I need help. Why does my engine over heat when it reaches 180 degs. It is a 255 Merc. with a new 32 shortened Walker Z type radiator and a 13# cap. It ran fine with a 52 radiator.
Overheat? The coolant won't boil at 180 degrees. What is it doing that makes you think it's overheating? Is it vapor locking? Or something else?
Water will boil at 212* and with a 13 lb cap it will raise the boiling considerably. Most modern engines operate at 205*
Where are you reading the 180 degs? I.E. where is the sending unit for the gauge? Have you verified that the gauge is accurate with a 2nd known temperature reading device? Are you monitoring temps on both sides? Could one side be overheating due to a bad head gasket, cracked cylinder, etc and the temp is being monitored on the opposite side? Are we correct to ***ume that you have functional thermostats in the standard location at the top of the cylinder heads? And at what temp do they open? What are you considering overheating? Is it pushing coolant out of the rad cap while idling? Details, Man!
Water boils at 212° F, increasing the pressure in a closed system increases the boiling point. This means that a cap rated at 13 lbs. will increase the boiling point in a system by 39° F. to 251 degrees F. 13 lbs, is putting a lot of excessive pressure on your hoses and radiator.
180 is my target temp. I want to see a well managed 175-185 on a summer day. A nice warm and tight engine runs best. I too would like to know where the heat is monitored.
You may have trapped air in the system somewhere. If the radiator is shortened you have lost a good deal of its ability to cool a flathead. You really need a 4 row radiator and high volume fan. I've found electric fans just don't cut it in this application. Run the engine for a while with the radiator cap loose and check to see if it pukes water out. Look for bubbles in the water with water filled to the lip on the fill hole. Did you follow the proper procedure for re-torquing the head bolts on a new engine? Test the thermostats in a pan of water at 190 degrees and see if they open when they should. That should be enough to keep you busy for a while. I'll keep an eye out for any progress.....
HEY thanks I am realizing that there is pressure being built up but it did it when I just in stalled the 32 radiator. The mechanical temp is just in the left head, the fan is a stock 8BA fan with the belt going to a double pulley and the engine in a bare ch***is. I did re torque the heads then the carb. fouled up. I must be happening when it reaches 180 Degs. I am re building the carb. and will check again.
As mentioned 180 won’t cause it to over heat, was it a new radiator? If so I’ve seen some with a plastic tight fitting cap inside the hose connections. The ones that slide over to keep junk out are easy to spot, but the ones that slide into the tubes could be easily missed on install.
A few questions -- Does it overheat to the boiling point while it's running, or after shutting it down? Are you filling the radiator clear to the top? Does it do it while driving, or sitting still (at speed or idling?) ? A little more info would help. Also, how far is the fan from the radiator? If you have the 3 blade 8BA fan , get rid of it and find a 17 or 18 inch 4 blade fan. Those 3 bladed numbers weren't much good when they were new and never got any better. Does your new radiator have a baffle under the fill neck? I advised loosening the radiator cap for a reason. Better yet, run it for a while without the cap. It will let any trapped air pockets release any bubbles and leave the system. I don't like those high pressure caps for your installation. See if you can find a 7 lb cap for it. Be sure you are running good thermostats in the engine. If no thermostats, there are some cars that can push the coolant through the radiator so fast it doesn't have time to cool. These engines are not a good candidate for high flow pumps.
180 sounds too cold to me. I’m use to engines running 210-225. My current ride stays around 180. Thinking about using a hotter thermostat and raise it some. but 180 sounds about right for a flathead.
@jimvette59 So your gauge shows 180 degrees, but it's puking coolant? Please describe EXACTLY what is happening. Is the top of the radiator the highest point in the system? Do you have a coolant recovery system, or just an overflow tube? Keep in mind that if you completely fill the radiator in a system that does not have coolant recovery, the coolant expands and has nowhere to go except out the overflow tube. There needs to be some air space in the top of the radiator of a system without coolant recovery. Air can be compressed when the coolant expands with heat.
Where do you come up with this nonsense that 180 is overheating? That's 32 degrees below the boiling point and you have to be well past the boiling point to "overheat" I know that a lot of guys new to old cars or new to temp gauges think anything over 160 is cause for panic but 180 will barely be warm enough to get reasonable heat out of the heater. Shortened radiator = lower profile, Are the radiator hoses by chance higher than the inlets of the radiator as now in a big curve? If so that could have created an air lock. Anything higher than the place you put coolant in that holds coolant can cause an air lock if you can't figure out a way to vent the air out. On the other hand top tank radiators are going to puke coolant 90% of the time if you don't leave room in the tank for expansion. Meaning that if everything in the cooling system is otherwise copesetic and you overfill the radiator it will most likely puke coolant at below the boiling point. Each pound of pressure of the cap raises the boiing point 3 degrees so in the real world that system should hit over 13X3 = 39 212 + 39 _____ = 251 Meaning that that system as it stands should not boil over until it hits 251 degrees in theory. Now won't that make you wet your pants?
