I have a 95 inline 6 automatic,
Idk how many miles exactly, it has a "junkyard" odometer from the last guy, reads 399,000.
Anyways, I have a few problems, one being the cooling system is over pressurized, leaking from under the new rad cap, after getting warm.
The idle is high, think it's one tooth out, think that made my new pipes manifolds glow red.hot!

So it has new Or reman
ALL NEW OR REMAN LISTED BELOW.
Motor mounts, starter, battery, egr delete, radiator, radiator cap,water pump, themostat(180°) oem calls (192°), upper rad hose, cylinder head (reman from millers), cylinder head bolts(fel-pro),Chase, tap, clean, air blast, all head bolt threads) severe duty head gasket, oil pump, p/u screen, tensior pully, exhaust manifolds, y pipe (cat is off for now), lifters, pushrods,oil pan gasket,e3 spark plugs, new spark plug wires, freeze plugs, expansion plug, pcv, oil, coolent 50/50,oil filter, idle valve air control (ivac) , throttle body sensor (tps), serpentine belt,fuel stabilizer,fan clutch, lifter cover plate, lifter cover plate grommets, new vacc lines, gas caps (2), and all other gaskets that come.with the head gasket set. Basically ALL OF THEM.

SO after a good rebuild, why so much pressure in the upper radiator hose, im about to boil my new themostat I just removed (yes it was facing the right direction)
Its a 180°, about to buy a 160° but think that will not help, and all the sensors to be changed soon too. Jumpy and high idle, HELP. LEAKED FROM BOTTOM OF THE NEW RAD CAP, REPLACED WITH A NEW ONE, SOON TO TEST THAT OUT PRESSURE RELEASE VALVE IF NEEDED

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You need to put a real Motorcraft t-stat in. That's my first approach.
I would also check it by boiling it. I do that to every t-stat I install.
Also, remove those E3 plugs and put just plain Autolite Copper plugs in or Motorcraft copper plugs.

 

Secondly run a stock temp, what is it with people always putting in cooler ****?

Your truck will not run correctly with a coller temp, now its going to throw more fuel into the mix to warm itself up.

Start with the basics, change the sensors if u havent, change the thermostat to STOCK temp. and do a cooling system pressure test.

Just because you rebuild the engine, doesnt mean something was overlooked or didnt seat all the way.

Also I second removing those plugs, you wasted money, it doesnt seem like its a performance truck, Just use the OEM copper cores, not autolite tho. thats just sad.

 

Yes, this. Thermostats help with heating up the engine to proper temperature, not cooling. If your engine doesn't run at the correct temperature, it's hard on the engine, and your mileage. Some cases even makes it run like crap.