oldsdriver1218

just finished a restoration on my71 442 convertible including rebuilt engine it had this problem before and still does if the car is sitting at a light the temp will just keep rising I have heard of the cooling system having a air bubble in it. Read this in a car craft mag a while ago what I don't remember is how to eliminate it. If it is in fact the problem the car has a new 4 core radiator with stock fan and shroud any help would be great

oldcutlass

An air pocket will generally give you some really wild gauge swings, it will fluctuate 30-40 degrees quickly and then drop back. What temp is it creeping up to at a light? Does the car maintain temp at speed? Is it a clutch fan or fixed?

oldsdriver1218

the fan is fixed it will cool down when moving have not driven it real far don't want it to overheat at a light it will climb to 200 and higher

442rocketdave

What thermostat are you running? is it a flex fan with those narrow blades or a factory style with large blades? I have had best results over the years with 160 thermostat running a 40/60 mixture of coolant /water. Our race team used water wetter and it works!!! I also have had very good luck with the 7 blade fans with a clutch. Also make sure you have the little rubber shields on the side of the radiator as they make a difference. Make sure your timing is not too advanced I used to turn it back just a couple of degrees for driving on hot summer days and then advance it if running during the night or at the drags. Also we used two bottles of WWETTER in those 4 core radiators with the 40/60 mix and it worked great. Just some ideas that might help.

tbirdman

Just went through this. I just detailed my 70 442 which included removing the radiator. When I filled it back with coolant I failed to bleed the system. This consisted of leaving the radiator cap off and running the engine until the thermostat opens. Add coolant to bring the level up. My symptoms was the gauge will move very quickly from mid gauge to H.

m371961

Don't know if it is possible on your car, but is the fan installed backwards? It should suck air in, not blow out.

s i 442

Thats an interesting thought.

rjohnson442

start to worry around 230,you don't really have a big problem here.

Fun71

Getting hot at idle then cooling down while moving is a classic sign of not enough air flow across the radiator. Check the fan and clutch if you have one for proper operation. Make sure the fan is not too far into the shroud or too far away from it. Also check your ignition timing - not enough initial can cause increased temps at idle. I go through that every year when I detune for emissions testing.

W30Olds

I have the same problem, i have that dinky, fixed 4 blade fan with a 3 core. I'm going to put a 180 high flow in it, they've always worked great with my small blocks, solid 180-190* in all sorts of driving. I dont know about big blocks and high compression though.

Oldsmaniac

My 67 400 was wanting to run 200-220 plus in stop and go on a hot summer day. I found out I had the clutch fan too close to the radiator. I moved it back about an inch and changed the fan blade from a 6 to a 7 blade with a slightly larger diameter. I do have the factory shroud and it helped quite a bit. Then I added a bottle of water wetter to my new 3 row radiator and that helped even more. With a 160 T-stat my stop and go temps are 180-190.

MDchanic

No it won't. It will be less efficient backwards, but it won't blow the opposite way.

Sit down with a fan or a piece of paper and a pencil and work it out.

- Eric