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I am running a heater core. I am currently running it with no thermostat and radiator hoses disconnected to see if the water pump is pumping. I'm filling the engine through the lower hose connection but unless I keep the water running nothing comes out the upper hose with the engine running. Is this normal or do I have a bad pump?
Edit: I just ran it with the garden hose running through lower hose and the revved it up. I got a little more water out of it but really expected more.
Unless you get the pump submerged in water it won't pump water with all that air. Make sure when you spin the pump by hand the impeller is spinning. The only way it wouldn't pump would be if the impeller isn't spinning. If it is only overheating on the highway sounds like air flow is restricted going threw the radiator. In my 1992 silverado i am using the stock radiator withe one electric fan with a shroud with a/c and my temp is rock solid all the time. Where did you plumb the cylinder head vents to?
I have a feeling we are missing something that is staring us all right in the face.
Do we have the basics satisfied-
1- large enough radiator?
2- sufficiant airflow through the radiator?
3- radiator not internally clogged (coolant flowing freely)?
4- water pump in good shape and pumping as it should?
5- ALL AIR burped out of the block & heads?
6- NO hose restrictions?
7- cap holding pressure?
8- fan well-shrouded and pulling enough air?
Sorry if any of the above is covered in previous posts, just covering the bases. I'm sure I missed something somewhere......
So one more thought if your 79 has a stock lower grille it doesn't flow any air. On my 79 LS swap I cut out all the grille holes for better air flow. But and there is always a but It did cut holes thru the crash bumper that's behind the lower grille.
I was running a shroud but pulled it out, it is better without it. I have been considering cutting holes out in lower grill and bumper for more air. I bit the bullet and ordered a coldcase radiator and am going to give that a shot next.
Finally seems to be good. I ended up putting a cold case radiator in it. It dropped the temps so much that I ended up putting a 185° thermostat back in and going down to one 16" fan and no shroud.
Yeah overheating while cruising is a radiator or tuning issue. I don't run a thermostat at all I'll share a pic of what I run. I'm running a Summit dual pass radiator which has a big a/a intercooler in front and a single Ford fan. On E85 with tuning specifically to keep it happy (ask me if curious) I cruised yesterday in 85F heat at 19x, and in bumper to bumper traffic I was 189-197.
I always recommend running a surge tank, especially if your radiator is NOT the highest point in your cooling loop. Even if the radiator is higher than the engine I will run one just because it is how these engines were set up from the factory.
I also run with a big A/A in front of rad. My rad looks similar to yours. I have a 160 thermostat and dial in the temp I want to run with the fan which is brushless (Volvo JY), and full shroud over rad, variable speed and closed loop. Cruising is dialed in for 195-198. At the track, it's dialed in for 180.
There is definitely more tuning to be done but I just couldn't get the temps down enough to get it completed. I ended up with the 185 thermostat because it would stay around 165 without it.
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