my 1977 300d will not start. the 300d runs perfect when started -if i can get it running. the fuel keeps getting air int the lines. so, i changed the lines and put new crush washers. the line that runs from the secondary filter to the injection box has a hissing noise when bleeding the air from the lines. then a few minutes later, i can see air in the lines. the problem started a few months ago,. i had to use s starter fluid to get the car to fire. the problem just kept getting worse. i'm just looking for the best place to start with-out wasting a lot of money.

andy

get the valve clearances checked.

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1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
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1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD

with these symptoms to replace the priming pump.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Although this is technically a "Vintage" vehicle, you will get MUCH more help on this in the Diesel forum. I'll leave a redirect here for a few days so you know where the thread went to.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Try leaving your fuel tank cover off just in case you have a vaccum. Simple and eliminates that possibility although it's not likely. Tom's suggestion two posts earlier is more in line. The check is when pumping the pump no fuel should be coming out there. If there is quite a bit leaking out certainly replace the hand pump. If fuel leaks out air can leak in. It's less than 20.00 for the new improved type if test indicates it is required.

How old are your fuel filter?

Adjust the valves and if the hand primer is leaking, replace it.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

is that what the hisssing noise is when i pump it? it doesn't really build up any pressure. i've replaced all the fuel lines and filtlers. and no leaks

Loosen the spin on filter and see if its full of fuel. If it is then the primer pump is doing its job.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

the filter is full when i took it off. the primer pump will fill it with gas and the a few minutes later, you will see bubbles in the line and airpockets will develope. my understanding is that there should be no air in the system. plus, at the end of each pump, there is a psssst.

The noise is probably just the return valve noise on the injection pump as fuel is processed.

I neglected to mention that you may be fixated to the fuel system. Your glow plugs are working well? The only true answer is to check them out.