Reinstalled ac parts that had previously been deleted from my 71 Skylark that now has 455 in it. Had the radiator cleaned which is a original 3 core from the original engine. Have not had overheating problems until now in 95 degree heat. Just now tried ac since install in winter. The temp got up to 240 sitting still and made me nervous so I shut it off and temp returned to normal. Do I need a bigger 4 core radiator or do I need to just run water or what?
Run the AC with the hood up and feel how much air the fan is pulling when you rev it a little. It should practically blister your face at these temps, if it's pulling enough air. Do you have a 5-blade or 7-blade fan? Also, do not run straight water, it'll boil over even sooner. In fact, you will have better boilover protection at about 70% antifreeze/30% water.
Look at the face of the clutch where it faces the radiator. If there is a spring coiled up there, it is a thermostatic clutch.
Car originally had 350 so it has that radiator cowl and 7 blade fan. The leading edge of the fan blades is about 1/2 inch outside of cowl. The fan is not on the inside of the cowl.
Took the Buick out for a cruise to check out the temperatures again today at 90F. The cars temp ran around 210 at 45mph. Next I ran it with the a/c on at the same speed and watched the temp slowly climb to 230F and then turned it off to bring it back down to 210. When I got back I watched the fan as I turned it off and the fan freewheeled 7 or 8 revolutions before stopping. I believe I have read this is not right for a thermal clutch. What do you think? Also, I use a 160 thermostat. Thanks.
Just found on the site an article Hot Running Buick By George Nenadovich that recommends the 215103 torqueflow which extends further into the shroud. I plan to get one for a start. Is the r&r just a matter of bolt and unbolt?
You should look at getting a fan shroud from a 455 car. The clearances around the fan & shroud make all the difference with respect to pulling a ton of air through the rad or just pulling it from everywhere else.
At 45 mph you don't even need a fan; in fact the fan and cowl at that speed probably cause more restriction to cooling than going without both. If you get hot at that speed you might have a defective vacuum advance. Pull off the distributor cap, apply some vacuum and see if the advance plate is moving. A three core copper-brass radiator is not "heavy-duty cooling" for these cars so don't be suprised if that is insufficient. Good luck!
What type radiator do you suggest ex. 4 core? Also, why would it only overheat with the ac on if it's vacuum advance? I'm pretty sure it works but I will check it and also I power timed it along time ago and it seems to run well.
Water does not cool best. But water with a surfactant (Water Wetter) is an excellent coolant. Pure ethylene glycol gives the best boilover protection, but should never be used in non aqueous solutions because it's inflammable. Given that most drivers are concerned with freeze protection as well as cooling, a 50/50 mix, plus a surfactant is the best choice. http://www.jcna.com/library/tech/tech0011.html
The best radiators today are alluminum; for this application it would be a two row unit. Bad vacuum advance is one reason (of several) for the engine to run hot at freeway or close to freeway speed. As soon as somebody says it is hot at speed when you have tons of air through an otherwise adequate radiator think vacuum advance and/or sticky advance plate. Overheating only with A/C on is a function of putting all the heat from the interior out into the condensor, on a system that sounds taxed already. I run no shroud and no mechanical fan (and no electric fan 99 percent of the time). As long as the car is moving at 35 mph or more it runs very cool - usually one or two hatch marks on the stock guage (we do 100+ degree summers here). It won't boil over until it goes to 8 or 9 hatch marks - that is probably way hotter than 240 degrees. Anyway, check it out and move to the next possible issue. Good luck.
Good news, replace clutch fan and saw a world of difference. Cruised around for a while and stayed about 190 then turned on ac and stayed at 210 max. Then I sat with ac full blast and after about 10 minutes in drive sitting still got to 225 degrees. I am happy with results but plan to install an aluminum radiator anyway to get even better cooling. Thanks.
Okay, improved cooling problem alot but still have a problem with climbing temps when sitting still with AC on in 90+ temps also high humidity. I replaced stock radiator with 2 core aluminum radiator, new fan clutch on 7 blade fan, vacuum advance works, coolant is 50/50. The temp does not get above 190 at cruising speed, maybe higher in stop and go traffic. This is with the AC on. With the AC off runs 185. The problem start when sitting for extended periods of time such as a drive thru window. Then it slowly climbs to at least 240 which is as high as I let it go before I either turn the AC off or drive to supply more air. Either one immediately drops the temp back down to an acceptable level. I guess I could live with turning the AC off in this situation but I hate having to keep up with it. Any suggestions? Thanks.
OK, Went back over everything and noticed that the new radiator to shroud wasn't a great fit so I made some adjustments and got it to seal pretty well. Still would like any suggestions. Thanks.
