My first post ..so be easy on me. I took the leap an bought a 1984 300SD on Ebay. Looked for months locally (anywhere near SW Missouri) but the few that I could find were way more of a project then I was looking for.

Oil pressure is pegs at 3 when idling and temp hovers a little above 80 cruising. All windows and door locks work. Interior is darn near perfect. 1-2 shift is pretty hard sometimes and others it's not. From the sounds of it that's pretty normal. Trans fluid is where it's supposed to be and smells brand new. I know it's vacuum controlled but for now I'm not to worried about it. I'll take that on later.

So what's the engine RPM supposed to be at 70 mph? It seem a little high at just over 3000.

So far the the short list includes brakes, glow plug trouble shooting, tearing into the front end and adding a block heater. (any comments on the pre-made assembly from Diesel giant would be welcome)

It refuses to to start under 45-50f. No block heater that I can find. Glow plug lamp never lights up. But I do hear what I assume is the glow plug relay kick out about 30 sec after I turn the key. Put the clamp-on amp meter on the battery cable and see 45-50 amps until I hear the relay click then just a few amps which seems normal. 80 amp fuse tells me I'm missing a few glow plugs. I did unplug the 6 hole plug connector from the box on the driver side fender to check out the connectors. Turned the key on while the 6 hole plug was removed and to my surprise did see the glow plug light up. So the light works which is a relief. I searched the archives for glow plug stuff but did not see any that explained my problem. Since I don't the history of this car I think it's time to replace all the glow plugs. So should I get the "upgrade relay kit" from Mercedes Shop?

I'll better shut up for now. You guys are great!

Thanks,
Travis

Congratulations on buying a MB! They're truly wonderful cars. And welcome here, this place is half the reason I bought a Mercedes diesel to start with.

I'll reply only to what I know.
At 70, just over 3000 is completely normal. It seemed a little high to me as well, especially afer my Cummins diesel that was under 2000 rpms until about 72-73, but completely normal.

I'm sure others can help you on the rest. I have never heard a click of my glowplug relay turning off. Not saying that it shouldn't, I just haven't heard it. If you get those glowplugs working, and have somewhat reasonable compression, you'll start just fine in the cold.

Enjoy the new car.

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1985 300D, 237k.
1994 F-350, 6.9 diesel, 5 spd manual, Banks Turbo. 261k.
Sold: 1985 300CD- 267K

Look for the block heater plug under the passenger side bumper, sometimes people will tie the plug to the tow circle.

Does your oil pressure drop to 1.5-2 bar when idling while the engine is warm ?

Check your reservoir tank and see if you have any of the green stuff... If you do, do a radiator flush, citrus cleaning and replace with MB coolant or any other coolant recommended for aliminium radiators.

Check this for hunting errant glowplugs :

http://www.dieselgiant.com/glowplugrepair.htm

Good Luck

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'85 300 D Diamond in the rust

Regarding the glow plugs, you want to check the glow plugs themselves before you consider changing the relay. The first step is to unplug the connector from the relay to the plugs (6 holes in the connector, but only 5 are used). Each of the holes has a small number corresponding to the cylinder number (#1 is the front of the engine). Use a muti-meter to measure the resistance of each glow plug between the connector "holes" and ground. With the engine cold the resistance should be about 0.6 ohms on each plug. Bad plugs normally give infinite resistance. I would guess that you have at least a couple of bad glow plugs.

Good advise from Craig. I'd follow that first.....

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Glow Plug Trouble? Free Glow Plug Diagnostic Sheet!

Or just replace all 5, they're cheap enough.. then you've eliminated over half the problem...

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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FACEBOOK: PANZER450

Thanks for all the help everyone.

I've been all over and under it 4 or 5 times and have never seen the plug for a block heater.

Yes, the oil pressure is always at three, even at idle when the engine is warm. It does move a little but never below three. Didn't seem right to me. It does fall to the bottom when the engine is not running so I know it's not stuck but that doesn't mean it's not broken. I think I see the sending unit on the back of the oil filter housing. Maybe it needs replaced. Definitely not something to ignore.

You read my mind about the coolant. I was trying to figure that one out myself. The stuff that's in there is amberish. Still, I think I'll do the flush when I install the block heater.

It acted like it didn't want to shut off today. Apparently I bumped a vacuum line during the last inspection. Looks like I'll be doing that vacuum game sooner than later.

Thanks so much.

TC MO
1984 300SD

Have you changed the oil? A wrong oil weight (re high) could make for hard starting and high pressure readings at warm idle.

Yes, I changed the oil. Used Rotella-T 15w-40. PO told me he had just changed the oil but I changed it anyway. No difference. Went to town this evening (7 miles one way) and at the stop light, still in gear and ~700 rpm's oil pressure dropped to 2.9.

TC MO

Congrats on the purchase !. You mentioned an "upgraded " relay for the glow plugs. Explain please.

Tanks
Alan

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92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1X30FAM361XK19AZUM&year=1984&make=MB&model=300-SD-002&category=F&part=Glow+Plug+Kit

I hope you can follow that link. I spoke to Phil (at Mercedesshop.com) on Friday and he confirmed that he can get that kit even his though his website indicates it's temporarily back ordered.

Best,
Travis

This may come under the 'silly things overlooked' and is not intended to judge, but have you refueled? I helped a 300sd owner with starting issues only to find out he put 100 miles on his new MB that came with 3/4 tank. That fuel must have been very old and showed signs of the dreaded black crud. Fresh fuel did wonders.
One easy way to eliminate fuel in the search for a cause of trouble is to keep a temporary tank like used in Diesel Giant's purge and run the old gal with known fuel to have a bench mark.
Another easy tool is 0-60 time. I tweak fuel (all non-greasy flamers can go eat their burgers now) and the 0-60 time helps keep the fuel blend matched to Wisconsin three dog nights.
Check out the hood hinge wells and plug any holes now before you start cussing water on the rear floormats.
Oil presure: try installing a gage at the filter housing. You may have built up crud in the lines & or air.
What is the state of valve cover cap blowby? Poor conpression will cause poor starting. Strong compression should start in 50*F without glow plugs. This is not my experience but handed down from an even older fart.
Good miles ahead and welcome to the dark side.

No problem Lostyankee. I'm a "keep my eye out for the obvious" sort of guy myself.

PO said he'd just put new fuel filters in and it sure look likes it. I can see nothing but nearly clear fuel in the prefilter, no debris. When I got the car it had less the 1/4 tank, I waited until the reserve light came on before I filled up. Starting problem did not change. Keep in mind even though the air temp might be 50f the overnight low was low 40's or lower.

On the blowby. So what's the benchmark and the test procedure on that? I think that's a test where you remove the oil cap on the valve cover and see how much oil comes out right. I did that once and there was just barely a very light mist.

I test the compession and see what I find.

I can tell you this project is lot more fun for me then my wife. She's been a trooper so far but I can see a storm on the horizon if I'm not careful. Is there some owners support group for spouses?

Best,Travis

1984 300SD

Sometimes people pull the cord from the block heater and it appears you dont have one but really you just do not have a cord. The cord detaches from heater. Look on passenger side engine in middle bottom for 2 pins sticking out of a round big hex thing on the side of an engine. That is the block heater screwed into a "freeze plug" . I went all last winter thinking i did not have a block heater when really i did. I really could have used it too.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius