1974 240D IP Timing off after head swap? - Page 3 - PeachParts Mercedes-Benz Forum

Delta 4 Wheel · #31 12-17-2008, 03:41 PM

Quote:

Originally Posted by barry123400

The engine getting enough fuel to idle very high is not a head or timing problem I believe. Especially since you apparently can restore normal idle conditions by manipulation of the pump lever with the linkage disconnected. I have got that right? It seems to me that if the linkage duplicated the same position you establish by hand the idle should be the same.

Yes, If I lift the pump lever (not the lever to the fire wall, but the valve cover bracket) up about 3/4 of the movement range it lowers the idle to ALMOST normal. But in relation to the normal movement of the linkage, this direction I am moving it is in the direction of wide open throttle which begs the question why the rpm's would lower instead of go up.

Quote:

Originally Posted by barry123400

If the 76 has the linked flap in the intake manifold it might bear some attention to make sure the function is there. Basically what I am still missing is why by hand on a disconnected linkage do you get a normal idle but not when the linkage is hooked up?

My throttle body has 2 butterfly valves. Look in my pics in this post and you can see. The inner one seems to move freely with no control from the linkage unless that butterfly is wanting to be closed and the linkage is wanting it to be open. It has a bracket on it that is bumped by the throttle linkage that passes through the throttle body. No, with all disconnected, and all checked for binding, the rpms are still high. can lower rpms by holding the free moving, inner butterfly but you can clearly tell that this is choking off the motor and the motor is doing all it can to fight me while spewing pure fuel out the tail pipe.

Quote:

Originally Posted by barry123400

This alone tends to eliminate any head or timing effect in my mind. Yet I might be missing something is a possibility. Is the butterfly linkage disconnected at the same time? Do you even have the butterfly on a 1976 engine? I have never worked around one of those.

The small amount of increased compression if there indicates at worse the timing may be a little ahead. This in itself would not up the idle like you are experiencing in my opinion.

Or even if it did then the manual manipulation of the injection pump lever would not stop it. If your description is correct you are looking for what is different between linkage hooked up and hand manipulation of the lever. Is the lever bearing sound? Side play on the shaft present?

Everything worked like a charm until I swapped the head. I changed nothing on the linkage or the pump. Just hooked it back up and this is what I got. No apparent side play in the arm.

Delta 4 Wheel · #32 12-17-2008, 03:43 PM

Quote:

Originally Posted by leathermang

Manual manipulation of the idle speed brings up that little knob on the dash for some cars...
often they are broken or do not seem to work...but could that be messing with the idle situation ?
This feature was built into the design to compensate for wear later on ...is my understanding... so many don't use it, need it , or know about it until decades later when it has been sitting too long to work without lubrication , etc...

I do have this now and it is all the way loose and the cable has slack at the pivot bracket so this is not causing the issue for sure.

Delta 4 Wheel · #33 12-17-2008, 03:44 PM

Quote:

Originally Posted by mplafleur

I believe the only cause for this is you are giving the engine more fuel somehow.

So an advanced IP cannot achieve this? Other that crankcase oil, where can I be receiving excessive fuel?

mplafleur · #34 12-17-2008, 05:52 PM

I'm bringing a 24D back to life as we speak. The engine rebuild is done and it starts, but likes to run at 1500 - 2000 rpm. It can run at about 900-1000, but stalls with any less throttle.

I've put my injection timing tester on it. It's pretty hard to get accurate timing because it varies so much at low rpm. I'm supposed to time it at 750 RPM and I can't get much under 900, but it looks like I may be as much as 40 degrees off. I've already got the IP rotated in toward the block as far as it will go. I guess tomorrow we will set the engine back to 24 deg btdc and remove the IP and set it again.

So I'm thinking that if you are off in IP timing, idle will become worse to the point the engine will die.

Delta 4 Wheel · #35 12-17-2008, 07:06 PM

Quote:

Originally Posted by mplafleur

I'm bringing a 24D back to life as we speak. The engine rebuild is done and it starts, but likes to run at 1500 - 2000 rpm. It can run at about 900-1000, but stalls with any less throttle.

I've put my injection timing tester on it. It's pretty hard to get accurate timing because it varies so much at low rpm. I'm supposed to time it at 750 RPM and I can't get much under 900, but it looks like I may be as much as 40 degrees off. I've already got the IP rotated in toward the block as far as it will go. I guess tomorrow we will set the engine back to 24 deg btdc and remove the IP and set it again.

So I'm thinking that if you are off in IP timing, idle will become worse to the point the engine will die.

I cant get lower than that even with manipulating the injection pump lever. So is this the best way to proceed, if I find my timing off? Does the 1974 injection pump have a way to lock it for re-install?

(1) Remove front collar from pump
(2)Align the gap in the splines with the mark on the pump housing
(3)Install the collar back onto the pump without rotating anything...
(4)Have crankshaft and camshaft set at the 24 degrees BTDC on the pulley pointer on compression stroke
(5) Install pump as close as possible to the center of its adjustment slot without rotating anything
(6)Install the hold down nuts...leave a little loose...
(7)Hook lines and hand pump to bleed air...
(8)Do the Start of delivery timing and lock IP down

barry123400 · #36 12-17-2008, 08:35 PM

Quote:

Originally Posted by Delta 4 Wheel

So an advanced IP cannot achieve this? Other that crankcase oil, where can I be receiving excessive fuel?

If you were really far advanced I would think the engine would be knocking much harder. You would know the difference.

A long shot might be to make absolutly sure you are on the right power stroke though. I am not sure exactly how your engine would run on the wrong one but they are known to run with the cam out of time in relation to the injection pump. Remember in that senario the cam marks still line up as well. Excess fuel out the tailpipe would not suprise me in that senario. In fact I would actually expect it.

