Cold weather problems with shutoff valve OM617? - PeachParts Mercedes-Benz Forum

Zacharias · #1 01-19-2013, 01:44 AM

Short version: Has anyone ever experienced cold-temperature-related problems, or problems due to big changes in ambient temps, with their shutoff on an OM617 (or 616)? We have had several violent temperature swings over the last week (from almost 40 deg F down to -9 F in about 24 hours, then back up to 23 F).

Full story: Yesterday when I left work the '85 300d wouldn't start at -15 deg C (about 5 F). It was plainly not getting any fuel. No smoke when cranking, and when I tried the primer pump I was pumping air. I had to have it towed home.

This morning, after a night on the block heater, it started right away at -10 deg F. I suspected some water in my fuel filter(s).

As I didn't want a repeat of last night, I left the car idling all day in the parking lot at work.

Today the weather turned much warmer during the late afternoon. When I left work it was around 23 deg F.

Now it won't shut off unless I use the lever under the hood. I checked and the line is connected. No evidence of oil from the area of the ignition. That was as much as I could do in the dark and cold tonight.

In the past, when I have had a shutoff valve fail on other cars it gradually started slowing down until it failed completely. This one has given no warning, assuming it is the valve. I will have to figure out where I hid my Mityvac and test it tomorrow.

In the meantime: any ideas, suggestions?

Phillytwotank · #2 01-19-2013, 08:47 AM

I had one that was on it's way out for sometime and it's problems where exacerbated by even SC winter temps.

Makes sense... It is rubber that makes the vacuum seal inside the shut off valve. Also, i belive no oil in the lines is not necicarily indicative of the health of the valve. If you had a small leak that only manifested itself in extream cold temps and it was only sitting at idle, there may not be any oil in there yet.

I have a few used valves that test GooD if you are in the market for a used one.

kerry · #3 01-19-2013, 10:54 AM

The problem is probably somewhere else in the vacuum system, likely the climate control. A pod is leaking and not allowing enough vacuum for the shut off.

Biodiesel300TD · #4 01-19-2013, 11:38 AM

It's pretty common for vac leaks to develop when it gets cold. Things shrink a tiny bit and they get brittle, so they can tear easier. I'd suspect leaks elsewhere or a connection somewhere. Maybe a hose popped loose while it was sitting and idling. But don't count the shut-off valve out either, the diaphragm inside could have cracked.

Zacharias · #5 01-19-2013, 01:08 PM

Quote:

Originally Posted by Biodiesel300TD

I'd suspect leaks elsewhere or a connection somewhere. Maybe a hose popped loose while it was sitting and idling.

Thanks. I thought I could see everything last night, by flashlight. Not so. Today I went out and found a vac connection had pulled off elsewhere.

All is well. Nothing more to see here....

pop & blow · #6 01-19-2013, 05:55 PM

With and original will do that mine did it was original and at very low temps seemed to happen, you would think in very hot weather it would do that , but never did but cold weather did. must be binding internal?

Zacharias · #7 01-20-2013, 12:39 PM

Quote:

Originally Posted by pop & blow

With and original will do that mine did it was original and at very low temps seemed to happen, you would think in very hot weather it would do that , but never did but cold weather did. must be binding internal?

Well I may yet be proven wrong, but I am pretty sure I have now nailed the issue. I check the tension on the claims for the fuel hoses at least once a year, but when I changed the fuel filters yesterday I found the clamp at the inlet to the lift pump housing was really loose. Also the clamps on the cigar hose could have been tighter. I thought I had been thorough back in the fall, obviously not so much....

So I am hoping that, and/or water in the spin-on filter, were the causes.

The tricky part is that I will need to take a chance on a very cold day by leaving it parked long enough to find out, so I'll have to wait for a weekend as I don't want to pay for another tow home from work.

We have extreme cold weather coming this week, but the predictions are such that I will likely leave the car idling all day in the parking lot at work anyway.