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Old 09-15-2002, 03:54 AM
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Question inherited 1975 240D - lots of questions

Unfortunately, my grandfather is not able to explain a number of things to me about his 1975 240D. He bought it new and it has 82000 miles on it. I think he has had it serviced regularly by a MB dealership. I do not have anything but a parts-type manual for reference. Where do I get a good owners-type manual? Why doesn't the fan work for heat but does work when the air conditioner is on? When running, is the oil pressure supposed to stay at the peg at 45 psi? Is the water temp supposed to hover around 175? What is the little knob just to the left of the key -- if I turn it the idle changes -- It turns about 180 degrees. I seem to recall the passenger door locks being able to be controlled from the driver door, but that apparently no longer works. Any ideas? How much is too much in terms of engine knocking? How much is too much in terms of exhaust smoke? Why is it more difficult to (re)start after its been running for awhile than it is after it has sat overnight? I would certainly appreciate any ideas you may have.
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Old 09-15-2002, 08:09 AM
engatwork's Avatar
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,234
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Old 09-15-2002, 08:09 AM
engatwork's Avatar
Join Date: May 2000
Location: Soperton, Ga. USA
Posts: 11,234
You need to free yourself from all these worries and let me have the car real cheap - JK .
a) Look on ebay for manuals.
b) Can't tell you anything about the fan issue.
c) Oil pressure sounds fine. After the engine has been run hard and the car gets some miles on it do not be surprised to see the oil needle drop to about mid-gauge at idle.
d) Water temp sounds fine. Start trouble shooting if it goes above the 212dF/100dC mark. Make sure you change the coolant about every year or two. I use MB coolant but if you do a search on coolant you will see there are alot of differing opinions on this matter - just like oil. Make sure you use diesel rated oil - this is the most important thing when it comes to deciding which oil to use.
e) Little knob is idle adjustment. Open the hood and have someone move it while you are watching the throttle linkage. You will see how it works. It is usually used when first starting on a cold day. After the engine is hot usually not needed. Always leave it at the lower idle setting. Also, you will want to lube all the little ball and socket throttle joints every now and then. I use ATF to lube them but again, lots of different opinions.
f) Door locks work off of vacuum. Purchase a Mighty Vac from you local discount auto parts place and start unhooking and testing vacuum lines. Also, do a search on here. Pretty straightforward.
g) Can't say much about knocking without actually hearing it. You may want to purchase some Diesel Purge and run it through the system to clean out the fuel injectors OR pull the injectors and have an injection shop go through them.
h) ditto g above about the smoke.
i) I would suspect fuel issues with the hard hot starts. See g above.
You have a good car there - change the oil often and hot and it should provide you many miles/years of service.
good luck
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Old 09-15-2002, 08:15 AM
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Join Date: Jul 2001
Location: Atlanta
Posts: 194
If you have never owned a diesel the engine noise may startle you a bit. THEY MAKE A LOT OF NOISE!! Good luck with the car. It is one of my favorites.
G. I. JOE.
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Old 09-15-2002, 10:26 AM
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Join Date: Dec 2000
Location: Battle Ground, WA
Posts: 576
Fan problem...

Hi there,
I believe your fan problem is the same one my '75 280 had... the motor is bad. The air conditioner uses a separate fan on those cars, and the fan for the heater is really buried up in the dash behind almost everything. Replacing it took me a couple of days on my 280, as I had to remove both front seats, the center console, move the air conditioning evaporator unit out of the way, remove the heater core and housing, and then I could see the fan. I got a used one and replaced it, after making sure the new/used one was well lubed. The old fan had fried it's windings because the bearings had seized up. If this sounds like a lot of work, it was, and since my car's heater worked as long as the car was moving, it never bothered me, but my wife insisted that it should work when the car was stationary. Before going to all this work, make sure that the fan does indeed have voltage to the motor! The air conditioning switch must be turned completely to the counter-clockwise position to allow the heater fan to come on. I could be way off base here, never having had a 240D.

