Andy's Automotive Urinal

Doesn't anybody screen these calls? Apparently not.

This week on Car Talk, Tom and Ray heard from Andy, whose car overheated while driving through Moab. (You can here his call right here. Out of water and out of ideas, his girlfriend suggested using some fluid he had on hand, in a manner of speaking. That's right -- he took aim, and peed in his radiator.

His question for our hosts-turned-automotive urologists: did his piddling into the cooling system cause any lasting damage?

Tom and Ray thought not. But, what do you think? Would a healthy dose of urine cause any untoward automotive symptoms? Share your thoughts right here -- and thanks.

Fresh urine has nearly neutral ph and goes alkaline as it ages, so it shouldn’t cause metal corrosion.

I was shocked, SHOCKED to hear one of you gentlemen opine that antifreeze isn’t necessary in the UT desert, but is a definite requirement in MA. The colligative properties of matter swing both ways, sirs! 50:50 propylene glycol:water gives you another 54 degrees F on both ends of water’s liquid phase. Not only do you avoid a cracked frozen engine block in MA winters (and probably UT desert winters, now that I think of it), you avoid the warped cylinder head from engine overheating in the UT desert (and MA summers, now that I think of it). And the Andys of the world don’t die of dehydration trying to keep the cooling system hydrated. And btw, urine has 1/3 to 1/2 tsp of salt per liter, and a male bladder full to gasket-bursting capacity can hold 0.8 liter, even a full liter. Piddling in your radiator is a most excellent stopgap measure, but I doubt the salt is great for the cooling system.

Quantity wise, I don’t think that’d be enough to help the overheating issue at all.
Interesting in theory buy in practical application an overheated radiator would need a gallon at least.

Dare I bring this up. This brings us close to the question of distilled water vs. tap. The urine is removing unwanted minerals from our bodies. Its composition will depend on what we’ve eaten, drank, and/or smoked. To me, this would exceed the worse case tap water.

I think the biggest concern here is that those unwanted minerals may deposit themselves in the cooling system. I think in this case, a complete drain, block and radiator, and refill with a distilled water and antifreeze mix would be in order.

Andy should probably look at the maintenance history on the vehicle, it might be about due, or maybe even overdue for this service anyway. While he’s at it, it might be a good idea to look at the condition of his hoses, thermostat and radiator cap.

Urine is corrosiontive, I work for aircraft maintenance repair operations (MRO) which I see lots of corrosion in lav. areas. This is most repair aeras we see. So radiators are now made with aluminum which urine will corroded.

"I was shocked, SHOCKED to hear one of you gentlemen opine that antifreeze isn’t necessary in the UT desert, but is a definite requirement in MA. "

It is not antifreeze. It is automotive coolant. It’s first job is to move heat. Water alone can’t do it.

In a modern car you might be able to get by with antifreeze in the summer, if the temperatures are low enough, but I would recommend the coolant recommended by the maker of your car. (not the dealer)

Back in 1970 on trip home from Georgia to Ohio the car overheated and needed water. We determined that it had a bad head gasket before our trip but decided not to prepare better only stop frequently for water. Stops in many areas were too far apart and decided to urinate in the radiator so that we could make it to the next stop. My brother and I did make it home after many stops. My father a mechanic helped us rebuild the engine when we arrived home. We told him about the urine. He said though not the best coolent for the engine it did get us home. He did laugh at our discription of laying over the engine on the side of the freeway in maybe a less than modest roadside waterstop. Years later I read about someone else doing the same in the book Riding Rockets written by an astronaut on a road trip with his father in his when he was younger. No you are not the only one to do this. A laugh for many years to come.
Thanks for being brave enough to admit to this on public radio.

I would think the only real problem would if it overheated again and depending how much got put in, the odor is going to make people question you. On the other hand, if you had an engine with an alumamin head and alumamin water pump, which they commonly are, or one of those rare engines these days with an alumamin block and the entire cooling system was filled with this and nothing else, and it was kept that way for a long long time, then the salt content might cause some corrosion problems with the metal and the gaskets. Especially if you have an alumamin radiator.

A week after this show aired, you had your chemist buddy on the show. He instructed not to release directly to the radiator as an electrical shock might occur. This is not the case. As evidence, I provide a great show called Mythbusters, and a show about peeing on the 3rd rail. They set up a dummy of average height and let him go all over the 3rd rail of a subway to see what kind of shock he would get. They were surprised as he received none! The liquid breaks up too much and does not get a flow of electricity back to the person doing the deed. So go a head, stand up tall, and use the radiator as a urinal. You will not get shocked if you miss the 3" opening, and get a little on the battery cable.


you obviously didn’t pay much attention to the show in question because:

a. The dummy did receive an electric shock, just not a lethal one
b. when this myth was retested in 2004 with an electric fence and a real person, it was shown to be possible
c. they did manage to kill the dummy when they raised the rail for the original episode (to about the same height as a car engine)

also i’ve spoken with people who were shocked in this manner by electric fences, so I know that it is possible