Sorry to have to put this out here as I'm sure it's been answered before - I just haven't found it in the archives.

I have a '02 RAM 1500 4.7 quad cab. The radiator started blowing a mist last week so I replaced the radiator. The passenger side of the rad never heated up after I filled and waiting for the thermostat to open. After driving it a couple 30 minute trips, the upper hose swelled to about twice it's normal size. Still no heat on the pass side of the rad. The heater works well - blowing normally. The small bypass hose from the upper driver side of the rad is returning a healthy stream to the coolant resivour.

I figured I had a t-stat stuck in closed position. So yesterday I replaced the t-stat (195 deg), lower and upper hoses and refilled. Oh, I replaced the radiator cap also. Don't know why that wouldn't let off pressure before the radiator blew or hose swelled? Refilled the radiator according to Haynes manual - rad cap off, fill coolant resivour with engine running and wait for t-stat to open. T-stat still won't open. Driver side of Radiator gets to about 155 degrees at top by upper hose, bottom drv side of rad is not as hot, maybe only 80 deg. Passenger side of rad is cool to touch. It's like the heated coolant is not passing through the radiator.

So does this sound like an air lock? If so, is there a simple way to burp, solve?

Otherwise, is there something else I'm missing?

Thanks in advance for any help!

 

That is crazy! never heard of such a thing. Take cap off radiator and let the engine run for a while with cap off...probaby 30 minutes or so. See if it doesn't burp itself some more

 

My mom years ago had a mini van that blew a head gasket. It would run and drive fine for a few days but eventually it would slow build pressure in the cooling system to the point it would run hot.

With that being said, welcome to the site!! However, take a look around and you will see a lot of guys here who have over heating issues, most of them have 4.7s. With that being said, most find it to be bad head gaskets or cracked heads.

 

Bleeding the system of air should only require using the bleed screw just aft of the upper hose. It sounds like an obstruction at the pump inlet, unlikely in my opinion. I think the guys are closer to an answer than I am on this, possibly head gasket.

Get a shop to 'sniff' the coolant for presence of exhaust gasses. That is how I diagnosed a seeping head gasket on one of my 2nd gen SHO's years back.

Then again, without the vehicle in front of us it realylly is hard to diagnose properly. My approach would involve pressure testing (cooling & cylinder), back flushing, sniffing.

 

Thanks for the info and suggestions guys!

I removed the bleed screw and squeezed the upper hose and fluid was fluid there.

Does a head gasket leak mean I'm getting exhaust into the cooling system, which in turn is building pressure stopping the t-stat from opening?

There is coolant circulating in the pressurized reservoir from the small 3/8" hose coming from the top of the drivers side radiator tank, with discharge hose from reservoir goes to heater core. So that circulates through the eng. I have good (regular) heat coming in the cab from the heater and the temp gage is in the normal position - about two needles thicknesses left of top center.

I stopped by the dodge dealer and one of the guys was looking at it and suspects head gasket, but is puzzled by the cool-to-touch radiator. He suggested a block pressure test, coolant pressure test and coolant flush and refill - because I used prestone anti-freeze (green). He said even if they say the green is safe, it is not. Says it will eat the fins in the water pump.

I bought this truck with 27k on it and it has always used about a 1/4" of coolant between every oil change (3k). Maybe only in the summer and not as much in the winter. Could it be there has been a head gasket leak for 8 years?

Any other ideas would be welcome. I'm thinking I'll try the flush and refill, hopefully getting coolant circulation through the radiator. but that could be a waste if exhaust pressure is keeping the t-stat closed. ??

Still stumped!

 

Normally a blown head gaskets means coolant getting in the oil or in the combustion chambers. But sometimes it allows air to be "pumped" into the coolant system and causes it to over pressurize.

 

i try the water pump they are know for having the fins coming unattached and free spinning on the shaft (they normally make a high pitch noise) have also seen where the anti-freeze eats the actual fins the heat from the steam allows the hears to work normal but the blow off in the overflow causes lose of fluid. (normally a ford thing but have seen it in many Mitsubishi's as well. {Mopar parts are mostly Mitsubishi.... sadly}) and as for the flush and fill i would strongly requimend it because it will get the old fluid out and put fresh in. (also lowers also acid levels)

 

I want to give an update as all of you have been very helpful and perhaps someone with a similar problem may benefit.

I decided this truck has been too good to me for me to stick my head in the sand and not have a block test done. So I had the dealership do a block test and a coolant system pressure test. They said all is okay, no head gasket blown or warped or cracked head. But they still couldn't answer why the radiator was only hot in the upper driver’s side - other than an air lock. They wanted to put in another t-stat, radiator cap because they weren't OEM and also replace the coolant reservoir (for $650). I can get those parts for about $60, so I declined their offer. I wanted to go and try disconnecting the lower and upper rad hoses from the engine and see if I would be able to get fluid to flow through the rad. - still figuring an airlock.

I've been babying the accelerator all this time as I was afraid I'd be stuck on the side of the road. On the way to the dealer, I tried a full acceleration (0-60 on the floor) and the temp gage dropped considerable and then climbed back up to the normal range. I'm not sure what that was but after about 3 more repeats and the whole rad warms each start and seems to be flowing. Some coolant added to the reservoir, but not much.

Today there was a faint high pitched sound - so perhaps it is the water pump beginning to fail. There is no fluid coming from the pump's weep hole. And I'm not sure if it is a water pump going - how would that cause the upper hose to expand, unless from overheating.

So I'm thinking I'm going to continue to monitor the temp gage (never gone over normal) and coolant jug and watch for signs of a water pump going down.

Again, thanks all for the help and if I'm missing something, appreciate any ideas.

 

Sounds like you cleared a blockage/air pocket.

 

Thanks - appreciate the guidance! I'll update if anything further develops.