someone help me with my slant 6 problem

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MY68/6GT

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i've got a built /6 and it will not stay cool, please pm me or call me and i will tell you everything i've done to get this prob solved , we are stumped. 843-602-4704 craig
engine builders welcome PLEASE HELP
 
Did you remove the thermostat? If you did, put it back if it works.
Have you pressure checked your radiator cap? Should be 16 PSI.
Was the cylinder head & block hot tanked/boiled out? If not, drain coolant and knock out a large freeze plug. If there is a bunch of junk in the bottom of the block, you can imagine what's in the top.
Is the water pump under-driven?
Back in the way back, when Dupont first introduced Xerex anti-freeze, one of its features was to seal leaks. It also sealed heater cores and valves. Never made a study of the /6 cooling system, but if there are small passages that could have been similarly sealed. (Thinking mass quantites of Barr's Leak.)
How's the head gasket. If it's bad, it could be blowing hot gas on the intake. If compression is good and even, rule this one out. Can also paint small areas of head to block seal with soapy water without bubbles. (Won't stay in place long enough to use on large runs.) Turn engine over by hand. If you got bubbles, you got problems.
Can increase cooling capability with three or four row radiator. Think most /6 had a two row unit.
 
Slants, even built ones, are notiriously cold blooded. My money is on a bad rad. I had all kinds of over heating problems till I got a NEW rad.
 
put a six blade alum fan on,gonna hook up a more accurate water temp gauge,run a 160-180 therm,change to electronic ign . the only thing not new on mtr is starter and valve cover...and i know that aint it . LOL
 
70 Valiant is correct. You need to fix your radiator. Ill bet it is plugged. I learned the hard way that the "hot tank and or other cleaning" will loosen up a lot of debris in the system. Then when you put your rebuilt motor in and start it up ,Woosh all that crap is now plugging you radiator.
I now put a strainer in the hose for the breakin period ( I have a hose I cut in 2 and inserted a s/s basket strainer then put back together) Then I put a regular hose back in after the breakin.
My02.
Frank
 
are you sure timing is not advanced? too much advance will make a motor run hot.
 
Just a stupid comment on my behalf as I did not read the entire thread and maybe this was covered but if you are not spitting out fluid or turning the upper rad hose into a 'Ball Park Frank' it may be as simple as changing the temp sending unit. The little post up in the front of the motor right by the valve cover that the brown wire connects to. My Swinger was running hot at least I thought it was until I changed out the sender. Of course this was AFTER I flushed the system, tanked the radiator, changed the thermostat and hoses! At least the car runs normal temp now.
Chas.
 
I've been having the same problem with overheating. One of the problems was with the thermostat; it refused to open once installed in the car. At first, I thought it was a faulty one, so i bought a different one. This time I tested it in boiling water. Opened up when it was suppose to until I put it in the car. Once in the car, nothing. And yes, I was putting it in the right way. I finally gave up on trying to make sense of it and tapped the center of the thermostat out. Tomorrow, I'm taking the car to work with me so when I punch out, I'm going to flush the system because there is rust in the antifreeze.
 
sounds silly but did you belch the system? air can cause overheating.
 
ChazRam said:
Just a stupid comment on my behalf as I did not read the entire thread and maybe this was covered but if you are not spitting out fluid or turning the upper rad hose into a 'Ball Park Frank' it may be as simple as changing the temp sending unit. The little post up in the front of the motor right by the valve cover that the brown wire connects to. My Swinger was running hot at least I thought it was until I changed out the sender. Of course this was AFTER I flushed the system, tanked the radiator, changed the thermostat and hoses! At least the car runs normal temp now.
Chas.
Click to expand...
Sounds exactly like what I just went through except I can't find a temp sending unit that works. First one maxed out the temp guage. Second one barely moves the needle.
 
Timing can be an issue. My 76 Duster ran hot on the highway till I figured out my vacuum advance was pulling in over 50 degrees total timing. Once I got that sorted out it was cool as a cucumber.....
 
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