I feel that the fuel introduced at so wrong a time might give the strange symptoms you quote as well. When you advance the lever on the injection pump because of the non existant efficiency the engine kind of floods out and slows down or some other strange effect is created.

Your symptoms are so strange. I wish I were more knowledgeable and able to help more. Take the short time to verify the right power stroke for the injection pump is present.

Anytime a head is removed this senario does become a possibility. At present otherwise I do not really have a clue. Thats if I ever had a clue to start with. :rolleyes.

It is also a possibility that what I earlier mentioned that it was not a pump out of time was wrong in a way. The pump to engine timing could still be close or dead on. Just injecting on the wrong stroke.

leathermang · #37 12-17-2008, 08:50 PM

Since you were smart enough to paint everything when you started...
what is the possibility that you could open things up and check to see that that relationship is still there ?
I am only suggesting this due to the dropped chain statement.
It is very hard to find what is wrong if there are two things out of whack at the same time.

barry123400 · #38 12-17-2008, 09:49 PM

Quote:

Originally Posted by mplafleur

I'm bringing a 24D back to life as we speak. The engine rebuild is done and it starts, but likes to run at 1500 - 2000 rpm. It can run at about 900-1000, but stalls with any less throttle.

I've put my injection timing tester on it. It's pretty hard to get accurate timing because it varies so much at low rpm. I'm supposed to time it at 750 RPM and I can't get much under 900, but it looks like I may be as much as 40 degrees off. I've already got the IP rotated in toward the block as far as it will go. I guess tomorrow we will set the engine back to 24 deg btdc and remove the IP and set it again.

So I'm thinking that if you are off in IP timing, idle will become worse to the point the engine will die.

Post # 36 on this thread might apply to you as well. If only well advanced a lot of hammer and knocking like crazy should be present. If well retarded the idle would also be slow. So much so it would tend to idle slower than normal as well. Engine would still run at 700 rpm in my opinion. Only quitting because of the lack of inertia somewhere below that.

The stalling can be the inefficient factor introduced by the wrong valving for the fuel introduction time. Just an opinion.

Little seems to be known of exactly how the 240ds run when fuelled on the wrong stroke. It is just known they can run. The engine quitting above low normal rpm is kind of symptomatic of the poor system of fuelling when the injection pump is fuelling on the wrong stroke. Worth at least checking in my opinion in your case as well.

t walgamuth · #39 12-17-2008, 10:03 PM

Quote:

Originally Posted by leathermang

Tom , I was sorta kidding ... thinking you would not share that info... I will put that into my address book for sure.

So you are saying he is the machinist equivalent of the Seinfeld " Soup Nazi " ? LOL
Everyone should follow certain " normal " rules anyway...

I agree that the cam position is not changed or the problem.

Since the ' beginning of start' on the fuel is pretty easy to determine I suggest that be next on the list. The FSM is very sincere about keeping tension on the chain when rolling in a new one... and looking at the crank will not show the problem until the engine is started and the tensioner gets oil pressure.

No he's nothing like the soup nazi, he's really a great guy, but if insulted does not suffer fools gladly.

t walgamuth · #40 12-17-2008, 10:04 PM

Quote:

Originally Posted by mplafleur

I don't see how IP timing could do this. Fuel delivery is regulated by the ALDA and the throttle lever. If just moving the IP timing can increase RPM without adding more fuel, then you've found a more efficient timing position for the IP than the factory specified position.

I believe the only cause for this is you are giving the engine more fuel somehow.

I didn't think there is an alda on a non turbo motor.

mplafleur · #41 12-17-2008, 10:25 PM

Quote:

Originally Posted by t walgamuth

I didn't think there is an alda on a non turbo motor.

There is an altitude adjustment thing on top of the IP. It isn't connected to anything, just ambient air.

barry123400 · #42 12-19-2008, 05:56 PM

Thread originator pay attention! It was the cam out 180 degrees on the second posters car on your thread with a very simular problem. See his thread for conformation..He was injecting fuel on the wrong power stroke.

We now know one symptom of how a 240d runs with the cam 180 degrees out and the injection pump fueling on the wrong power stroke. You cannot seem to get a decent low idle to start with.

Stevo · #43 12-19-2008, 08:00 PM

Quote:

Originally Posted by barry123400

Thread originator pay attention! It was the cam out 180 degrees on the second posters car on your thread with a very simular problem. See his thread for conformation..He was injecting fuel on the wrong power stroke.

We now know one symptom of how a 240d runs with the cam 180 degrees out and the injection pump fueling on the wrong power stroke. You cannot seem to get a decent low idle to start with.

That happened to me on the first one I pulled apart, my daughters 240, we tow started it, and it ran so BAD, even I new there was something drastically wrong

Delta 4 Wheel · #44 12-22-2008, 01:54 AM

Quote:

Originally Posted by barry123400

Thread originator pay attention! It was the cam out 180 degrees on the second posters car on your thread with a very simular problem. See his thread for conformation..He was injecting fuel on the wrong power stroke.

We now know one symptom of how a 240d runs with the cam 180 degrees out and the injection pump fueling on the wrong power stroke. You cannot seem to get a decent low idle to start with.

I set the engine at TDC before I pulled it apart. I looked for cam timing marks, they were lined up I then painted the cam gear and chain with white paint in two places.

When I put it back together, I set it all back the way it was. I was puzzled a bit when I put it back together because the cam thrust washer has 2 key-ways, 180 deg. out from one another. The cam gear, however, only has one key. Giving this, I cant see how I can have the cam timing out 180. Where is my logic wrong on this one?

jt20 · #45 12-22-2008, 11:09 AM

were the lobes on the cam for #1 pointing up or down when you reassembled?

same issue here:
NO START after HEAD REBUILD and install...