Running with loose Radiator cap

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Howdy and good afternoon fellow Bitogers:

Home for lunch right now which consists of leftover fried chicken, mustard greens, black-eyed peas and for desert, boiled eggs pickled in beet juice.

Meanwhile, the on-going saga of the "Bluesmobile" cooling system continues. (The happy but tired "Bluesmobile" is a 1993 Ford Taurus GL, 3.0 V-6).

Radiator on said "Bluesmobile" started leaking the beginning of this week. Check the upper hose, (which I replaced last November) and sure enough, the clamp next to the rad was loose. Tightened it only to discover there is a small crack on the composite side of the rad below the hose. It only leaks when pressure builds, so in my travels today, I loosen the cap and ran with it loose. Temp guage ran below normal, (about 1/3 on gauge).

My thinking is this, the car is 20 years old, (soon to be 21 and a legal drinker - perhaps that's the reason it's started leaking). The transmission is living on borrowed time. The interior is almost a carbon copy of the vehicle Mad Max drives in "The Road Warrior" and the exterior is painted flat black with a flat white roof. While the back tires are somewhat new, the front tires are cracked and worn. Long story short, this car ain't worth much and I really can't see the wisdom of dumping more money into the ole gal.

Therefore, rather than install a new radiator, what is the problem of simply running full time with the rad cap loose? It doesn't overheat and the coolant is low enough it doesn't splash out.

My old 1950 Case tractor is not a sealed cooling system and it has run that way for decades, (coming from the factory that way). What would be the problem with running the long suffering "Bluesmobile" in the same manner?

Thoughts, opinions, menus for dinner tonight?
 
I have run many a clunker with zero pressure. As long as you never get too hot you lose nothing except the seal.

Can't see a problem here...
 
Towards the end, I had to run my 2001 Taurus with no cap. The steel lines were turning into swiss cheese. Without the expansion tank cap, I would only go through about 1/2 gallon of coolant a week.
 
Originally Posted By: SteveSRT8
I have run many a clunker with zero pressure. As long as you never get too hot you lose nothing except the seal.

Can't see a problem here...


+1... Or too long. Id imagine that thermal expansion makes some "puke out", which results in lower and lower levels... and under high temp operation, there will be a continuous loss.

Just drive with a gallon of coolant, and avoid medium-speed, high power ops where cooling is less optimal and waste heat generation is high.
 
Dude's in florida, so water is a good carry-along. Maybe some of that used antifreeze from the junkyard to keep it around 25%.
 
I've had a couple of vehicles that simply wouldn't run without a pressure cap. The T-stat temp was so high that without pressure in the system, the coolant WOULD boil in the cylinder heads, so there would be a geyser out of the cap as soon as the engine reached operating temp. The 93 Chrysler 3.5 was that way, and I suspect the Jeeps would do that also if I ever tried one of them (210F thermostats).

On the other hand, my old cars (160F to 190F T-stats) would run just fine with the cap off under normal conditions. There would just be gradual loss due to evaporation.
 
I would try draining the radiator, pull the hose off, and applying RTV or some type of patching agent where it leaks. Then after a few hours ,put it back the way it's "supposed" to be, and give it a test run. Maybe you can you find a lower pressure cap that fits? That should buy you some time until it rolls over and dies.,,,
 
No problem running with no pressure as long as it stays under the boiling point. You may want to put the electric fan on a switch as its not designed to come on untill 225f or so.

Old cars did not have a pressurized system just like your antique tractor. But they had a solid mechanical fan and a 160 thetmostat.
 
Originally Posted By: Chris142
No problem running with no pressure as long as it stays under the boiling point. You may want to put the electric fan on a switch as its not designed to come on untill 225f or so.

Old cars did not have a pressurized system just like your antique tractor. But they had a solid mechanical fan and a 160 thetmostat.


Depends on how old you mean by old. :)

My '49 Plymouth was pressurized... but the 4 psi cap it requires was a special order item even back in 1980. So I used a 14 psi cap with the check valve removed- splash/proof but unpressurized. That engine didn't care less.
 
A new radiator, thermostat and cap can be had at AA for $71 plus tax with codes.

How long do you want or need the car to last?

Do you want to pop the hood every time you get in, or feel anxious if you get caught in a traffic jam?
 
Lots of good advice here. If the car is on it's last leg and you just want to squeeze the last few dollars of value out of it, then you're doing the right thing. It's what I would do.

Depending upon how far south you are, weak coolant and water are OK, but just straight water is not a good idea.

I'd look into a junkyard radiator, although I do recall that being a problem area on Taurases of that era, so finding a good one may be tough, but maybe not. For that matter, Rock Auto shows 4 or 5 new radiators in the $70 dollar range.
 
