Stop Leak review (I have my flame suit on, so go for it!)

[Zachariah]

Old Guy - I have a 2.7T thats leaking from either the thermostat housing or water pump. Its dribbling quite small, just down the front of the passenger side oil pan corner....especially after the car sits overnight. How much should I put inside a biturbo Audi allroad?

[old guy]

I would not recommend using the stop leak for fixing either of those conditions. If the water pump seal is leaking you really need to replace the pump. Unfortunately the thermostat housing is plastic and prone to cracking and eventually sometimes coming apart. If it were one of your radiator end caps I would say go for it. The radiator is a non-moving component that typically just seeps coolant and doesn’t have the potential for a catastrophic failure like those other two components.

With that being said I do not think you would cause any damage by using it. I you do decide to try it I would recommend adding no more than ¼ of the total amount at first and see if it stops the leak. Add more only if necessary. Just keep a really close eye on everything.

[Zachariah]

I would not recommend using the stop leak for fixing either of those conditions. If the water pump seal is leaking you really need to replace the pump. Unfortunately the thermostat housing is plastic and prone to cracking and eventually sometimes coming apart. If it were one of your radiator end caps I would say go for it. The radiator is a non-moving component that typically just seeps coolant and doesn’t have the potential for a catastrophic failure like those other two components.

With that being said I do not think you would cause any damage by using it. I you do decide to try it I would recommend adding no more than ¼ of the total amount at first and see if it stops the leak. Add more only if necessary. Just keep a really close eye on everything.

Thermostat housing is the aluminum S4 one, replaced about 20k ago. I think I'll heed your advice and add 1/4 bottle at a time first. Thanks!

[Timtheguru]

I'd be surprised if this stops your leak on the O-ring seal for the thermostat, or the paper gasket with (hopefully) RTV gasket maker. You'd be better off replacing the seals honestly.

How do you know it's either of these?

[Zachariah]

I'd be surprised if this stops your leak on the O-ring seal for the thermostat, or the paper gasket with (hopefully) RTV gasket maker. You'd be better off replacing the seals honestly.

How do you know it's either of these?

I'm not certain. Many allroad owners say it could be either of the two, based on where the coolant drips. The intake manifold area, is dry to the bone. I just put a 1/3 bottle in just to see what happens next...

[old guy]

I'm not certain. Many allroad owners say it could be either of the two, based on where the coolant drips. The intake manifold area, is dry to the bone. I just put a 1/3 bottle in just to see what happens next...

If it's gonna work it should only take a few minutes. It stopped my radiator leak almost immediately.

[slow_N_lowe]

During a conversation with my mechanic about a leaking head gasket, he mentioned that VAG coolant had a small percentage of some form of stop leak in it from the factory.

That was the first time I'd heard that. Can anyone confirm or deny?

[Zachariah]

During a conversation with my mechanic about a leaking head gasket, he mentioned that VAG coolant had a small percentage of some form of stop leak in it from the factory.

That was the first time I'd heard that. Can anyone confirm or deny?

I know when G12 fully dries, it leaves a crusty, pink residue, similar to sugar crystals. It may be so...

[Zachariah]

If it's gonna work it should only take a few minutes. It stopped my radiator leak almost immediately.

Old Guy, you did your research well. A 1/3 bottle(about 6oz.) STOPPED the leak, after driving for only 15 minutes! You might have done what no Audi owner ever dare venture to attempt....successfully use aftermarket additives. In this case - you proved the purists WRONG. The real key to using this stuff is to apply small increments of it, just to be safe.

You can put the flame suit away. You have now achieved GURU status...

[MEDEL51480]

Old Guy, You can put the flame suit away. You have now achieved GURU status...

I'm getting desparate to stop chacing this leak, after reading this thread, I'm going to try the Bar's product Old Guy used... fingers crossed!!

[MEDEL51480]

So I went to the local parts store here, they had Liqui Moly Radiator Stop leak (http://www.liquimoly.co.uk/index.php..._details&id=16) and a different looking Bar's Leak that looks like this: (http://www.conrad.de/ce/de/product/8...s-Liquid-150-g).

I didn't buy the yellow Bar's Leaks can because it wasn't the same one that "Old Guy" used, and because it was $20 for the can, I bought the Liqui Moly instead since it was a single shot for $6. Do you guys think ill be safe with the Liqui Moly radiator stop leak instead of the generic looking Bars's Leaks??

[Timtheguru]

lol

If you think a bottle of stop leak is the correct way to fix the problem, you're mistaken. Only a matter of time... Carry on.

