Smokin' 420 SEL - PeachParts Mercedes-Benz Forum

E150GT · #1 01-19-2007, 03:40 PM

Hey guys and Gals,

I got an 86' 420 Sel that sometimes when I nail the throttle produces large amounts of what looks like white smoke coming from the tailpipe. It does not smoke on any other occasion the a full throttle downshift that I have seen. I alson have only noticed it a handful of times. The car has about 200,000 mile almost and the heads were rebuilt about two years ago. I have a full engine crankase with clean mobil delvac 15w40 and I dont need to add oil between 3 month oil change intervals. Im not sure if its burning oil or maybe just blowing accumulated carbon or something. Are these engines suseptible to carbon buildup? Should this be a major concern? Any input would be appreciated. Thanks.

E150GT · #2 01-19-2007, 04:10 PM

Come to think of it, I just topped it off last week with antifreeze. How does it burn coolant?

gmercoleza · #3 01-19-2007, 04:19 PM

Quote:

Originally Posted by E150GT

Come to think of it, I just topped it off last week with antifreeze. How does it burn coolant?

Cracked head or blown/warped headgasket will allow coolant to leak into the combustion chamber where it turns to steam during combustion. It exits the exhaust as a white steam cloud.

gmercoleza · #4 01-19-2007, 04:22 PM

How are your brakes? Sometimes a leak through the master cylinder and booster diaphragm can make its way into the vacuum boost tube and produce similar results. The first things I would do are compression test and then vacuum test using a Mityvac on the brake circuit if the compression checks out OK. Of course if you're not losing any brake fluid then you can probably rule out the brakes.

E150GT · #5 01-19-2007, 04:45 PM

I also had to top off the brake fluid twice in about 10 days

david s poole · #6 01-19-2007, 06:24 PM

one more thing,when the modulator goes bad the vacuum line will draw trans fluid into the engine and burn it.i had a car driven in with trans on last legs because of no fluid.check trans fluid level.