I'm taking a low mile 500 Caddy out of 71 Eldo to use for rod project..in running up engine for testing it overheats after 15 minutes or so of idling/driving..I've had radiator boiled and cleaned, replaced thermostat, no hoses are collapsed.. does this mean that water pump is failing? its not making any noise...
Might want to spend some time on www.cadillacforums.com/forums I've been able to find some decent tech there in between the my opera lights are the wrong color posts.
First, from what your are saying, it sounds like you may not have enough air flow thru the radiator. Second, Since you have changed out the engine from one car to another, what temp guagues are you using to verify it is in fact over heating? Third, Beg borrow or (*&^&^ one of those thermal imaging temp probes to verify what you in car gauges are reading. Fourth, Verify what thermostat you have, if you are using a late model engine, it more than likely has the hotter stat, for use with the computor controlled engine. Back to the first, are you using the orignal fan on the engine or using a electric fan? Is the temps overly hot? or is it just puking out the over flow?,, If it is just puking out the overflow, it may be that you have just over filled the radiator.
Is the temps overly hot? or is it just puking out the over flow?,, If it is just puking out the overflow, it may be that you have just over filled the radiator.[/QUOTE] Or you may just have a bad radiator cap, or too low pressure cap. It happened to me on a 68 pontiac. It would overflow coolent past the cap until it got low and started to overheat. Like an idiot I changed the cap last, after the thermostat, waterpump, and a radiator flush.
Thanks guys...it is still in the Eldo and I can drive it around so it should be getting good airflow..it does puke out the overflow a half gallon or so, I did put a new cap on and it doesn't seem to be overly full of water..I only have an idiot light so can't really tell whats going on (idiot light isn't coming on) I just want to solve this problem before I use it for rod project...
Just an idea but you might check the vacuum advance. I know might seem odd but they rely pretty heavily on it. I have a 472 in my 51' Caddy and had the same problem til we replaced the vacuum advance and that cured my overheating problem. Good Luck!
Hmmm....Another thought is...If you are still driving in the original car, is the stat froze in the closed position? Could be the orig is not opening if it is an original, This would cause a heating problem in the first 15 minutes of operating time. Just a thought. simple things first!!!!
Or you may just have a bad radiator cap, or too low pressure cap. It happened to me on a 68 pontiac. It would overflow coolent past the cap until it got low and started to overheat. Like an idiot I changed the cap last, after the thermostat, waterpump, and a radiator flush.[/quote] Definitely check the radiator cap. Is it the right pressure? I just went through this with a Mopar 383. Had a 7lb cap, overheated, replaced it with a 16lb cap. Problem went away.
Hey Rick,does the car have a recovery tank on it? How many Lbs is the new cap? If the light isn't coming on an it's just shoving some coolant into the tank and after it cools it pulls some of it back in the system and isn't a constant loss I wouldn't sweat it much. But with all the stuff you hacve layin' around there surely you have a used mechanical gauge you can install and check it out for real. Ohh and how about that intake we talked about? W***suuuup?
I don't have the time to cover everything right now. I can post more later. Just remember that you are now working with an engine that was designed for low revs, and is being made to run at higher revs. It is a very thinwall block that weighs not much more than a SBC and somewhat less than a BBChevy. at least on the weight charts published. It was also designed to live in a BIG engine compartment with lots of breathing room. It will radiate HUGE amounts of heat,and because of it being thinwall, it is also very sensitive to those higher temps. In a confined space it will overheat almost everything around it including steering boxes, hoses, master cyls , you get the idea. I have had to do quite a few things to keep my 472 from getting too hot and frying everything in the neighborhood in my daily family-car Stude. I have used mine as a family car with the 472 for over a dozen years, so I can give you a long list of things I have encountered along the way. I will write a better explanation later when I have time- IF I CAN FIND THIS THREAD AGAIN.. First and foremost is PUT IN AN ENGINE OIL TEMP GAUGE!!! RIGHT NOW!! I can't stress that enough. I learned that the hard way. Run to Wal Mart right now and buy a $20 temp gauge to put in the oil. You may even cut your next test drive short when you see the gauge readings! Keep it in the low 200's and your crank will last a long time. If you keep it in the high 200's or allow it to hit 300 as I did once, you will lose crank bearings very fast and wonder what went wrong... like I did. Sometimes it may take a 3-4 hour drive before the temps climb up high; sometimes it can go up really fast, and sometimes it will creep very slowly upwards. Remember your bearings are just about like soft solder, and oils don't help much when they are thinned out by heat. Localized bearing temps can be much higer than oil temps, so be alarmed when you see the gauge climbing up high. I truly believe that all those many Cad swaps promoted by the car mags several years ago have vanished for a reason... Things often appear to work fine for quite a while. The biggest problem a Cad swap has is RADIATED heat- with not enough underhood airflow in a compartment a fraction of the size of the original Cad. This can be overcome, but is usually found out the hard way, often by high oil temps and crank bearing failure for no apparent reason. I had TWO in the very early days (late 1980's), and NONE in the past 15+ years, so I think I am on the right track. I had to wrap the exhaust pipes, raise the rear of the hood as an airflow help, run taller gears (don't worry, the Cad has more than enough torque to overcome that), add an engine oil cooler, and watch my oil temps. YOUR NEW FAVORITE BRAND OF OIL WILL BE DICTATED TO YOU BY THE OIL TEMPS YOU WILL READ ON YOUR GAUGE on long trips. I'll explain that later. I have made myself a list of oil brands to use and brands to NEVER use, all based on low oil temps and sky high oil temps during actual use in the toughest testing lab than can be devised- a huge Cad engine in too small an engine compartment. The next "FIRST THING" to get is a big radiator. I had mine re-cored to a 4-row br*** radiator. I think a better thing would have been to go to an aluminum rad. The next thing is gearing and timing. Retarded gets hotter. Use enough advance to run right. Forget the idea of running hot rod gears unless you use a HUGE oil cooler and a HUGE radiator. Even the difference between 3.25 gears and a 3.00 can be seen in both the gas gauge and the temperature gauge. 3.50's gave me 9 mpg and VERY hot oil temps. 2.75's give me 17 mpg. 2.75's will still smoke the tires easily, so I haven't lost anything. Next, an oil pre-luber will save you 5-8 seconds of dry-starts waiting for the oil cooler lines to fill with oil pressure again. I made mine from an old fire extinguisher. I use a 9 quart oil pan, engine oil cooler, oil primer, HIGH QUALITY oil, tall gears, lots of air thru the engine compartment, wrapped pipes, shielded steering box, homemade air dam to force air into the radiator, and replace soft-sagging engine mounts every few years. I have never had high transmission temps, but I run a separate cooler anyway so I don't add heat to the radiator. If you want me to go into more details I can, but I have to run for now...
Wow! saving this post, lots of good info here. DARE-TO-BE-DIFFERENT I hope you can find the time to post more. I've got a 472 waiting to be swapped into something as well as one in a 68 Deville and this is all extremely valuable info.
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