Reviving a 300CD Turbo

[johnathan1]

Hello! I'm a n00b here, hehe...I am an active member of the Toyota Supra forums, but I recently acquired a 1981 300CD Turbo.

Anyway, it has been sitting since 1998...I was told it was running perfectly when it was parked, the old guy that owned it (90 years old, original owner) just didn't want to deal with finding a mechanic to replace the front brake shoes.

So is there anything I need to do before I try to start the car? I have been told to drain and replace the fuel, and change the oil, as well as the secondary fuel filter?

I am a total n00b to diesel engines and Mercedes in General, so I need some help. ;)

Thanks!

[johnmci]

Also replace transmission fluid, brake fluid when you have the front pads (not shoes) replaced, anti-freeze, and do the power steering fluid.

Plus check the A/C system. Likely needs a test/charge & oil too.

Tires? There has been discussion now from the tire manufactures saying that tires on the order of 10 years old should be replaced, yes tires age...

Other items like rear diff lube, and wheel bearings also come to mind, and follow the instructions in the owners manual to tune up the emergency brake pads.

[G. Johnson]

If it has been sitting up for awhile, you may have algae in the fuel tank. I would drain the tank and replace all the filters. You can buy an additive to kill the algae and keep it from coming back.

[johnathan1]

Ok, so I'll drain the fuel tank. Is there a drain plug, or do I have to siphon the old fuel out?

[Maxbumpo]

DO NOT USE ETHER TO TRY TO START THE CAR!!!!

Ether ignites too soon in the compression cycle, before the piston has reached top of the cylinder. MB diesel engines are indirect injection, which means there is a pre-chamber where the combustion process starts. Ether can pre-ignite and destroy the pre-chamber, which will drop pieces into the engine and turn it into a nice big doorstop. This damage is possible about 5 to 10% of the time that ether is used, so you will hear stories of people that use and won the gamble, but don't try it unless life/death depends on it. Get the engine in proper operating order (see below) and it will reward you with a 500k mile life of reliable and inexpensive service.

There is a drain plug on the bottom of the tank - will make a massive mess if you remove that with more than a few gallons in the tank. Try getting the fuel to drain from the supply line first, then try to siphon. Last resort would be to pull that plug. However, once you get the fuel out of the tank, you will need to pull this plug because the other side is the fuel tank strainer which is probably all gummed up as well. Just get a new one from the dealer, they're not too expensive.

Glow plug relay might very well have died. It is located inside engine bay on left front fender. Black box, about 4x3x2, cover is a press fit. There will be a bundle of wires that run from the box to the glow plugs, which are screwed into the engine on the side of the head. Pull the cover and check the fuse by removing it - it may crumble when you touch it. If the fuse is good and the battery is fully charged, but the glow light in the instrument panel does not come on, then your relay is probably dead.

Once you get the fuel and filters in order, you'll need to prime the fuel injection pump. There is a hand pump on the injection pump. Original is white, handle is the top knurled part, you unscrew and then work it up and down vigorously. Upgraded pump is black cylinder, you just push it up and down. If either one leaks, it will need to be replaced. Pump vigorously, maybe 50 to 100 pumps, until the noise changes to more of a whine or whistle sound and resistance increases. Pumping the hand pump puts fuel into the injection pump, but it will not push fuel out the injection lines to the injectors, so once you get her primed, you will still need to crank the engine for a good bit to get fuel to the injectors.

The first start may be really tough, you may need to pull start the car. There is a procedure in the owner's manual. Yes, you can pull start an MB with an automatic transmission because it has a secondary hydraulic pump for the transmission that is driven off the drive shaft.

[Merc Winston]

Hi,

I would also replace the thermostat. If the car as been sitting that long, the thermostat could be frozen and cause your car to overheat and that could lead to a major problem. It happened to me when I first got my '87 190DT, and I was on a trip. Also, I would test the new one in a pot of hot water to be sure it opens properly and at 80c.

Best,
Merc Winston

[johnathan1]

Awesome guys! Thanks for all of the tips...I am still waiting to go pic the car up...most likely next week, but here are some pics I snapped of it:

http://img.photobucket.com/albums/v286/johnathan1/55659d89.jpg

http://img.photobucket.com/albums/v286/johnathan1/9251bf05.jpg

http://img.photobucket.com/albums/v286/johnathan1/41bed776.jpg


Since these pics, I have rolled the car out, and THOROUGHLY cleaned it. Doesn't look bad at all. ;)

[nhdoc]

I'd worry less about the stale fuel and more about the possibility that the rings are frozen in place. Most of the time when an engine sits for years it is recommended that some oil like Marvel Mystery Oil be quirted into the cylinders and allowed to sit and soak, then try turning the engine by hand before engaging the starter. If you have already cranked it then it is too late, but if not try this.

