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Discussion Starter #1
Hi,
I know nothing about cars, but have a 1978 300D because it looked cool. I am aware of the issue of cold weather and diesels and used to plug it in at night. However, even thought the glow lights come on and I give them a few on/offs the car has not been wanting to start after just being out for a couple hours. Heck, should I be pumping or not pumping or holding down etc...My mechanic who actually used to own this very car (talk about a coincidence) found out that the block heater wasn't working so is trying to find one (hard apparently). I am very frustrated...without a car too...he said I may need to replace the glow plug relay system entirely (as I said, it used to work find last winter). The car wants to start but doesn't. It has a new starter...what else can I do? Do I put out yet more $$$$? or are there other things that might be wrong? New oil filter, new fuel pump, oil change etc. I only wanted to keep this car until next summer...and it's becoming a sinkhole...:( It's in my garage right now and this is not what I need right now...


Is there a way to start it without a block heater warming it up? I heard someone mention ether but that sounds dangerous and ultimately inefficient in the long run...what's this I read about coolant heaters and or oil pan heaters...any other things that should be checked?

thanks for any advice.
 

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'73 450SL, '83 300CD, '01 E320 4matic
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I'm a heavy duty diesel mechanic. Ether is fine if you're SURE the glowplug system isn't working. It can however under some circumstances cause massive explosions- under the right conditions it can crack your cylinder head or worse... ie. bad idea.

If your car has the old style glow plug system you could update it to the newer style 'pencil' plugs and you may see an improvement. Do a search on glow plugs and you'll eventually find it.

You should adjust the valves if you have not already (or if you have no idea when it was last done).

You could also check the compression to make sure the engine has enough to start. Low compression on a diesel can make it impossible to start cold.

If the engine has good compression, and the glow plug system is in good order, it should start just fine down to 0 degrees without much difficulty.
 

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Discussion Starter #3
Hi Aaron, thank you so much for your suggestions. the mechanic said the glow plugs were working (new ones were put in last year by him too) but that the system might need replacing if I wanted to keep the car longer - but that was even before I couldn't get the darn thing to start now. You say the new system MAY fix the problem? I wonder if it's worth spending the 400-500 to do this if it's only a MAY fix the problem. I don't want to be spending all winter worrying about whether the thing will start when I come out from school...
 

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Valve Adjustment & glow plugs

I worked on an '85 today that was stumbling a bit on startup now that colder weather has hit. Sure enough, bad glow plug. Light still came on as normal for the owner, but didn't start like it had previously. The glow plugs were all new, so new they're still shiny. Guess what? Didn't matter. I pulled one and saw it was autolites.... Needless to say, they're now all replaced and the car started up as though it was a 90 degree day.

Good glow plugs are under 10$ a piece. Even if they're brand new, they can be dead/bad. You can test'em out pretty easy - google 'diesel giant glow plug' and you'll see just how easy it can be.

What a difference.

A valve adjustment can really help too, for colder weather. That's the cost of a valve cover gasket and a bit of time, if you can borrow the wrenches from someone locally.

Good luck and don't lose heart, they're a labor of love.

Dave aka Ghan
 

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1984 300D
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Some of the Posters have missed the point. Since kane123 has to pay someone to work on his Car he is trying to find a way to get his Engine going with the least expense.

Also from his description his Glow Plugs are working. I believe his Mechainc wants to replace his system with the pencil Glow Plugs.

The Valve adjustment should be done if it has not been done.

The next cheapest to instal a Heater inline with his lower Radiator Hose (like a Block Heater but attaches to 2 sectins of your lower Radiator Hose). The one in the below site/thread has amazon selling them at $18 each + shipping.
Installing one would be cheaper labor wise than replacing the original Block Heater.

In-hose heaters
Diesel Discussion - PeachParts Mercedes ShopForum

As far as "Cool Car" goes they have gas Engined 123s.
 

