# Pepper in a car's radiator? **URL:** \ **Category:** Factual Questions\ **Created:** [July 17, 2005, 7:04pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893 "2005-07-17T19:04:40Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [July 17, 2005, 7:04pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/1 "2005-07-17T19:04:40Z")
Someone at work was telling me how used car dealers will dump a can of black pepper into a radiator to prevent overheating. I found one reference on the web that talks about black pepper as a leak stopper. Neither of these sounds feasible. Does this actually work, and more importantly, _how_ does this work? ---
**Author:** ![wolfstu](https://avatars.discourse-cdn.com/v4/letter/w/d6d6ee/32.png) [@wolfstu](https://boards.straightdope.com/u/wolfstu)\ **Post date:** [July 17, 2005, 7:10pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/2 "2005-07-17T19:10:19Z")
WAG: Pepper, intorduced into the coolant water, absorbs some of the fluid and swells. Any leks will have a small flow towards them, and the pepper might drift with that flow towards the hole and, given the hgh internal pressure, be pressed against it, blockng it. I’m not sure how effective that would be, but Googling for [pepper radiator car] gives a bunch of sites mentioning this practice. Presumably, if this acutally does act to plug small holes, it would prevent overheating by preventing loss of coolant. ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [July 17, 2005, 7:11pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/3 "2005-07-17T19:11:26Z")
There’s powder you can buy specifically made to pour into a radiator to stop a leak. I used, it would indeed stop my leak temporarily. I suppose pepper might also work, although probably not as well. I assume it just clogged up the leak. ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [July 17, 2005, 9:53pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/4 "2005-07-17T21:53:04Z")
Yes, It’s a silver colored powder and works well as a TEMPORARY way to stop leaks. (I can’t think of the name.) I’ve also heard (no cite) that pepper also works as a leak stopper. I’ve also heard the oatmeal does the same thing. Personally I wouldn’t want to dump that crap in my cooling system, but sometimes you do what you have to do. ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [July 17, 2005, 10:42pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/5 "2005-07-17T22:42:36Z")
- - - - The silver powder is called Aluma-Seal, I think. Pepper is common also. The argument in favor of pepper is that it is non-binding; it isn’t sticky like the plastic goop used in commercial radiator sealers, and so it doesn’t cause any more problems than it solves. Pepper just clogs up the leak; the commercial sealer-stuff usually has a plasticizer in it as well. - Generally, radiator sealers are useful particularly if you are on a long trip–they can slow down a leak much but won’t really fix it. The correct way to use them is to pour in a bit at a time (and add more water also) until the leak subsides. The problem with the concept is that impatient people want to pour the whole bottle in there (like the instructions tell you to) to deal with it just once, and the extra stuff gunks up the inside of the cooling system. ~ ---
**Author:** ![Revtim](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/revtim/32/1042_2.png) [@Revtim](https://boards.straightdope.com/u/Revtim)\ **Post date:** [July 17, 2005, 11:01pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/6 "2005-07-17T23:01:04Z")
> [@Jake](#): > > I’ve also heard the oatmeal does the same thing. IIRC, using oatmeal was mentioned as a practice used by shady used-car dealers in Steinbeck’s ‘The Grapes Of Wrath’. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [July 17, 2005, 11:05pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/7 "2005-07-17T23:05:47Z")
> [@Chefguy](#): > > Someone at work was telling me how used car dealers will dump a can of black pepper into a radiator to prevent overheating. I found one reference on the web that talks about black pepper as a leak stopper. Neither of these sounds feasible. Does this actually work, and more importantly, _how_ does this work? Not familiar with the black pepper remedy. One commercial product is “Stop Leak.” The Old Timer/Red Neck solution is Horse Manure. No s…t, it real was. ---
**Author:** ![Biffy\_the\_Elephant\_Shrew](https://avatars.discourse-cdn.com/v4/letter/b/e47c2d/32.png) [@Biffy\_the\_Elephant\_Shrew](https://boards.straightdope.com/u/Biffy_the_Elephant_Shrew)\ **Post date:** [July 17, 2005, 11:54pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/8 "2005-07-17T23:54:56Z")
> [@spingears](#): > > Not familiar with the black pepper remedy. > One commercial product is “Stop Leak.” I’ve heard the Car Talk guys mention pepper as an emergency measure (or sleazy used-car salesman move). Stop Leak works like a charm, but but not permanently, and if used repeatedly it builds up and wrecks your cooling system. The ex and I had a Toyota that required such repeated applications. ---
**Author:** ![easy\_e](https://avatars.discourse-cdn.com/v4/letter/e/eb8c5e/32.png) [@easy\_e](https://boards.straightdope.com/u/easy_e)\ **Post date:** [July 18, 2005, 12:35am UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/9 "2005-07-18T00:35:09Z")
On “Mythbusters,” they cracked a raw egg into the radiator to stop a leak. I imagine it’s the same principle–as the egg cooks, it plugs the leak. It worked, but I wouldn’t try it. ---
**Author:** ![Foaming\_Cleanser](https://avatars.discourse-cdn.com/v4/letter/f/f05b48/32.png) [@Foaming\_Cleanser](https://boards.straightdope.com/u/Foaming_Cleanser)\ **Post date:** [July 18, 2005, 12:54pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/10 "2005-07-18T12:54:10Z")
Stop Leak also coats the heater core, making it more expensive to get heat again than to fix the original problem properly. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [July 18, 2005, 3:14pm UTC](https://boards.straightdope.com/t/pepper-in-a-cars-radiator/312893/11 "2005-07-18T15:14:36Z")
So I guess my only dilemma now (if I was to do such an odd thing) would be to decide if I was going to use Tellicherry, Muntok or Sarawak. . .