I have heard of 10 year old diesel running just fine, it does not go stale like gas. If it looks clear and clean in the tank you can safely try and run it with it.

[johnathan1]

Well, the battery is dead, and all I had was the battery charger, so I turned the key to the on position, and all of the dash lights came on, etc...

I tried to crank the engine, but it would only crank partially and very slowly...I'm guessing because fo the extremely low voltage, but I could see that the belts had moved, so the piston rings aren't frozen, and I am going to squirt some oil into the cylinders before the initial startup.

[nhdoc]

The rings maight have BEEN frozen but the power of the starter, even with low juice could break them free (and break them). Since you've already moved the pistons it's really too late to worry about it, just go forward with your restoration plans...good luck!

[Don350SDL]

I have heard of 10 year old diesel running just fine, it does not go stale like gas. If it looks clear and clean in the tank you can safely try and run it with it.

I have to respectfully disagree with my friend from up north. Drain & replace the fuel, period. Not worth the potential grief.

Don

[nhdoc]

I have to respectfully disagree with my friend from up north. Drain & replace the fuel, period. Not worth the potential grief.

Don

It certainly doesn't hurt to drain the fuel from the tank, but, like I said, diesel OIL is much more shelf stable than gasoline and so if it is clear and has no signs of algae in it then I wouldn't hesitate to burn it up, but that's me. There have been folks on the other MB boards who have found cars sitting for years with old fuel in them and they fired right up like they just shut down yesterday.

If it was me I'd first replace both fuel filters and hook up a temporary gerry-jug with fresh diesel direct to the pre-filter when I first started it up, then, assuming it ran on that I'd hook back the main tank and run it off that which would prove that the fuel in the tank is either good or not...I'd still bet a nickle it would run just fine on that old fuel as long as it is still clear.

[johnmci]

Ok, well assuming he broke the rings, what would impact be? Would he have enough compression to start the engine? Would a pressure test later indicate this issue. Otherwise you are into disassembling the engine to have visual proof?

[nhdoc]

Ok, well assuming he broke the rings, what would impact be? Would he have enough compression to start the engine? Would a pressure test later indicate this issue. Otherwise you are into disassembling the engine to have visual proof?

Depends on which rings and how many cylinders are affected...I would say once he's cranked it and moved the pistons it's too late to worry about it...sure, he can still squirt a little MMO into each cylinder, couldn't hurt, but the best way to go about reviving a sleeper like this is to first let it soak a little then gently turn it by hand...that's what I've read from those much more experienced than I am.

[JIMZ-MBZ]

----Charging battery ,, need to take to autozoo and have them test & quick/heavy charge ,,,, (had a 1 year battery from them that sat 'charged at home til full' no-workee===== had it charged and now works good,,,

if it does turn over,, wait for an additional 5-10 seconds after the glow-plug light ""the curly light at bottom right of dash""" goes out, this lets the glow plugs get hotter

if it does start,, let it idle,,,,,,, check dipstick for any funkiness (foaming,etc)

you will want to drive it ,,, but just be cautious,,, they dont have the zip that sports cars do off the line,,,many times i turn into traffic in the lowest gear

your gonna have a bunch of questions------------ plan on spending money being methodical w/ your new toy to preplace all fluids/hoses etc,, be logical

>>>>>>> most 123 chassis cars get 500,000 miles,,,

search threads,,,, or search my posts to get a feel for the water ""its not bad"

I have been learning for over 1 year and mine is a daily driver

Jim

found all parts I need at buymbparts.com

[johnathan1]

I have some news!

I just got the car home today, replaced the battery and started it...it started the first time! :D

I let it idle a little, and checked the dipstick, and all looks well... It sounded really good too. Now I just need to put in some MB coolant, change the oil, tires...and other maintenance stuff...

And I also should mention that I didn't drain the fuel...I looked at it, and it looked fine, pumped by hand, and it started perfectly. :)

Thought you guys might be interested...more updates to come...

