240D IP blowby problem and more?

[mfreborg]

I've been having some shutdown trouble with my '82 240D (auto, 230K). It shuts down okay (not quite immediate like my 300SD, though) IF I drive for less than 15-20 minutes, but much more than that I have to turn the ignition off, leave it in drive, and wait for the slow wind down, which can end in a car-shaking, shuddering halt, usually in 5-10 seconds, but sometimes it can take much longer. I can't imagine what bystanders must think of this spectacle, but the little diesel does eventually stop. I don't use the stop lever under the hood because pushing it only reduces the rpm and does not stop the engine. The problem seems to worsen as ambient temps rise.

My questions:
1) I measured about 16 in. hg going into the shut off valve when key is turned off. Is that sufficient to operate the valve? I ask because I seem to have 20+ in. hg off main vacuum pump line and at vacuum line splitters. Door lines are blocked. I have been searching the site extensively, but I haven't been able to find definitive vacuum reading specs.

2) Is it possible to get blowby out of the rear area of the IP? This engine is a little tired, and blowby from the oil filler hole on the valve cover is pretty bad. I cleaned all the surface oil off the IP and surrounding area, but I still have a very obvious oil vapor coming from the vicinity of the back of the pump.

Many thanks for responses.
Mike F.
'82 240D 230K
'82 300SD 180K
currently tempted by an '84 300D that seems to have my name on it

[dmorrison]

Shut off is not a blowby factor it is the ability of the fuel to be cut off at the injection pump. Her is the step by step method of determining where the problem is. You have done some of this.

Get a Mityvac or equivilent.

Disconnect the large black hose going from the vacuum pump to the brake booster at the booster. Disconnect the 2 small vacuum hoses coming off the large black hose. Connect your Mityvac to one of the small connections and use a golf T to block the second small connection. Block the hose with your thumb while the engine is running. You should have 22-25+ inches of vacuum. If not then its your vacuum pump. It can be rebuilt.

If the vacuum is ok. Use your Mityvac, while the car is running and apply vacuum to the IP shutoff valve. The engine should die very quickly. If not then it is your shutoff valve. Look for oil in the lines. If oil then you need to replace the shutoff valve OR the vacuum pump( or rebuild). You may need to clean the vacuum lines and then determine where the oil leak is comming from.

If the vacuum pump and shutoff valve are good then it something in your vacuum system that is robbing the vacuum. Doors are the usually suspect. Where the vacuum lines go into the cabin right next to the brake booster are 2 yellow colored lines. Disconnect them at the black rubber 3 or 4 way connector. Block the connector openings with golf Tee's and then try shutting the car off. If it shuts off normally its your door lock system. If not then its the vacuum system in the engine compartment or the AC vacuum system. The Ac system is the Green colored line going into the cabin. Try the same method.

Dave

[mfreborg]

Thanks for your detailed reply, Dave. I'll use it to do a more thorough check. I've been taking readings with my Mityvac and it looks a lot like I'll be changing the shut off valve (no response to vacuum). Vacuum lines are clear and readings are in the 20+ range except for at the shut off input where it is a little less. I'm still mulling over where the blowby--or at any rate, oil vapor-- is puffing out from at the rear of the IP (definitely coming from somewhere in the vicinity).
MF

[pawoSD]

The blowby could be going around the engine from by the airfilter housing possibly.....if there's a lot of it it could drift...it does on mine.... Just and idea....