Head Gasket Checks

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Nov 25, 2006
Al Ain, UAE
What checks can I do to determine if there's a small leak in the head gasket?

The problem lies with disappearing coolant. Maybe once a week I need to fill the overflow, especially after a day on the highway.

I changed the radiator cap, and the hoses (there was visible corrosion leaking out onto the metal). Then I flushed and refilled with Toyota red, following the excellent directions in the faq.

That seemed to fix it, and I was happy a week or so - today, again the overflow was empty.

There is no visible leak from the radiator, or anywhere else. I guess there might be a microscopic leak in the rad fins, so that's what I'll check and change next, but my biggest fear is that it's leaking out the exhaust.

How can I check for a head gasket leak without opening everything up?
There are some other methods as well.
But more expensive.
Try the looking for the bubbles first.
..02 cents....some shops provide a pressure test, if you know a reliable shop...as a last resort....it might bring that small leak out in the open...

Good luck.....
No bubbles at 3000 rpm - just out of curiosity, would that have pinpointed a head gasket leak, or just that there's air getting in somewhere?

Onto find a place that can pressure test. (not that easy out here, guys!)
If you know someone who works at a shop or has access to a gas analyzer, you can get it up temperature with the radiator cap off & check for hydrocarbons in the radiator. Even if you have to pay a shop, it should only cost $20 to $50.00. I have the same problem & found 11ppm HCs:frown: Oh well, just have to talk my wife into giving up the cruiser for a bit.
Felt like forever, 3 actual minutes on my watch. It was easy with the hand throttle. Was that long enough? It was running at normal temp before and after.

Still, what do the bubbles, or lack of bubbles show with regards to the head gasket? I suppose it shows that air's getting into the system, or that there already was air caught in the system.

No fancy gas analyzers here, bud - the only gas analysis possible is "Pwew, you gotta eat something else beside lentil curry, Babu!"
The bubbles would indicate that exhast/combustion gases are being pushed out via the head gasket. If you see them, it's a sign of a HG issue.
Bubble check is the easy, no cost check. If you were loosing a lot of coolant into the block, you should be able to see that in a smokey exhaust. Next thing I'd do is get one of those die kits, put some in the rad. fluid and run the light over the vehicle to see if you can spot a leak. Don't know if your model as the rear heater, but if so, you've got some lines that run under the vehicle that have been know to rust out and leak.


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