[johnathan1]

I noticed that the turbo inlet duct doesn't firmly clamp onto the air cleaner...even with the clamp tightened all the way. Is there something that I'm missing? I can't get it to clamp firmly.

Also, the tach isn't working, and no dash lights come on with the lights...any ideas? :)

[Highway Star]

You should replace ALL of the fuses, get the valves adjusted, and purge the injectors and pump.

http://dieselgiant.com/injectorcleaning.htm will show you how to purge it yourself.

[johnathan1]

I drove the car for the first time today, and I must say...I really like it! :D

It definitely doesn't have the power of my turbo Supra, but it isn't Totally gutless... I actually thought it would be more sluggish.

Everything seems to be working beautifully, except for the gauges...the speedo and oil pressure are the only ones that work...the gas gauge jumps around when you go over bumps, the tach still isn't working (still haven't tried that DIY "cigarette butt" fix) and the temp. gauge hardly moves above the 40 mark...is this normal? And the gauge cluster still won't light up...I checked all of the fuses, and they seem to be in good shape, none looked blown...

[johnathan1]

Anyone????

[johnathan1]

........:)

[JIMZ-MBZ]

Ill give you some attention,,,

you may want to start a new thread,, sometimes they get old and people dont dive-in,,

I use the 123 forum, there people are tuned into your chassis, Ive a 300D turbo,

re your turbo,,,, if you are talking about the 'u' thing - if so there are 2 "different sized" 1" wide o-rings that you should replace,, mine were old and i had to break it to got it out ((1 of them was pushed back and not seating properly)) clean out the 'u' thing

-- check your air filter bracket, for they are known for breaking, it is the 'T' shaped gizmo that has the cushion mounts that give threads inside of your air cleaner to hold it on --- you will notice allot of vibration if it is broken buy 3 new cushion mounts the are like 2$ ea,, the bracket is $25
------> in the air-filter housing,, have you noticed that bent tube of plastic 'hanging' just above Big hole at the conter/bottom of the housing?????? HMMMM I took some small gauge wire and psyically tied it back to something !!!
I dont want that falling from those 2 teeeeeny-weeeny plastic tabs and direcly into my turbo........
-- check to make sure that you air filter housing removes and re-applies freely to the threaded studs, and metal tube at the back/bottom of the AF housing (( mine wasnt fitting properly because someone b-4 me didnt place the cushion mounts on in the right place (( the replacement AF bracket has 2 - sets of holes for the cushion mounts to be used on various years/chassis etc))))

re your gauges:
TEMP GAUGE: suspect that you may have a thermostat stuck Open,, it should read about 80+/- after warmed up >>>> you may want to get better advise on this.

TACH; try that cig butt thing,, the cap takes some coaxing by hand to come off == shipping peanuts etc,,, that didnt work for me,,
Ive been told to clean the pick-up - mine reads off your harmonic balancer (right side) ,,, i think its a bummer to get to/off ,,, my tach doesnt work.

FUEL GAUGE; least of your worries right now, if its stable overall and your reserve light comes on at 1/10+/- tank then just liave with it for now,,,,,,, I have removed repaired sending units w/ mixed results.

OIL PRESSURE; should read 1.7 when at idle warmed up ,, mine pegs when first started then gradually settles down.

SPEEDO: dont trust its readings til you can verify them,,,,, mine is slow by 10 MPH

NOW,,,TA DAA,,,, your dash lights, try your dimmer knob (left), maybe it needs a jiggle,, if not,,
the dimmer is famous for going bad, its almost lengendary
you can order a new dimmer 'dashpot' _OR_ take a piece of 12awg or bigger ((Check the Size w/ others)) wire and solder a jumper between the terminals and bypass it for now (like me - mine work fine ,, not too bright),,
but to do this you must remove your instrument cluster (( easy to do for a diy'r ))
-- your inst cluster/panel is just pressure fitted into the dash,,,,,, I have removed mine by bending a small nail to give a small hook (bent sideways),, insert between dash and panel and coax it out,,, it will come out a little ways,,unplug electrical connectors and have a 10 mm?? open-end wrench to unscrew oil-pressure line
------ then poof out she comes-----
you will have to do this if bypassing or replacing the dimmer-dashpot-variable resistor. you may want to replace the lightbulbs while your there,, I get mine from a foreign auto parts store. you can test the lightbulbs, (but the instr panel must be out) with other light from your climate control panel =====> remember that the test bulb/socket MUST be put back into the panel (( It is a circuit board ))

there, hows that for attention?
good luck
Jim

[Maxbumpo]

Change your thermostat, and put in fresh coolant that is MB approved (Zerex G-05 is one brand, usually found at Napa or other auto parts stores).

