cold starting problems / IP start of delivery on '84 300D - PeachParts Mercedes-Benz Forum

airbus · #1 02-04-2007, 12:24 PM

OK, I think I'm on the right path here to fix my cold start problems. I tried to adjust the start of delivery with the drip method but I could not find a spot where I would get 1 droplet per second. I put everything back together and now it ran like crap. I probably moved the IP to far away from the engine (retarded it). Next I moved it all the way towards the engine and WOW: the next morning it started at 27F without the block heater. Before it sometimes wouldn't start below 30F even when it was plugged in. It still needs two or three minutes of "playing with the gas pedal" before it stays running by itself, though, and that's the question: If I pull the IP out and "jump" one tooth and then advance it even more, what could possibly happen? Would this solve the problem or create new ones? Any other ideas?

barry123400 · #2 02-04-2007, 07:19 PM

Make sure to check your chain stretch. If the pump was that far retarded it might be a lot. Try to also acertain why the drip test did not function for you. Read what is available.
At the moment I am not sure why it did not. I guess if you could not reach the slow drip point it would be signifigant. Yet you indicate it was well back in the adjustment slot when you stopped trying to adjust your pump. All your forward movement beyond the original position the pump was in was just to make up for the stretch of the chain I think. Do not ignore it as it may be really excessive. If that proves so and you land up changing the chain all should work out well. You will have to borrow or buy a dial gauge and stand if you do not own one to check it. Harbour freights cheapie is acceptable for this.
If the chain turns out to have acceptable stretch you can go back to completing the drip test. You might land up moving the pump by a front spline movement. One chain tooth would be too great a movement.

Stevo · #3 02-04-2007, 08:49 PM

Quote:

Originally Posted by airbus

OK, I think I'm on the right path here to fix my cold start problems. I tried to adjust the start of delivery with the drip method but I could not find a spot where I would get 1 droplet per second. I put everything back together and now it ran like crap. I probably moved the IP to far away from the engine (retarded it). Next I moved it all the way towards the engine and WOW: the next morning it started at 27F without the block heater. Before it sometimes wouldn't start below 30F even when it was plugged in. It still needs two or three minutes of "playing with the gas pedal" before it stays running by itself, though, and that's the question: If I pull the IP out and "jump" one tooth and then advance it even more, what could possibly happen? Would this solve the problem or create new ones? Any other ideas?

I once pulled and swapped the IP because I couldn't get the timing to "work" then I figured out I had forgotten to disconnect the vacuum line

Don't let this happen to you

airbus · #4 02-05-2007, 09:35 AM

I went strictly by the book (Haynes) and double checked everything. The chain has been replaced about 10k miles ago. I have to add that the car never started right when cold, even before the new chain. So, I think I can't blame my mechanic who did it, he just put everything together the way it was. The screw up (I don't think it's chain stretch) must have happened a long time ago.
I was thinking of pulling the IP out a little, turning it away from the engine and then just put it back in, hoping to jump exactly one spline (?) to give me more room to advance it. I was not planning on jumping the chain one tooth (?), sorry for the confusion, but English is my second language.
Thanks a lot for your input; now I have to wait until the temps are back in the 20's. It's just too f*ckin' cold to work on the car right now...

barry123400 · #5 02-05-2007, 12:09 PM

Quote:

Originally Posted by airbus

I went strictly by the book (Haynes) and double checked everything. The chain has been replaced about 10k miles ago. I have to add that the car never started right when cold, even before the new chain. So, I think I can't blame my mechanic who did it, he just put everything together the way it was. The screw up (I don't think it's chain stretch) must have happened a long time ago.
I was thinking of pulling the IP out a little, turning it away from the engine and then just put it back in, hoping to jump exactly one spline (?) to give me more room to advance it. I was not planning on jumping the chain one tooth (?), sorry for the confusion, but English is my second language.
Thanks a lot for your input; now I have to wait until the temps are back in the 20's. It's just too f*ckin' cold to work on the car right now...

