block / headgasket tester question

[redsvx94]

Hi All,

I'm trying to check whether my car has developed a headgasket leak or not and trying to use a block test kit from NAPA. This is the type where air on top of coolant are drawn into a transparent cylinder in which the testing liquid changes its color, if exhaust gas in present in the atmosphere.

I hope this is not a stupid question, but did any one try this type of test when the coolant seems to be not circulating well in the coolant system? If circulation of coolant is limited (as I suspect it is for mine), would this type of test sensitive enough to detect leak?

It seems compression test is not good choice for a small leaks on headgasket.

[Beav]

Thatis an extremely reliable tool/method. If you are really concerned that you may not have enough CO for it to detect, spray some flammable carb cleaner into the intake while it is running. That will richen the mixture more than enough.

Quite frankly, we use that tester at work and never have to enrichen the mixture for results. And yes, the CO will disperse throughout the cooling system. CO is a gas and is lighter than water, so it will accumulate at the highest point.

[redsvx94]

O.K. I see. It's detecting CO. Then it make sense to have high sensitivity. The instruction says warm up the engin but, then I guess I don't need to wait for engine to warm up completely right? I don't want to risk another overheating to do the test!

[Beav]

Instructions?? We don't need no steeenking instructions! heheheeh I don't think any of us has ever read the instructions, and I've been using that tool for over 35 years.

[nipper]

As an engineer that used to write the instructions, we never read instructions, just our own
Dont we have to report him to the union for reading instructions or something?

(btw if its showing CO without the car warmed up, your done. you have a HG issue. If it didnt read co cold, you would wait for the thermostate to open to make sure)

[cdigerlando]

Wouldn't it stand to reason in order to get CO saturation of the coolant, the coolant would have to circulate through the block? I would warm it up to optimal temperature with the radiator cap off, shut the motor off, then do the test. if you still don't have circulation then you have a thermostat or pump problem. You should not overheat this way.

[nipper]

Originally Posted by cdigerlando

Wouldn't it stand to reason in order to get CO saturation of the coolant, the coolant would have to circulate through the block? I would warm it up to optimal temperature with the radiator cap off, shut the motor off, then do the test. if you still don't have circulation then you have a thermostat or pump problem. You should not overheat this way.

except that the thermostat is on the bottom of the engine. CO (espeically in this case) is a pressurized gas that it lighter then water. Since there is nothing to block it from being pumped (combustion presures) to the highspots in the cooling system (the radiator) it will show up there first.
In cars with the thermostate on top of the engine, your correct. the CO would take longer to show up, unless its a gross HG leak. The test is done with the car funnning, while the CO is being pumped by the engine.
If you dont have water curculation, of course your going to over heat. The water pulls the heat out of the cylinder block to the radiator and disipates the heat by transfering the heat to copper then to the air.
for the 10-15 minutes to take the test, with no load you wont over heat. If you Do its because the CO has alrady made an air pocket in the coolant, staurating it, and the test will show that.

nipper

[redsvx94]

Thanks for the comments. Thanks for the definitive answer Beave. I did the block test and couldn't see any color changes until the t gauge needle rose to normal temperature. It seems water pump is the culprit for overheating and I don't have to worry about the headgasket leakage for the time being.