65 365 hp runs a little hot....help?

[neelfryer]

Hey guys -- it's neelfryer again -- ypu remember me the guy who bought my brother a 65 vert...well in the brief time I've had it (it's safe and dry in storage until Novemebr 4th when he gets it) but when I drove it it really heated up quickly --

the gear shift gets hot and I can feel the heat from the firewall and the temp gaude can creep to the limit in 45 minutes

I have a feeling many of you c2 veterans are laughing at me now as this is probably some typical wart of these cars...they just run hot ...can you throw some suggestions my way about the issue

otherwise the car is amazing -- i will or i should say my brother and I will probably take the motor out for full resto -- so really toss all comments my way from small fixes to major global suggestions -- thanks again -- sean

 

[BarryK]

first of all, the gearshift does tend to get pretty warm during normal use and these cars are notorious for throwing a lot of heat out thru the firewall and the transmission tunnel. Staying warm in these cars is NOT a problem and sometimes I wonder why most of us put them away in storage for the winter as the heat is better than any new car!

As for the actual engine temp, what is your gauge reading so we know if you are really having an issue here or is it only the heat being thrown off into the inside of the car your issue?
If the temp gauge is reading high it could indicate a number of possible issues that could cause the motor to run hot but first tell us what the gauge is reading and what the conditions were - ambient outside temps, highway or stop-and-go traffic, etc.

 

[neelfryer]

if the gauge is maxed at 220 which i think it is ... i have had the needle right at 220 -- that day i was driving it on the ventura freeway that had bad stop and go traffic for over an hour and it was hot outside 90+

but i also had it in the city driving light to light for 40 minutes and it still warmed up really high pretty quickly -- it didn't get to 220 but was definitely up there...again it was southern california summer time heat but still...it's about 25% warmer per the gauge than I'm comfortable with....

 

[motorman]

Hey guys -- it's neelfryer again -- ypu remember me the guy who bought my brother a 65 vert...well in the brief time I've had it (it's safe and dry in storage until Novemebr 4th when he gets it) but when I drove it it really heated up quickly --

the gear shift gets hot and I can feel the heat from the firewall and the temp gaude can creep to the limit in 45 minutes

I have a feeling many of you c2 veterans are laughing at me now as this is probably some typical wart of these cars...they just run hot ...can you throw some suggestions my way about the issue

otherwise the car is amazing -- i will or i should say my brother and I will probably take the motor out for full resto -- so really toss all comments my way from small fixes to major global suggestions -- thanks again -- sean

does the engine have a vacuum advance distributor and is it connected to full vacuum at idle?

 

[BarryK]

ok, first of all, max on the temp gauge on a '65 L76 (365hp) is 240* but in either case, if the gauge was maxed out you may or may not be having a problem. I just went through this on my own '65 L76 a few weeks ago (3 days fighting it and a 4-page thread about it on here that you can find thru the search function).

1. first thing I'd strongly suggest is if you don't have one go out and buy an IR temp gun and shoot the radiator house where it connects to the thermostat housing and find out what the coolant temperature is and if it is different than your gauge readings! It may be as simple as the temp sending unit has gone bad if it's the original one. If the temp sender unit is a replacement, they are notorious for being inaccurate and typically read high. After three days of trying to find the same problem on my car I went out and got the IR temp gun and found out nothing was wrong at all except the temp sender was off and reading 40* higher than normal!!

2. IF you find it wasn't as simple as an inaccurate temp sender unit, you could be running hot for various reasons. If the timing is off it will cause the motor to run hotter than normal, especially if it's retarded too much so you should check and confirm your timing is set accurately. Should be at about 10*-12* initial, 34*-36* advanced, and 50*-52* total.
Do you actually have enough coolant in your system and how old is the coolant? With the motor cold you should have approx 1/2 the expansion tank filled with coolant I believe.
Is your t-stat functioning properly? It's possible the t-stat isn't opening all the way and restricting coolant flow. If needed, get a replacement t-stat. The best is the Robert Shaw #330-180 180* t-stat. It's also marketed under the Mr. Gasket brand with part #4364.
Is your fan clutch operating properly?
Do you have the proper fan shroud in place?

While you are driving, does the temp gauge go all the way to max and stay there all the time or does it show a lower temp as you are on the highway cruising compared to city driving?

As I mentioned above, I fought this for 3 solid days and it turned out to be only the temp sender unit plus my fan clutch was bad so the first thing you should do it get that IR temp gun and check what your real operating temp is.
IF it turns out you really do have a problem than you can go thru the other items to check one at a time.
You may want to check my previous thread on this same issue for other ideas to check that others suggested http://corvetteactioncenter.com/forums/showthread.php?t=72718

 

[neelfryer]

Barry
once again you amaze me -- i will use your check list -- but yes -- the gauge will go to 240 but it will come down if it gets a little air cooling -- i think the restriction may be the problem -- the fan and the shroud look to be perfectly placed...but i am gonna run through your list -- thanks -- sean

 

[Kid_Again]

Not sure that I saw you post the basics on your vehicle. How old is the radiator, is it an original brass/copper or aluminum? Are you running an antifreeze mix, which ratio?

Replacement temperature sensors read high so the IR gun is a good idea and the price on those has dropped to about $60.

I can't see your posts but I recollect that it runs "hot" even at speed. Check the cooling system first, then vacuum hoses, then timing. Are you using a vacuum advance? Lots of posts on the latter about which can to use and how to set the timing.

 

[ctjackster]

hey Sean - glad to see you are "test driving" your brother's gift a little, all in the name of getting it in shape for him

these forums are full of "help, my C2 runs hot" posts, if that makes you feel any better. these cars did not seem to have very much "margin" cooling-wise, although I would not agree that they all seem to run hot - just that when a few things get tweaked, that small margin is easily exceeded. And then, sometimes, we have learned that what the gauge tells you is not reflective of the truth, as Barry found out (the 3 page thread he referred to.)

My 65 L76 came to me with a chronic run hot condition too, if it makes you feel any better. In fact, I am convinced the previous owner (he owned the car for one year) soured on the car because of this problem, which he chased without success (replaced a copper/brass rad with a new copper/brass rad, installed electric fans, installed a more aggressive main fan, etc.) The very first thing you should do is what Barry suggested, see if you really have a problem at all (especially true if you have never actually puked any coolant, and are relying solely on the temp gauge for your concern). After that, I would surely think it wise to confirm just what rad you have in there, as Kid Again suggested (it might be the old Harrison, which has surely reached the end of its efficient life, more likely it is a replacement copper/brass rad, which is about 30% less efficient than the Aluminum Harrison rad that was originally installed in your 65). sounds like a no win situation, but a solution does exist - company called Dewitts makes the exact Harrison aluminum rad that car orignally came with.

Other things to look at are fan clutch function (if it runs cool at cruise and only heats up at idle, this is one possibility), ignition timing, bubba-neering of the fan, shroud, etc., and of course flush and replenish the system with fresh coolant (pull off the two block drains to get all the gunk out) - do that BEFORE you install a new rad.

good luck and post back with your results, Barry can talk you through it!