Help! COOLING SYSTEM QUESTION

[VETTE1966]

I have a 1966 convertible, 327/300 original motor, no air or PS or PB. I have from time to time had overheating issues in hot city trafic here in Texas. Thus, I have a new Dewitt's radiator, new fan clutch, new 180 thermostat, new hoses and a recently flushed cooling system. I think my gauge is fairly accurate as I have tested it with an IR gun. My issue:

After driving on the freeway for a while (half-hour+ at 60-70mph), after the car warms up the temp edges slowly up from about 170-180 to almost the 210 point and it sits there as a I drive between 200-210. When I get off the freeway and have driven a mile or two, the Temp drops to about the 170-180 point and stays there unless I am in heavy stop/go traffic. This seems to be the exact opposite of how it should act. I think I'm either losing my mind or I have a car from Mars. Am I missing something?
Any help appreciated.

 

[Jeff Farrar]

Check the condition of your lower radiator hose. Does it have the spring inside? My guess is that you are partially collapsing the lower hose while driving at speed. Also check to make sure nothing is block the flow of air while moving (front license plate?). For example, this problem is common in C3's that don't have the lower air deflector in place.

Good Luck!

 

[VETTE1966]

Jeff,

I did have the front plate in place (Texas law) but many vettes here don't have it in place. It's easy to remove. I'll try that and check the hose as well. THANKS!!!

 

[JohnZ]

How is your timing and spark advance map set up? If the initial timing is retarded, the centrifugal advance is sticky, the vacuum advance is inoperative or connected to the wrong vacuum source, any of those will contribute to "running hot".

Depending on what the ambient temperature is where you're driving (and yours could be around 100*F), 200*-210* isn't out of the realm of reality. Does it "puke" coolant out of the overflow hose, or are you just concerned about seeing 200*-210* on the highway?

 

[SMOKINGJOE]

Jeff,

I did have the front plate in place (Texas law) but many vettes here don't have it in place. It's easy to remove. I'll try that and check the hose as well. THANKS!!!

Hi Jeff
LIV has the front plate mounting for Auto/AC that mount the plate to the left side which will allow more air into the Rad.

 

[VETTE1966]

JohnZ,

I have checked the timing (6 degrees BTDC). The distributor and advance were replaced a few years ago and I had a mechanic I trust check it out last spring. I think it's OK but will double check again.

It doesn't seem to lose coolant or very little if it does. This situation happened last weekend here when the ambient temp was about 90 at 11am. While I usually don't drive the car long distances, the 200-210 just seems unusual for extended highway driving. I have pulled the front plate and checked the lower rad hose which seems Ok--it was replaced two years ago---and I'll see what happens this weekend. thanks to all for the suggestions.

 

[LVMYVT76]

radiator cap in good condition?

 

[VETTE1966]

The Radiator cap is also about two years old when I changed out a lot of the cooling system equipment. After driving a while, I don't notice any hissing or leaking by the cap so I'm guessing it's OK unless there's something more subtle or hidden. Only the expansion tank remains as original. It does not leak or have any dents or anything so it has survived.

 

[magicv8]

Move the initial advance up a couple of degrees. Check inside the distributor to see that the vacuum advance rod has a plastic or metal collar on it's end, where it rides in the hole of the plate that the points mount onto.

I lowered my front license bracket and tilted the plate back to admit more air at higher speeds.

I also I replaced the lower splash shields with some aluminum to allow air to exit the compartment at high speeds.

According to Dewitt, your rad is more efficient than mine, so my A-C car running at high speeds should run hotter than yours, but it doesn't - even with A-C running on 100F plus days.

More details here: http://corvetteforum.net/classics/magicmachine/

 

[VETTE1966]

WOW--a wealth of great information and things to try---thanks. I'll be experimenting this weekend and next. Have a great holiday.

 

[crowvet]

WOW--a wealth of great information and things to try---thanks. I'll be experimenting this weekend and next. Have a great holiday.

Have you thought about adding a electric fan? My 67 coupe is a A/C car so what I did was buy a 12inch cooling fan and reversed the blade so that it would pull air instead of push it. then I mounted it inside the shroud on the engine compartment side of the radiator. You cant see it unless you are really looking.

 

[JohnZ]

See the August issue of "Corvette Enthusiast" magazine (just hit the mailbox today) for my feature technical article on Corvette cooling systems ("Beatin' the Heat"); I timed its publication for this month on purpose, as this is the time of the year when the posts start appearing about "cooling problems".

