61 Overheating - Radiator?
A friend of mine has 61 that has a overheating problem after engine rebuild. It was not bored out. It's a base motor. We have checked everything from timing, water pump, 160 thermostat, guage and sending unit. He never had an overheating problem before rebuild. The old radiator had a small leak in it, so he installed an aftermarket unit from Cal West that appears to be just little smaller from original. In cool weather it does not overheat, but anything temp above 70, it will boil over. It will idle and stay cool until driven, then immediately overheat. He had the old radiator repaired, but it leaks worse than ever so we can't reinstall it. Has anyone had a Cal West radiator? Any other ideas?
-
-
Re: 61 Overheating - Radiator?
Are you sure you don't have an air pocket that is keeping you from having an adequate amount of coolant in the system?Comment
-
Re: 61 Overheating - Radiator?
My friend had the SAME problem , turned out the intake gasket was leaking out side air making the engine run to lean.Seen this condition many times when some one installs a new 350 engine then uses the original 1x4 or 2x4 intake , the ports gasket don't match both , Running water along the intake to head center area some times shows the water being sucked in. Also if leaking from the bottom area you see smoke out the pipes.Comment
-
Re: 61 Overheating - Radiator?
From my experience, an intake leaking/sucking air causes the car to run rough at idle and smooth out as the engine speed increased. We would squirt engine oil along the intake gasket interface, the oil would temporarily seal the leak and the car would run smooth for a few moments until the oil was sucked in. Of course if it was leaking from the underside, then oil would be drawn in and cause smoke. A cracked cylinder wall could cause pressure to force out liquid and overheat as the engine speed increases.Comment
-
Re: 61 Overheating - Radiator?
Have you checked the fan clutch, if so equipped?Bill Clupper #618Comment
-
Re: 61 Overheating - Radiator?
Jerry,
If originally equipped, was the exterior tank eliminated after the new radiator was installed? It is not meant for overflow but rather it is an integral part of the cooling system. Coolant regularly circulates through that tank and while it is not as efficient as the radiator at giving up heat, the additional tank surface area and coolant contained within helps to keep things cool. Many replacement radiators are not configured to work correctly with that tank. People mistakenly connect the replacement radiator overflow hose to the tank which is a dead end (it is above the radiator cap) thereby causing the coolant flow to be screwed up. The original design plumbed the tank to the radiator (ostensibly below the cap) and along with the water pump connection on the bottom allowed for regular circulation.
If you have the tank correctly connected then double check the above suggestions by others. So many things might be causing the overheating problem but start simple and determine if there is uninterrupted circulation. Check for circulation by peering into the tank once the thermostat has opened; you can see the water moving (be carefull removing the cap!). If no circulation, make sure that there are no air bubbles trapped by removing the thermostat neck and fill there, and while you have access, check that the thermostat opens (in a pot of boiling water), also check that the lower hose is not collapsed when running at temp.
You can also check for hot spots by using a non-contact thermometer ($40 at Harbor Frieght) and to be sure that it is boiling over due to high temperature, not just a faulty radiator cap that lifts too soon. Don't trust the dash temp gauge as it is notorously innacurate. You may also want to pressure test the system including the radiator cap. Some auto parts stores will loan or rent that tester.
Best of luck,
MikeComment
-
Re: 61 Overheating - Radiator?
Jerry,
With the new radiator, does the shrouding fit the very same as the old radiator? If there are any places air can get around and NOT go through the radiator, plug this up.
Do you know if the new radiator has same total surface area as the original? The originals had a lot of design and development put into them. If you do need to replace everything should be equal. (i.e. Fit, surface area, etc.)
Also does the over heating happen when just cruising or drivin harder? If driven harder I would agree with Clem and check the bottom hose for the internal spring. If you can get under the car and squeeze the bottom hose closed it could be collapsing with water pump starts drawing hard.
Good Luck and keep us posted,
DavidComment
-
Re: 61 Overheating - Radiator?
Jerry -
If the car originally had a Harrison aluminum radiator, there is NO aftermarket replacement (other than a DeWitts reproduction) with the same cooling capacity as the original. What type was the original radiator, and what type is the replacement?Comment
-
Re: 61 Overheating - Radiator?
Thanks to everyone for your help. The bottom hose does have wire reinforcement. It's new. The original radiator was the original to the car, without the surge tank on top. It is definately getting hot. It will boil over and is hard to restart. The aftermarket looks a little smaller. We took it to a radiator shop and had it flow tested and it worked fine, but we did not find out what the flow rate was. It came from Cal West. It looks like the original in appearance. I'm wondering if the small holes in the head gaskets they make today are large enough. Most gaskets have one on each end and two small ones in the middle. Just a thought. We have swapped fan clutches around also, but no help. He is going to have the old radiator looked at again at another shop. I think it's going to come down the new radiator or the head gaskets. Your thoughts?Comment
-
Re: 61 Overheating - Radiator?
Flow rate has nothing to do with it, if the heat exchanger area and/or transfer coefficient are too small. The system will only flow as much as its smallest restriction, which is the thermostat orifice. That's all beside the point, because your engine temp is dependent on the heat rejection capacity of its heat sink/heat exchanger (radiator). Unfortunately, the engineers back in the day designed very little extra capacity into OEM radiators. At the slightest inefficiency, whether it be scaled internal passages, boundary layer film, or externally restricted fins, most vintage cars will begin to overtemp. Remember how many overheated cars you used to see on the highway shoulder in the summertime? Ever wonder why you don't see that anymore?
Your new radiator cannot reject heat fast enough from your coolant to the atmosphere. You can pressurize the inlet to 500 psi and run water through the radiator at high flowrates. You can add a 100,000 cfm fan to the front of the car. These won't help because the new rad has insufficient capacity.
Put a band aid on the old radiator and put it back on as a test. That will solve the problem, until you get yourself a replacemant job from DeWitts.
Last edited by Joe C.; July 29, 2008, 07:14 PM.Comment
-
Re: 61 Overheating - Radiator?
Extremely well put Joe.
I agree completely (not that it means much) but the little I know about these cooling systems his explaination hits the mark.
DavidComment
-
Re: 61 Overheating - Radiator?
You might try replacing the radiator cap. It is cheap enough and maybe the other one was bad out of the box.
DougComment
Comment