he was referring to the water. the PDC, the air box, the transmission, the distributor cap etc... aren't water proof in the rams and submerging them in water isn't good.

 

**** guys, lets stay on topic here. The pcm is the least of my worries....

the truck runs fine,

drives until it hits operating temp then suddenly the heater stops working, truck goes to overheat. I turn it off and go to the radiator, take the cap off and it lets a whole ****load of air out....the reservoir outside is full so i fill all of that into the radiator. Put the cap back on and keep driving and it works great. after a little while its the identical thing again...it pushes all of the water into the reservoir and then overheats. put the water back and its fine....what the hell could it be.

 

sounds like one helluva an airlock

 

i've got the same problem... intrested to know whats going on. i have looked mine over. i see signs of dried up coolent from the fill area. i think the cap may be bad.

also my heater is'nt blowing hot heat.. at best "warm". i'm going to try a new cap, flush it and see what happens.

 

i replaced the cap and that wasn't my problem...replaced the waterpump....i just don't know anymore...i'm going to test compression tomorrow morning and see what i get...wish me luck haha

 

okay i have around 120 psi in each piston so they're fine....i got a cooling system tester and pumped it to 16 psi....it went down after a bit so it has a hole somewhere...i just don't know where. I don't know what to do next....it'll go to the shop on monday

 

neattouch, i have the same exact problem with my dakota. it would be great if you posted the results. i compression tested last night and all seems to be fine. i have random overheating and random missfire in cylinder number two. i thnking that may the truck wasnt hot enough to open what ever crack or leak there is..

 

My truck runs hot because the timing is approx 9.7º advanced, which is an issue with the PCM. Other than that, the truck runs and idles like a Swiss watch. So yes, the PCM could be an issue with his truck.

 

ok actually trucks are designed for work.... things like jeeps and quads are actually designed for offroading from the factory for certian abuse related to offroading that many pickups dont come with stock....try buying a truck with a warranty then driving it through a deep creek and shorting things out and taking it to the dealership and see what they say about your theory and if they replace everything under warranty....there's a smart wat to go offroad and prepare and mod the vehicle for such things as submerging the engine in water and a not so smart way.... you said your pcm is screwed up and I say with abuse like in your sig picture without preping the system to waterproof it somehow that its no suprize...show any good mechanic that pic and they would say the same thing. I'm not trying to start anything with you but its the truth...

I offroad however I also understand my truck wasnt designed to run through creeks and rivers.. if it was the pcm would be waterproofed as well as electrical connections and it would likely have a snorkle to keep the water out of the engine (yes they are not just for looks).... driving through deep water without it or at high speeds is a good way to hydrolock the motor and trash it...do a search and you see a thread where one person did it just driving through a deep puddle in the road from a backed up storm drain...its not likely in that case but possible.

I had a jeep wrangler and did my fair share of offroading it it...I also messed a lot of things up with mud and water like my alarm system my fuel gauge and I even dropped my engine right out onto the sand dunes at the beach.... all of this was my fault due to me "thinking they were designed for it"

 

^ word, i can understand where you're coming from. But on average water will dry out and every thing will go back to normal as long as you dont get the water into the intake. which our stock airboxes do a fairly good job of keeping that from happening.