When I take my 67' 250s on the freeway and then at any point decelerate a plume of white smoke comes billowing out the tailpipe. I don't even have to brake, If i just take my foot off the gas this happens. Any thoughts? Thanks

White smoke is usually either a vacuum modulator leak or a brake master cylinder leaking into the booster.

Blue usually means valve guide seals.

I'll 2nd this and say from my experience, it's the vacuum modulator for the AT that causes my huge mosquito fogger cloud of white smoke.

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I'll 3rd it. Pretty easy fix as I recall.

- Peter.

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1971 108 280S

So you guys are referring to a Automatic Transmission? I have a manual. And I have been told about the brake booster but it happens even If I don't brake.

The valve stem seals are passing oil at high vacuum. The valve guides may be worn also. It's a typical problem.

You don't have to brake for the fluid to be sucked into the intake manifold and in fact the act of letting off the acc. pedal "creates" a higher vacuum.

Have you noticed any loss of brake fluid?

The only other cause of white "smoke" I know of is actually white vapor from burning coolant but you should have noticed either a coolant loss or overheating.

On a side note, I didn't think anybody ever let off the gas pedal in Sacramento.

The difference between "white" smoke and "blue" smoke is not great.
Brake fluid will not be moved into the intake manifold until the brakes are applied.

a chevy 3500 did this in front of me today.

i thought the guy had a cracked head

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2006 E320 CDI, 57K bought at 67K "Liesl"
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1987 300TD (Chuggin Along), 292K "Friedrich"
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Thanks guys. The valve guides make since I have a decrease in oil level.

There ya go! Another case solved by the collective minds of the Peach Parts Posse!

Motto; "Resistance is futile, it's usually caused by corrosion at the terminal ends"

On the plus side, this head is designed so that the valve guides can be changed without removing the head. Probably the only place that could do this would be the Mercedes dealer since it requires a set of special tools to do this, but it can be done.

A quick lesson in how this was accomplished....

Remove the spark plugs, remove the camshaft.

Install the special tool into the spark plug hole for the cylinder you are working on. This tool screws into the hole and has a air hose connecion on the back of it. Connecet an air hose and apply 600 psi (yes, 600 psi) of air to keep the valves from falling into the block. Remove the valve springs and then use another special tool to remove the valve guides from around the valves.

Use another special tool to insert the new valves guides. Replace the valve springs. Slowly bleed off the air pressure and move on to another cylinder until you have done them all.

Replace the camshaft and adjust all the valves.

Replace the spark plugs.

I have never done this and I have never seen this done and I have never known of anyone that has ever done it. But Mercedes did write up instructions on it so I guess it can be done.

I would just have a valve job done, myself.

Ummm, I don't think so. Somebody made a mistake doing the conversion factor. 600 PSI would probably blow the head gasket clean off the block

I know what you mean, but 600 psi is what the manual called for. Maybe someone still has the factory book and can look it up. My feelings won't be hurt if something I have posted is corrected.

It seemed way out of line to me as well. I questioned the mechanich at the time, which was 40 years ago, and he said they did not have the compressor to do the job, much less air hose that would hold 600 psi. I mean, who does?

They did have the factory tools, though, but that was a 'if you are an authorized dealer you must have all the tools' sort of thing.