Electrical gremlins can be tough to exorcize; start by changing all your fuses. Fuel sending units are known for getting gunked up and not working correctly.

[johnathan1]

Yea, I just put distilled water in for now to flush the cooling system out with...I'll take a look at the thermostat as well...where is it located? I went and bought some MB coolant, it comes in a concentrate, and not a 50/50 mix, correct?

And all of the fuses look good, but I guess it isn't too difficult/expensive to replace them. Also, I haven't been able to get the instrument cluster out...is there a apecial technique you guys use? I just can't seem to get a good enough grip on it.

And the fuel gauge seems to have completely stabilized after putting fresh diesel in, and driving it a bit...I guess the sender was a little funky from sitting for so long....

[Don350SDL]

There have been folks on the other MB boards who have found cars sitting for years with old fuel in them and they fired right up like they just shut down yesterday.
Just like that old VW Beetle in the Woody Allen movie "Sleeper"!

I think we pretty much agree. Diesel is definitely more stable than gasoline, and if it seems OK then mixing it with a half tank of fresh fuel won't do harm. It does depend on how long its been sitting though.

The car won;t start because it's not cranking fast enough. Fix that and then see what happens. betcha is runs pretty well. The oil & filter should be changed first.

Don

[nhdoc]

Glad to hear my (lonely) advice about running it on the old fuel proved fruitful and timesaving for you...you're not the first to get in one of these cars after a number of years and have it start and run just fine.

As for your other troubles, yes, the thermostat is probably the culprit for the low operating temperature. It is located in a housing held on by 3 (if I recall correctly, 3) bolts where the radiator hose goes into the top of the block at the front. Some recommend draining the coolant first but since you have water in your cooling system anyway, you can just go ahead and pull the three bolts out (soak them with PB blaster first) and replace the t-stat and gasket.

Be sure to go for a BEHR brand thermostat - OE is not necessary, but I absolutely recommend BEHR as it is OEM. If it has an arrow on it point that up. Be sure to get the right gasket too, that you may have to go to MB dealer for as the NAPA store I was at recently only had an o-ring which is not correct. If you go to the dealer for the gasket you might as well get the t-stat there too, last time they were actually cheaper than NAPA (about $22). Be very carful tightening those bolts. The housing is aluminum and easily stripped. Just tight enough is tight enough, don't crank down on them.

Drain the rest of the water out of the cooling system and then to properly fill the cooling system disconnect the top hose from the radiator and fill into it until coolant comes out, then reconnnect it. That will reduce the chances of getting air in it. Also, when you start it up keep the cap loose and turn the heat on full blast and drive it around to purge any remaining air. It can be a little tricky getting all the air purged from these, and if the heat isn't working you will know you have a bubble in the heater core circuit. For that you need to disconnect the heat hose at the firewall and fill into it.

The dash lights not working are probably caused by the dimmer, but you don't have to remove or replace it to get it to work. Just turn the dimmer knob back and forth about 100-200 times or more to clean the contacts. First you will start to see it work in various spots then it will work throughout the range of the dimmer...I have been able to fix every old Benz I've owned this way and so have others.

Don't be too surprised if the fuel level sender gets jumpy again when the tank gets low. They almost always smoothen out above 1/2 tank but below 1/2 is when they get jumpy when they are dirty.

[Maxbumpo]

I went and bought some MB coolant, it comes in a concentrate, and not a 50/50 mix, correct?
Yes, you need to dilute it in accordance with ratio for the temperature range of your climate.

And all of the fuses look good, but I guess it isn't too difficult/expensive to replace them. Also, I haven't been able to get the instrument cluster out...is there a apecial technique you guys use? I just can't seem to get a good enough grip on it.

The fuse metal changes with time and becomes a very unreliable conductor. It may look just fine, but sometimes they disintegrate when you touch them. After 10 years they start to get flaky, and as you pointed out they are not expensive. Cheap and easy and may cure some of your electrical ills.

To get the instument cluster out without using the special pulling hooks, you can remove the kick panel below and then push it from behind. The oil pressure gauge has a direct line from the engine; use a counter-hold wrench while loosening or tightening the fitting. When you first push out the IC, you will only be able to get to a few of the connections on the right side. Next, unscrew the speedometer cable, then there is a big round electrical connection, and do the oil pressure line last. Have some paper towels ready in case it drips.

You can make the hooks from some stiff wire if needed. Bend the last 1/2 inch or so back, make a handle at other end, slip them between dash and IC on left and right, twist to catch the cluster (do not catch just the clear plastic face - go deeper) and pull.

[johnathan1]

Ok, I bypassed the rheostat, and restored full lighting back to my dashboard! :D

The rheostat was completely destroyed...extremely corroded, and the coil was completely FUBAR'ed.

I also tried the "cigarette butt" fix for the tach, but that didn't work...:( What is the next thing to look for?

I also pressure washed the engine bay, and noticed that the vacuum line to the turbo wastegate actuator had completely seperated, so I replaced that...and when I took the air cleaner off, I noticed that the rubber "seal" that goes between the air cleaner and that "U" tube was kinda pinned sideways inside the "U" tube...so I pulled it out, but I can't get it fit properly...I am guessing it is swollen since it was soaked with so much oil?

I noticed that my door locks and trunk latch will only work for about a minute or two after I shut-off the engine...I am guessing the door lock check valve is bad, or I have a vacuum leak somewhere?

Thanks for the help guys! This seems to be a great community to be a part of! :)

[Maxbumpo]

Recommend you start new threads for your problems. We've gotten you over the major hump with this thread...

[JIMZ-MBZ]

you may want to start a new thread,,,, I had trouble finding this again-------

-- there is a 1"wide o ring on each end of your U tube,,, it should be placed in the U tube 'channel' first then it pushes onto the other,, these rings should be pliable,, you probably should replace them,*,,, its almost easier to remove the U tube from the turbo/AF hsg first,,, losen both clamps + pulls straight forward (( just kinda awkward to get the AF hsg to --weezel-- into the U tube ))

-- as for your tach, you may want to clean the sending unit ( mine is right-top of the harmonic balancer),,--detailed previously

-- yes you have a vac. leak re your doors ( I have bypassed mine ) and unlock doors the old-fashioned way

* you can buy all sorts of stuff at buymbparts.com rusty has always been very helpful, or there are others

--- replace>>> ALL <<< fluids brake fluid,, differential grease, re-pack wheel bearings, etc
Jim

[johnathan1]

Ok, I have done the following:

- Flushed cooling system, and put in MB coolant (although I haven't gotten to the thermostat yet)
- Tried fixing the tach, but I can't seem to find the sensor located near the crank pulley.
- Pulled the driver's side door panel off and replaced the window regulator.
- And the gas gauge has gotten jumpy again after going below 1/2 tank. :rolleyes:
- Put new tires on...feels totally smooth. :D
- Then I noticed a fuel smell the last time I drove it...checked, and the fuel return lines are leaking like crazy...:rolleyes:

So the car is down until the replacement hoses come in...I ordered the kit from dieselgiant.com, as well as the replacement transmission flapper things.

[nhdoc]

You'd have saved yourself some trouble doing the thermostat while the coolant was drained...but that's water over the dam now. These cars don't like running cold, it's better to get them up to operating temp when driven...put that on your next to do list.

Also, I had previously mentioned the fuel gauge will probably act up again below 1/2 tank. Some have claimed success by removing the sender and cleaning it by shaking vigorously up and down. Removal of the sender is easy, just remove the first aid kit (2 phillips screws) and then remove the sender by means of a 1 13/16" or 45mm socket, IIRC.

Personally, I live with it jumping around in my 300CD but eventually may replace the sender in mine. They are not cheap though. Eventually you can learn to gauge the fuel level by the distance you have driven, assuming your odometer is working, that is.

[johnmci]

In my 83 300TDt the sender was 1/3 full of dead algae. Certainly worth pulling and taking apart to see whats going on inside.

[johnathan1]

Just thought I would revive this old thread...since it's been about 9 months since the last post! O_O

I don't have my 300CD anymore, I sold it to a very deserving fellow...and I now have a 300SEL...it's not a diesel, but I sure like it ;).

Also, what happened to Marshall Booth? I remember him posting on here, and being a very knowledgeable guy...hope he is okay...

[Maxbumpo]

Regretfully, Marshall lost his battle with cancer. We all miss him dearly.

[johnathan1]

Wow...I'm really sorry to hear that...RIP Marshall :(