I had the car out yesterday for about an hour. Was running at around 210 after about 20 minutes of driving. I am usually at 180. I was not using the AC and really not too much stop and go traffic. Total drive about 20 miles. Outside temp about 92.

A little over a year ago, had the original radiator totally gone through by a pro shop. Car has all new foam seals, etc. 180 thermostat also a year old. The car used to run at 210 all the time, but found out that heat riser was badly rusted and stuck closed even though weights were freely moviing. Once that issue was resolved, temp guage at around 180 all the time when driving.

Somehow...I seem to have melted my original tonawanda valve cover decal...lasted 43 years. I hate the idea of replacing it with a repro sticker, but want to figure out what caused the high temp.

Any thoughts?

Gary

 

Plastic bag/leaves sucked up between radiator & condenser?

Fan clutch going bad?

Ignition timing off?

 

Dude... are you seriously retarded? You're asking us why your car is running hot and yet you have in your pictures some hot babe in your Engine bay? Pull her away, problem solved.

 

I'm not a big fan of having a shop "go through" a 43 year old radiator. My bet is a Dewitts will solve your problem. I finally dumped my original copper/ brass big block radiator in my 427/390 as the car would get up around 210 in warm weather. It runs 180 under all conditions now with a new Dewitt's aluminum radiator.

 

Is there an easy way to test the fan clutch operation?

With my 63, yemps go up a bit when sitting at a light, but decrease again when driving. The 69 temp stays even the whole time and doesnt spike.

Gary

 

Do you have the GM lower hose with the spring in it? If not, the lower hose could have weakened to the point it is partially colapsing.

Basically you're saying the car was fine one day and with no changes it by anyone, it runs hotter. II'm not questioning it, just want to confirm my understanding of what the situation is.

 

I was out in the 94 degree temps with my 350/ air. Car usually runs 180/185 ish. With air on in traffic at light will sometimes push 200..203.

On yours, sounds like circulation, thermostat sticking or something like that. Maybe air in the system?

 

Havent changed a thing. I had my original radiator cap rebuilt a few months ago. I will try switching back to the parts store cap later today.

I will try to check the timing tomorrow.

Gary

 

I'm in FL too, just took my BB out for a ride about 35 minutes. Running at 2200-2400, which is around 70-80, on I95. My temperature was steady at 205 degrees. If air temperature was 10-15 degrees lower I'd be running 165-170. So for me, it's just the air temp being so high. Maybe the same for you.

 

My guess is the fan clutch, I had this issue a few years ago. Of course after the fan clutch, it was the radiator, which I had recored and I have been fine since them(about 8 years now).

 

Hi

The valve cover sticker does not melt away due to hot water in the engine, but due to hot oil ( oil fumes ).
210 F is not too hot regarding the normal 195 F thremostat that should be installed.
Running an engine too cold ( 160 or so ) might even damage the engine because all piston to wall gaps are concipated for around 200 F engine temp. Running cool grows the gaps , even the fuel consumption climbs.

I agree that a new radiator is due after 43 years. May be a electric fan also helps here.

Good luck & rgds . Gunther

 

I think my issue was timing.

Somehow had slipped to around 12 degrees at idle without vacuum advance. Bumped it up to 16 degrees and all in at 2400 and now after a 20 minute ride it was back at the usual 175 degree temp mark...hopefully problem solved...

But now my thoughts are at why the timing slipped...74k miles and timing chain still original. My mechanic said it might be time to change it before I run into any issues.

Gary

 

I live up the road from you and I think it's just this time of year and the humidity we're having with all the recent rains. Last year I remember running warm in town with the factory shroud and clutch fan on my '76 without air conditioning installed on the car and on the interstate with air moving it ran below 180 but upwards of 205 in traffic.

This year after reading numerous threads I installed a Lincoln Mark VIII electric fan which kept things cool in traffic but on the interstate got warmer, then a month ago I installed a Vintage Air system on the car and with the condenser in the way (running the air or not) my temps in traffic are running 190ish but on the interstate 210.

Last Saturday I installed a Dewitt's radiator and it is a beautiful product.

I removed the Mark VIII fan after the Dewitts radiator didn't help but left a 14" electric pusher fan I installed on the left side of the condenser, put the shroud back on and installed the clutch fan and also tried a 17" flex fan with a heavy blade pitch. Drove the car to work Friday for "national drive your corvette to work day" and in the morning (7 am ) on the turnpike headed to Jupiter I was running under 170 but a solid 180 that evening coming home. In traffic I hit 200 at the first long light I sat at.

Last night I ordered a 7 blade Flex-a-lite fan in a larger size based on a friends success so I'll see how that does but somehow I think we just have to live with hot temps in traffic down here.

 

Have you looked at your distributor gear lately. I don't know if you have an aftermarket cam or not, but if the distributor gear wears, won't that retard the timing? I had a mismatch at one point that wore out the gear very quickly.

 

I agree with your mechanic. A four degree shift in timing is quite a bit to happen all of a sudden. A worn timing chain will certainly result in retarded timing and valve events. Your original cam gear has nylon teeth and those are notoriously weak.

Replacing your timing chain with a modern double roller chain and steel gears is not a horrendous job and would be a peace of mind improvement. If your nylon timing gear fails altogether it could cause a piston to valve collision, or best case, not being able to get the car restarted after it stalls. Happened to a friend of mine while he was in the midst of making a left hand turn. It wasn't fun both when of us jumped of his car to push it around the turn to clear the oncoming traffic.

 

If you're pulling the timing cover, you have to break the pan seal anyway, and depending on what the nylon looks like on the cam gear, you might take the pan off completely and check for bits of nylon in the pan and in the oil pump pick-up below the screen.