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Discussion Starter #1
I am in cold weather (typically 0 -20 F at night).The car has a block heater plug which I use overnight, and with that it starts fine.

However if I am parked outside all day, at the end of the day it is a real problem starting, and twice this past month I have had to have the tow truck come, tow me a few hundred feet while in first gear with the key switch on, and then it will start.This last happened at a ski resort this weekend and was a real pain.Once the truck arrived, it pulled me about 200 feet and the car started up.Once warmed up it started again with no trouble.

I use winter diesel blend (#1 and#2 diesel 50/50), also Diesel Kleen cetane booster, keep the tank full.

These are German cars meant to start in German winters. Any suggestions?
Could it be the glow plugs need replacing? Should I switch to synthetic oil?
I am out of ideas. I have started with a fully charged battery and tried over and over to start,until I have run the battery down.

My 240D manual trans is a great car, but it is trying my patience. Any advice would be really appreciated.
 

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ive started my 240D in similar condition with no glow plugs. just pumping the gas. three or four tries. i finally broke down and bought 4 new glow plugs along with a new relay. i dont use a block heater at all. it wasnt inbetween 0-20 for to long. but im assuming its the glow plugs, because with good glow plugs i have no problem
 

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Takes less time to check the glow plugs with an ohm meter han it does to read this thread everyday. :) Good ones will read about 0.7 ohms cold.

Len
 

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I struggled with the same problem on my "new" 1979 300SD , changed the GP , tried a different Gp relay ,adjust my valves ............without any improvement .
Then , I changed my oil ( previously 15/40 dino) to 5/40 synthetic !
Et Voila....now she starts in 20* with no more than 10 seconds on the starter .
 

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Discussion Starter #7 (Edited)
thanks for the suggestions. Should I specify standard factory glow plugs or something more specific. Same with the relay. Think I will also consider switch to synthetic if the MB mechanic agrees. I am the original owner of this 1979 240 and would like to keep it indefinitely.
 

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I believe you have the loop style GP's, when one goes, none will have power, I think. Somewhere there is a kit to upgrade to the newer style, when one goes, the rest will work.
 

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I'd definitely upgrade to the newer style glow plugs. There are several vendors who have kits to retrofit new style (pencil) plugs in place of the older loop style plugs. There are a few advantages to the new style: 1. They don't take as long to heat up - therefore you can start your car sooner. I believe they glow warmer than the old style too. 2. If one plug goes out, the others still continue to work. 3. You don't have to deal with ceramic discs or the resistors between the glow plugs.

I changed to synthetic oil (Rotella Synthetic 5w40) on my 300D as well. It most certainly helped with cold starts. I've had it sitting in 8*F weather all day and fire up just fine. Oddly enough, it seemed to stop the oil leak I had out of the rear main seal too. Prior to changing to synthetic, 8*F was out of the question w/o the block heater, and temps in the teens resulted in difficult starts.

Have you checked your valve adjustment? Overly tight valves could cause lower compression and therefore make cold starts a bit difficult.

How many miles do you have on your 240D?
 

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Takes less time to check the glow plugs with an ohm meter han it does to read this thread everyday. :) Good ones will read about 0.7 ohms cold.

Len
Is the 0.7 ohms cold the same for a w124 5 cyl. 300D turbo? Mine starts hard in 30s! And the GP light comes on for a minute or so after it starts. It starts fine in the 50s.
 

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Is the 0.7 ohms cold the same for a w124 5 cyl. 300D turbo? Mine starts hard in 30s! And the GP light comes on for a minute or so after it starts. It starts fine in the 50s.

Yes.

Len
 

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I updated my '78 with the pencil type, and it works great!, but rather than paying all that money for the tow truck i would invest in a $3.00 can of starting fluid, but just use it if you have to.
 

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I updated my '78 with the pencil type, and it works great!, but rather than paying all that money for the tow truck i would invest in a $3.00 can of starting fluid, but just use it if you have to.
Starting fluid is a bad idea. Use WD-40 instead.

Also make sure the battery is up to snuff and the starter is cranking fast.
 

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Thanks. I decided to order some from AZ anyway. I'm pretty sure they are shot. The GPs were only 11.99 a piece! And they were Bosch.
 
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