Hello, I hope someone can help me. Thank you in advance.

If my '84 300SD sits for more than about a half an hour, it becomes hard to start. When it does start, it makes quite blast of inky smoke.

The glow plugs are working.

I put the battery charger on it in the morning to help with the 30 seconds or so of cranking it takes before the engine fires up. When it does start and I shut it off before it has a chance to warm up, it starts right up again cold. (The engine block heater is plugged in when the car isn't being driven.)

I thought my old style extraordinarily leaky hand primer pump was the problem, so I put in the new style Bosch hand primer pump and replaced the fuel filters, but the problem hasn't changed at all. Pumping the hand primer pump while cranking doesn't seem to help it start any faster.

It does start right up if I only wait a few minutes after it's been shut off, and it runs fine, no excessive smoke.

There aren't any external leaks, nothing dripping fuel since I replaced the hand primer pump, could it be an injector leaking?

I'm the second owner, it was dealer maintained by the original owner and now has 226,000 miles on it. I change the filters and oil every 3000 miles or so. I use Rotella. I don't use any fuel additives.

1984 300d Turbo 135k
2001 E320
Pull Cover On Relay Box On Right Fender, Pull Connector 5-6 Pin Connector Inside The Glow Plug Relay Box , Check Each Pin For A Reading Of 1 Ohm Or Less To Ground I Found 4 Open Glow Plugs Out Of 5 Plugs, Auto Zone Have Glow Plugs $10.00 Ea Diy, The 80 Amp Fuse Is 12 Volts All Times, Take The Ground Connector Off The Battery First Step

The glow plugs are all checked and working.

Air seems to be leaking into the fuel system over time.

Would tend to make me think that you have some injectors that are leaking. That being said though these would have to be pretty catastrphic failures to give you a big cloud of smoke. Can you tell if it smells like just unburned diesel or if it is maybe oil leaking into the cylinders?
As you cna tell I'm fishing a bit here...

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Sounds like IP failure or Injectors are leaking. Could be all of the above. You may also want to change out the lines to the injectors as well. Change out all rubber connection hoses to the lines and injector pump.

The smoke smells like un-burned diesel. After a mile or two on the highway, it clears up.

As I crank the car, before it starts or the battery dies, the smoke wafts out of the tail pipe and fills the garage even if the car doesn't start.

Then, as it starts, the big cloud blasts out the tail pipe.

After the car's been running for a while, there's no smoke at all to speak of at idle, but there seems to be a little more smoke than there used to be on acceleration.

leaking air for a certainity.

Check the following:

• injector lines at IP
• injector lines at head
• the spring thingies UNDER the injector lines at IP
• lastly - the lift pump (the actual thing that delivers fuel from tank to the IP on the drivers side of the IP can be cracked from overtightening and let in air)
• Oh, almost forgot - the most common cause is the hand pump at the IP

__________________
1982 300SD (214 k, excellent shape) kidmobile running mostly biodiesel, gets 31 mpg hwy with 2.82 rear from a euro 500SEL



1976 115 body 240D 4-speed (traded for Jeep parts) - Engine lives on in my CJ7

See, that's the thing.

Since I replaced the really badly leaking original hand primer pump with the new style Bosch hand primer pump and the car still has the same exact, unchanged problem it makes me think that the new primer pump must be defective.

The old primer pump sprayed a solid stream of diesel fuel all over the engine compartment when I used it to bleed the new filters, so I was sure it was what was wrong, it was SO bad.

It seems to me the new primer pump must be defective, too. Changing it out made no difference.

There aren't any fuel leaks on the outside of the new Bosch hand primer pump or anywhere else in the engine compartment or on any of the fuel lines or fittings.

That has to be what it is.It would be a fantastic coincidence if two things went wrong at the same time.

But...

Could an injector be leaking fuel into one cylinder when the car is shut off and letting air into the system?