View Full Version : Large oil leak down front of engine after belt change

04-08-2017, 02:47 AM
I'm in need of some advice. 08 ncv3 I had a belt tensioner fail. Replaced the belts , tensioner and the idler pulleys. Van ate the new belt in less that 30 miles. I figured I didn't seat the belt correctly and bought new belts. Replaced the belts and had a skilled mechanic take a look. He said all looked good.

Finished the job tonight and as I was buttoning things up I noticed a large oil leak coming down the front of the oil pan. This oil leak is new! Was not there when I started the belt job.

Getting the front (fan clutch) belt on was a bitch. I used a large socket to turn the crank pulley and vice grips to hold the belt in place. 99% of the time I was pushing wrench on the crank bolt clockwise if you are facing the radiator. I had one instance where the vice grips got hung up and I had to go against the grain on the crank bolt maybe half a turn . I immediately went back in the correct direction I don't think I could have backed off the crank bolt?

Perhaps the broken belt damaged the crank seal?

Thanks for any advice.

04-08-2017, 02:47 PM

This is what the front of my oil pan looks like.

Could a high leak cause oil to cascade here? perhaps the turbo?

My other thoughts are crank seal or the dreaded oil cooler leak?

My van only has 44k miles on it.

04-08-2017, 03:56 PM
can't see your picture.

belt damaged front crank seal.
turbo leak or oil cooler will leak on an back of the engine

04-08-2017, 04:21 PM
Have recently changed the oil? Spilled any?

04-08-2017, 04:27 PM
https://flic.kr/p/T5Duc5 Sorry- Here is a link to the image.

Thanks Morre- That is what I suspect as well. Does anyone have a good diagram of this engine?

I'm guessing new crank seal involves removing the crank pulley/HB, replacing the seal, then installing it all back with a new crank bolt/washer?

Is this a job that I should leave to a pro? Is there enough space to do this job without having to remove the radiator?

04-08-2017, 04:28 PM
Have recently changed the oil? Spilled any?

The oil has not been changed in probably 7,000 miles. No sign at all of this leak before the belt incident.

Dr. Soot
04-10-2017, 02:20 AM
Is the oil leak above the balancer?
Is your van making a chirping sound while it's idling?

Sent from my iPhone using Tapatalk

04-10-2017, 04:58 PM
I tried looking up there with a mirror. As far as I can tell the oil is leaking from the bottom of the crank pulley. I wish I lived closer to Golden I would take it to Linden, but I don't think I should drive far with this size leak. I'm going to see if one of the local mechanics can do this for me.. I don't have the necessary puller or flywheel tool.

04-18-2017, 05:40 PM
Hi All- I appreciate the help on this. I just wanted to follow up and let everyone know that the problem was indeed the front crankshaft seal. There was a piece of the old broken belt melted into the seal which deformed it and caused it to leak the oil. A really nice local mechanic was able to do the job for me, he ended up removing the entire front clip (lights, grill, radiator, etc) due to lack of specialty Mercedes tools. He was able to do the entire job in 6 hours only parts required were the seal and some fluids.

I would recommend that everyone with a NCV3 inspect their belts for wear and make sure your pulleys are spinning free. A simple broken fanbelt set me back a grand. New tensioner, idler pulleys, and then this seal job once I realized the oil leak.