[MEDEL51480]

lol

If you think a bottle of stop leak is the correct way to fix the problem, you're mistaken. Only a matter of time... Carry on.

I haven't even said what's leaking or what I've done so far to try to fix it.

I'm literally close to pulling the head just to check the head gasket, and if I do that, I'm gonna pull the whole motor since it has high mileage.

[Timtheguru]

Old Guy, you did your research well. A 1/3 bottle(about 6oz.) STOPPED the leak, after driving for only 15 minutes! You might have done what no Audi owner ever dare venture to attempt....successfully use aftermarket additives. In this case - you proved the purists WRONG. The real key to using this stuff is to apply small increments of it, just to be safe.

You can put the flame suit away. You have now achieved GURU status...

I haven't even said what's leaking or what I've done so far to try to fix it.

I'm literally close to pulling the head just to check the head gasket, and if I do that, I'm gonna pull the whole motor since it has high mileage.

Not talking about you.

[MEDEL51480]

So I have some good news and some bad news about the Liqui Moly Stop Leak. At first when I put it in, the coolant leak seemed to stop and the white smoke from the tailpipe cleared up. I thought it was a success at first, until the next day when I drove about 45 minutes away. The drive there was fine, but on the way back about 30 minutes into the drive, the temp gauge started rising and the low coolant light came on. This is exactly what happened when my water pump went out 3 months ago. (I have already replaced the water pump with the ECS kit with metal impeller pump and new thermostat.) at first the lower radiator hose was cool, but after letting the car sit for a few minutes, the lower hose got warm so I started he car and everything seemed normal...drove home the rest of the way with no problems. I immediately thought the stop leak may have made the thermostat stick intermittently so I removed it and tested it in boiling water, everything tested fine. (Boiling water = 100*C, thermostat opens at 87*C, I didn't have a thermometer to see what exact temp the thermostat opened, but it defiantly opened at boiling point.). I even looked into the engine block to verify the metal water pump impeller was still in tact and turned when the engine was cranked. Reinstalled everything and took it for a test drive. Now the car cools fine and blows hot air from the HVAC when its driving under a load above 2500 rpm's, but as soon as it stops for idle, the air gets cool and after long enough, the engine temp goes up. Drive off again and things go back to normal. What would be causing this, and did the stop leak have anything to do with it?

Also, the 45 minute drive I took was to go to a shop to do a TDI 5th gear mod, that's where I replace my 0.83 5th gear for a 0.71 5th gear from a TDI transmission. I don't see how they're related, but I figured I'd throw that in just in case.

[jacobsen]

I read the post and then I was startled to see it was old guy.

[SaabtoAudi]

So I have some good news and some bad news about the Liqui Moly Stop Leak. At first when I put it in, the coolant leak seemed to stop and the white smoke from the tailpipe cleared up. I thought it was a success at first, until the next day when I drove about 45 minutes away. The drive there was fine, but on the way back about 30 minutes into the drive, the temp gauge started rising and the low coolant light came on. This is exactly what happened when my water pump went out 3 months ago. (I have already replaced the water pump with the ECS kit with metal impeller pump and new thermostat.) at first the lower radiator hose was cool, but after letting the car sit for a few minutes, the lower hose got warm so I started he car and everything seemed normal...drove home the rest of the way with no problems. I immediately thought the stop leak may have made the thermostat stick intermittently so I removed it and tested it in boiling water, everything tested fine. (Boiling water = 100*C, thermostat opens at 87*C, I didn't have a thermometer to see what exact temp the thermostat opened, but it defiantly opened at boiling point.). I even looked into the engine block to verify the metal water pump impeller was still in tact and turned when the engine was cranked. Reinstalled everything and took it for a test drive. Now the car cools fine and blows hot air from the HVAC when its driving under a load above 2500 rpm's, but as soon as it stops for idle, the air gets cool and after long enough, the engine temp goes up. Drive off again and things go back to normal. What would be causing this, and did the stop leak have anything to do with it?

Also, the 45 minute drive I took was to go to a shop to do a TDI 5th gear mod, that's where I replace my 0.83 5th gear for a 0.71 5th gear from a TDI transmission. I don't see how they're related, but I figured I'd throw that in just in case.

Does your cooling fan turn on?? Your fan should kick on once it gets hot enough at idle. While moving the air flow cools down the radiator. Sounds to me like you rad fan isn't running

[MEDEL51480]

Does your cooling fan turn on?? Your fan should kick on once it gets hot enough at idle. While moving the air flow cools down the radiator. Sounds to me like you rad fan isn't running

The fan was working fine, when I pulled over to check the radiator hoses, the temp was already high and the fan was running too. The lower hose was warm, not hot. It's almost as if the coolant doesn't flow to the radiator at idle.

