1982 300d cranks but does not start

[areza317]

A buddy of mine gave me his 300d that had been using since he could not take it with him since he was moving. He told me it was driving fine and then one day would not start. It sat for about 3 months and I just put a brand new battery in it. The car cranks but does not start. It does sputter out smoke from the muffler when I am trying to crank it and the glow plugs come on and shut off when I turn they key. I have tried to start it in Park and Neutral with the same result can anyone help me out. My buddy said some guy who own a junk yard told him that he has a rebuilt engine and that he should just replace the engine. I just think he is trying to make the sale.

[BigRed0803]

I would start by actually checking your glow plugs with an ohm meter at the GP relay. Sometimes the light can still work with a bad GP. I would change both fuel filters and prime the motor good using the hand pump. Make sure that you are getting fuel to the motor, you could possibly have a stopped up tank strainer. Let us know what you find out.

[engatwork]

Loosen up the injector lines at the injectors and make sure you are getting fuel out while cranking over. You need fuel coming out of at least three lines to get it going (I'm assuming a five cylinder w123 car).

Welcome aboard.

[areza317]

Ok I got it to start but the only way I can get it to start is with Starting Fluid. If I drive it for a while and shut it off it starts back up but if I leave it off for a long period of time 1 hour or more than I have to use the starter fluid again. Any ideas on what could be causing this?

[just-n-time]

diesel starts on compression,that means it starts by supper heating the fuel as it compresses, there fore starting when it is warm you took the glow plug job out of the starting loop. I must agree that your trouble sounds like it is in the preheat system. Either you are not getting full voltage to the glow plugs or your plugs are defective. Be causes of either to much can cause a large enough explosion to split a cylinder.

[TnBob]

Starting fluid is not a recommended item for diesels.

[barry12345]

Read up in the archives what you can about the glow plugs and their circuit. The probability that this system is not operating properly is very high on the list. Ether use is really frowned on for these engines. If you do not have a cheap digital voltmeter you may need one. A less that 5.00 type from places like harbour freight is fine.

Many engines will not self start with just a couple of malfunctioning glow plugs. Almost the most common difficulty on diesel engines as well. Do not kill your engine with ether before repairing it.

[Air&Road]

Originally Posted by areza317

Ok I got it to start but the only way I can get it to start is with Starting Fluid. If I drive it for a while and shut it off it starts back up but if I leave it off for a long period of time 1 hour or more than I have to use the starter fluid again. Any ideas on what could be causing this?

Be CAREFUL!!! Using starting fluid on a glow plug engine is RISKY!!!!!

If you use it, disconnect the glow system first!!!!!!

Sounds like you have a problem with the glow system. Most likely the plugs.

[Air&Road]

Originally Posted by TnBob

Starting fluid is not a recommended item for diesels.

Starting fluid is fine for occasional cold weather starting diesels. JUST DON'T USE IT ON GLOW PLUG DIESELS!!!!!!

[kerry]

99% of no-start conditions on these engines are caused by inoperable glow plugs. You need to confirm the correct operation of all the glow plugs before doing anything else. Make sure they are getting 12 volts for about 30-40 seconds with the key in the glow position and that none of them has resistance over 1 ohm when they are checked with an ohmeter while the glow plug harness is unplugged from the glow plug relay. Do those tests and report back. Us no starter fluid in the meantime.

[Air&Road]

Kerry recommends a good step for this point in the troubleshooting. I would add, however, that it is not at all uncommon for pin type glow plugs to pass the resistance test and still be bad.

It is common to remove a pin type plug that passes the test only to find holes burned in the shell.

[kerry]

I agree the test is not definitive. The plugs could show appropriate resistance and still be bad. But to my knowledge, the reverse is not true. A plug with high resistance is never good. So if he or she gets either no voltage or a plug(s) with high resistance, the next step of providing voltage or replacing plugs is in order. These diagnostic tests should take no more than 5 minutes and will provide information which will determine the next step.

[Air&Road]

Absolutely! If it fails the resistance test it's bad!

[mach4]

Very high probability of glow plugs being the problem as stated above.

Yesterday I test started a junk yard 617 for the first time. Did a valve adjustment, followed by a compression test (350 or above on a cold engine) and used a set of matched pop tested injectors. I thought I might be able to get it started without glow plugs as my other engine will fire off within 8-10 sec without glow at 70 ambient or so. No luck. So I hooked up a glow circuit and the engine popped instantly with 6 sec glow with ambient at 70.

While compression and injectors could be problematic, without a known good glow plug system you'll likely not get the thing to start.

[Jonrich]

I have 1982 300sd that had the same problem it turned out to be the glow plugs. If you do replace them use the Bosh brand (the others don't work).
Also I recommend a Mercedes battery if you don't all ready have one they are expensive but are well worth it in my opinion.
Best wishes Jon