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major overheating

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alleycat

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Hi Yall
I have a newly rebuilt 250 in a 51 pickup. From startup to 200 degrees takes about 15 minutes on a good day. So far I have changed the thermostat twice,taken the thermostat out,changed the water pump twice,checked the timming,checked the heat riser,taken out the radiator and flushed with phosphoric acid,i have an electric fan in front of the radiator,a giant barn fan blowing on it,finaly went so far as to pull the head of and check for sure the head gasket was right( the engine builder told me i was crazy for doing that but I'm grasping for straws now.) I have checked the temp gauges against thermometers in the radiator. I have talked to all the "experts" in town and it has them all scratching there heads. Now it time for the million dollar question. WHAT AM I MISSING ????????????????????????????

thanks Rick
 
Over heated engine!

Hey Rick

Wonder if you cleaned the block water channels before install ? You could flush them channels with hot water but low pressure , then try to pore phosphoric acid 30% mixed with water in the system . close it with a prop of a kind and let the solution stay there fore 3-4 days. Clean out with low pressure hot water and see what comes out.

Use eye protection and cloves!!!

Martinius.
 
yep. did that. I checked with the engine builder first and he told me they did the vat thing. since I had the head off I did the straight acid thing, when i flushed out the block it was as clean as a whistle.
 
I shut it down at about 210 degrees. only takes about 15 minutes ( I usually get about a cigarette smoked till it's time to kill it). once the temp. starts to climb it slows down at 180 for a few seconds then steady climbs.
 
yep. first thing i checked. stuck a meat thermometer in the radiator to verify temp.
 
What help Me with Overheating

I think it was Nat, that asked me about my water level, and I filled up to much and did not have room to circulate or expanded.
 
alleycat said:
Hi Yall
I have a newly rebuilt 250 in a 51 pickup. From startup to 200 degrees takes about 15 minutes on a good day. So far I have changed the thermostat twice,taken the thermostat out,changed the water pump twice,checked the timming,checked the heat riser,taken out the radiator and flushed with phosphoric acid,i have an electric fan in front of the radiator,a giant barn fan blowing on it,finaly went so far as to pull the head of and check for sure the head gasket was right( the engine builder told me i was crazy for doing that but I'm grasping for straws now.) I have checked the temp gauges against thermometers in the radiator. I have talked to all the "experts" in town and it has them all scratching there heads. Now it time for the million dollar question. WHAT AM I MISSING ????????????????????????????
thanks Rick
Click to expand...


Is the electrical fan in front of the radiator running all the time or just when it heats up and is it pushing or pulling?

Is the electrical fan have the radiator blocked off (shrouded) to where it is only cooling a super plate area?
 
it's an electrial fan,pusher in the front of radiator with thermostat set at 190. I even took it off thinking it might be blocking the air.l put the original engine fan back on (temporairly since it just clears the radiator). I still keep the big barn fan running. No difference or not enough to notice.The barn fan blows hard enough that if I forget to chock the wheels it takes off across the floor (found that out the hard way).
 
Running Hot

As it's not reaching 212? F & boiling over , technically it's not actually overheating .

I'd say : to test , remove the E-Fan and run it , place your hand flat against the radiator core , slide it side to side going down ~ it should heat evenly from side to side and get cooler as you tough lower .

Any inequities or cool spots indicate plugged tubes in the radiator .

What's the ignition timing set to at idle ? .

No vacuum signal to the dizzy @ idle , correct ? .
 
I had a different brand vehicle with this same sort of problem. Turned out my distributor advance weights and springs were not functioning correctly. Timing was fine at idle but messed up at anything higher than idle. Took the dizzy apart, tightened up the springs and cleaned out all the gummy gunk. No more overheating issues.
This was on a 48 Willys flathead. Don't know how it might apply here, but timing issues can cause overheating.
 
already pulled the electric fan and checked the cooling, you don't want to lay your hand on it about the top third, the bottom two thirds gets a little cooler.
I had a guy come out and set the timming to specs. I don't remember what it was now. He checked the weights in the distributor and the vacum while he was at it. He's like me,pulling his hair out trying to figure this thing out. If you speed it up to a fast idle(about 1500rpm) you can actually see temp. gauge rising. the meat temp gauge in the radiator shows 210 and the one in the dash is about centered at 212. From start up to that point is about 10 minutes max. SHUT ER DOWN and wait till another day.
I even had the hair brained idea maybe a bird got up in the muffler and built a nest so I pulled it off. Like I posted earlier I'm grasping at straws now as to what to try next.
 
My '50 3600 with a '59 235 just recently started running hot on the gage and then drops to 180 and will stay there just fine. It is a bit nerveing to watch the temp gage sitting at 200+ waiting for it to drop down. Once it gets back to 180 it stays there fine. I believe the thermostat is sticking and am looking at replacing it. Any thoughts on mine?
 
Rick,
You seem to be both thoughtful and pragmatic in your approach and darned sure not lazy. How much was your 250 overbored? The 194/230/250/292 engines are known as "thin walls" or thin castings and many can't take more than a 0.030 overbore. Some have gone 0.040 or 0.060 but they were lucky. Here's how we isolate coolant volume from air flow and radiator capacity. Do the "boat in a lake test" which is having your lower water pump hose in a tank with with water from a faucet flowing into it and letting the water from the top hose drain out onto the ground. Raise the idle to the point you said caused rapid heat build up. If the temp gauge rises above the thermostat rating then there is too much internal heat being generated and it's a lost cause. If not, hook up the bottom hose but not the top (cap off top hose neck) and put the hose from the faucet in the radiator and balance the inflow to the outflow. If it now overheats the radiator doesn't have enough flow and/or capacity. If it doesn't then air flow is the problem.
 
All of the above is valid only if the timing is right, the exhaust is unrestricted, and the fuel mixture is not too lean. Remember, only 15% of the heat from an engine is removed by the radiator; 85% goes out the exhaust.
 
Is your heat riser valve in the exhaust manifold stuck in the closed position ?

You stated that you replaced the thermostat 2 times.... did you replace it both times with a 160 thermostat ?
 
160 Thermostat

Rick

I understand you have a 180 F thermostat installed. But if the waterflow in your radiator is bad heat is staggering in the system. It opens but to late to keep the temp, down. Evans suggestions are very good to find out if this is the case.

I new my old radiator whas`nt functioning very well . It should be warmer on top and center but a bit colder in the bottom . I changed it out with a new standard radiator and installed a 160 F thermostat wich opens a bit earlyer and water temp. stays at 180 now.

Martinius.
 
I guess the next thing to do is the boat test. I think I uderstand this right. Drive it into the lake, if it sinks problem solved,if it floats I have to fish it out,right. JUST KIDDING. I'll work on that when I get back in the mood. About the thermostat, I couldn't tell any difference with it in or out. I would think it should have taken a little longer to heat up but ut didn't. I don't have a clue how much they bored it out and it doesn't say on the invoice.
 
Bored cylinders !

Rick
You could phone them and ask because it is important in this case , you can eliminate some of the mentioned problem issues. Get there details how much them cylinders where before and after they where bored. Normally they keep data on this.

Hope the water is`nt to Cold :) , dont give up Martinius.




alleycat said:
I guess the next thing to do is the boat test. I think I uderstand this right. Drive it into the lake, if it sinks problem solved,if it floats I have to fish it out,right. JUST KIDDING. I'll work on that when I get back in the mood. About the thermostat, I couldn't tell any difference with it in or out. I would think it should have taken a little longer to heat up but ut didn't. I don't have a clue how much they bored it out and it doesn't say on the invoice.
Click to expand...
 
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