hard starting 300TD diesel
 

I have an '81 300td wagon suffering from all the aches and pains of its age, but still running strong. The biggest issue now is that it is hard starting, and I'm wondering if anyone can give me some tips on correcting the problem. My husband knows these engines inside and out, but isn't quite sure what's going on with this one. We have a new battery, I plug in the heater for several hours, and he's checked the glow plugs, air and fuel filters, and alternator. It just doesn't seem to get enough power to get the cold(but heater-warmed)motor turning. We end up having to hook up a charger or jump it every morning, then it will start the rest of the day. He has an old 240D with lousy compression that starts up on the coldest days without a heater, so I'm wondering why mine with a good motor has so much trouble. Recently the pre-glow indicator quit, though it is still pre-glowing, and the car has a long history of annoying electrical problems; fuses blowing, headlights burning out within days, etc. Any ideas out there? Thanks!

Heat, fuel, compression... gotta run. Somethings missing out of these or not enough of some.


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Have you adjusted the valves lately? More often than not the valve adjustment is overlooked as being a contributing factor to a cold start complaint.

You might also want to address the inoperative glow lamp.........maybe it will cure the problem, maybe it won't. None the less it will work as designed.

check your grounds, especially the large, thick one that attaches under the lower starter bolt - make sure it's clean and tight.

hard starting 300td
 

Checking valves has been discussed...also the starter. But when fully charged and heated it cranks fast enough, and once running it runs great, not a skip or a hint of a stall. If it is preglowing ok but the light doesn't come on, would the bulb be the most likely culprit or a switch, fuse, or relay somewhere? I know only what I've picked up from my hubby the expert over the years, so am not perhaps as aware of the possibilities as he would be. He doesn't like computers though, so I'm trying to muddle my way through here asking you guys(prompt response, everyone; I'm impressed!). He also doesn't like anything electronic, so the thought of trying to track down the reason for the preglow indicator failure makes him nervous. He wants me to just listen to the relay, but that isn't so easy. I'll see about checking valves first, and see if there is an easy way to fix the preglow light. Thanks for the advice! Anyone who knows of a nice old 300TD wagon for sale, garage kept, 60,000 miles, no rust, driven by a quiet, obsessive librarian and maintained perfectly, let me know. My dream car.

Is the engine cranking over fast enough? My thoughts for a reduced cranking speed issue;

• Voltage drop over the pwr/grnd circuits
• Alternator bearing (seen it)
• Water pump bearing
• A/C comp bearing
• Weak battery

We can help him overcome his fear of not being able to see or touch the electron, ve have vays of helping doz who do not understand, YA! :cool:

It could be a bad starter. Check the draw on the starter when it's cold to see how many amps it is drawing, then compare it to the draw on the 240d starter.

"If it is preglowing ok..." leads me to ask if you know if it is pre-glowing OK, and how?

The pre-glow lamp will not light if 2 or more plugs are bad, or of #1 is bad. The relay will click on and off regardless how many plugs are bad.

We need to find out if it is indeed the lamp, or some glow plugs that are bad.

Let's be sure before we replace a light bulb, and a relay, only to find some other problem.

hard starting 300TD wagon
 

We know it's preglowing because he put a test light on each glow plug while preglowing. And it starts great after it's been heated and had the charger on it for a few hours.
Starter test tomorrow, maybe that will pinpoint it.
If we have to begin with serious stuff, should it be the starter (remove and test it) or the valves? I guess the starter test might help determine this.
Apparently the electrical supply has been checked and is ok.
Ve hav vays, but since he grew up in Deutchland he already knows them all!
Thanks everybody, I appreciate the input.

How to check the glowplugs...
 

Hi there,
Your husband's method of checking the glow plugs is faulty! All he is verifying is that there is voltage to each glowplug terminal, but it doesn't mean that the glow plug itself is any good. He will have to remove the wire from each glowplug and check for resistance on each one. You could very well have 5 open glow plugs. Just like a light bulb, they have to complete the circuit to light up. If they don't "glow", the car won't start.

Of course, you could always give up on that smelly, oily diesel and install a nice Astrovan V6 and transmission like I did! HAH! (I have almost twice the power, and still get 28mpg on the freeway.) Gasoline is now cheaper than diesel, also!


Good luck,
Richard Wooldridge

'82 300D/4.3L V6/T700R4
'79 450SL
'75 280C

Valves
 

I would bet its the valves. I had a 84 300TD same problems after 40 Degrees, It would not start. My valves were over adjusted. I reajusted them to specs and 18 degrees car started every time.

sounds like
 

classic case of glow plugs not working.

or bad ground on starter or engine. the starter could be bad but more likely one of the above.

tom w

As others have said, this only shows that voltage is applied to each glow plug. If the glow plug is bad, the voltage will have nowhere to go, like flipping on a light switch to a bad light bulb; nothing useful happens, but a test light would say the circuit is OK...

Glow plugs help start the engine, and are not needed once it starts, or if it is warm enough. If the starter cranks it around enough times, the compression heat will build up until the fuel can ignite, and it will start 'great' each time there after as long as it stays warm ...

Check the 'sticky' posts at the top of the forum for glow plug testing. It involves a multi-meter set to resistance (ohms) and a few simple procedures. Start there, and work your way to valve adjustment, etc.

problem solved
 

Ok, it was the glowplugs after all. it was just some mix up in the testing, so he thought they were all good. In fact 2 were shot. Now it should start, and the light should come on as expected. Thanks all, it's been fun. Now, how about the broken heater, air conditioning, windows, door locks, suspension, fuel gauge, antenna, leaking sunroof, and an unidentifiable rear end clunk clunk clunk when going up a steep hill slowly? Just kidding. As long as it starts, I can live with everything else. Have fun dieseling. Kirsten


Also, since everyone else does it...
'81 300TD turbo wagon
ancient 220D
more ancient sacrificial 220D
moderately ancient 240D
Iveco diesel box truck(not drivable, great motor)
Chevy diesel flatbed truck
rehabilitated diesel Case backhoe
Numerous and sundry diesels of every concievable type and condition
See a pattern here?