Okay so i had a high idle problem along with a exhaust manifold leak.
98 Dodge Dakota 2.5 five speed
[Parts Replaced already...]
Water pump
Thermostat
IAC
Manifold Pressure sensor
Throttle postion sensor
Radiator
Radiator Cap... otc cheap one.
Manifold gasket...Intake and exhaust same on truck
All radiator hoses including heater core hoses

[Things checked or added]
Radiator Stop Leak
Checked for Vacuum leaks
Checked for leaks around Gaskets
No oil in coolant or vice versa no leaks around head

Okay so here we go. Before Replacing my manifold gasket truck high idle and high coolant pressure. Replaced the manifold and MAP sensor. TRUCK RAN BEAUTIFULLY NO PROBLEMS like a brand new truck really.

Then a week later the high idle came back as bad as before 2300 idle, BUT it DOES NOT get hot the pressure just rockets out of control. Then it overheats... I let the coolant pressure off... idles beatifully again. Go down the road high idles again.

No other problems with the truck... it never really overheats just pressure really high i shut the truck off after i get to work and 5 mins later the temp goes high. Not leaking on the ground or anything

My thoughts are that the Radiator cap is blocking the seep hole from the resivour. OR that the stop leak had messed my water pump.

PLEASE I NEED SUGGESTIONS OR TO KNOW IF ANYONE AGREES WITH MY THINKING!!!

 

My first thought would be somethings clogged and letting just enough through to keep the engine cool but causing high pressure. If I had to guess I'd say the stop leaks the culprit. That stuff is notorious for plugging things up.

 

Stop leak is the worst thing you can put in the cooling system. Its only meant for on road emergency so you can get home and fix the problem. The longer the stop leak is in there the harder it will be to get out. It clogs all sorts of things like heater core,water pump parts in the rad. You need to get it flushed asap! You might have to flush it a hand full of times.

 

Flush it for sure. When the coolant gets hot its the radiator caps job to open up and let the system pressure down, hence the overflow bottle. You probably have something clogged or you over the counter cap is junk. Where is it flowing out of btw?