Sounds like you have it under control. If english is your second language you are doing very well.
Part of changing the old chain out 10k ago was to retime or at least check the pump timing. In that your mechanic might have failed you.
You are right as sometime before the new chain was installed. Perhaps the pump was moved one spline to get a drip timing position with a really stretched chain. It could have happened. I was just concerned for you having a badly stretched chain in there right now causing your problem. Glad at least that was not so.
The injection pump timing and chain stretch should be checked including the chain guides on every new to us 123 or 126 we bring home. The results of not doing it can be loss of the engine or poor running/starting efficiency. That of course does not apply if you know from the past owner all these things were kept on top of or records to indicate it was done exist.

Stevo · #6 02-05-2007, 04:50 PM

Quote:

Originally Posted by airbus

I went strictly by the book (Haynes) and double checked everything. The chain has been replaced about 10k miles ago. I have to add that the car never started right when cold, even before the new chain. So, I think I can't blame my mechanic who did it, he just put everything together the way it was. The screw up (I don't think it's chain stretch) must have happened a long time ago.
I was thinking of pulling the IP out a little, turning it away from the engine and then just put it back in, hoping to jump exactly one spline (?) to give me more room to advance it. I was not planning on jumping the chain one tooth (?), sorry for the confusion, but English is my second language.
Thanks a lot for your input; now I have to wait until the temps are back in the 20's. It's just too f*ckin' cold to work on the car right now...

I wouldn't try that "pulling the IP out a little, turning it away from the engine ", thing... Your apt to just "muddy the water", next step should be to time it and see just whats going on. Your are going to have to do that in the long run anyway, of course you could nail the "sweet spot" or hit the Latto

airbus · #7 02-05-2007, 05:51 PM

Quote:

Originally Posted by Stevo

I wouldn't try that "pulling the IP out a little, turning it away from the engine ", thing... Your apt to just "muddy the water", next step should be to time it and see just whats going on. Your are going to have to do that in the long run anyway, of course you could nail the "sweet spot" or hit the Latto

But I did try to find the "sweet spot" within the entire range of adjustment and I couldn't. There was always a steady stream coming out, diminishing to a fast dripping and after the pressure was gone it almost abruptly stopped. I pumped again and again with the same results, no matter how advanced or retarded relativ to its original position the IP was.
The engine was at exactly 24 deg. BTDC, all vacuum lines to the IP disconnected, throttle linkage fixed at full throttle with a piece of wire and fuel valve taken out of #1 element. Did I miss something?
However, I observed much better but still far from perfect "starting behavior" (still won't start below 20F) after I gave up with the drip tube and advanced the IP all the way.

Stevo · #8 02-05-2007, 07:58 PM

Quote:

Originally Posted by airbus

But I did try to find the "sweet spot" within the entire range of adjustment and I couldn't. There was always a steady stream coming out, diminishing to a fast dripping and after the pressure was gone it almost abruptly stopped. I pumped again and again with the same results, no matter how advanced or retarded relativ to its original position the IP was.
The engine was at exactly 24 deg. BTDC, all vacuum lines to the IP disconnected, throttle linkage fixed at full throttle with a piece of wire and fuel valve taken out of #1 element. Did I miss something?
However, I observed much better but still far from perfect "starting behavior" (still won't start below 20F) after I gave up with the drip tube and advanced the IP all the way.

Sounds like you need to step back and and maybe try another method. I use the drip method where you basally blow air through the IP while rotating the eng, when the bubbles stop, there you are, do a search on "drip method" Most folks here like the drip method but I could never get it too work and its messy

winmutt · #9 02-05-2007, 11:21 AM

This problem you are describing is the exact same I am currently experiencing. Have to be WOT to get the car warmed up. Once it is car runs just fine. I plan on timing my pump in a few more weeks.