I'm having hard starts on my 79 300sd. It has 360/350/360/355/340 compression. The glow plugs were tested out of the vehicle and lit fine. The glow plug relay seems good as we're getting 12v everywhere. Just had a valve adjustment and changed the air filter too.
Any insights? Is it the 5th cylinder being weaker than the others?

Jason

You should only begetting 10V to each glowplug. Are you sure you have verified voltage at the plugs?

When was the last fuel filter replacement, both primary and secondary filters?

Is your primer pump leaking fuel, could be getting air into the fuel system. Notice any other fuel hose leaks? Carefully inspect the hard plastic lines, they are known to split after so many years and allow some air into the system.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Your valve clearances probably need adjusting. Especially if you have no ideal when they were last done.

Required to at least check the clearances every fifteen thousand miles. Common for decreased gap on the valve train to cause hard starting as well or contribute to it.

The OP stated he just had a valve adjustment. Im guessing he did that prior to the compression test.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Is your screen name an indication of the fact that you've been running the vehicle on SVO? If so, how long? Failure to start on a vegetable oil car is often an indication of a failed IP due to not running on diesel.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I did have a valve adj. and changed both filters. I took a test light to the glow plug ends.

good call Kerry.

It wouldn't surprise me if the fuel injectors were full of crap from the SVO. And as Kerry suggested, it could be a failing IP.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Thanks for your fast replies. Hard, coughing starts were a problem before running SVO. I just started using that.

On diesel, It will start, I just have to hold the accelerator down while cranking. It will then start, lose rpm, then rev. RPM swings up and down for a few seconds after ignition.

I believe there was a thread about your last symptoms on here about a month or so ago, also on a 116SD. My recollection is that replacing the lift pump solved the problem. Can't think of a good search word to find the thread.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

One other oddity was that when priming the fuel lines, the primer pump was pulling back when I pulled it out to extend it. I attributed this to a bad primer.

I attribute this to a restricted fuel line.
Was this with the system full of diesel?

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Sounds like a clogged fuel line, could be a blockage, the strainer in the bottom of the tank could be clogged. Check for kinked fuel hoses.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

Maybe also a failure in the lift pump.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

My 240D was hard starting a few weeks ago because it had a small air leak at the fuel filter, it was letting air into the fuel system overnight.