Richard Wooldridge
'82 300D/4.3 V6
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Old 09-15-2002, 03:02 PM
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Join Date: Mar 2002
Location: Great White North!!!!
Posts: 400
the button to the side of the ignition sounds like a manual choke.pull it out or turn it all the way 'til the engine warms up-and like someone said they are loud,noisy and less than smooth.with 82000 miles in 27 yrs i think the car could use a few good months of regular if not spirited driving regardless of whether the service was dealer performed or not.after that you would have a better idea of it's real condition.i'm under the impression that you've made alot of guys envious so that would tell me to stick with it and work on it.there's a diesel forum-you should post your questions there first for better replies
'95 s500 (bought for wife but can't bear to share!!!) 125kms
'92 legend 180kms
'88 tbirdturbo(fantastic car-only regular maint.)120kms
'87 mustang gt(gone)
'86 tbirdturbo(gone)
'85 mustang gt(gone-but not forgotten)
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Old 09-16-2002, 11:41 PM
Palangi's Avatar
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Join Date: Dec 2000
Location: Republique de Banana
Posts: 3,484
Welcome aboard siwash1.

Owners Manual... You can order from the dealer or call MB on their 800 number. Also, might find one on E-Bay. Shop manuals (paper version) are out of print but you can still find from a few sources. Chassis manual and engine manual will be about $75 each or more. Wiring diagram, I think is about $25. There is also a manual available on CD ROM, but I prefer the paper manuals.

Heater fan... Could be a fuse. These German fuses can look OK and still be bad. On mine there are 3 or 4 fuses located in little square boxes around the engine compartment. I'm not sure, but I think the heater fan fuse might be one of these located away from the main fuse block.

Oil Pressure.... Should stay on the peg except will drop down to mid scale at idle after the oil warms up.

Water Temp.... 175 is good. It may climb a bit on a long uphill grade.

Little knob.... Idle speed adjuster. Supposed to be used kinda like a choke to increase the idle until the engine warms up. On mine, I don't fool with it. I just increased the base idle a bit. That works for me, but may not be a good idea if the engine mounts are worn as evidenced by severe shaking on shutdown.

Door locks.... You have a vacuum leak somewhere. Need to find it if you want central locking to work, or plug it if you don't care about the passenger doors locking automatically. Also, I haven't studied the circuit, but there is a vacuum operated switchover relay which controls whether the A/C fan or the heater fan runs. It is conceivable that a vacuum leak could be keeping the heater fan from running. Maybe somebody more familiar with this setup could comment on that.

Engine knock.... These things can be pretty loud. Hard to quantify over internet. Sometimes some fuel addatives can quiet them down a bit, but it will always be noisier than most gas cars.

Smoke..... Not uncommon for them to put out some black smoke. Sometimes a good dose of fuel addatives like Redline Diesel Fuel Catalyst can reduce the smoke by cleaning the injectors up, but, it's still gonna smoke some. Basically, black smoke is pretty much harmless (at least to the car). White or blue smoke is bad news except for maybe a little puff at startup.

Hard to start when hot..... I assume you have figured out the gorilla knob and know you might have to glow it for a few seconds even when it's warmed up. I would want to change fuel filters just on the assumption that they havent been changed in a long while. Let us know when you are ready to do that, and we will guide you through changing the main fuel filter. Also, if the fuel is old, it may be no good. Try some fresh fuel if the car has been sitting a while. Hard starting when hot can also be due to a weak starter not turning the engine over fast enough.

If, after all is said and done, you decide that this isn't the car of your dreams, please post it here on Mercedes Shop if you want to sell it. There are always enthusiasts here looking for 240D's. It is hard to sell a car like that on the open market anymore. It's mostly a hobbiest car nowdays.

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

And remember folks, Only You Can Prevent Hilliary.

Last edited by Palangi; 09-16-2002 at 11:48 PM.
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