I was wondering if anyone has a digital pic of the pistons that go into my 300 or 420?

Are these pistons the same size?

Are they dished? Flat?

Thanks


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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

They are flat with valve relief cuts and swirl cavity on one side of the piston.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

Do you know the compression ratio on these 2 engines, 300 & 420? I would assume 10:1?

I am satisfied with my 3.0 L. How about you? What were some of the pros and cons of this engine.

BTW, thanks.

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

I love my M103. Compression is either 10:1 or 10.5:1. Not sure, but who cares... High revver, smooth, rock solid bottom end. Plenty of meat in the block. Head is a little weak (kinda soft aluminum alloy). Know for eating valve guides and seals. Performs like a much bigger engine. Not much bottom end, but I never expected a dragster when I got the 300E.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

Considering proper maintenance, what is the expected mileage life of these engines? 300,000? 200,000? 400,000? How much before replacement / massive rebuild?

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

Matt, who knows?? Keep changing the oil every 3000 miles and keep up on the scheduled maintainance. Could outlive you

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE

I think the 103 had 9.2:1 and the 104 had 10:1.

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Benzmac:
Donnie Drummonds
300E
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I don't know engine numbers so I am right by saying the 103 is the 3.0L and the 104 is the 4.2L

If the 3.0L is only 9.2:1 , then why do I have to put premium gas? Can I get away with 87 octane? This seems like low compression to have the hi octane??? The 4.2 I can see, but not the 3.0?? What do you think?

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

Matt, I think the M104 is essentially the M103 with a 24 valve DOHC head on it. They might have upped the displacement to 3.2, but I am not sure. I don't think that block could ever be stretched to a 4.2.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE