Hi, My '56 Cadillac has a little problem. When I drive, her temperature is fine, stays at 160 degrees. But if it stays in idle for more than a few minutes after driving for a while, the temp. starts creeping up,up,up...and it won't come down until I'm moving at a good speed. I did install an electric fan in the front of the radiator to help cool it, but it only slows down the upward rise of the temp. Still goes up. I have a summer thermostat (160), water pump was rebuilt a few years ago, as was the rad. It even has been modified with "three rows, extra cooling". -How long does a thermostat usually last? -Could the engine oil be the culprit? (Was changed late April '10.) Last year, I flushed the block and the temp seemed fine after that. But now, it's going hot on idle! It has the original 365 V8 with heads from a '58. The engine was not rebuilt, but the piston rings were changed. Car runs fine. Help?
Piston ring change wouldn't cause a rise in temps... Thermostat may be stuck partially closed, especially if you've had the rad rebuilt. I'd suggest adding a shroud. Could be the rebuilt water pump isn't up to it, if you rebuilt it a "few years ago". I'd also be concerned about the heads, maybe the head gaskets aren't correct and are blocking coolant holes. R-
I don't think it's the head gaskets, because the block is the same from 1949 to 1962. Isn't it? I did check to make sure there was no obstruction when I installed the gaskets. Thermostat? Hmmmm.......but wouldn't it cause the car to run hotter when it's driving? Because it stays well below 170 degrees while the car is in motion. Just asking.
Take thermostat out, If you have a regular gas stove place the thermostat over it and see if the thermostat opens up after a while. The gas heat will act as water temperature. If it doesn't or looks odd replace it. Kragen sells thermostats that stay open when they fail other then particularly closing or closing all the way. Best get this fixed because after all it is a cadillac and thats all that matters.
It'll keep going up until it overheats, or until I shut the engine, or it stalls. I had the temp read over 245 degrees before it stalled last time when I got caught in a mega-traffic jam. I'm ***uming the stalling is the fuel vaporizing from the heat.
Have you tried increasing the idle speed whilst stuck in traffic? Water pump. Either restricted, or impeller clearance might be too much. If that helps, you could install a manual throttle cable to pull out a little when you know it's going to be stopped in traffic to increase the coolant circulation. Take it out of gear, idle it up, reduce the idle before dropping it back in gear. Yea, I know, a lot of h***le, but better than waiting for it to overheat............
If it cools while running down the road but not sitting, it's a function of not moving enough air at idle, period. You either need a bigger fan, shroud or the 3 row radiator may actually be contributing to the problem. The more cores, the harder it is to p*** air through it. Look at the core really close and check for bent/folded fins and straighten any you find. You should be able to see through the radiator looking straight on. A mechanical fan will move more air than most electric fans. Use a 4 blade 19" GM fan and you will move a lot of air real fast. Your electric fan in front is actually contributing to the air flow problem, it's blocking the core. SPark
I don't think the water pump is bad. Worked fine last year. A mechanical fan? You mean a thermostatic fan? The one with the clutch on it? For the radiator, I'll p*** the hose on it to clear up any debris tha might have lodged itself. I think a trip to the junkyard is in order for a fan and shroud. And I'll check the thermostat. Thing is, last year, I was stuck in traffic, popped on my electric fan, and the engine stayed cool. I was told that engine friction can cause overheating. When I changed the oil this spring, I put in 10w30 grade. I usually put 20w50.
Engine temp climbing at idle, but maintaining operating temp at speed, or decreasing at speed is almost always an air flow problem. Most vehicles without electric fans and some even with will raise temp when it's hot outside when sitting for periods of time in traffic. You want to run a shroud. You didn't say what size electric fan. Probably should be a least a 16 inch single, or 2 smaller fans. Make sure fan is running in proper direction. Most have reversible blades. For puller, (engine side of radiator), or pusher (grill side of radiator). If you have a good fan and shroud installed and temp still climbs at idle but drops at speed, you may need to have the radiator rodded. Bad thermostat, head gaskets, cracked heads, bad water pump, can probably all be eliminated. Usually those type of problems will cause the engine to overheat faster under speed, such as highway speeds faster than at idle. Also make sure the radiator is not clogged with debris, such as bugs, dirt, etc so air can flow thru radiator.
Last time I had one get hot at idle it was a bad thermostat that didn't open. One hot day idling the temp climbed and climbed until I shut it off. Eventually it clicked over to open, it was fine when I started it next, and I never realized what happened until it got cold out and I turned the heater on and had no heat. And be aware I've heard of reman water pumps, brand new, that the impeller's come loose and doesn't spin or doesn't spin enough to move the coolant. Worth a check.
Start with the 'stat since they're dirt cheap. Does your radiator hold pressure well, what are you using for a cap? I'd go with at least a 13-lb cap which will raise the boiling point. Make sure the fan belt isn't slipping, easy to overlook something that simple. I doubt you have a serious problem, I'd change the water pump next since rebuilds are iffy and **** the bed once in a while after a few years. Bob
Thanks for the great tips guys! For the size of the electric fan I have, it does not cover all the rad, but most of it. I still use the stock fan on the engine side. I only pop the elect. fan on when stopped for prolonged periods. The Radiator cap is a 12lb, based on factory specs. It does tend to leak a little after shutting off the engine after it warmed up long enough. Maybe it's time to change it,too. So, I'm going to check the thermostat, clean the radiator, change my fan and add a shroud,and change rad cap. If it still overheats, then I'll inspect the water pump. After that........move to the north pole???
Do you have the stock exhaust manifolds? Check the heat riser; I believe it will be on the p***enger side manifold. The heat riser could be stuck closed or only opening part way.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
I'm not a fan of electric fans (no pun intended) being installed where they weren't meant to be installed. If it still overheats with that, you have something out of whack. Go through your new and improved checklist and you should be ok. Bob
Yes, I have the stock manifolds. But no heat-riser valve. Old one was stuck, so I just removed it. It's only good for cold weather anyway. Thanks!
Lol! I hear ya! I'm not a fan of those either. But I put it there to help cool the temp. I'm a little paranoid of overheating in traffic! Will check my list properly.
Yes, the old Caddys did not have fan shrouds from the factory...in those days none was needed. But with today's ****py fuel and most auto parts built in China, I'd certainly put one on...there are several available already made up, but you'll have to check your rad size to find one that fits...make sure you cover the rad top to bottom...and your fan should stick inside it so that only about a half an inch of the fan sits to the outside...good luck. R-
Update.... Well, I think I found the problem...I noticed some bubbling in the coolant in the rad. I think my head gaskets are toast. There'a probably a very small compression leak that causes the coolant pressure to lower just enough to cause the engine temp to increase on idle. -I flushed the cooling system, changed the thermostat (160 degrees),changed the rad cap. That only improved slightly the heating problem. But it's still there. I guess some new gaskets are in order.
Did the compression test today. All cylinders are over 120lbs. My question is, Wouldn't a compression or exhaust leak in the cooling system cause the compression to go down? Or is it an early stage of Head gasket failure? There is no oil in coolant and no coolant in the oil. I'm on the verge of taking my engine apart. I have no garage...Hot sun...rain...bugs.......case of beer!!
I changed the engine and transmission for a 350 and 700r4. The original engine needed a total rebuild. Would've cost me too much. Causes of overheating: -Plugged rad. -wrong heat range spark plugs -bad water pump -sludge in water jackets in engine -sticking brakes The list goes on...
Ester Eddie; When your '56 starts to run hot (until you fix the problem) if you turn on the heater in the car in will draw some of the heat out of the motor and raditor; this will help a little bit.......
Yeah I drove it to work yesterday and was fine but on my way home overheated.I turned the heater and defroster on no help.The water pump is only a year old and I only used it one summer.I did a compression test last week and all was fine .I was thinking head gasket too.I am going to go with the new Rad.
Your last part of the post above is where I would look. I had a 2.8L Merc V6 that would get hot (especially on hot days) when idling. But would cool right down when going down the road. I attributed it to the almost zero oil pressure at idle when the engine was warmed up. I would check the oil pressure after warmup at idle. Bet it is really low!
Man .....I put in a new radiator today and its still overheating .Someone told me I should drill a hole in the thermostat ..Any thoughts on this? I'm at a loss up here.
A small hole in the edge helps to let air out so you dont get any airpockets inside. Have you checked the timing??? Common cause for Flathead Fords to overheat. Ive heard of cadillac water pumps where the impeller stopped spinning because it had became loose.
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