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Discussion Starter · #1 ·
Hi again, I am in the process of changing my thermostat (thanks to expert guidence from ronnie) I have a small amount of mayo on the oil cap and have seen in other posts about a sniff test. what is this?? it does smell awful is that a good thing or a bad thing.:confused
 

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A garage will have the engine running with the coolant cap off and "sniff" the coolant with an exhaust gas analyzer to check for signs of exhaust gases in the coolant. A reading of HC will indicate a head gasket failure due to them escaping into the coolant system. If this is the case the hoses will be really hard with the rad cap on due to pressure from the compression. :thumbsup
Are you doing short journeys? A small amount of condesation is normal with short journeys and cold weather.
 

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A sniff test is easily performed and only takes a few mins...........if u want - you could get a kit yourself from either the likes of snap-on, ECP, E-bay, etc.

they will range from about 30-55 squids........the one we have is a Snap-on but they all do the same thing- basically after the car has been run up air is drawn up from the coolant expansion tank/radiator into a chamber (part of the kit- kinda like a big ass syringe), the upper half of he chamber is filled with the test liquid- as the air from the coolant system is drawn-in, the test chemical will change colour- our snap-on one

kit has a blue liquid, if there are cumbustion fumes detected in the coolant system then the liquid will start to change to from blue to green to yellow- depending on the amount of fumes detected- if the colour changes then that's bad news- means you have a cumbustion leak some where, i.e head gasket, cracked head, etc.

as with the pro you've got with the mayo stuff under tour cap.........have you checked the dipstick? is there the same mayo stuff around the dipstick at all? does the car over heat? drive bad at all, misfire? if the answer is no to all the above then I would'nt worry dude.............some/most vechiles will get smoe mayo build-up wich show's up under the cap due to moisture build-up, caused by weather conditions and if the car has been stood for some time.....mercs are pretty known for this and half the beemers that come in to us show this also........nothing to worry about mate. BUT if you are having issues with car and you need peice of mind then the sniff test is the away to go.
 

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Discussion Starter · #4 ·
Thank you guys,
I think it will be ok now my thermostat had died so the engine was always running cold. i hope that it will clear up,
Thank you both very much
 

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Rather than spending cash on a gadget to do the sniff test for you, use your nose. That would be the idea of the sniff test.

If you can smell exhaust gases in your oil chamber, your gasket is on its way out.

As said above, a small amount of mayo can be expected with short journeys and cold weather, as condensation appears in your oil, long journeys tend to burn this off, erradicating this.
 
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