Thanks for all the wisdom and insight guys - will run the ever popular "Bluesmobile" "topless" and see how it goes.

It's not only the money, but the time spent in repairing it as well. I did check a couple of "U-pull-it" places in these parts and used rads are going for between 35-45 bucks each - about half what a new one would cost. But then there's the gamble of simply buying one that is already cracked or about to crack.

The car is driven locally, 15 miles away from homebase max. The real kick in the pants is it needs new brake pads on the front in a bad way and there's no way around that. I'm pretty sure Saturday will be brake pad day.

As far as how long it will last depends on the tranny which is still running on the unholy mixture of tranny fluid, Lucas trans repair, Sea Foam Trans Tune and two bottles of Lubegard Red, (all added March of this year). I hate to give up on this car as the motor doesn't burn a drop of oil nor does it leak a drop of oil. There's that and the car has a ton of memories, (funny how you can get attached to a thing - but it's like part of the family). But the reality is there has to be a point in time where I stop putting money into the ole gal and start looking for a new ride. It will be a sad day.

As far as breaking wind is concerned, the heat has never bothered me but I hate cold winters, so I'm trying to do my part for Global warming.
 
You know, I had a pinhole in the rad tank on our old 93 LH car near the end of its life. I used a file to turn the pinhole into a conical pit (don't file DEEPER, just widen the top). Clean thoroughly. Fill with a good two-part epoxy and let cure.

That lasted until we sold the car about 2 years later, WITH full radiator pressure. Its not that hard to get a really good bond to the plastic tank, you just have to get it CLEAN and expose a bit more surface area around the leak.

I'd do that rather than run without pressure. Without pressure on a modern vehicle, you really risk forming steam pockets inside the engine and getting some pretty severe overheating in localized areas. It'll never show on the gauge, either.
 
It 's a 20 yr old Ford sedan, there is prolly a bounty on them. I ignored the signs and resurrected a 94 Ranger. Parts are very cheap, and available from the AZ down town. I never dreeeeeamed it would need so many of them. Marina asked me why I didn't just go buy a whole truck at once. Instead of having FedEx and UPS delivering it piece by piece.
laugh.gif


It was a good way to way to get recreation during the winter of 12.Fixing the thing.That is putting an "up spin" on a dumb impulse move. It was not a smart 4WD vehicle consideration. Therapy for my discombobulated right side.
And mind sharpening puzzles to keep me from getting senile. But all that time and money, and I have a 1K$ truck with problems. Be careful of what you wish for ...

If the Taurus performs well enough to still have some utility in it, use it up, then get rid of it as cheaply as possible. Old Fords are beyond practical repair, once they get to a certain point. If you can keep ahead of the leak , drive it until you can't. Then Junk it.
 
Last edited:
Originally Posted By: andyd
It 's a 20 yr old Ford sedan, there is prolly a bounty on them. I ignored the signs and resurrected a 94 Ranger. Parts are very cheap, and available from the AZ down town. I never dreeeeeamed it would need so many of them. Marina asked me why I didn't just go buy a whole truck at once. Instead of having FedEx and UPS delivering it piece by piece.
laugh.gif


It was a good way to way to get recreation during the winter of 12.Fixing the thing.That is putting an "up spin" on a dumb impulse move. It was not a smart 4WD vehicle consideration. Therapy for my discombobulated right side.
And mind sharpening puzzles to keep me from getting senile. But all that time and money, and I have a 1K$ truck with problems. Be careful of what you wish for ...

If the Taurus performs well enough to still have some utility in it, use it up, then get rid of it as cheaply as possible. Old Fords are beyond practical repair, once they get to a certain point. If you can keep ahead of the leak , drive it until you can't. Then Junk it.


I've thought of doing this very thing - looking for an early 90's Ranger with a V-6 and doing a motor swap since I would have a ready source of parts. I actually found one about a year ago with a stick shift - cute little purple truck. Saw it on Craigslist Friday night, went there Saturday morning and it was gone - oh well. From what I can gather from your post, that might have actually been a good thing.
 
I run my '98 Grand Marquis with the cap loose and have since 2010, added maybe a quart of coolant in that time... With a 50/50 mixture, it idles in traffic on a 95* day, A/C on without any issue at all...

BTW there isn't anything wrong with that car(yet to turn 60K mi), I just don't trust those cheap [censored], POS plastic intakes that were all the rage back then... Figure if it cracks they'll be a slow drip vs a gusher if it has pressure...
 
The pressure from the cap raises the boiling point of the coolant. Once the coolant begines boiling it doesn't transfer heat as well as pressurized coolant. I've seen cases where nucleant boiling destroyed water jacket surfaces in aluminum passages to the point that cavitation cause it to break through to the outside. Of course it'll take a while for that to happen. One of the auto companies paid me good money to study a few of these warranty claims.
 
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