84 300D 100K does not start - Page 2 - PeachParts Mercedes-Benz Forum

kerry · #16 01-28-2007, 10:54 AM

Quote:

Originally Posted by mdisav

Car still did not start. I took the injector lines off and cranked it to see if fuel was coming out. It was not. So I pulled the vacuum line to the shut off valve and cranked it. Fuel shot pretty high! I put the injector lines back on and with in a fuel cranks she fired. I replaced the shut off valve with a new one I had and all is well. Upon removal of the old one it looked fine and functioned fine. Was it just sticking? How does the valve stay pulled keeping the fuel stopped? Ignition switch bad???

I will see how it starts in the morning.

This raises an interesting issue. A number of forum members have posted problems with the starter not functioning at colder temperatures. A forum member recently traced the problem, not to a starter problem but an ignition switch problem. Your situation makes me wonder if a similar ignition switch problem, exacerabted in the cold, may the cause of the difficulty. I have not looked at the ignition switch. Is there anything in the mechanism which releases vacuum from the shut off valve when the key is switched on, that might be slow or not completely effective in cold weather in the same way that the starter component of the switch fails to function in cold weather?

Brian Carlton · #17 01-28-2007, 11:08 AM

Quote:

Originally Posted by Shorebilly

....and you want "crisp" starts?? It's also a diesel, and it's chilly outside......

My definition of a "crisp" start would be starting in a couple of revolutions....no more.....

SB

Before the head was replaced, the SD would struggle to start at temperatures below about 15F. It would crank for 5-10 seconds or so. Anything close to 0F. required the block heater unless you were really a gambler.

Interesting to note that the new valves allow the SD to start in one second at 0F. The benefit cannot really be attributed to anything other than the valves.

I've got a strong suspicion that the valves on some of the older engines are "marginal". The seats are not what we would call "burned", but there is definitely leakage at some points around the face. Doesn't take much leakage at crank speed to drop the compression and kill the start prospects.

mdisav · #18 01-28-2007, 11:20 AM

Very good point Brian! I had a suspicion that the valves were not up to par.

I took a look at the pump timing mark and the mark on the pump was higher than the mark on the block. Someone had adjusted it. Is that late or early timing? I lined it back up and it starts fine. It did have to get the air out of the lines. I will go back in a little bit and see how it starts now that the air is purged.

Brian Carlton · #19 01-28-2007, 11:23 AM

Quote:

Originally Posted by mdisav

Very good point Brian! I had a suspicion that the valves were not up to par.

I took a look at the pump timing mark and the mark on the pump was higher than the mark on the block. Someone had adjusted it. Is that late or early timing? I lined it back up and it starts fine. It did have to get the air out of the lines. I will go back in a little bit and see how it starts now that the air is purged.

There you go.......messing with what was already properly adjusted.

The mark on the pump should "normally" be above the mark on the block on older engines. As the timing chain wears, the IP needs to move closer to the engine to keep the IP timing on the money.

What you did confirm, as I previously mentioned, is that the IP timing, even when late, won't have much of an effect on the start.

mdisav · #20 01-28-2007, 12:02 PM

So rotated towards the block is advanced or early and away is retarded or late?

Brian Carlton · #21 01-28-2007, 09:37 PM

Quote:

Originally Posted by mdisav

So rotated towards the block is advanced or early and away is retarded or late?

Rotating toward the head will advance and away will retard. Whether it's actually ahead of the specification is unknown until you test it.

mdisav · #22 01-31-2007, 08:29 AM

It is 25F and it did not start again. I took off the fuel lines and no fuel again. I disconnected the vacuum line to the shut off valve and fuel pumped out the delivery valves just fine. I put everything back together and left the line to the shut off valve off. I cranked for a while and it did not start. But I do have a bunch of air in the lines. I will go back out when it is a bit warmer and crack the lines at the injectors and see if it starts.