 

[Viet Nam Vett]

I tend to follow the "Jonh Z" school of thought. In my set up Every part of the ignition system and most impotantly the Vacuum advance and distributer cuves and mechanical advance along with base timing was addressed. As you can see..my 65 is powred by a 502BB..It runs 180 in traffic and max 190* with the air on at highway speeds.

All the systems work to geather to keep it cool.

Once your ignition system is know to be functioning correctly according to spec. Other items could then be checked and eliminated as the smoking gun in regards to overheating.

These cars will run cool when every thing works together. It has been my experience that the Corvetts I have helped friends solve overheating problems on, that 8 out of 10 times it was always a Vacume Advance, Mecahical advace distributer advance cruve advance, base timeing problem and or bad avacuume advance hoses or bad or week diaphrams in the advance unit. Or Vacuume drawn from the wrong place on the carb.

Before yo tare you hair out or drop oddles of bucks on after maket fix's...go back to basic's and revisit your ingnition system. Barry K's Web site has quite a few articlals linked & written by "Jhon Z" and others which will save you many hours of agg.

Cooling is a big issue...start at the Factory..(What the GM Engineers Designed Back In the Day) Those crew cut hair bow tie wareing guys knew what they were doing.

Good luck with your quest.

 

[VETTE1966]

Can you give me Barry K's we site info? And I just got the CE article. Both sound like great reading. I prefer to not add additional electric fans and hurt my original look. THANKS to all and will let you know how the quest goes.

 

[BarryK]

here is the link to the Tech Articles page on my website.

hope some of the articles help you out.

http://lbfun.com/Corvette/Tech/vettetech.html

 

[Viet Nam Vett]

Gotta say Barry... That's a Great set up on your home page. Just went back and read one of the articals to freshen up. Nice job.

 

[BarryK]

thanks Mark, I appreciate it.

I haven't made any updates to the entire site, except for the tech articles page for quite a long time now, I've gotten lazy and most of the time I can spare to spend playing with a website usually gets taken up now by our Corvette Club's website.
I do try to keep the tech articles page updated when I come across new articles or links but the rest of the site has been getting neglected.

One thing I really do want to update though is the tech articles page. The current layout was fine when I started and only had one or two dozen articles but now there are approx 130 or more articles and links and I want to find a better way to organize them other than simply a long list to have to scroll through. I just haven't figured out HOW I want it organized though that would be easy, well organized to find topics, and would hold up well in the future with the addition of other articles as time goes by.
I think I've outgrown this layout and don't want that to happen again so I'll wait until I figure out the best way.

 

[Viet Nam Vett]

thanks Mark, I appreciate it.

I haven't made any updates to the entire site, except for the tech articles page for quite a long time now, I've gotten lazy and most of the time I can spare to spend playing with a website usually gets taken up now by our Corvette Club's website.
I do try to keep the tech articles page updated when I come across new articles or links but the rest of the site has been getting neglected.

One thing I really do want to update though is the tech articles page. The current layout was fine when I started and only had one or two dozen articles but now there are approx 130 or more articles and links and I want to find a better way to organize them other than simply a long list to have to scroll through. I just haven't figured out HOW I want it organized though that would be easy, well organized to find topics, and would hold up well in the future with the addition of other articles as time goes by.
I think I've outgrown this layout and don't want that to happen again so I'll wait until I figure out the best way.

You could do a "Fim Strip" ICON layout ..you know a pic of a "Radiator" indicating all Cooling relate articals etc.. And so on. But either way it's still great to have all that info there. I have used it many a time over the past year.

They should make it a Sticky on top of this Board.

 

[BarryK]

yeah, that's not too bad, I've thought about something along those lines of using different pics or icons to represent different areas of the car as topics, just not sure how I want it to look and be laid out.
Oh well, one of these days i'll work on it and re-do it. Right now I have other issues that are more important to deal with as I'm sure you can guess what they are from previous conversations.

Hey, if Bob, Tom, or any of the other moderators want to put a sticky at the top with the link to my tech articles page they are welcome to but not sure how they would feel about that since the CAC has their own tech articles section I'm sure they would rather refer people to (although I do seem to have many more articles than are available on here) to keep viewers here onsite rather than refer them offsite