1981 300SD No shutoff - how do I find vac leak? - Page 2 - PeachParts Mercedes-Benz Forum

mannys9130 · #16 01-05-2016, 05:45 PM

DAMN!

The 60x shut off actuator is 35 bucks. The 61x is 100 bucks more! Wow!!! Unbelievable.

tyl604 · #17 01-05-2016, 08:19 PM

Agree.

tyl604 · #18 01-06-2016, 01:27 PM

Well, this is not good. The car would not shut off today using the shut off valve under the hood. Ran for probably five minutes as I kept trying to use the shut off valve. Finally it stopped running.

What the heck is happening?

jabstick420 · #19 01-06-2016, 02:23 PM

if pulling vacuum to the valve doesn't shutoff the engine then it sounds like replacement time.

here is a good writeup: How to Repair Your Shutoff Valve

BillGrissom · #20 01-06-2016, 03:00 PM

I bought a lot of those shutdown valves from a surplus house and sold ~7 on ebay over the last 2 years for ~$70. Might be able to repeat, but they sold very slow and I don't like risking fussy M-B owners complaining and bashing my good feedback. They were made in India, which turns off half the people here even if from the same plant that makes M-B branded ones. I offered a 1 yr warranty and only one guy complained it didn't hold vacuum (I tested all). I told him to put a nail in place of the stop valve and see if that holds vacuum. Never heard back. Some people have no diagnostics skills, which are the ones I don't want buying and fussing. If enough interest I might risk moving another batch, though P-P wouldn't appreciate the competition.

tyl604 · #21 01-06-2016, 04:38 PM

Jab - thanks for the DieselGiant pics; that will be a big help.

But I am confused. So far I have not had time to track down the vac leak with the Mityvac. Are you guys saying that because the shutoff lever would not work today - that for sure I need to replace the actuator behind the injection pump? Is this conclusive? Or do I need to go ahead and test the vac with the Mityvac?

Bill - if for sure I need a new actuator, would be glad to buy one from you.

So what do I do now - do I go through the vac tests with the Mityvac or just for sure replace the actuator? What exactly does the shut off lever do? Does it pull on the actuator or what?

Oh, also where is this rubber boot on the ALDA? Have no idea where to look.

Thanks. Still confused.

mannys9130 · #22 01-06-2016, 07:52 PM

OK, so you turned the key off and the motor refused to turn off, but you pushed on the stop linkage and that also didn't turn the engine off?

tyl604 · #23 01-06-2016, 10:58 PM

Absolutely. I was amazed. The stop lever did not stop the engine. I tried holding it fast, then varying how much it was pushed and tried everything. The engine just kept running. Not sure why it finally stopped.

So how can the stop lever not work? Is it tied to the actuator and this proves that the actuator is bad? This is the only explanation I can come up with now without input from you guys.

mannys9130 · #24 01-06-2016, 11:25 PM

Your stop lever and throttle linkage must be getting held up by something. Perhaps a clean and lubricate is in order for all the ball and socket joints. The stop lever actuates the same linkage on the inside of the pump that the shut off actuator acts on. That linkage cuts fuel off to stop the engine. The actuator pulls on the linkage using vacuum on the diaphragm inside of it, and the stop lever is connected in the same way so that pushing it pulls the same way.

tyl604 · #25 01-07-2016, 12:45 PM

Manny - Well that's not good news. Sounds like you are saying that by pushing on the stop lever it should cut off no matter what - even if the actuator is bad and needs to be replaced. I can see nothing that seems to be stopping the lever from full travel.

Does anyone have a pic of exactly how the linkage should look? I did not notice that anything was missing.

Also where is the rubber boot on the ALDA that DieselGiant should be removed so you can put a spray can top over it in case of run away engine. Actually I do not even know where the ALDA is located.

Just used WD40 on the rods; does not seem to need it. Afraid to fire it up again; may not be able to shut it off.

tyl604 · #26 01-07-2016, 01:40 PM

1981 300SD No shutoff - how do I find vac leak?-img_20160107_132911.jpg

Went out and looked at the linkage again and cannot see anything missing or unhooked. Here are some pics. See anything?

tyl604 · #27 01-07-2016, 02:53 PM

Better pics from a real camera.

mannys9130 · #28 01-08-2016, 12:08 AM

I don't know exactly what a 617 linkage should look like. Hopefully somebody can verify that for you.

I'd think the spray paint can cap would go over the turbo inlet, not the ALDA. The ALDA is the square thing on top of your IP right to the left of your golf tee vacuum line plug. Its job is to restrict fueling until the turbo spools up boost, which then acts on the internal diaphragm and allows maximum fuel to be injected when you floor the pedal. Touching the ALDA wouldn't stop a runaway.

I don't think it'll runaway if you start it. You just must not be able to push the stop lever far enough.

The part about running away is if you install the new shut off actuator wrong, it will push the linkage that it connects to in the opposite direction, and the engine will go to mechanical redline as soon as it's started. Turning the key does nothing because the actuator arm is on the wrong side of the linkage.

tyl604 · #29 01-08-2016, 08:53 AM

Agree that it sounds like I am not pushing the stop lever far enough but do not see anything in the way.

Where so I find this rubber ALDA boot? Where is the turbo inlet?

Thx.

mannys9130 · #30 01-08-2016, 11:55 AM

I don't think there is an ALDA boot. The turbo is directly beneath the air filter. Air goes into the front facing hole in line with the car front to rear, and it's blown into the intake from the "snail shell" housing up toward the hood.