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1971 Dodge Powerwagon 383ci 'Overheating issue

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1971 Dodge Powerwagon 383ci 'Overheating issue

Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/25/14
07:03 PM

So, the powerwagon overheats. ( 120k miles on odometer ) I've done some troubleshooting with my truck;
        I figured that my water pump wasn't working ( corroded blades ), I replaced the water pump only to find that the ' old ' one was actually replaced sometime in early 2000. The thing was brand new, looked almost just as good as the one I bought from Napa. I then installed the new water pump, then turned it over. The issue with the truck, it overheats., But the truck doesn't even have to be in motion. It overheats at Idle. The new water pump didn't even put a dent in the problem. I then took the thermostat off, ( hoping to resolve the issue and keep the engine at least right under the danger zone ) but it only took a few moments more to overheat. I read up on a Mopar website of other 383's having this issue, I had tried everything they suggested, besides checking heat on the Rad and checking to see if the timing was right.
           I let her sit for a couple of hours and turned it over again, turned out that a friend of mine had screwed the timing screws out almost completely in a failed attempt at making it start better. I quickly tightened them upon start and not only did it run better, ( it quit falling on its face as bad when hitting the gas ) but it took a lot more time for it to overheat. The next thing I was going to try was to check and see if I needed a new head gasket(s) or if it had cracked the block/head(s). That would turn out to be a lot of money to spend on parts. It's been sitting all winter and I had to replace the battery and switch from a side post to a regular, water pump anti-freeze and fuel filter. I got some other goodies, but above all I'd just love to take the old girl out for at least another 10,000. I just wanted to see If there was at least on more thing I can try. Can anyone help me?  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 04/26/14
09:59 AM

a few questions..

how is it overheating..

does it instantly blow the coolant out..

or does it build up heat until it overcomes the pressure held in by the cap?

does the cap hold pressure...

i have a quick test.. actually several..

some sandwich wrap.. over the radiator filler neck.. push a depression with a finger..  stretch a rubber band around it to seal the film to the neck..

block off the overflow hose for this test..

crank or start the engine for 15 seconds.. Engine COLD..

it should NOT puff up the plastic.. if it does.. then you might have a blown head gasket.. cracked combustion chamber..

if you find this puffs up.. and you want to PROVE which one is bad..

do you have access to an air compressor???  a compression tester hose that you can hook directly to the end of your air hose..  adapter quick connects are needed sometimes.. a remote starter button will save a lot of time..

perform a cylinder leak down test with the compression tester hose with the valve core removed and stored safely.. so you can put it back when done..

each piston at the TDC of its compression stroke.. and you have to get it perfect as the motor can and will spin when you hook up the air pressure..

if you get bubbles in the radiator.. or if the film pops up or blows off. you have found your leaker..  i use this test in shops.. i leave it hooked up so i can just walk up with the customer. hook up the air and sell the job instantly..

it will not find cracked exhaust ports that some heads have.. but it sure sells jobs..


the water pump pushes coolant into the block and around the cylinders. up thru the back of the openings in the back of the head gaskets. forward thru the heads and up to the thermostat housing where it is either directed back thru the bypass and thru the water pump block and heads again..  or when the circulating temp is warm enough to open the thermostat. it will exchange the hot coolant into the radiator with the cooler coolant in there..  this cooler coolant will actually close the thermostat.. and keep the bypass circuit flowing..

the bypass circuit on most mopars also includes the heater core and heater control valve.. if you note.. some have  a crossflow connection.. that when the heater flow is turned off and blocked..  it crosses and returns back to the water pump inlet..

the bypass is really not visible in most big blocks.. if you look directly under the thermostat you may see a hole that leads back into the center of the water pump impeller cavity..  if that's blocked..  you will have cooling system issues.

if your heater hoses are blocked off..  or the heater control valve is hooked in backwards.. so heater flow is blocked. you could have issues..

how about some pictures from under the hood.. use photobucket.. paste links..  

Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/26/14
11:09 AM

Sure, I'll get some pictures in here, don't worry. It doesn't blow coolant, it just gets really hot. Honestly, It hasn't got as insanely hot as it used to since I've taken the thermostat out, and tightened the carb. screws. I will continue to search for my heat gun that has also mysteriously disappeared. When it overheats it just gets really hot, there is also a possibility that there could be air, and I will look into the waterpump housing and check if it is blocked.  

Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/26/14
06:33 PM


wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 04/27/14
08:03 AM


find your infrared temp gun...

usually without a thermostat.. the eventual overheating gets worse...

if you car going to check various things in your cooling system...

i wonder if your heater core is clogged since i cannot see any heater control valves.

you might want to install a new thermostat.. to prevent damage to your upper radiator tank..  without a thermostat.. you can have enough circulation that the upper tank can be super pressurized at highway speeds and bulge it out until the soldered seams split..  use a 180 thermostat.. not a 160..  

Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/29/14
08:00 PM

I got a 180* thermostat and the temp gauge goes all the way up. Doesn't even take any time, found the heat gun and engine was at 181 ( highest it got within 25 minutes ), I then shut it off. Found a small leak in my lower radiator hose and tightened it up ( could have also been the overflow because I put a tad bit too much in ). Before all of that the water in my rad wasn't flowing So I assumed that the engine wasn't really that hot, ( that is when I checked with my heat gun ) so I ordered a new temp-checker and I'm going to install that tomorrow after I put my starter and new fuel filter on.

              Just for sh*ts and giggles, would my 383 be worth it to spend the remaining vehicle fund of $1,300 dollars on? I'd really like to get new tires and wheels since the stock 16.5 split rim's really suck.. But I'll have to save up a little more for those. The damn thing is sweet if you ask me, but I'd like to get some more MoPar Fanatic Opinions, since I seem to be the only one in Montana.  Tongue  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 04/29/14
09:48 PM

ford and dodge 8 bolt wheels will bolt right on.. and are available in 16"

if you want to eventually run mudders..  you can still get 32.5 x12.5 x16.5 and taller..   32.5" tall   12.5 inches wide.. and 16.5 rims..

if you want to go to a tall tire.. try a 265 85 R 16..  or something like that. check tire rack for sizing..  

this is if you have 8 bolt wheels.. you did not mention which powerwagon you have..

what were you thinking about for rims and tires??? some junk yards have matched sets of rims and tires..  craigs..

lets move on .. there is a ground strap from the back of the engine to the firewall.

lets perform a quick test..

do you own a hand held volt meter????? they are cheep.. 5 to 20 bucks..

engine running.. headlights on...

volt meter set to 20 volts DC..

1. Negative battery post to the positive battery Post..  14.1 to 14.8 volts

2. Negative battery post to the engine block.. 0.04 volts DC max..

3..Negative battery post to the body.. usually the firewall. but the core support will be fine..  0.02 volts DC MAX..

4. Engine block to the firewall.. 0.02 volts DC max...

5. Positive battery post to the alternator output stud..  0.7 volts DC max.. yes.. 7/10ths of a volt. thats because mopars run their alternator output thru the firewall to the amp meter. then back thru the firewall to the starter relay a fusible link and then to the battery positive..

please post your test results..

this is a digital volt meter.. these are only 20 bucks at HF stores..


why such small voltage on tests 2 thru 5.. if you get more than the specified voltage.. you have a bad connection between those parts..  this is an easy test to find out if the wiring is hooked up properly..

why do i want you to  perform this test.. the ground circuit from the engine to the body and the battery is half the sending unit circuit..

the temp sender is just ONE wire..  from the intake to the gauge.. the other side of the gauge has around 5 volts that's pulsed on it..

can you with the engine cold.. OHM the sending unit??? touching the terminal and the shell .. post that info with the engine cold.. and also at operating temp.. 181F..

did you see this other post from last week??


Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/29/14
10:37 PM

I hope it isn't too much of a burden to not only ask for help with the overheating issue, but to ask for opinions!  

Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/29/14
10:37 PM

Thank you! I will try the OHM test and see what I could be missing, but I live 20 miles from the closest Napa auto-parts store, So I don't see that happening in the late future ( sort of stuck at home ATM ) Also I really Appreciate all the help man!

Also., the Truck is a W200, four wheel drive with locking hubs ( one year before full-time four ). Dana 60 axles ( I assume     ? ) 8 lugs, I am sure I could fit some 33's under there, but I would like to at least raise it an inch or two before I do that. Can't find any wheels or tires close to where I live, my girlfriends father has A LOT of tires and Not one of them will fit my 16.5 split's. Currently I have 17 inch ford 3/4 ton wheels on one side with tires that are an inch shorter than my stockies, its quite sad. The truck leans to one side, and yes I've thought about putting the smaller on front, but I had hoped I'd find some tires or wheels by now. There is a possibility that I could snag the wheels and tires off of their Ford Ranger that is a 1970's truck, but that's a long shot.

The reason I ask about my engines worth is because its a ' Discontinued ' engine if you will, it is no longer in production ( unless you order one to be milled out of course ). I know of its rarity, and how exceptional it is to have the original, well.. Everything. Even the 435 four-speed is intact, same transfer-case and everything. Since everything was just so original, I decided to keep my other two split rims. Unfortunately no one really sells anything to fit a 16.5, ( and honestly they suck, i'd only use it to show the truck off. ). Just a lot of big plans for the first vehicle I've ever owned is all.  Grin  

Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/29/14
10:37 PM

any mods that'd you'd suggest after I repair the overheating issue?  

wayne712222 wayne712222
User | Posts: 121 | Joined: 10/13
Posted: 04/29/14
11:42 PM

almost any 80s thru current ford van..  most ford pickups..  once in a while you run across one with 7 lugs.. be careful what you buy..  dodge trucks and vans also..



20 miles from a napa store is not a good description.. i was going to look in crags for you.. see if i could spot something..

and don't scrap those odd 17 inch wheels.. Ebay them..

many years ago.. my brother in law called..  he had broken down near sea tac airport in the seattle area..  i figured out what was wrong.. gave him the part numbers told him to go find a napa store.. they will have the parts..

since i kinda knew where there were.. i called the 3 napa stores and had them put the parts on the counter and described my in law and his helper. i did not hear from him for months..  when i did.. i ask what happened with the break down.. he said. that was really spooky.. he and robert walked into a napa store they had never been in before..  they were greeted by name as soon as they got in the store..  the parts were sitting on the counter they needed and the invoice was printed in their name..  exactly what they needed but how did they know..

i should have never told him. that i had called the 3 possible stores and anywhere he went he would have gotten the same treatment.

sometimes practical jokes just work out without much of my help..

there was a LONG line at a local AZ store.. the korean guy standing in front of me had one spark plug.. and six exhaust studs.  the spark plug was an AC. CR43TS.. when i saw it.. i mentioned to him that the exhaust studs for his 4.3 astro van are hanging on the wall down that isle..  and that make sure they give him the proper spark plugs.  he looked into his palm.. and said.. how did you know what kind of van i had.. all i have is one spark plug.. i told him that i am a mechanic.. i have to know what cars fit what.. .. but its JUST ONE SPARK plug.. i said.. yes.. i know..  he was just amazed..  i never told him that the CR43TS spark plugs were almost always used in astro vans..

i love to  mess with people.. ..  please don't call the ads listed.. i just wanted to give you an idea of what to look for..  

Robby Walsh Robby Walsh
New User | Posts: 10 | Joined: 04/14
Posted: 04/30/14
08:16 PM

Try Kalispell