Now carb problems are showing up, huh? Retarded ignition timing will make an engine run hot, just like lean conditions or vacuum leaks. Bad ignition systems will cause fuel issues too. "It was fine and all of a sudden..."
Am I reading this right? 180 is not overheating. Let the thing find it's own fluid level. Don't over fill it, it will seek its own happy place. A shortened radiator has lost a lot of its cooling ability. You need to compensate for that. Lots of good info given here. Heed the advise and systematically go through it if you think it's not working right.
Ran the engine today and it didn't spit out any water. It ran at about 170 degs. . This is my first flat head I am wondering why the timing mark on the crank pulley is on the other sideand the pointer on the engine is on the p***enger side ?
Now there is a very interesting question........ If it is running, my guess would be that the distributor has been installed 180 degrees out, when number 1 cylinder was at TDC on the exhaust stroke instead of the compression stroke, and then the plug wires were rearranged on the cap to compensate. I don't see any other way it could be that far out and actually run. Did you build the engine, and if so, does what I have said ring any alarm bells...??? Easy fix, if that is the problem. Reinstall the distributor with the timing marks aligned (number 1 at TDC on compression stroke) and then fit the plug wires to the cap as per standard firing order setup... EDIT - IGNORE THE POST ABOVE... TURNS OUT I'M AN IDIOT...
Like my post said......."my guess". I am not a mechanic or engine builder by any means. I would suggest getting some more input from others with more engine knowledge before you do anything. How about you just check it in the morning. It is not something that is urgent or necessary if it is running.
And I'm not a flathead guy, but... putting the distributor in 180 deg off then moving spark plug cables around the cap to compensate would not result in the timing marks and pointer being on opposite sides of the pulley. The typical first step is to verify the timing marks on the pulley are accurate using a fixed piston stop. There are many threads on this, do a search. You may have to fabricate a new pointer to match up with the timing marks (or remark the pulley). But with all of that said, you still haven't cleared up exactly what's going on and why you think it's overheating when the gauge shows 180*. You've got a bunch of guys here scratching their heads trying to figure that one out, and people are simply going to stop trying to help if you don't clear things up.
Sorry @Blues4U , you are absolutely correct. The timing marks should align at TDC on both compression and exhaust strokes. Like I said, I am no mechanic. Just ignore me............... @jimvette59 , please ignore my bad info in post #21.
As long as the firing order is correct it doesn't make a damned difference temp wise if the distributor is 180 out as long as you put a timing light on it and actually set the timing. The mark comes up to TDC on every revolution. The wiring setup just looks like **** to anyone who knows that number 1 should be there > rather than here< . Still ******** 180 is not hot for any engine no matter what the Face book experts say. Why guys **** on their shoes when the gauge shows 180 is beyond me. That is operating temp and not hot. The cooling system puking coolant, now that is an issue that needs to be taken care of. Same as if you put a 350 in a hot rod and the 350 had a 205 thermostat in it's original vehicle but you put a 160 stat in it and now it wants to run 185 and you **** your pants because your hot rod engine is running 185 and omg it's going to die.
Hello again I think I solved the problem of "overheating" it was a wrong diagnosis it was blowing out hot water at 180 degs. . I am re torquing the heads as we speak . What I don't under stand is how can the engine run when the timing is so far off. The pointer is on the p***enger side of the engine at about 10:00 and the dot on the crank pulley is at 2:00 .
Most likely either the pulley is marked wrong, or the pointer is in the wrong place, or you're reading it wrong. Like I posted above, verify the timing marks using a fixed piston stop, the method has been described many times on this forum and elsewhere, do a search and you'll find the information on how to do it. https://lmgtfy.app/#gsc.tab=0&gsc.q=hamb how to check timing marks ford flathead v8
The only timing pointers I've ever seen on 8BA and 8CM is on the right side, about 10 o'clock as described. I can't think why the pulley is turned to have the mark on the other side. That's probably one of the things that should have been verified as it was ***embled. Put number one at TDC and see if the pointer lines up with the mark on the pulley.
Lets end this with my apologizes. I had the timing lite on #4. It's not easy getting old and stupid at the same time. I am glad I'm not working any more. What was normal is now difficult.
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