[xhackerekx]

The fan was working fine, when I pulled over to check the radiator hoses, the temp was already high and the fan was running too. The lower hose was warm, not hot. It's almost as if the coolant doesn't flow to the radiator at idle.

radiator clogged for me.

[Albertk]

Bumping this thread. I've got a 3.0 and am definitely leaking coolant. Nothing outrageous, but I can smell the burning coolant.

Is this worth a shot?

[SJorge3442]

Bumping this thread. I've got a 3.0 and am definitely leaking coolant. Nothing outrageous, but I can smell the burning coolant.

Is this worth a shot?

My guess would be that you are leaking from one of the rear coolant pipes. These sit right about the downpipes and they overtime start to leak. Can you see where the coolant is coming from? Typically if it is leaking from the hard pipes or the heater core hoses (both on the rear side of the engine) the coolant will drip down along the trans.

[Albertk]

My guess would be that you are leaking from one of the rear coolant pipes. These sit right about the downpipes and they overtime start to leak. Can you see where the coolant is coming from? Typically if it is leaking from the hard pipes or the heater core hoses (both on the rear side of the engine) the coolant will drip down along the trans.

I haven't had a chance to look in a while. But if the leak were coming from one of the hard pipes of core hoses, would something like liquid aluminum work?

[SJorge3442]

I haven't had a chance to look in a while. But if the leak were coming from one of the hard pipes of core hoses, would something like liquid aluminum work?

doubtful. The heater core hoses have plastic quick connects on the end of them and those tend to weaken. The hard pipes have o rings that are responsible for keeping the coolant in I believe. Neither of which can or should be fixed without replacing the leaking part.

[old guy]

Bumping this thread. I've got a 3.0 and am definitely leaking coolant. Nothing outrageous, but I can smell the burning coolant.

Is this worth a shot?

The first thing you need to do is to determine the source of the leak. As I stated back in 2009 when I started this thread I did not recommend using this product for anything other than a leak from a “fixed” component connection such as a radiator end cap. I would not try to fix anything like a leaking hose connection or a water pump shaft seal.

I also didn’t recommend anything other than the one particular product that I linked. I spent quite a few hours reading reviews, technical data sheets, forum feedback and any other information I could find. At that time the Bar’s Liquid Aluminum was consistently the highest rated as well as completely compatible with the G, G+, G++ type of coolant.

I ran it for two years with no adverse effects. As a preventive measure I went ahead and changed out the radiator at my last timing belt service so it is no longer in my block.

[Albertk]

The first thing you need to do is to determine the source of the leak. As I stated back in 2009 when I started this thread I did not recommend using this product for anything other than a leak from a “fixed” component connection such as a radiator end cap. I would not try to fix anything like a leaking hose connection or a water pump shaft seal.

I also didn’t recommend anything other than the one particular product that I linked. I spent quite a few hours reading reviews, technical data sheets, forum feedback and any other information I could find. At that time the Bar’s Liquid Aluminum was consistently the highest rated as well as completely compatible with the G, G+, G++ type of coolant.

I ran it for two years with no adverse effects. As a preventive measure I went ahead and changed out the radiator at my last timing belt service so it is no longer in my block.

Thanks old guy! Helpful as always.

[matthewcody]

First off, I'm sorry to hijack the topic here but I hope this is somewhat relevant. I've got a 2007 A6 4.2 with a 'mystery' coolant leak. The dealer has pressure tested it and can't find an external leak; there's also no evidence of a leak (i.e. puddles, drips) and I just heard that the mechanic feels this is a 'bypass leak'. Don't kill me, I'm not a mechanic, but what was explained to me was that the cooling system has a line that actually runs through the engine. On the interior of the engine are two flanges with seals; one of these seals is leaking and (apparently) leaking fluid into the crankcase.

The dealer went on to explain that this is probably a 15 hour job to repair. Personally I don't think I have a choice - I can't drive the damn thing like this - but when I saw this thread I thought it might possibly offer a shred of hope.

Old Guy, sorry to impose - but what do you think?


PS - car is out of warranty but I found it really odd that the mechanic (and the shop manager) both told me that "as long as you change the oil regularly and you keep an eye on the coolant level you shouldn't have any problems". To me this seems like a recipe for disaster - I'm contaminating my oil, I'm assuming that I'm fouling plugs and probably causing all other kinds of damage.... or am I wrong???

