Not sure if htis is the right place to post thisbut here it goes Just wanted to say whats up to all I now have a rebuilt 69 430 in my 68 225. This car runs around 190-200 degrees on the street in the summer, as soon as Im on the highway for more than 10 mins it jumps past 220. Lot of play in the fan even through I put a new clutch fan in. What would be my next steps to get this thing to run cool. Sucks not rollin down the highway. Thanks all Paul
Paul, Sounds like you don't have a big enough radiator. If it heats up on the highway, that is the most likely cause. What thermostat do you have? Are you running a fan shroud? How much anti freeze to water? Anytime you rebuild a motor, it will tend to run hotter. Some blocks are more of a problem than others. 4 core radiator is usually a must. Aluminum radiator is better.
I've had this problem before. Turned out the motor was running a touch lean, with the timing really retarded. I changed the original Q-jet around, then freed the advance weights up, installed an adjustable vac advance unit, and presto. Problem solved. Easist/cheapest place to start :beer
Yes timing is another thing to look at, but if he had no mechanical advance, he would probably notice a real lack of performance. Retarded initial timing would cause the motor to heat up at idle. Out on the highway, the timing should be adequate unless his vacuum advance is not working. Still, it worth a look.
At highway speeds there should be enough air going through the radiator to cool even if you didn't have a fan on the vehicle. When I worked in retail auto parts sales I know that whenever we sold an engine, that a new radiator was recommended. Yes a new engine does run hotter than a used engine for some reason. Also timing is very important. A friend of mine bought a 70 Electra and on the way home from purchasing the car it got so hot the water in the overflow container was at a rolling boil! I switched the hoses on his ported vacuum switch to match the ones on my 69 and it never ran hot again. Seems the advance signal was coming from the wrong end of the carb. Might want to see if, after you rebuilt the engine that those hoses got hooked up correctly. Good luck and let us know what worked for you as I am sure you won't be the last person to have this problem.
Collapsed lower radiator hose Did you change the lower radiator hose? I had the same problem on a '82 Turbo Regal I used to own. I replaced the original lower radiator hose with a replacement lower hose that did not have an internal wire spring to support the walls of the hose during operating. Sounds crazy, but what was happening is that the lower hose was collapsing shut and was restricting coolant flow to the radiator causing the car to overheat at highway speeds. I cured this by replacing the lower hose with one made by Gates, which has the internal wire support spring. Some of the cheaper (AutoZone) lower hoses do not use this internal wire spring on their replacements. It is something that I now always look for when I replace the lower hose. You can always reuse the spring out of the original hose if you can get it into the new hose, if this is the problem. to check to see what hose you have, just squeeze the lower hose. If it has the wire spring inside it won't collapse easily. Hope this helps. Ken
I'm blown away by all your ready responses here at this board! :TU: Not sure what type of thermostat- What kind should I look to get? A buddy of mine said the fan is not keeping up with the engine speed and thus causing it to run hot since there is so much play in it. Any truth here? I ran it all over town this weekend in about 55-60 degrees. No highway, no long ideling either and the temp never went past 190. I'll check with my guy who put the motor in about a new radiator. Any thoughts on what kind? Do I need a flex fan plus an electric one on the other side in the grill? Timing will get checked this weekend? Can an old points distributor thats off cause this also? Thanks a Million PC
No special thermastat needed but there are different heat ranges you can buy. If it is rated at 165 degrees for example then it won't fully open till 175-180 deg. so keep that in mind. To check your therm. take it out and boil it in a pot of water, use a thermometer to read what temp it opens at. There are failsafe ones that stay open when they break instead of failing closed and blocking the water flow. Describe the playy in the fan? Is it the water pump wobling? the fan belt? or the fan it self? You could try an electric fan or even two but your problem probly lies elsewhere. Get the points changed to HEI, but again that probly isn't the problem here.
For what it's worth I had the same issue on the same engine - changed the fan clutch and it still overheated at highway speeds. :af: Mine turned out to be a clogged radiator (factory 3-row). Recored it and ~voila!~ the heating problem went away. :TU: Some other things to check before going this route, however: Leaves and debris in front of A/C condenser are you running with a shroud? the cooling system may be airbound, although this shows up at low speed too thermostat may be shot or in backwards (unlikely I know but it happens) - make sure "the bullet is in the Buick" and the copper pellet is inside the engine part, not the hose part lower hose is collapsing as noted above water pump vanes may be rotted out Good luck and let us all know what it turned out to be.
As Larry said, If your temps are fine in extended driving NOT on the highway and then when you get on the highway the temps steadily climb - the radiator you have simply cannot exchange the amount of heat you are generating. If you plan on keeping your car I would look into an aluminum radiator. ....Flex fans, Electric fans etc. are band-aid solutions. At Highway speeds there should be enough airflow through the radiator that with No fan or shroud you're pushing enough air through to cool effectively
Oops - forgot about the rebuilt part so I'm guessing you've already replaced the water pump. Scratch that one.
Check timing FIRST!!! Cheapest thing to do when looking for the problem. Replace NOTHING until you do this job FIRST. When you check timing there is more to check than just putting a timing light on the car; if you have vacuum advance make sure it is working. At cruising speed vacuum is high and that advance cannister should be "all-in."
Can you post the name and source of some of these failsafe thermometers. I think I would like to put one in my car especially now that I will have the aluminum heads. Thanks. Allen allioop108@aol.com
i also had the same issue on 2 different cars and it was 2 different problems. one had a bad clutch fan, i even had 2 new gm clutches, still over heated. then i put in a good flex fan and the problem was gone. another ended up being a clogged radiator. new radiator and it ran nice and cool. radiator size can do it also. my friend has a mild 455 with a be-cool radiator and a single electric fan and it runs a max of 200. good luck.
I also went through the same thing. Mine was overheating all the time...I went for the jugular. New fan, fan clutch, radiator, hoses, thermostat, and guage!!!lol :blast: :af: eat that over heating problem! Needless to say it was one of those, lol.-Alex
I turn my fan off when I,m on the highway don,t need it unless the rad is blocked. I would say timing is the problem.
I worked on an 01 dodge caravan that was horribly overheating. Coolant was circulating, and the fans were running. which kind of left me stumped. I decided to start basic with a flush, since it was apparent that the thermostat was functioning. turned out the trans cooler developed a leak in the tank of the radiator. that really messed things up. I replaced the rad, and flushed the living crap out of the system. really tough cleaning the trans fluid out.
