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Sister-in-law drove the S60 without the coolant expansion cap for a month

ErikS

FWD!
Joined
Nov 28, 2007
Location
Lakeway, TX
Said the low coolant light was on, so I popped the hood, and there was the cap sitting next to the expansion tank. She had been driving without it on for a month :wtf: as she had an oil change and I guess the jiffy lube/whatever topped it off for her but forgot to put it on.

To my surprise there is no sign of coolant anywhere, and it had just gone down to right below the minimum line which I think was due to evaporation.

Without the system pressurized running for so long, what kind of damage did you think she did? I let it warm up and sounds fine, although I hear a whine that might be related to the water pump.

While it has been cold in Houston, we've also had quite a few days in the 70's and 80's. I don't get why she hasn't overheated and fried the engine, and it took a month for the low coolant light to come on.
 
The pressurized cap isn't essential to the system in cooler weather.

It only helps keep the engine cooler when everything gets nice and toasty, and the coolant temp gets over what would normally be its boiling point.

We had a failed cap on our 4Runner for who knows how long - wasn't holding any pressure at all. The only time it ever showed any symptoms was out in Colorado, working hard up a high mountain pass - where the combination of working hard plus the lowered boiling point (due to altitude) finally got it to boil. And even then, no damage done, just topped it off again, drove to a parts store and bought a new cap.
 
How much did you have to add?

Maybe a cup. It was barely at the minimum level. I guess with the modern engines its not such a big deal since its not directly on the radiator.

Had it been summer it would have probably boiled over and overheated.

The pressurized cap isn't essential to the system in cooler weather.

It only helps keep the engine cooler when everything gets nice and toasty, and the coolant temp gets over what would normally be its boiling point.

We had a failed cap on our 4Runner for who knows how long - wasn't holding any pressure at all. The only time it ever showed any symptoms was out in Colorado, working hard up a high mountain pass - where the combination of working hard plus the lowered boiling point (due to altitude) finally got it to boil. And even then, no damage done, just topped it off again, drove to a parts store and bought a new cap.

Thanks John.
 
Did the same exact thing to the old family 850 and never hurt it. Light would sometimes flash on upon start up and that was it. Boy did I feel dumb though.
 
I've run cars long-term with a loose cap as a countermeasure to a small leak. My Alfa has a cracked coolant tank, I've been running the cap loose for two years without issue.
 
You're fine man. As long as coolant stayed in the system, only thing that may have happened is the e-fan may have run a little more than usual. Coolant was still circulating, keeping the hot things cool, the cool things hot, and the moving things lubricated.

Install cap, ream the jiffy lube flunkee, buy a lotto ticket and have a beer.
 
I'd hit up that crappy lube joint that "serviced" the car without replacing the cap. So many of those places have been busted on investigations from not putting oil in the engine to charging for services they don't perform. If the vehicle is damaged, you could be able to get some compensation if the car requires major repairs as a result of their junk work.
 
I'd hit up that crappy lube joint that "serviced" the car without replacing the cap. So many of those places have been busted on investigations from not putting oil in the engine to charging for services they don't perform. If the vehicle is damaged, you could be able to get some compensation if the car requires major repairs as a result of their junk work.

May even have a case had the oil been changed, filter got left loose, oil cap left off and the car sent out sans oil for a dead engine three miles later.

Alas... The cooling system cap was left off in this case. It didn't get hurt. Sorry... No big winners in the Lawyer Lottery.
 
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