Went to my local auto parts store and got another fan to try, same thing. Both had re locked springs.
I think many people have replaced everything, and still get poor results. I think the fan clutch is to blame in many instances.
Originally Posted by Randy G.
All good information, but after doing and confirming all that it didn't help my 1962 at all.
This did, though. I installed a SPAL 16" electric fan hidden behind the fan clutch and fan. Mine ran up to 235-240 even with a brand new Dewitts restoration radiator which is rated highest for BTU dispersion. Now it never gets over 185 even when stuck in parade like traffic.
Before:
After:
Installation in process. I made straps to support the fan:
Installation done. Shroud back on with fan and fan clutch back on. No one sees it unless you point it out:
Stuck in gridlock New Years Day on Pacific Coast Hwy in Laguna Beach. Took 30 minutes to go 2 blocks. Sure took the worry out of having fun in the car:
Didn't get hotter than 180*. Notice the speed on the speedo. Parked watching the signal light go green/yellow/red/green/yellow/red.
I added a Powermaster 90 amp alternator that looks and mounts like an original generator. I have a digital voltmeter that plugs into the cigarette lighter. At idle, headlights on, fan running it holds at 13.6 volts +.
383 CID Blueprint crate motor, 700R4 4 speed overdrive automatic transmission, 2,200 RPM stall speed lock up converter. Life is good. I could daily drive this thing.
65 miles per hour (GPS speed confirmed), 1,990 RPM, 185* and holding. It actually runs cooler in traffic.
So, I've got a new-to-me 65 convertible, so naturally, I have an overheating question.
Taking it out, either city or highway speeds, and the temp is stable at 180. But when I find myself at idle after some driving (whether on highway at 60 or in city at 20-50), the temp immediately spikes over 220. After reading the FAQ threads, I bought an IR gun and confirmed that the thermostat housing read 225 after coming home in traffic and idling. What's more, I've got receipts from the previous owner confirming a new Dewitts radiator installed 2008, along with new hoses. Fan shroud looks to be well sealed.
What do you think? Ignition timing? Could deposits have killed the radiator so soon?
Hi flohmann
Before you go and buy expensive fans and radiators, first replace your thermostat with a new one, even if it is new. Your problem sounds like a lack of water flow. Not a lack of air flow. At 40 mph, you don't even need a fan. If it is overheating at freeway speeds, it is either water flow, timing, or a too lean condition. Your spark plugs will be white or gray if it is too lean. Timing is easy enough to check.
If all of this checks out, then have your cooling system checked for combustion gases. It might be a head gasket starting to go.
Before you go and buy expensive fans and radiators, first replace your thermostat with a new one, even if it is new. Your problem sounds like a lack of water flow. Not a lack of air flow. At 40 mph, you don't even need a fan. If it is overheating at freeway speeds, it is either water flow, timing, or a too lean condition. Your spark plugs will be white or gray if it is too lean. Timing is easy enough to check.
If all of this checks out, then have your cooling system checked for combustion gases. It might be a head gasket starting to go.
Nope, doesn't overheat at freeway speeds, only at idle after being warmed up. So that points to the fan clutch, not the stat, no?
I'm not sure whether it's yes/no but it sounds to me like an air flow problem. You may have a fan clutch that is not engaging at the proper temperature as noted above. If it's a replacement clutch, it may need to be re-clocked as noted above, again.
It's your fan clutch. Most replacements are set for Over 200 degrees to begin to engage.
My car never over heated, ever. My original radiator began to weep in 2008, 43 yrs! With the OEM fan clutch, and spec timing, never had an issue.
Put new Dewitt's repo radiator in in 2008, no change in temp behavior.
Did a SD to Phoeniz AZ trip in 2009, and my OEM fan clutch gave up. The bearing was fine, but showed signs of fluid being slung. Bought a Napa replacement so I would have a spare for the trip home.
Bought a reproduction OEM type, installed it and immediately ran 20* warmer at idle. (Rebuilt engine in 06, new hoses, pump, etc) so the only factor was the fan clutch. Went to my local auto parts store and got another fan to try, same thing. Both had re locked springs.
I think many people have replaced everything, and still get poor results. I think the fan clutch is to blame in many instances.
At the insistence of many I installed a Hayden #2747 HD truck style fan clutch on it. Hooks up sooner and locks up 20%+ more than a stock fan clutch when hot. I think the fan clutch is so far away from the radiator in a C1 it doesn't see the heat like it would if it was only an inch or so away. Infared temp gun confirms that. I even flipped the thermal spring on the back. Slight change but not enough.
I moved the timing at idle in 2* increments locked all in from 12* to 26* total. Each test it got hot. After installing the SPAL fan I have 24* total timing at idle, all in with vacuum can connected. The can I'm using is an 8*, meaning it moves the timing 16* at the crank, so it's set with 8* initial with vac can disconnected. Hook it up and it jumps to 24* total. BTW, at 3,500 RPM the timing is steady at 34*.
I mentioned in another thread about how an intake manifold change helped. But we had a few warm days before the holidays and the coolant temp got too warm for my liking.
My 327/350 67 4-speed with factory air that blows cold never overheats even on 90-degree summer days in slow traffic. Follow JohnZ's advice and make sure all components are doing their job. No need for electric fans.
yet another overheating thread
