time to ask the gurus. overheating.

Well i got some time today so i changed radiator to a used one that i got with the car. (Bigger 26 inch rad) same results. so i took out my ir temp probe, after the car is run, and the new temp gauge is at 210 i start probing and find that my new temp gauge is reading 30 degrees warmer than the ir gun. so i run the car until the ir gun says the water pump housing is 208, gauge reads 230, rad reads q196 at the top, 165 at the bottom. shut the car off and the water is boiling in the engine i check the water pump housing, right next to the temp sensor(mechanical sunpro from advance brand new), the block, heads anywhere on the engine i can point the ir probe, highest reading i get is 215. Im thinking its all because it had plain water in it..... dumped the water out, put antifreeze mix in it drove it a couple miles, gauge reads 230, ir probe the water pump, block is all right around 208, top of the rad reads 190, bottom of the rad 156. shut off car, no boiling sound...... fyi i checked, the thermostat i put in is a 180. im thinkin of tossing in a 160.....thoughts?

Is it normal when you shut off the engine for the temp gauge to climb a bit? like goes up to 250 (remember the gauge reads 30 degrees warmer than actual) according to ir temp probe...

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kawdude said:
the thermostat i put in is a 180. im thinkin of tossing in a 160.....thoughts?

Is it normal when you shut off the engine for the temp gauge to climb a bit? like goes up to 250 (remember the gauge reads 30 degrees warmer than actual) according to ir temp probe...

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Click to expand...

I was always under the impression you want the engine to run warmer, then cooler. The engine wears out faster with the cooler temps.

It is normal for the temp to go up after shutdown. Gotta figure, theres no more water flowing, so the water is just sitting there warming up. After starting back up the temp will drop right back down.
 
Those 22 inch radiators never seem adequate for a big block engine. If you want to keep it, then I would have it rodded out to make sure there is no sediment in the bottom, restricting flow. Even the 26 inch radiator might have the sediment in the bottom and having a 22 inch opening does restrict the flow across the 26 inch radiator. I don't use 160 thermostats since all they do is take longer to let the car overheat, maybe a couple minutes and then the rest of the time 160 is too low for optimum heater capacity and might hasten bore wear from more prolonged cold starts.
 
I had the same problem with my 68 Newport, they found it was a combination of things from sitting too long, Fan Clutch was bad and the radiator needed rebuilt and the fan shrroud was missing.

Just read what you have done so far--see if the fan clutch spins freely, iit should turn but be fairly hard to turn, They showed me the difference between my new one and the old--the old spun freely by hand.
 
plugged radiator would make sense. the pump can't push the fluid through causing a hard upper hose. no flow to upper hose until thermostat opens.
 
No fan clutch, solid fan.

Drove it again a little bit ago, took a bit longer but still gets hot, 220 i shut her down. thinking im gonna have to buy a radiator....

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I don't think a 30 degree temperature drop over the radiator is that bad, if the cooling fluid circulation is good that's a respectable number at which the engine shouldn't overheat. On the other hand if the flow is restricted that number is easily reached.
Did you change the size of the water pump pulley? Or is it the stock one that was originally on?
 
Which water pump did you get, the a/c one flows less giving radiator more time to dump heat as it is behind a/c condenser. My car runs about 215 at the top inlet on a 90+ day rad loses about 40-50 degrees on same day. My stock gauge is always on top of sweep to H I have changed every piece except the gauge itself just the way the car has always been turn up the radio and keep driving.
 
Water is not whipping through the radiator, honestly i dont see it move much at all. guess im buying a radiator. the pump is the only one autozone lists for the car. it has 8 blades on the impeller.

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So....
Recore?
New OEM replacement?
New aftermarket OEM "fit" replacement?
New aftermarket aluminum "says it's a perfect fit but it ain't" replacement?

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If you bought a cheapo thermostat (like I did...), I'd recommend replacing with a better quality one. But I guess you said you also tried running your car without a thermostat and it still overheated? Collapsing the lower radiator hose sounds a bit suspect to me.

As I mentioned, I put in a cheap $6 thermostat (found out later it was 192°, dummy me didn't think to specify to the nice parts man) and it failed closed after a few months of use. I then sprung for a 180° thermostat (which happened to be $20) and things are much improved. Before the swap and failure, the temp gauge would nearly peg and then drop some, but after the stat swap, the temp comes up nicely and levels out perfectly mid-range. But I still have a 22" radiator that might need upgrading at some point...
 
IT'S NOT THE THERMOSTAT. There. Kawadude, can you take it to a radiator shop and let them put it under pressure and check the flow. Then you will know for sure before you buy a new one.
 
Tonight when i got done work i pulled the water pump housing off just to assure myself theres not a ton of scmutz pluggin up the ports in the block and water pump housing. theres not, blow air in there it shoots out antifreeze so im convinced its the radiator, so im gonna make some calls tomorrow to see if i can find a radiator man, if i cant im gonna order one new.

I can appreciate the cheap thermostat theory, but i have the same brand thermostat in my 99 jeep 4 litre and believe me when i say i hammer the piss out of that poor thing and it just keeps goin. yes i know that anything can fail just sayin. :) also, i have been a mechanic my whole life and i am a commercial parts manager for a large auto parts chain, (that in itself should start a healthy debate) so i see what brands have issues all the time and what dont.

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