84 300D vs 85 300D - PeachParts Mercedes-Benz Forum

irishflyer · #1 06-01-2009, 10:17 AM

Hello..I am looking at purchasing either a 1984 300D turbo and a 1985 300D turbo, had a chance to buy both of them (85 for parts..the body is getting to be a Flintstone car). My question is, where there any major differences between the two that would prevent parts from being exchanged in the engine, tranny, etc? Just curious.

snookwhaler · #2 06-01-2009, 10:33 AM

Different rear axle ratio (2:88 in the 85) and different vacuum systems under the hood.

irishflyer · #3 06-01-2009, 10:42 AM

Did the 84 300D vacuum system have problems with a hole in their diaphram? The air cleaner had a misting of oil in it, and I have read where vacuum problems could contribute to that. The car doesn't smoke when driving or idling. What was the ratio in the 84?

toomany MBZ · #4 06-01-2009, 01:35 PM

That misting should be taken care of via the oil separator. Excess blow by?
If you're referring to the vac pump, should be the same both years.
As mentioned, there are many differences, but the main items are the same.

irishflyer · #5 06-01-2009, 02:38 PM

I don't think the blow by is that bad. I read where you plug the valve cleaner tube and count the seconds til the engine dies. I counted 9 seconds, and I have read 8-12 means you are good...

winmutt · #6 06-01-2009, 02:45 PM

85 has different turbo, ip, transmission, vac system and electricals.

A *few* differences.

Brandon_SLC · #7 06-01-2009, 04:39 PM

Quote:

Originally Posted by winmutt

85 has different turbo, ip, transmission, vac system and electricals.

A *few* differences.

Do any of those make the 85 models better? Curious why so many changes during final year of production.

What is your unbiased opinion???

Hit Man X · #8 06-01-2009, 04:43 PM

1985.

Has updated vac control for transmission (blue UFO dealy)

Taller rear for better economy

More efficient AC condenser (double the heat dissipation ability!)

Plastic fan with more blades for more efficiency with smaller water pump pulley

The emissions stuff is goofy on Federal '85s, but nothing so difficult you can't go around. I have all mine removed and bypassed, if you need pics just PM

winmutt · #9 06-01-2009, 04:49 PM

Quote:

Originally Posted by Brandon_SLC

Do any of those make the 85 models better? Curious why so many changes during final year of production.

What is your unbiased opinion???

It is a change over year. All manufacturers that I know of do this. They road test many of their changes on the year prior to that of a new launch, helping ensure bugs are ironed out. The 2.88 rear diff certainly makes it better. It's also more efficient at speed due to the ARV turbo. The transmission/ip electronics are used to help control when the EGR is engaged. It also decreases potential vac leaks by removing the 3/2 valves.

Another difference is the sunroof motor and that is a $300 suck.

Personally I have yet to make use of the rack sensor but I have plans to. I would stick the 2.88 rear end in any turbo diesel w123. That is a no brainer.

Hit Man X · #10 06-01-2009, 04:52 PM

You're talking about that plug on the side of the IP for the A-B light? I thought '84 cars had that too.

winmutt · #11 06-01-2009, 04:54 PM

Quote:

Originally Posted by Hit Man X

You're talking about that plug on the side of the IP for the A-B light? I thought '84 cars had that too.

No that is the timing port. I am refering to the rack sensor which is a square block mounted on the engine side of the IP.

Hit Man X · #12 06-01-2009, 05:00 PM

Quote:

Originally Posted by winmutt

No that is the timing port. I am refering to the rack sensor which is a square block mounted on the engine side of the IP.

Ah, guess I never looked that close on that side of the IP.

DeliveryValve · #13 06-01-2009, 05:29 PM

Quote:

Originally Posted by winmutt

... I am refering to the rack sensor which is a square block mounted on the engine side of the IP.

The 1984 California version has the Rack Position Sensor and ARV also. The 1984 Federal do not.

Hit Man X · #14 06-01-2009, 05:30 PM

Quote:

Originally Posted by DeliveryValve

The 1984 California version has the Rack Position Sensor and ARV also. The 1984 Federal do not.

Yeah I just took a peek at the rack sender.

DeliveryValve · #15 06-01-2009, 05:32 PM

Quote:

Originally Posted by Hit Man X

1985.
...

Plastic fan with more blades for more efficiency with smaller water pump pulley

....

The '84 also has the plastic fan with 9 blades. But both years still have the bigger 7 inch pulley. Only the '84 and '85 300SD got the smaller 6 inch pulley.