Does it seem like I have a faulty ignition switch? The shut off valve is new. What would cause vacuum to be present when I am trying to start it?

Brian Carlton · #23 01-31-2007, 08:45 AM

Quote:

Originally Posted by mdisav

Does it seem like I have a faulty ignition switch? The shut off valve is new. What would cause vacuum to be present when I am trying to start it?

The only thing that will casue that is the ignition switch. When you turn the switch to the #2 position, all vacuum to the shutoff valve should be released. You can do a quick test for this.

mdisav · #24 02-06-2007, 06:12 PM

I disconnected the vacuum line to the shut off valve to rule out the ignition switch and shut off valve affecting starting. Still no start after plenty of glows and lots of cranking. Today I decided to put a lift pump on because I had a good one in the shed. I put a new battery in and cranked like heck. It eventually fired and I took it for a good ride. I will see how it starts tomorrow at 20F.

captainmonk · #25 02-06-2007, 06:29 PM

any starting is good starting crisp is good for the crease in your trousers

mdisav · #26 02-12-2007, 06:07 PM

Even did not start at 45F. After cranking for about 30 seconds or more it fired but geez. I am starting to think something is up with the glow plug system. I do get 12v on all leads. Maybe I have some bad plugs. They look new and all ohm out like new.

BillGallagher · #27 02-12-2007, 07:19 PM

Quote:

Originally Posted by mdisav

The car did start decent this morning. No long cranking like before. So I guess the shut off valve is working properly. I wonder if the pump timing needs to be adjusted to make it start better when cold??

It does idle a bit low when cold and then picks up. I want it to start really crisp. Valves rechecked and are just right. New fuel filters.

Anything else to check but the pump timing? I will make sure the rack dampner is not too far in.

Can you be more detailed on how the idle is after first starting? This will indicate a bad glow plug because one or two cylinder is not firing because the temperature in the cylinder is not high enought. After 5 to 8 seconds, then the fault cylinder will be working and the idle is higher. Black plug tip show bad, I have replaced plugs about every year now, in the past it was 3 to 4 years.

Bill
p.s. since the tank was full of JHB9&0-H, stick to the fuel system as the cause and related issues this will cause. In other words, remain focused....

mdisav · #28 02-12-2007, 07:36 PM

It does do a little bu bu, kinda of like a miss for a bit just after it starts. That is if it has sat for a bit after it was started for the day. But when I start it for the day it always idles fine because it is a pedal to the floor crank like heck clearout start. The idle is not that low though. All glow plugs looked like new when I took them out.

When I take off the fuel lines and crank, fuel does come out all the time now and does shoot pretty high out of all five delivery valve holders.

BillGallagher · #29 02-12-2007, 08:44 PM

Quote:

Originally Posted by mdisav

It does do a little bu bu, kinda of like a miss for a bit just after it starts. That is if it has sat for a bit after it was started for the day. But when I start it for the day it always idles fine because it is a pedal to the floor crank like heck clearout start. The idle is not that low though. All glow plugs looked like new when I took them out.

When I take off the fuel lines and crank, fuel does come out all the time now and does shoot pretty high out of all five delivery valve holders.

Still sounds to me like a glow plug issue since the engine is missing when not used for a long time in cold weather. And when started and used during the day, there is no problem since the engine is somewhat warm compared to overnight.
I will still remove the glow plugs and check them by your eye, and then move on to the relay issue...but really feel it is a glow plug issue...

Bill

mdisav · #30 02-13-2007, 08:56 AM

I think we are onto something. 31F here and she started excellent. Cranked right over with no pedal and held a nice idle.

The ignition switch has been suspect the whole time. With the shut off valve possible issue and it not shutting down immediately when turning the key off.

It is sometimes hard to turn the key on and jiggling the steering wheel does not help. Well today I found if I insert the key and turn it with slight pressure outward it turns very easily. And what do you know... It started like a champ.

I will do a search on replacing the ignition switch.
Thanks a bunch for all of your help thus far!