[Myst420]

Are you getting coolant into your oil? I'm clueless about the 4.2, so I can't help with any specifics, but if you are getting coolant into the oil, then that sounds like a bad head gasket. I would also recommend taking it to an indy shop and see what they can find. It seems really odd that the dealer can't find the leak.

[matthewcody]

Are you getting coolant into your oil? I'm clueless about the 4.2, so I can't help with any specifics, but if you are getting coolant into the oil, then that sounds like a bad head gasket. I would also recommend taking it to an indy shop and see what they can find. It seems really odd that the dealer can't find the leak.

I had the oil changed on Saturday (when the car was at the dealer) and they're reporting no coolant in the oil. I specifically asked about the head gasket and they said no.

Absolutely headed to an independent... I also need to replace the engine breather valve (I believe this is the PCV valve but asking dealer for specific part number) so I have some work to do regardless.

[DaSkorpion]

OG is unflammable - just cant flame our dear OG he is too nice to be flamed.

[old guy]

First off, I'm sorry to hijack the topic here but I hope this is somewhat relevant. I've got a 2007 A6 4.2 with a 'mystery' coolant leak. The dealer has pressure tested it and can't find an external leak; there's also no evidence of a leak (i.e. puddles, drips) and I just heard that the mechanic feels this is a 'bypass leak'. Don't kill me, I'm not a mechanic, but what was explained to me was that the cooling system has a line that actually runs through the engine. On the interior of the engine are two flanges with seals; one of these seals is leaking and (apparently) leaking fluid into the crankcase.

The dealer went on to explain that this is probably a 15 hour job to repair. Personally I don't think I have a choice - I can't drive the damn thing like this - but when I saw this thread I thought it might possibly offer a shred of hope.

Old Guy, sorry to impose - but what do you think?


PS - car is out of warranty but I found it really odd that the mechanic (and the shop manager) both told me that "as long as you change the oil regularly and you keep an eye on the coolant level you shouldn't have any problems". To me this seems like a recipe for disaster - I'm contaminating my oil, I'm assuming that I'm fouling plugs and probably causing all other kinds of damage.... or am I wrong???

As I have stated several times in the thread I don't recommend using the Liquid Aluminum Stop Leak unless you know the nature of the leak. If it is something like a head gasket you are better off fixing it properly and not risk doing more damage. For a pesky little leak like a radiator end cap it will do the job just fine. I suffered no ill effects from running it several years before I finally replaced the radiator during a timing belt session.

[matthewcody]

As I have stated several times in the thread I don't recommend using the Liquid Aluminum Stop Leak unless you know the nature of the leak. If it is something like a head gasket you are better off fixing it properly and not risk doing more damage. For a pesky little leak like a radiator end cap it will do the job just fine. I suffered no ill effects from running it several years before I finally replaced the radiator during a timing belt session.

Understood - the Audi guys seemed pretty sure about their diagnosis. I guess for the few dollars the additive costs I may give it a shot and see if it stops -if not, (sadly) it'll be time to find an independent shop and get it quoted.

[old guy]

Understood - the Audi guys seemed pretty sure about their diagnosis. I guess for the few dollars the additive costs I may give it a shot and see if it stops -if not, (sadly) it'll be time to find an independent shop and get it quoted.

Well, it's not going to hurt anything by trying it. Just use this exact stuff. I can't vouch for any of the other ones out there. Clicky click

Good luck!

[matthewcody]

I promise - I would not have the balls to try something like this had it not been vetted out as thoroughly as you've done. I really appreciate reading this thread and all the research time you put in - that small skull-and-crossbones container is one of the best things I've ever seen on a car forum!

I bought the exact stuff you tested and I'll be doing it 1/4 bottle at a time and will probably give up at 1/2 a bottle. I'll come back and let you guys know what happens.

[matthewcody]

Early days yet but so far so good. I've been taking photographs of the coolant level and I can't detect any fluid loss anymore. The real proof will come over time, I suppose, but for now I couldn't be any happier.

Thank you very much for such a meticulous and well-documented report. As I said, I'd have never even considered going this route if you hadn't done all the work... and posted about it. Really appreciate it!

[bspellman]

Thanks, after I got the system flushed and the overheating problem and heater working I got the same leak on my radiator. I just put this stuff in after seeing your post and the leak is gone. So glad I saw your post !

[puck]

Alright. Im very new to this forum and joined to share my experience. A quick background on me and cars; I dont know much but I like to learn. I have a 2005 A4 AMB with 182K on it and Ive replaced my PCV valve and the entire system it controls, Ive done the valve cover gasket and then of course the brakes and such. Very recently I had some major coolant leakage going on and turned out it was the coolant flange and the heater hose. Also got the CTS changed as well. I let the pros do it since Ive been pressed for time and figured Id pay for the convenience. Before I took it in I also noticed I was starting to have misfires on #2. This was a week ago.

