I recently acquired an '81 300SD, and want to make sure everything is in decent shape before a swap. I have no idea of the vehicle history (202K miles on the now-fixed odo, but the wire was cut when i got it, so no true sense of miles), so i want to cover as many bases as possible before pulling the engine.

I've been describing the efforts to my wife as the 'air' side of the engine, and the 'fuel' side of the engine. Seems to be a good descriptor of how to tackle two of the key systems.

ANYWAY: I've already cleaned up the 'air' side of the engine: rebuilt the turbo, deleted the EGR, tanked both manifolds, new manifold gasket, new air filter, thermostat, chain-tensioner gasket, oil-return seals, alda banjo ...

Now I am on to the fuel side. My hope is to do the following (in the order listed):

1. Valve adjustment
2. Timing-mark method to assess chain stretch
3. New valve cover gasket
4. Diesel purge (likely 2X ... but who knows)
5. Compression test (fingers crossed!)
6. New fuel filter (pre- and primary)
7. New primer pump (currently have the white plastic version)

Does this order make sense and best use of resources?
Am I missing anything?
Should I add anything?

I'm trying to be most economical with all my efforts ...both time and money ...and would like to make sure my order of operations makes the best use of each.

I should also point out, I've seen a small amount of fuel leaking on the top of the primary fuel filter ...I've read solutions here, but thought i would wait until i install the new filter and crush washer...


Many thanks,
Geoff

__________________
'81 300SD ---> '46 IHC Metro (some day)

I would do the compression test immediately following the valve adjustment.

Is there an issue with how the engine now runs, that is prompting you to want to do a diesel purge, or is it just for preventative purposes? Opinions differ on diesel purge. Some people seem to have long-term luck from using it as a cleaning agent. I really haven't, except for very mild problems. I think it's better used as an occasional 'tonic'.

If you suspect one or more dirty injectors, for all the work happening here, I would suggest you have the injectors professionally cleaned (and any nozzles replaced, as needed). Or go ahead and install new nozzles across the board.

In terms of leakage around the top of the large fuel filter, you mean you have fuel pooling on top of the filter housing? If you mean that the top edge of the filter is leaking slightly, that can occur simply from overtightening the filter.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

well noted ... but the compression test would require bleeding the lines afterwards, so i was thinking i would do this after i did the purge and changed the filters?!

the engine is running rather well ... little oil consumption, good power, marginal tailpipe smoke. i would say that my purge would be 'preventative' for sure. did not know it had negative ramifications. i assumed it would help the IP and the injectors.


10-4 ... i was thinking about new nozzles, but though i would make a game-day decision when i pull them out during the compression test.


it is pooling on the top ... on the casting.

thank you!

geoff

__________________
'81 300SD ---> '46 IHC Metro (some day)

I didn't meant to imply anything negative associated with it for that purpose. The Diesel Giant website has a DIY on doing it properly, with the feed and return lines running from a separate container. When I do it, I run two bottles of purge through.

Unless you're a trained Bosch tech, or have a pop/spray pattern tester, I'm not sure you will be able to tell much from just looking at them . If the car is running well and idling evenly, i'd say it sounds good.

Sounds like quite a project you've got going there. I'm sure we'll all want to see pics....

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

I have yet to do a diesel purge.

It sounds to me as if you are doing all the right things. Everything on these mb diesels is so long lived I seldom replace anything preemptively. My feeling is that in many instances any replacement part is likely to be of a lower quality than the factory parts. IE I never replace hoses unless they fail. I have some on my 30 year old benzes that are factory and doing well.

The exception is can chain guides which clearly wear and eventually fail. Cam chains can be examined but are extremely long lived. The oil pump chain on the turbo motors is an item that is out of sight but often fails before the cam chain with disasterous results. I'd consider changing that while the motor is out.

Good luck!

__________________
[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.

32 Benzes ... and never a diesel purge?
why is that process so highly regarded in so many circles?
i already have two bottles as a birthday gift ... so I will likely do the purge to see if i get any gains at the IP. ...a bit of a 'can't hurt' mentality

I should also point out that I'm not in the mindset to do any major-fluid changes prior to the pulling. The transplant will hopefully happen this winter, so I thought I'd save things like oil-pan gaskets, check-valves, ATF flush (assuming i'm going to keep the AT in the Metro), fuel-tank filters ... until the transplant.

I may do a timing chain replacement prior to transplant if i find it way out of spec...

For now, here is my revised OOO:

1. Valve adjustment
2. Timing-mark method to assess chain stretch
3. New valve cover gasket
4. Diesel purge (likely 2X ... but who knows)
5. Compression test (fingers crossed!)
6. Get nozzles inspected
7. Re-install injector assembly
8. new braided return lines
9. New inline fuel filters (pre- and primary)
10. New primer pump (currently have the white plastic version)

finally, I've also been curious about valve stem seals but also need to go in and look to see if i actually need them... I've read the posts on green/black/orange/whatever colored seals, and am aware of the precautions.

again, thanks to everyone for the help

geoff

__________________
'81 300SD ---> '46 IHC Metro (some day)

I do purges, with new-to-me cars, not sure if it helped, but I feel better.

__________________
83 SD

84 CD

I remember Marshall Booth talking against a diesel purge. I had just acquired my 85SD.

You didn't really explain the current running status or your intent for the car/engine long term.

I would do a valve adjustment as a matter of fact. I would do fluids and other maintenance items after determining that the engine was sound and that I would keep it.

Compression test and diesel purge would wait until I was trying to diagnose a problem.

Before spending money, make a list with prices of other things ie shocks, brakes, suspension, tires, interior, climate control, rust.

__________________
85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Sorry if I was a bit ambiguous ... most of this is new to me, and i don't possess all the right vernacular to describe symptoms 100% correctly. If I describe something incorrectly, then there is a pretty high risk of incorrect remote diagnosis.

Anyway, here is a whack at current running status:
starts first try every time down to 50°F ambient
a bit of self-reving while coming up to temp as it searches for idle
transmission is strong with some small hiccups that will be addressed later
some 'blow-by' but not too bad, i don't think
no visible oil burn on the only long trip i've taken (437 mile drive home)
previous owner and i corroborate about 28-30 mpg
was some oil on turbo inlet, so that was rebuilt.
valve cover gasket is a mess, so lots of 'air side' oil/sludge (see other post by me)

Intent:
I will be parting out almost all of the car ... and keeping the engine/air/fuel/exhaust/tranny for my transplant.
I am lucky to have the whole vehicle as a test-bed for now...and make sure the engine is as sound as possible before the transplant.

agreed with this rationale, my thought would be to use the compression test to ensure the block is sturdy ... and expose some potential diagnoses along the way.

i definitely have this list ... with $$$ ... half from the 617 engine ... the the other half from the '46 Metro.
Just don't show it to my wife, okay!

I have most of the tools already from previous projects ...

cheers and thanks

geoff

__________________
'81 300SD ---> '46 IHC Metro (some day)

There's a sadly missed name in Mercedes diesel circles.....

Marshall was THE greatest advocate of the "Italian tune up"... ever.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

New primer pump before fuel filter change. The new style primer is much better than the old style for pumping up the filter. Do the filter change with the engine warm. Much easier to start.

__________________
Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE