Help identifying a leak at bottom of engine

[mach45]

This leak was pointed out on my 2006 XC70. It's all dry at the top and everything looks good from the hood, but the bottom noticed this leak by the engine. Anyone else experience this? Can someone help pinpoint what it could be, or give me an idea how bad? No drips seem to be on the ground. Thanks much ~Lilly

[SuperHerman]

Looks like you have two leaks.

The one that is the biggest concern is the bevel gear shown in the first and final two photos. You need to clean that off check your bevel gear fluid level and top off as necessary. Then monitor very closely and figure out where the fluid is seeping from. The oil should smell different than standard motor oil - more sulfur to the smell. The bevel gear only holds about 700ml if I recall correctly, if it gets too low it will take out that very very expensive part. It looks like you are leaking from the case housings, which is typical in the early models but I was under the impression the later models did not suffer this issue. The two halves are finely machined and sealed with anaerobic sealant - generally when this fails it has to be opened up and resealed. It is not a formal gasket. My knowledge is based on an earlier design that was found in the 2001 V 70XC - but the part appears very similar. It could also be leaking from an internal seal between the transmission and bevel gear.

Hopefully some one familiar with the newer models will chime in and clarify.

The second leak appears to be one or all of three sources. 1) Oil pan plug, 2) oil filter housing, and/or 3) engine oil cooler (that rectangular box with two hoses shown in a number of your photos - but in the fourth one you can see a white Volvo label on it) With the engine oil cooler usually two O-rings between the block and cooler get old and start to leak. Rare is for the actual oil cooler to spring a leak - but possible.

You should clean everything up really well, check your oil level, and watch it closely so you can pin point the source. Assuming it is the oil cooler leaking and the car is not leaving drips or puddles you are at the early stage of the leak and it will get worse.

If it is the oil pan drain plug it might be cross threaded, pan damaged, not tight enough or the copper washer is lacking/damaged/used too many times.

If it is the filter the plastic housing sometimes these crack, (just happened to mine after 14 years), the filter housing was not tightened correctly, or the O-ring is messed up.

Because any oil will blow back from the source as the car goes forward at speed it is hard to tell what the source of the leak is.

At this point - for all your leaks - unless the car is leaving puddles - you should be able to get by with cleaning and monitoring until you can pin point the problem. Just top off all the fluids and take a look everyday - keep the splash guard off to make things easy. With the splash guard off you should be able to lay down a piece of carpet, cloth or cardboard lay down on your side armed with a flash light and monitor from the front or passenger side.

If you have been doing the oil changes on your car - you should know what to exclude from my list pretty quickly. Plus you can exclude sloppy clean up (or include it I suppose).