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1985 300CD Turbo coupe, 2006 E320 CDI sedan
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The next cheapest to instal a Heater inline with his lower Radiator Hose (like a Block Heater but attaches to 2 sectins of your lower Radiator Hose). The one in the below site/thread has amazon selling them at $18 each + shipping.
Installing one would be cheaper labor wise than replacing the original Block Heater.
Kats used to make/sell a reliable inline heater at a reasonable price. But not so in the last 2 years or so, they're simply reselling cheap Chinese clones of their old heater. The farm tractor and construction equipment forums contain plenty of testimony to this.

I put Wolverine oil pan heaters on two of my diesels. When sized properly, they keep the oil at a constant 125F. Heat rising off the full oil pan then warms the coolant by virtue of conduction. Assuming you have an 8 liter oil pan like mine, the 250w size will work just fine - AND save money on electricity (over the coolant heater types). CLICK HERE

Installation is do-it-yourself simple too. Degrease a spot on a warm pan that's just a bit bigger than the heater. After that's it's just a peel-n-stick operation and an application of edge sealant (included).

//greg//
 

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'73 450SL, '83 300CD, '01 E320 4matic
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You say the new system MAY fix the problem? I wonder if it's worth spending the 400-500 to do this if it's only a MAY fix the problem. I don't want to be spending all winter worrying about whether the thing will start when I come out from school...

The first thing you need to do (or have done) is the valve adjustment, followed by a warm up of the engine and a compression test. If a compression test reveals that the engine is in good health, then it's absolutely worth feeding the car some money to resolve the other issues that could prevent it from starting. If the compression test reveals that the engine is tired, then you have some thinking to do.

Is the car in good condition? If it is, you'll probably find that with a little bit of money and love you'll have a car that will last you a good amount of time, and it should be relatively inexpensive to own if you keep up with the basic maintenance. Sure, it's an old car, but price an EGR valve, for example, on a 2000+ ANYTHING. Plus they're just cool cars....

But you need to determine the health of the engine. An engine with poor compression is not going to start well in the cold no matter what else you do. And the results of the compression test will allow you to easily decide whether or not you want to sink any more money into it. If you need to have this test done, it should be inexpensive- at least less than the cost of new glow plugs, the updated relay, and the necessary wiring.

Once you know it's healthy (and it probably is)- consider updating to the new style plugs and relay. The relay can be had for a couple dollars at most junkyards from a turbo model (82+) It is easy to install in the engine compartment as a retrofit to your early style, and it's faster, more reliable, and works better.

Good luck.

EDIT: Where are you located? You may find that a forum member is nearby, and we're a helpful bunch here- A 6 pack is a lot cheaper than paying a mechanic :)
 

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1982 300D Turbodiesel 212K or so, it doesn't work anymore :-)
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seriously...reach out for help...just because you can't do the work yourself doesn't mean you have to result to paying extremely high priced mechanic's fees...

if you did everything described so far, i can't see you spending more than a couple hundred bucks on parts, about 2 six packs, and about 4 or 5 hours of time...

these fixes aren't bad...a block heater replacement is around 75 bucks almost anywhere...they screw in and screw out and that's it...no sense in paying hundreds of dollars...

the glow plugs are stupid easy...replace a relay, screw out screw in the new plugs, update some wiring and that's about it...

and ill put my two cents in on mechanics...unless your mechanic is willing to give out free advice, he's probably going to screw you on labor...the trick to finding a good mechanic is finding one that is enthusiastic about your car...most of them just have the knowledge, they don't necessarily care about what they are doing, thus, they'll screw you when they get the chance...

There are lots of mechanics on this forum that are enthusiastic about these cars and are willing to help out when they can...also, if you do need there help, it's always more than a fair price and you can be sure it's a good price...
 

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1979 280CE
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kane123, lets not jump the gun here.

