sniffer in coolant tank for headgasket test?
09-12-2007, 02:05 PM
#1
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sniffer in coolant tank for headgasket test?
A coworker was told he needs a new headgasket (ford 3.0 V6 taurus) based on an emmision test sniffer in the coolant tank saying that the HCs are high.
Is this a valid test?
Is this a valid test?
09-12-2007, 02:11 PM
#2
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I think a lot of things can cause high HC.
I got mine to drop when I changed my AFM, FPR and Cat.
High HC means the car is burning an unacceptable amount of oil that the cat cant convert right?? maybe?
IM just talkin outta my *** here don't take that last part too serious.
But before I changed some parts my HC was too high and the guy doin my inspection said it was because there was gas in the oil... and therefore oil in the gas...? IIRC
I got mine to drop when I changed my AFM, FPR and Cat.
High HC means the car is burning an unacceptable amount of oil that the cat cant convert right?? maybe?
IM just talkin outta my *** here don't take that last part too serious.
But before I changed some parts my HC was too high and the guy doin my inspection said it was because there was gas in the oil... and therefore oil in the gas...? IIRC
09-12-2007, 06:14 PM
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you can use a chemical test on the coolant to determine if byproducts of combustion are present, telltale sign of HG problems. Or take theplugs out pressurize the sysytem with a press. tester crank motor over, if no coolant comes out you're safe.
09-12-2007, 09:33 PM
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http://tinyurl.com/23jkvj
It's cheap enough for your friend to buy and do his own diagnosis.
09-12-2007, 10:02 PM
#6
Yes, this is a valid test. There should be no Hydrocarbons in the coolant system, they get in when the headgasket starts leaking and allowing combustion gassess to enter the cooling system. I wouldnt start ripping the head out yet, you should do compression and leakdown tests to furthur verify headgasket. Be very careful with a Taurus though, if they get even a little hot they will warp the head.
Mark
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09-13-2007, 01:33 AM
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A leakdown test is the best option. Some coolant expansion tanks, like the 944, are designed as extensions of the cooling systems. Hydrocarbons might not reach the tank to register against the chemicals. This is coming from personal experience.
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09-13-2007, 09:47 AM
#8
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The problem I have found with any of these tests: yes they will work if you have a large headgasket leak.
But if you only have some slight pressure seepage at full load/high rpm, a compression, leakdown, or combustion gas/coolant check indicate there is no headgasket problem.
The cylinder pressures at full boost/full load are huge compared to the 100-150 psi used with a leakdown or compression check, and the coolant test is done with the car running at idle. You will get a lot of false negative results using these methods, until the headgasket leak gets worse. You will likely start seeing coolant in the oil by that time.
But if you only have some slight pressure seepage at full load/high rpm, a compression, leakdown, or combustion gas/coolant check indicate there is no headgasket problem.
The cylinder pressures at full boost/full load are huge compared to the 100-150 psi used with a leakdown or compression check, and the coolant test is done with the car running at idle. You will get a lot of false negative results using these methods, until the headgasket leak gets worse. You will likely start seeing coolant in the oil by that time.
