M103 - Testing for combustion leak into coolant
 

Battling coolant loss problem. Have yet to buy/rent pressure tester, but will likely do so soon.

I ran across something I saw posted @ http://www.mercedes.cx search facility awhile ago and would appreciate any thoughts on the validity of this "poor mans" test for combustion leakage into coolant.

One removes the coolant tank cap and ties a rubber glove(I thought about using a latex glove-mechanic's type) around the expansion tanks neck. The article didn't say what to expect, but I assumed the glove would fill with air after idling the engine for awhile.

I started out trouble-shooting this as an "air in the system" problem. With car on a flat surface, I removed the cap and ran the engine with defroster on to run coolant thru the heater. After 15 mins or so, the coolant level rose some, but did not gush out as it does when doing this on some Asian models.

Won't the glove "expand" as the coolant also expands whether or not there's a combustion leak?

Would appreciate any/all learned thoughts.

Thanks.

If you had a communication between the cooling system and any of the cylinders, you would expect to see loss of coolant and high pressure in the cooling system. Remove the cap, start the engine and if there is leaking, it will usually show as bubbling in the tank. If no bubbling or high pressure, start looking elsewhere, as there are plenty of other available places for leakage.