Radiator Stop Leak, Is There a Good Product?

[red71c10]

Running around today, and after shutting the engine off, I opened the hood to look at something else, and noticed a pin hole leak in the side of the radiator just below the upper hose fitting. Seems to stop when the engine is running. That side of the radiator has green streaks all the way down, so it's been going on for a while. Doesn't seem to be a big deal, but I'd like to stop it. Do any of those stop leak additives work, or will they kill my water pump? I saw some copper repair stuff that looks like the mighty putty you see on TV, should I slap some of that on the outside? Any suggestions would be great!

[spinning wheels]

Originally Posted by red71c10

Running around today, and after shutting the engine off, I opened the hood to look at something else, and noticed a pin hole leak in the side of the radiator just below the upper hose fitting. Seems to stop when the engine is running. That side of the radiator has green streaks all the way down, so it's been going on for a while. Doesn't seem to be a big deal, but I'd like to stop it. Do any of those stop leak additives work, or will they kill my water pump? I saw some copper repair stuff that looks like the mighty putty you see on TV, should I slap some of that on the outside? Any suggestions would be great!

I would try the putty stuff. I used it to stop a leak on a power steering reservoir and it held for years. I have also used it in industrial applications and even to attach brass ID tags to manhole covers. The stuff works, but there are so many different brands out there on the market now, it is hard to say which one will work the best.

If that doesn't do the trick. BARS stuff seems to work ok, but its only a band aid, not a guaranteed repair. Personally, I would try the putty as its something that I am not putting into the engine.

Good luck.

[LMN8UR]

You would think under the pressure of running it would leak more. Is it the expansion of the heat that closes up the leak?

How old is your radiator? If it is original try the external patch, but start shopping for a replacement!

[cdowns]

take out rad and bring to rad shop for repair or replacement

[truckdude239]

take it to a rad shop for like 20 buxs have them fix it. i uses that stop leak stuff once and wish i never had stoped up my t stat my water pump cost me more to actly fix the truck then it was to fix the leak the right way

[rob32472]

If you are in a pinch use black pepper..... but id just have it fixed if not

[lclippard]

DO NOT use bars, or others like it. it will stop up every "leak" it finds. meaning the t-stat, heater core, thre rest of the radiator. JB Weld works well on radiator leaks. clean the area well, scuff it up and apply while the radiator is cold. let it harden for the time recommended and maybe then some. if you really want to use a stop leak, try this....subaru has a stop leak that does not clog the rest of the system. this is because it never solidifies in the system. it stays in a gel form so it is safe. they use this to stop/prevent head gasket leaks that are ever so prominent on the H engines. it works very well. Justice Brothers has a similar chemical, but im not sure if they supply where you are. good luck man. if its a really old radiator, look into replacing it. Webster Radiator has good prices, and sells to the consumer, not just wholesale.

[El Jay]

KW Block Seal works most excellently.

But you have to follow the directions explicitly. That is you have to flush out the cooling system and have ABSOLUTELY no antifreeze in it; and then go from there.

[Longhorn Man]

some decent advice, some crazy talk.
I have personally used the stop leak stuff that you dump in the coolant, many many times, and I have never ever had a part go bad, nor an engine get clogged. I've dumped 4 times the recomended 'dose' to get the job done... again, never a clog.
Fixing it externally is not a bad idea, I would deain the rad, and I would just use JB weld, or that A and B putty. Drain the level down, remove paint and corrosion in the bad area, and wipe down with brake clean.
However, as pointed out, that is a $20 fix at a rad shop, plus, they'll pressure test it and see if it needs more work, they'll look in it and tell you if you are spending money on a piece oif crap... ect.
As far as leaking only when the engine is off... for about a min or two after the engine is shut off, after being brought up to temperature, that's when the cooling system is under the most pressure.

[tvillebowtie]

The best way to fix a radiator is to brase it or replace it.I just replace a intake gasket on a 4.3 vortec.If you would've seen what I saw in those heads you would never put that crap in you radiator or motor.Remeber cheapest is not always the best route.My opinion

[meansting04]

I agree don't use it unless you have to. A new or rebuilt rad. will save you down the road. The stop leak will clogg everyting up.

[So.Cal.Super]

I have used the stuff that looks like pepper at the auto parts store(sorry don't remember the name) and I have found it built up on the t-stat when I changed that later on.

Once in a Toyota I had the radiator stopped flowing due to the P.O. using well water. I pulled it and had it Rodded for $50. a year later I had to replace it and it only cost me $90 for a new one. I wish I would have known because the new one lowered my running and temp and my A/C blew cooler.

Sometime its just better to replace it. My .02

[red71c10]

Originally Posted by Longhorn Man

some decent advice, some crazy talk.
As far as leaking only when the engine is off... for about a min or two after the engine is shut off, after being brought up to temperature, that's when the cooling system is under the most pressure.

That does seem to be the only time it's leaking. We have a local radiator shop that's been around for ever. They have a good reputation. I'll take it in and see what's up.

Thanks Everyone!

[rob32472]

I wasnt kiddin about the black pepper.... I was in the middle of no where one time and an old timer told me it would work so I tried it and it got me home of coarse i replaced it and flush the system afterward i was amazed but really did not think i had anything to loose.

[tim21391]

i had a small link so i went to autozone and got their "stop leak" its like flakes you drop into the radiator.. and they say dont use a whole tube or u will clog stuff up... i did it anyways... it stopped the leak and had no problem since

[tim21391]

best $1.99 i ever spent

[tvillebowtie]

O.k. We warned you.that 2 bucks is going to cost way more than that in the long run.

[Longhorn Man]

Originally Posted by tvillebowtie

O.k. We warned you.that 2 bucks is going to cost way more than that in the long run.

you must have missed his last post...

Originally Posted by red71c10

We have a local radiator shop that's been around for ever. They have a good reputation. I'll take it in and see what's up.

[westofb]

I have used a product called something like aluma seal. It is a powder comes in a small 1 inch tube about 3 inches long. It kind of looks like powdered aluminum...It will seal up small leaks. Never had any adverse reactions to anything else...cost like 2 bucks at most auto parts stores. I agree fixing it at rad shop would be the smartest thing to do, but the aluma stuff will cure the leak you described...

[special-K]

Courtney`s is the stop leak I use.He`s been doing radiators since before most of us were born and definately longer than all this goo was made.
Solder is the best stop leak.It doesn`t run through your motor.

[leddzepp]

Been using Bars leaks for over 20 yrs. Always works, never a problem.

[monte0185]

Originally Posted by tvillebowtie

The best way to fix a radiator is to brase it or replace it.I just replace a intake gasket on a 4.3 vortec.If you would've seen what I saw in those heads you would never put that crap in you radiator or motor.Remeber cheapest is not always the best route.My opinion

The 4.3 you are referring to did it have dexcool in it? The reason I ask is my G/F 2001 blazer was the same way and I know for a fact the only fluid ever put in it was the original. Theres a big lawsuit against them cause dexcool hardens after awhile and will stop up the whole engine. Hers stopped up the radiator and after I flushed the system and replaced the radiator It blew a intake gasket so I had to replace that as well. Nasty Nasty stuff!!!

Now back to your radiator problem. If its just a pin hole get you some map gas and a coathanger and just braise it up. Only takes a few min. Radiator shops can do it as well for next to nothing if you take it to them. Ive used the aluminum seal stuff and always had good luck with it but its always a temporary fix. Might as well spend the few dollars and do it right and have piece of mind.