Rinsed engine now vacuum problem - PeachParts Mercedes-Benz Forum

cewyattjr · #1 03-30-2010, 08:39 PM

So I had some antifreeze slop on the drivers side of the engine bay this weekend. I gave it a spray so I wouldn't have sticky/greasy coolant coated hoses and such. Not even a major spray, just a little one...

Next thing I know, I'm having problems shutting down when I turn the key. Coincidence? I checked the usual culprits ... the three prong intersection of hoses that lead out of the firewall, all connected.

One odd thing, if I hit the drivers side lock it will stumble to a slow shut down.

Guess I'll get the MitiVac out!

toomany MBZ · #2 03-30-2010, 09:27 PM

I doubt what you did had an impact, but check everything again anyway. Do your door locks work okay, slow?

cewyattjr · #3 03-30-2010, 09:44 PM

They are pretty intermittent and always have been. I've never had a shut off problem unless some obvious line was not attached under the hood. I think I need to learn a bit more about where the shut off valve is, I suppose it could be that. My brakes don't feel hard and the shifting isn't harsh.

My kids are particularly embarrassed when I have to pop the hood and hit the stop switch!

BTW, the shut off valve, or what I THINK is the shutoff valve, the white thing under the green check valve, makes a buzzing noise with the vac line connected, so that seems a little suspicious. Attached with large red arrow.

scoodidabop · #4 03-31-2010, 09:01 AM

Quote:

Originally Posted by cewyattjr

BTW, the shut off valve, or what I THINK is the shutoff valve, the white thing under the green check valve, makes a buzzing noise with the vac line connected, so that seems a little suspicious. Attached with large red arrow.

You're close! It's just to the right of that, and a little harder to see... The white thing is a vacuum modulator for the transmission... unfortunately since it's making that buzzing noise, it needs to be replaced. My wagon started doing the same thing one day... it was obvious something was wrong because my shifting became very erratic. I believe the buzzing is actually caused by some internal components rubbing together as a result of a leak... think of it as a tiny whoopie cushion.

cewyattjr · #5 03-31-2010, 09:13 AM

Hey scoodidabop,

OK, so the shut off valve is somehow wedged between the oil filter canister and that vacuum modulator thing, eh? It's always something! I have to bring the car into my indie mechanic next week for new axles, a new driveshaft and probably this as well.

Hey, I see your comment about Monark nozzles. They made a huge difference in my idle, along with a valve adjustment.

Now if I could just shut it off with a key!

Thanks for the wisdom on this!

Chuck

cewyattjr · #6 04-01-2010, 08:59 PM

Stumbled across this helpful link that describes how to get to the shutoff valve:

http://www.dieselbenz.info/dieseling_injection_stop.htm

vstech · #7 04-02-2010, 09:48 AM

hook a hose up to the shutoff line and suck on it. if it shuts off, you're fine there, and need to look elsewhere for the leak.

cewyattjr · #8 04-02-2010, 09:59 AM

That's the plan for this weekend. Right now, what's kind of odd is that if I have my door locks down and the CC on the "cool" side, it shuts off nicely. Pull up the door locks and put the CC on "heat" and absolutely nothing!

cewyattjr · #9 04-03-2010, 01:55 PM

Update: MityVac on the shut off proves that it works fine. Not the green CC line either, that works fine. Leak seems to be relate to the ones coming off of the yellow splitter check valve, like the one in Eric's example:

http://ericandkat.com/mercedes/W123VacDoorLockDiag.JPG

If I block off those lines coming off of the check valve, the vacuum to the shut off valve holds. So I'm guessing the vac switch in the drivers side door. Meanwhile using the golf tee trick, I can shut off my car.

biopete · #10 04-03-2010, 10:40 PM

You people's engines are way to clean. Its ridiculous. What do you do replace every little o ring as soon as it weeps? Seriously nice looking engine. I did some cleaning on one of mine this weekend. It was fun. My problem is I have too many. Plus I'm not that meticulous .

Cheers.

toomany MBZ · #11 04-04-2010, 11:25 AM

Quote:

Originally Posted by cewyattjr

Update: MityVac on the shut off proves that it works fine. Not the green CC line either, that works fine. Leak seems to be relate to the ones coming off of the yellow splitter check valve, like the one in Eric's example:

http://ericandkat.com/mercedes/W123VacDoorLockDiag.JPG

If I block off those lines coming off of the check valve, the vacuum to the shut off valve holds. So I'm guessing the vac switch in the drivers side door. Meanwhile using the golf tee trick, I can shut off my car.

Sounds like you've narrowed it down to a leak in the door lock system, that's what the yellow check valve with yellow lines operate.

cewyattjr · #12 04-04-2010, 03:02 PM

Yeah, I can't take credit for that engine shot, I found it online, as it was a good example of my 300D engine, and definitely cleaner!

cewyattjr · #13 04-06-2010, 08:53 PM

So should it be pretty easy to test that yellow check valve, like this one, does the air go OUT the direction of the side with one nipple (flowing in via the side with two nipples) ?

toomany MBZ · #14 04-06-2010, 08:57 PM

That is a vacuum check valve, suck one the one side, you should be able to, try blowing on it, should be a no go.

cewyattjr · #15 04-07-2010, 09:01 AM

I think it works as advertised. That would be an easy fix of course. What would it mean if the car shuts off when I push the locks down, but when unlocked the system leaks and no shut down?

Aha... just found this:

Car shuts off w/driver's door locked, but not when unlocked?

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