I know the newer models had WAAAAY more power than the turbo benz of similar years. and fantastic mileage.
popping noise is kind of hard to diagnose in text... perhaps you can record an audio clip or video of the engine with the noise, and post it here?
it could be as simple as a blown exhaust manifold gasket...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I would not agree they had WAAAAAAAy mor power. I am not sure I would even agree they had any more power.

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.

Run away....run fast, run hard!

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Current:
1985 300D aka Miss Margaret
1991 300SE aka Alarice
1995 SL320 aka Samantha
1997 K1500 Silverado
Past:
1999 E300 ex-wife got it and let her son ruin it
1984 190 2.3 ex-wife got it and let her son destroy a great car
1985 300D (CA version) aka Maybelline lost to deer at high speed.
1981 300D aka Madeline (went to salvage at near 400k) rusty, yet best car I ever drove
Wishlist:
McFarlan TV6 (only a few privately owned)
ReVere with Rochester engine
1917 Premier (only one left)

Per L of displacment the 5.7L Diesel has had WAAAAY less power than even MB's 240D.

The early engine had 120hp and 220lb/ft torque, later ones had less.

That is 21hp/L for the 5.7 and 30hp/L for the OM616. Consider the OM617a that had as much power and only 40lb/ft less torque with 40hp/L and was in production for the same length of time (78-85) and the GM diesel comes out pretty pathetic.

To be on the same scale as a 617a, it would have to put out 228hp, 171hp to match the OM616. Much more than the 5.7 is capable of without puking parts on the road.

Sounds like it might be time for a Cadillac-Benz... LOL

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92 300D 2.5L OM602 OBK #59

really? that low HP huh... the 'seat of the pants" power to weight, not power to Liter is what any driver cares about... the two wagons I drove were tanks but they sure did haul. they handled all the towing and cargo I could throw at it and the puking parts aside, they were pretty nice vehicles.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

If the popping noise comes from the air intake, then its probably a broken rocker arm pivot. Common part used in both gas and diesels in those years. Is necc. to remove the fuel hard line "spider" assembly to remove valve covers. DO NOT bend the hard lines to get in there! I was there when these were new. Much more powerful and shifted better than my 300CD. The block was a high nickel content block so it was much stronger than the normal cast iron 350.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

Thanks for the info, Carnut! I'll look into there and see what I can find...

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'79 300SD
'82 Chevy Chevette diesel