My vehicle is a 1985 300CD-T (California).

Issue:
I am seeking to remove and replace the original block heater element.

Question:
What, if any, issues/trouble are/is there with reaching the block heater element given the infamous trap oxidizer on this vehicle?

I intend to soak the old element with PB Blaster off and on for a couple of days prior to undertaking the job in an effort to perhaps ease removal.

Thanks for any advice or comments about this work.

It's not worth it. Install a lower radiator hose heater. A number of old threads on here about how difficult it is to remove the OE heater.

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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

The only proper way to remove the old heater involves heating the plug with a torch before cranking on it. I used a 6' extension and a torch to remove mine.

Wasn't there a recall on the trap ox devices?

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Ah!

How quickly I forgot!
Of course: The torch. My old standby. Used it successfully on the differential plug a couple of years ago...

Thanks!

The necessity of 6' of leverage in order to unscrew the heater element speaks volumes about the job.

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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 regret that I never had a picture taken of me standing above the block on my friend's 1983 300CD-T, using a piece of pipe on a breaker bar with a huge hex wrench on the end to remove the heater plug in the block. Would've been a great shot! Still got that old plug laying around somewhere...sat in the block for 20+ years before coming out.

The plumbing for the trap catalyst so impedes access that it makes sense to ignore it and instead use a lower radiator hose heater. That's what I did when I had a 1985 300D-T.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970