351w 93 mustang overheating
 

I've looked at all possibilities on way my 351w 93 mustang keep overheating up to the 240-260. I've installed a new 2 core aluminum radiator w/fan shroud , high flow water pump, two 12" fan each one rated 2150cfm , 180 deg thermostat. The fans thermostat is set at 185 to come on and off at 175. I've checked for blown head gaskets with the block tester fluid and there are good, I've used a Mark VIII fan on the high speed and it still overheated does anyone have an idea on what I may have over looked, thanks. 351w trickflow intake, 1.7roller rockers, F303 cam, long tube headers, Holley hp efi ,255lph fuel pump

how quickly does it overheat? a high flow waterpump has the ability to suck the lower rad hose shut if it doesn't have a spring in it to keep it open.

It takes about 20 minutes to reach 240 deg and that's when it's just sitting, if I drive the car it goes down to about 200-220 deg

I think I will remove my heads and see if the gasket were put on backwards that's the only think I can think is causing my overheating problem.

one of them probably is. it does happen from time to time

the only other thing i can think of is, the water pump spinning the wrong way, which is probably not the case

The water pump is counter clockwise and it was overheating with the stock water pump and I thought a high flow pump would solve the problem but it didn't. Lower hose is new and the upper hose is glass and the anti-freeze is moving through the car. So the only thing I haven't checked are the head gaskets.

if you want to check the lower hose that is new, just rev the engine and watch it. it will usually suck shut if that is the problem.

the hose sucking shut will usually cause erratic temp changes though

Im not sure about a 351,but on a 302 if you can see a squared off portion of the gasket protruding at the front lower corner of each head,where the head meets the block,that indicates the gasket is installed correctly.


https://cimg0.ibsrv.net/gimg/mustang...c6f831ee69.png

Thanks for that info wbrockstar, the head gaskets were on right but one of them was a felpro and the other was stock not sure why the mechanic did that but the stock gasket was much thicker than the felpro. And the end ports on both of the heads leading to the back of the engine had a lot of squishy substance packed in there, I cleaned both ports out so I hope that was the problem with the overheating. I'll put the car the back together sometime this week and give an update, thanks.

Are you referring to the rear as in (front or back side) or do you mean rear as in (deck surface of the head at the coolant ports that align to the blocks coolant ports) If its the first,at the passage that runs all the way through each head and exits at a port on the firewall side of the head,thats actually a thermactor system passage, used to route smog pump air to the heads.
This passage has nothing to do with the cooling system.If this is the port you're referring to,the squishy stuff may be rtv or sealant where someone tried to seal the port after they deleted the smog system, unless the system is still being used or it could be carbon buildup which occurs frequently at this location.....