Okay FE guru's... Im looking for a bit of help here...

The 390 outta my 75 (originally in a 73) is giving me FITS!! its getting hot. It takes awhile, but it'll slowly get hotter and hotter.

Heres some details... its .030 over, pretty good size Cam, the WP is fairly new, Electric Fan, 2 yr old radiator, 13 lb cap.. almost a 50/50 mix of Antifreeze/water.
The Water Jackets have a partial fill..So Its always run a little bit warm, but never like this...

Started this morning ... It'll get up to 160ish cruising around town, even a bit of highway driving. If you continue driving the temp just keeps rising. It took just under 20 miles for it to get up to the 210-215 range. The Fan and Radiator have always been able to keep temps under check in stop n go traffic, so Im at a loss as to whats going on.

I do usually run the Rad. Cap on the 1st notch, if that makes much of a difference... The block also froze this winter (didnt get all the water out, I know bad owner!) and it pushed out a freeze plug.

Should I go up or down on the pressure cap (more or less pressure)? Im going to pull the WP and see if maybe the fins got bent or something similar..

 

I have to ask why you don't pressurize the sytsem to 13 lbs by tightening the cap. You don't say anything about a thermostat and finally why don't you let the 50/50 mix in year round. What did you fill the water jackets with and I would like to ask why?
kotzy

 

No Tstat, and at the end of last year, I had been flushing the cooling system, since I drive a truck for a living, I dont always get home regularly.. so it was warm when I left...Freezing when I got home.

I beleive they used hard block - or something similar..done on recommendation from the guy who did most of the work on the shortblock back in 97/98

 

It's very unusual to fill the water jackets with ANYTHING on the FE unless you are pushing god-awful amount of boost/power. Something's fishy on that one.

Since you froze the block, I'm going to think you did something to the head gaskets, heads, something cracked, that's pushing exhaust into the cooling system.

If you have the rad cap on the first notch, it's NOT pressurized whatsoever. I'd turn it all the way and see what happens.

 

Usually wont that cause it to overheat quickly?? I guess I'll have to do a bit of tinkering and see what I find..

Im not inclined ot think its a blown head gasket or cracked anything, since it made a 40 mile run @ 70mph w/ no problem... only acted up on the way home...

 

Damn, and I love that truck. Still watch the videos from time to time.

Back to topic: Having a liquid under pressure raises it's boiling point. Having coolant boil in the block is the bigger problem over running a little hot.

 

I love that truck too and its pissin me off. Im gonna repalce the Rad Cap, Dbl Check the timing, and then if that doesnt help, pull the WP and make sure its not messed up. For all I know, the impeller could look like swiss cheese...(bare metal and straight water ran last year dont mix well)

I just have a hard time with the fact of it making a 50 mile run w/o any problems, then just slowly getting worse..

 

Got sidetracked for a moment, sorry.

Did you run any corrosion inhibitor?

So far what I'm reading is that with a lot of airflow over the radiator, life is dandy. Sitting at idle, relying on the fans to do what they did last year...

Did you use distilled or tap water?