I aint never seen one ..... but I do know they DO exist ....
The way I did mine on my Merc E240 was I syphoned off maybe half a jar full of water (When Warm!!) from the expansion tank into a "Pickle Jar" ( or at least a jar with a rubber sealing top) ..... & whizzed off to the local MOT testing station & got him to shuv his Exhaust gas analyiser into the jar!!!!!!..................
YEP Exhaust gasses present ........ HG FOOKED!!!!! ......
Haha what an excellent idea hooded, love it. Many thanks Ill find the nearest place and see if they will do it for me. Cheers again
trash- mot gas analyser far superior method and can detect a lot earlier on