DartSwinger

Hey, I've been having some troubles with my cooling system. This doesn't happen frequently, but it is still concerning. My 318 starts building pressure in the upper radiator hose. Making the hose swollen and rock solid. I don't know what is wrong..... I just replaced the head gaskets a couple of months ago. I'm not losing coolant. Just ran compression test last week, checked out normal. The oil is clean and it doesn't smoke.
I'm out of ideas. When it does this I have to manually release the pressure by lifting up on the radiator cap. And then a surge of air bubbles gets forced into the overflow. At first I thought it was air trapped in the system, but by now the air should have surfaced, right?
Thanks any ideas would be great.
Oh and I have been running it without a thermostat. could that be the problem or part of it.

78D200

You should be running a thermostat for daily driving/cruising, even if you make some trips down the track. The only time I wouldn't run a thermostat is in a dedicated race vehicle.

It sounds like you may need a new radiator cap or the one that you have on there is the wrong one.

Archer

Dart -

Temporary stiffening of the upper hose shouldn't be a problem, but as Tim said, the radiator cap may be a problem, Make sure you have the right pressure cap.

The bubbling may be more worrisome, but also may just mean there's air trapped in the system.

The stat thing is debatable and a lot of times depends on the car as well as the application. I run a 160 deg stat on mine (worked 440 + an over-sized aluminum radiator), but have had no problems temporarily running without the stat, even for street driving. Yes, I was a little surprised it ran as well as it did.

Archer

78D200

The "bubbling" could also be the coolant boiling due to the rise in pressure.

Minnesota Guy

How old is the radiator? 318's should run cool all day long...All small blocks for that matter...Go and get a new 16lb cap at NAPA..about 6.00...If you have used any stop leaks, or any of that stuff--It will plug radiator. Maybe pull radiator if old and go have it boiled out, or get a new one from Auto Zone...

DartSwinger

Thanks all for replying. I've got a 180 thermostat on order and I'm going to flush the system. pickup another cap and see what happens. As for the radiator, it was new ten years ago. But hasn't been used much till about two years ago, spending most of it's time drained in the trunk (started working on it but left for college and just got back to it).

Archer

Dart -

It's probably rusted out. Have a radiator shop look at it, but don't be surprised if you need a new one.

Archer

DartSwinger

Damn, never again will i start a rebuild and not finish it in a timely matter. Thanks again all.

1966sportfury

radiators dont rust.

DartSwinger

Yeah it doesn't seem to be rusting. The coolant is somewhat clean, but this weekend i'm going to flush it out. I just noticed recently that it only builds up pressure when i don't allow it the proper amount of time to warm up. I thought it was at random, but that's not the case. Been testing it for the last couple of days. Could not allowing it enough time to warm up be the culprit?

badsport

You might check and make sure you're bottom hose isn't collapsing. If you haven't filled the system yet remove the bottom hose and if there is no coil in there to help it from flattening out, you can make one with a coat hanger, just make a coil stretch it out and insert it in the hose.

Minnesota Guy

What temp is your coolant? Put in a gauge.Make sure if the radiator was out that mice didnt get in there...they wrecked a brand new radiator I had that I didnt button up the holes...make sure radiator isnt corroded on inside..they dont rust but they corrode..Otherwise you will have doing a little bulging--especially with a good new cap--how many cores is radiator-and when you say "new 10 years ago" where did it come from?

DartSwinger

It hovers around 190 - 195 doesn't really exceed that. Sometimes it'll raise to almost 200 driving on the freeway stomping on it, but it drops quickly. One of the first things that I did when i got it was have the radiator recored. so that is what i meant by new 10 years ago. I believe that I had it rebuilt stock, but this car is original, matching numbers so I haven't really done any mods to it. I installed a H pipe, flows, and electronic ignition but that is it. Never overheats (except when it gets backed up, of course), but other than the swollen hose everything is peachy.
Going to get cracking on it tomorrow, so I'll let you all know.

scotts74birds

Are you running with a fan shroud?

Minnesota Guy

Make sure you have shroud and radiator is unplugged....318's should run cool...Make sure the fan if viscous--is not shot....However 190-195 is not hot. Factory thermostat is 192

DartSwinger

I don't think that the car came with a shroud. Unless my grandfather took it off. I checked yearone and they have shrouds for a bodies with AC, but my dart doesn't have
AC.

Minnesota Guy

The thing is with a Dart, unless you are a numbers matching guy in general, 318 Darts with matching numbers or not do not really dont make much difference on the market. Numbers are important to the HP factory stuff. Is your radiator 2 core or 3? factory on these were often puny and you said you have matching radiator...Make sure you water pump is pumping the water (I have seen these go back and not push water) I would look at adding more cores to radiator or going bigger...If you have a factory 2bbl radiator--now have a 4bbl with more compression, headers, etc, it will run warmer and need more. Check you plugs and make sure they are grey and not white...If white--you are running lean--Check your timing as well --Leanness and overadvanced can make them run warmer as well...Chances are with radiator sitting w/o coolant in it for many years, I would go there first. Over and out.

blue 68 gts

195 is nothing to be worried about.

It shouldn't have a shroud. Make sure to run 50/50 and check to make sure that you've ran the system correctly.