calebmitterz

My ml320 has been having a issue of not wanting to accelerate, I assume that the issue is a vacumme leak. I also have the infamous hiss from the brake booster under the dash. Can the hiss be a big enough vacuum leak for the motor to act up when its under load in drive?

Maj. Dundee

Please UPDATE YOUR PROFILE in USER CP to include the year of your ML.

Maj. Dundee

Disregard my above post. Your info is complete.

Maj. Dundee

Did you perform any repair to the truck prior to this problem?

calebmitterz

I did change a coolant hose close to the firewall about 6 months ago, but I noticed the hose is leaking again and a little bit of smoke on start up near the manifold from the coolant leaking on the o2 sensor. I'm getting a lean code from the scanner. I'm not driving the ml320 at the time. If this helps for maintenance I changed out all the fluids for everything like the front and rear differentials, transfer case fluid, transmission fluid, engine oil of course and the coolant as well within the past year. Could the coolant leak on the o2 sensor on the passenger side cause the motor to run poor? I'm also going to attempt a smoke test with a cigar to check for vacuum leaks. Is there any test I should perform first?

Maj. Dundee

O2 sensors are always exposed to the elements so that wouldn't be a problem, unless the coolant drip has caused corrosion at the connector.

Are you getting lean codes on both banks?

When are you going to get a used booster as that might correct the entire problem?

calebmitterz

Hi, im getting a lean code on both banks. I do plan on replacing the brake booster very soon but I also noticed the black hard plastic line that runs from the booster to the back of the intake manifold is noticeably loose where it plugs into to the manifold. Since the coolant hose is leaking I’m planning on removing the coolant tank to replace the hose and I’ll have a little more access to the vaccume lines to see if I have any noticeable leak.

Maj. Dundee

Here are the parts that should be changed, no more than $20. It's is complicate to replace these parts since you will be working blind because they are at the rear of the intake manifold.