Quick cheap fix for leaky head gasket

Dear Tom and Ray,

I have a 1995 Jeep Cherokee with 115,000 miles on it. It has had overheating problems in the past and once, four years ago, blew a head gasket that required me to machine the head. Since that time it has had little overheating problems that have never resulted in a breakdown. It does result in me constantly watching the temperature gauge.

When the weather got cold in the past few weeks I noticed an awful lot of exhaust fumes coming from my heater and defroster. The car is only drivable in the cold with the heater off and the windows rolled down-- which is fine with me but not with my passengers. Every other aspect of this car works well including, most importantly, the four-wheel drive.

I am taking it to my mechanic on Wednesday but I have diagnosed, in advance, a blown head gasket or cracked head or something like that. I found a $100 product on the Internet that they call “a two-part ceramic fiber elemental carbon and iron metallic alloy compound suspended in a liquid” that I am supposed to pour into my flushed out radiator. I am then supposed to drive it hard to heat it up, let it cool down and do it again repeatedly to seal the leak. Then I will flush it, refill the radiator and drive off into bliss.

At this point, it’s either do this or donate it to my unknowing innocent public radio station.


1. This sounds too good to be true, is it?

2. I am going to walk into the mechanics shop and ask them to do it. Do you think my mechanic will have a problem doing this? Should I talk to them about it beforehand or just drop it on them?



I found a $100 product on the Internet … Then I will flush it, refill the radiator and drive off into bliss.

You already know the answer to this one don’t you? If not I have a bridge for sale.

I am going to walk into the mechanics shop and ask them to do it. Do you think my mechanic will have a problem doing this?

If they don’t have a problem with it, get a different mechanic.

First, don’t assume you are correct about what is happening to your car. Bring it in and tell the mechanic what you have observed and tell them of the prior head gasket issue. Don’t suggest what you believe is wrong, that’s their job and they are better at it than you. They are right there and they can do the testing and looking we can’t do directly.

Um… exhaust fumes coming from your interior vents? That’s no sign of a blown head gasket, that’s something else entirely. Care to elaborate on that one a little?

Definitely talk to your mechanic before doing anything to the car, especially anything that costs 100 bucks. It sounds like some kind of mega Bar’s Leak to me, and that is more like a $10 fix.

It would be worth spending the money to have your mechanic diagnose the issue. With an accurate diagnosis, you can them determine the next course of action. But being only 12 years old an acting as bad as that, I’d certainly get a diagnosis as you could have been putting up with a very fixable issue. But it could be something serious and if it is, the mechanic will tell you and you can then act accordingly.

Exhaust fumes (?) through the defroster and heater vents?

(1) Probably. I refuse to use ANY of these additives. I don’t trust any of 'em. But that’s just me.

(2) Honestly? I don’t think any tech worth his experience will touch it. You can tell him what you know about the stuff, but stand back when he throws it in the trash can. (Kidding)(maybe not)

No offense implied, but I’m not into Jeep (or any other Chrysler/Dodge) and suggest that if you want to keep this vehicle, either have the heads AND the block planed and reinstalled or replace it with a rebuilt motor.

Perhaps the head gasket(s) were slightly damaged during installation.

I agree with the others, if your mechanic doesn’t laugh at you, get a new mechanic.

I would get an accurate diagnoses, the exhaust fumes in the car sound more like an exhaust leak to me. Once you have a repair estimate, decide what you want to do.

Comeon, man, he said “head” not “heads”, it’s got a 4.0L and as much as I share your disdain for the pentastar clan, that motor will go forever.

Um… exhaust fumes coming from your interior vents? That’s no sign of a blown head gasket, that’s something else entirely.

It’s conceivable (but unusual). You’d have to have head and/or gasket damage that permits combustion gases into the coolant plus a leaky heater core that permits coolant into the passenger compartment air stream. Such head/gasket problems would likely show up with severe overheating, unless the heater core leak relieves enough pressure. More likely, there’s an exhaust leak in or near the engine compartment that is being draw into the ventilation system somewhere (although that would likely happen year-round, I’d think – is this problem only recent enough that the weather has always been cold?). The minor overheating would be a separate issue.

It’s too good to be true.
Try it anyway…you have nothing to lose but $100.
Don’t ask a mechanic. I wouldn’t use any mechanic that would agree with this.

There is something you can try. I have no information as to its effectiveness. You could take the head bolts out. Use a swab, hook, something to ensure that there isn’t anything in the bottom of the head bolt holes. Check the length of the bolts and compare to the depth of the holes. They could have stretched, and could, now, be too long. Install the head bolts and tighten in the correct torque steps, and pattern, to the final correct torque. Pressure test the engine cooling system.

Tom: Why do you think you have a head gasket problem? I,ll assume you have a 4.0 L6. By the way, to anybody posting a question: Wouldn’t it be nice to give at least make, model, year and engine size? Anyway, I,ve seen quite a few of these get an exhaust manifold leak- a crack where the 6 runners converge into one. Fumes could be getting through heat/ac system; coming out vents. If you get

it checked out, make sure mechanic can check it COLD- (takes 8 hr. for a warmed up engine to cool down). Also, make sure mechanic checks for leak as soon as he gets it up in the air 'cause leak may close up as engine warms. Unfortunately these manifolds are really expensive new- maybe go junkyard- if this is your problem. Thomas- you have an UNSAFE condition here, no matter how much you try to take precautions.

Get this problem solved ASAP. Let us know what upshot is 'cause I’m curious as to whether my guess is right or not . Good luck. P.S: Keep heater/ac on recirc- even if you don’t use it. And please forget about this miracle liquid crap- no offense. This stuff could clog up important orifices in engine.

You’re basing a head gasket diagnosis on overheating only? What about a sticking thermostat, inoperable (even erratic) fan operation, clogged radiator, etc.?

While not a sure-fire test you could loosen the radiator cap after the vehicle has been sitting all night. Retighten the cap, start the engine, and allow it to idle for about 45 seconds.
Shut it off and quickly loosen the cap again. If you hear a faint hiss then it’s possible a head gasket could be leaking.
Compression test, cooling system test, and hydrocarbon test could verify that.

I’m not a fan of any goop that is supposed to cure head gasket problems. Some cooling system sealers may work on head gasket leaks that are not into the combustion chamber but I would not put any faith into anything that is guaranteed to stop a combustion chamber leak.

Let’s cut through the nonsense guys . . . none of us think it will seal any cylinder head crack or blown head gasket and most of us believe that it will probably gunk-up the cooling system. I agree with the additional diagnostics . . . what could it hurt? And the actual fix may not be that bad . . . especially if the rest of the Jeep is in good shape. Good luck! Rocketman

After you use the stuff, you might need a new radiator or heater core. Tom and Ray are on another planet right now, but if you put tin foil on a window and tape your stereo antenna to it, you may be able to contact them.

I tend to use $10 (or cheaper) stuffs to find out where the leak comes from prior to taking apart the engine. They are quite effective for any radiator/heater core to clog, but from my experience none of them worked stop leaking.

Thanks for posting.



Yeah, Thomas, what the heck happened? How come you guys never get back w/the result? Please clue us in.