Greetings.
A year ago I got a 1965 C 2 equiped with a 396ci and sidepipes. I love it, it's really a fantastic piece.

The engine was rebuilt 10 years ago, I have pictures and it seems to have been well done. About 10 000 miles by now.

At first it ran ok, at least when driving on open roads. Then it started to overheat in heavy traffic (220-230 F), and once I put it to rest, I hear boiling water and atfer a few minutes I start loosing coolant underneath the car (I would say about a pint). All I did really was to fill the cooling tank.

I drove it today in 80 degrees weather, after a two months rest and it got worse. I reached 180 F after 15 minutes and the car drove okay. I then drove on the highway for 10 minutes and once I reached 200 F, I started to loose speed in 3rd gear. I then shifted in second and the engine accelerated again. 5 minutes later I had the same problem. I had to shift gears a couple of times to be able to accelerate again. I then decided to get off the highway and return home. In 1st and 2nd it worked ok. But I reached 220 and by the time I was home, engine temperature rose to 230F. however Of course I thought head gasket leak, but I did not notice any white smoke coming out of the exhaust pipes.

I parked and opened the hood, there was white steam coming from the cooling tank area. At first I thought it was coming from the cooling tank cap, but in fact more likely from the side, underneath the car. The steam stopped after one minute, and then I looked underneath the car. Steaming coolant was dripping from the area between the red gearbox and what is the first part of the exhaust pipe behind the engine block. It stopped after 10-15 minutes, after I lost one or two pints.

Can anyone help?
Many thanks

 

Stuck thermostat?

 

Thermostat? I would take that anytime ! anything but headgasket! I love that car so much I emptied my bank account to buy it !

 

Easy to check. Just pull it out and see if the problem goes away, and if so, just replace it.

Next I would flush the system, even if you find the thermo is bad.

Welcome to the spend your fortune club!

 

And that would be the easiest and cheapest thing to check/replace. I'd start there. Also make sure you are only filling your puke tank halfway.

Don

 

Easy to check. Just pull it out and see if the problem goes away, and if so, just replace it.

Next I would flush the system, even if you find the thermo is bad.

Welcome to the spend your fortune club!

If you don't have a temp gun, pick one up. They are a good tool to have for diagnosis.

 

thanks guys. Will start with that.
I figured I was going to spend money, but a C2 is such a reasonable way to do it!
Such a small price for freedom and rock n roll !
By the way I heard the big blocks are subject to severe overheating, is that your experience?

 

I would do a few things....first...because it sounds like the car sat alot...flush out the rad and system....then replace thermostat, make sure belts tight of course...wiggle fan to make sure water pump is good. We are assuming you have a fan shround of course. which fan is on the car? Also check your timing. As mentioned when you do refil the cooling system..do not over fill., when you over fill ...the car tends to find its correct fill level but pushing out the extra onto the ground. A temp gun or IR gun is a great tool. Let the car come up to temp...then shoot the thermostat housing with the gun and compare to your temp guage...c2 temp guages tend to be....off shall we say. Good luck...

 

belts ok, fan ok, I need to check therm and flush. The guys who did the engine overhaul fitted new water tem, oil temp and oil pressure gauges, so the reading is ok as the boiling confirms!) What would be, in your experience, a "normal" running temperature for a 396ci on open road or in heavy traffic?

 

my 427 when running along the highway...cruises around 185 ish depending on outside temps...traffic is another story...heavy traffic the needle hugs the 210 line...it has yet to overheat...knock on wood..even still...I put on a helper puller fan just in case this past winter. Its a Spal 16" hi flow fan attatched to a thermostatic control I have in the car..I can turn the **** and set it to come on at whatever temp I chose...I have a DeWitts Alum. rad...a 7 blade fan, hi flow Stewart water pump and reworked thermostat, 180. also I put on the rubber flap that the AC cars had to keep the air flow going through the radiator and not over it...I sort of went overboard but after reading all the stories about big blocks when I first got mine..I thought...be prepared. As I said we do not overheat and we have been in some horrific traffic jams while traveling the east coast. I will see how the fan works this summer in traffic...it should keep the engine a lot cooler while in traffic ..I hope.

 

I dont know if 396s were setup like 427s with ported sources for the VAC but changing the vacuum source to full time vacuum will help greatly with reducing low speed overheating.

 

I would check for a freeze plug leaking from where you say the leak is coming. I would pressure test the system.

 

1. Get an infra-red temp. gun and check the actual temp. - the original gauges are VERY inaccurate.
2. Don't over-fill your cooling system. If you fill it "to the top" it will overflow and steam once it gets to operating temperature.
1 & 2 will determine if you even have a problem.

I've owned several big block cars and they don't run any hotter than a small block car if everything is "up to snuff". BB cars didn't overheat when new, no reason they need to now.

Jim

 

how old is the radiator? is it copper or brass or aluminum. a new Dewits rad will help

 

He is losing fluid from rear of engine near manifolds and red gear box he stated. He NEEDS to find the leak. Im thinking the red gear box is the oil pan????/ You can put in all the radiators you want and will get the same problem until you fix the leak.

 

1 thing knowone mentioned ...is the t-stat in right side up? .... it happens!

 

What kind of fan is it? If it is a thermatic fan, just because it's spinning doesn't mean it's spinning fast enough.

 

The overflow for the expansion tank goes to the area you are talking about. If the system overheats, the cap will relieve pressure through the hose and it comes out under the car.

If the car is not overheating when you are moving, it is probably not the thermostat. I would guess the fan clutch. You can check it by using a rolled up newspaper to try and stop the fan at idle when the engine is hot. If it stops or slows, the clutch is bad. Just be careful you don't get your hands in the fan or belts, etc.

 

thanks you guys for all the help.
I have no ways to lift my car without going to my friend's shop and the guy is away for some time. So by stretching my arm underneath I can feel the leak is coming from the pipe and not the oil tank. and there is no oil, just coolant. And it's always leaking about the same amount. i.e. I fill the coolant tank half full, and after all that, I lose the other half of the tank but no more (I can see coolant at the bottom of the tank). and the leak stops when the engine is put to rest for 20 minutes. and no white smokes from the exhaust pipes. What worried me though was the sudden loss of power when accelerating in 3rd on the highway. I had to shift to neutral and down into 2nd and it worked. The second time I was in third, shifted to neutral and when to 3rd again and it worked. never had any gearbox issues so far.
As I said the engine was rebuilt 10,000 miles ago and the radiator is a new alloy piece, the fan was changed (stainless steel it seems). A high perf water pump. And all new additional gauges were fitted so the reading is correct (so is the boiling sound)!
I will check the therm and fan over the weekend...

 

I don't understand the loss of power; especially in only a few selective gears....unless coolant or steam was affecting the ignition electronics somehow causing a misfire. Any car that has overheated on me always signaled by a 'stumble' that got worse and then usually pinging and detonating badly before quitting altogether in some cases. Good advice above so I'd follow it...