Do the glow plugs get hot when you turn the key? If i were you i would turn the key on for about 3 seconds and see if the thick resistance wires between the glow plugs are warm. The longer the key is on the hotter those get, be careful they get very hot.

On a cold day let the glow plugs glow for 40 seconds, put your foot on the floor and crank.

Once you have made sure that the plugs are getting hot, you need to adjust the valves. There is a ton of info on the web abut valve adjustments.
 

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Discussion Starter #10 (Edited)
thanks for all the great ideas AND the support. I love this car though it's got rust etc and the windshield is cracked, and finding the rubber gasket for replacing that is difficult too...but I wanted to say that I've had the car looked at by a good friend who is a mechanic and he said the engine is great - that the problem was that the ball joints were seized - but I had those replaced now. I'm going to forward all your suggestions to my mechanic who is happy to have the new experiences - his father used to own the shop - now he does - and they only do mercedes and have been for ever...
He's a very nice guy and knows his stuff - and since this WAS his car, there's that neat connection. I'm looking for a block heater and haven't found a new one nor an old one yet (I'm in Kamloops BC which is 4 hours northwest of Vancouver). One auto parts guy i called asked what I had and his immediate reaction was: Wow! A Classic! :) I like hearing that and seeing people look at the car and smile when I drive by...Thanks again for all the good vibes!!! Jeff
 

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How long should a block heater be plugged in prior to starting, 1 hour, 2 hours, all night ... and does it make a significant improvement in starting?

I had trouble starting it last night, it was about 30F. She(Evelyn) has a block heater but this car has not seen a winter (according to service records, body condition and comments from previous owner).
... and no, I haven't checked glow plugs or made valve adjustments. Those are my next steps.
 

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How long should a block heater be plugged in prior to starting, 1 hour, 2 hours, all night ... and does it make a significant improvement in starting?
I have a timer for my block heater, available just about anywhere. I always had it come on two hours before I intended to drive the car, and never had issues starting.

... and no, I haven't checked glow plugs or made valve adjustments. Those are my next steps.
This is #1- the car will never start in the cold if the valves are tight and the glow plugs are not all functioning. A good strong engine will start without any help from a block heater down to at least 10F, I usually had no major problems starting at 0F on just the GPs when running 2 cycles.

A good battery in cold weather is absolutely critical.... so is good quality fuel. If you're getting below freezing, and your local diesel vendor has not switched to the winter blend, use an additive in your fuel to prevent against gelling fuel.
 

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Synthetic oil will also help. The engine won't be trying to turn over molasses and your engine will pressure up in a fraction of the time compared to conventional oil, drastically cutting down engine wear.
 

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Thanks for the heater info. I plugged it in for 2 hours last night and it started right away. I've got it set up on a timer so I'm good for the real cold.
Valve adjustment and glow plug eval./replacement come first.

I'd be concerned with leaks using synthetic on a 28 yr old car with 170,000 miles. Any comment?
 

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No issues with leaking on my 82 300TD w/ 250,000 miles and in really cold weather watch how long it takes before you get ANY oil pressure with standard 20-50 oil compared to almost instant oil pressure w/ synthetic.
 

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Discussion Starter #17
Here's an Update. I had the block heater replaced and yet it still won't start even when it is above freezing outside - unless I get the tow truck company out and it starts no problem. Compression is low, there's a button I can push a couple times...so would replacing the relay system make this thing run? I only need it to last me until May but I need it to be completely dependable.
 

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glow plugs all working properly? Have you checked the glow plugs system?
 

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1984 Mercedes Benz 300CD European Delivery
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I had the same thing and it turned out that a few of my glow plugs was bad. I replaced it and it started without a hiccup in 10 degree weather.
 

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Discussion Starter #20
the plugs have checked out okay. and he consulted with another mechanic and they can't find anything else wrong so they figure it must be the entire glo plug system...they kept it overnight, and it was hard for them to start in the morning etc. is there a test that can be done to check the system rather than just the plugs?
thx jeff
 
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