Got the car back and Im still having misfires on #2. Got new plugs and did a coil swap and still #2 was the culprit. I didnt think it was anything electrical in the first place because the coolant gauge kept moving back and forth when it happened, but due diligence. Each morning, Id check my coolant reservoir and Id be down about an inch below the minimum. So Im losing, coolant, Im misfiring on #2 and Im clueless. Cue googling and I come to head gasket issues. With 182K on it and a possible cracked head or blown gasket, Im looking at a lot of learning to be had ASAP or 2500 in repairs, at least. For a car worth about as much, It didnt make sense to go the legit way. Either scrap it or crapshoot. So I found this thread from old guy and read up on it. Seemed like Bars may be an option. The more severe suggestion to the radiator fix is their Head Gasket Fix. 8 bucks. I throw the dice with half the bottle into the reservoir...

Follow the instructions to the T. Add, idle, heat, cool. I get on the highway and its misfires galore. Maybe even worse than what it was. Every gear, just misfires all over the place. Im driving like granny to get home, but thankfully the temp gauge is solid in the middle. An improvement at the least. About 15 minutes in, Im noticing less misfires. Im curious. Theres a hill next to my house that I can punch it on and I start lapping the hill. Its noticeable that the misfires are less and less. Im getting through first gear solid and second and third struggle. Then Im good through first and second. Finally third is clean. Im maybe 20 laps in and Im punching it through as many gears as I can with zero misfires. Gauge is still solid in the middle. I call it for the night.

Let it chill overnight. Got to the car and filled the coolant that I knew I lost misfiring the day before. Add about an 1/8 of the bottle of HGF. I cleared the P0302 from the day before. Start her up, warmed up and rolled to work. Didnt baby it at all. Drove through traffic like I used to. Punched through the gears to pass, covered all the driving scenarios and didnt feel any misfires. Got to work. Pulled codes..... nothing.

Granted, its been a day, but I've got to say Im impressed. The thing is on its last legs for sure, but if I can get another couple months out of her, I'll take it for 8 bucks. Who knows, I could get out to my car today and have a bricked engine, but I doubt it. The HGF said that good candidates are cars that can idle for 20 minutes without overheating, definitely my case. Obviously something gave between the cooling system and #2 but it seems to be plugged for now. The HGF says that the additive becomes stronger than the head itself. One can only hope. Definitely not typical and probably not recommended unless youre in the same scrap it or wing it predicament Im in. I threw the dice and it seemed to play in my favor. Ill drive it till its in the ground.

Figured Id share.

[Seerlah]

Bump

Caught a coolant leak on my 2002 Maxima daily driver on a hard pipe under the car that is rusty. I remembered this thread, but not the product brand name. Searched this thread, got the brand, picked up at AutoZone, and this stuff really works.

Rather than spend money on this old car for the replacement part, shipping of said part, then installing said part (would have required coolant drain and refill), I figured give this $6 bottle of magic juice a shot.

I just watched the leak turn from a steady drip to nothing within maybe 10-15 minutes. Just sharing my personal experience with this stuff. So confirmation this stuff also works on rusted hard pipes.

[Seerlah]

I would like to add I personally would never put this stuff in my Audi, simply because I would not want that metal coating throughout my coolant system and block. But on my Maxima...

I also dilluted the metal pebbles with hot water, mainly because I wanted as much metal content since the leak was on a hard metal pipe.

[twfry]

This worked great for me. I had a very slow leak at the rear of the engine where the flange connects to the heater hose. This is an almost impossible spot to get to. The leak required a top off once every several months, but was trending towards once every month or two and you could see water at the coupling.

Put this stuff in and the leak stopped almost immediately. Coolant has held steady for several months now with no issues. Similar to OG it seems to have improved cooling for the reasons stated earlier in the thread.

Thanks OG, you saved me from having a horrible weekend which is what I am sure removing the rear flange would have turned into.

To those saying not to put this stuff in, there doesn't seem to be any evidence to it causing issues. I plan to pull the engine at the 20 year point for a refresh and can easily replace the hoses then and clear out the coolant passages if needed, but based on what I've seen that likely won't be an issue.

If you have a small leak, go ahead and try this.

Also, my leak was at a plastic coupling with an o-ring, there were comments in the thread that it won't work on plastic or o-rings. For me that wasn't the case and it worked fine here. Like others I used half a bottle. Might just put the other half in the wife's subaru as a preventative measure...