Rebuilt top end on '73 280E - won't start! Help me please!

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Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Sun 01 Jul, 2018 9:32 pm

Hey all, and thanks for looking. I registered on here to ask a question, so if you're reading this, thank you.
About two months ago I took my daily driver, a W114 280E off the road to replace a breaching head gasket. It evolved into a monster job (for me) and the head was reconditioned while I restored most of the engine bay. On reassembly I found some obstacles as I was not involved during some of the disassembly process, and had to figure out a few things with my semi-limited knowledge based mostly on a Sigma and a Fiat :)
Anyhow, the engine is now completely re-assembled, and very clean inside and out. New plugs, leads, coil, all Bosch. The car won't start. I keep running the battery flat just turning it over, and there's not even a cough or splutter.
I've checked the timing, if piston #1 is at TDC, and the DOHC sprockets are in the correct place with notches aligning, and the rotor is positioned at point #1, that should mean correct timing if I'm not mistaken? Fuel arrives at the rail no problem, and the leads deliver spark.
There was one part I couldn't find a home for, which was a strange rubber-covered sensor which connects to the base of the diagnostic plug. I did a lot of google-image research and found that on some pictures I could see the sensor sleeved around lead #1. Is this an imperative part of the startup process?
I'll add some pictures if I can. If anyone knows what it does, or can help me, that would be really appreciated. I'm trying to avoid calling a mobile mechanic as I'm totally poor and hoping to spend not too much more on this engine.

And a dumb question, but the rotor does spin clockwise, right?
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Henry Schuman » Wed 04 Jul, 2018 7:26 am

The part you are holding is the Tach sensor or part of the Diagnostic plug that the Bosch Tester hooked to and should not cause the problem you are experiencing.
I will be glad to help as well as many others here will if you are willing to try a few things and report back in THIS thread .
Did you align the Top dead center at the ballancer and have the cam marks lined up and the Rotor under the Distributor cap pointing to number one BEFORE you tore it down ?
If no to these questions then you could have the Distributor 180 degrees out and will need to put this right .
There are Many other things to check as we get more info from you .
Regards

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Wed 04 Jul, 2018 2:46 pm

Hi there, thankyou for replying!
I aligned TDC and notches on cam sprockets prior to pulling the engine down, and kept the timing chain from falling in while it was disassembled. I have checked the timing alignment by turning it manually a few times while reassembling and the notches and rotor are still in the position they are supposed to be in, with the rotor pointing at the notch on the distributor housing when at TDC with sprockets aligned.

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by CraigB » Wed 04 Jul, 2018 6:06 pm

I'm not sure why I couldn't see this the other day when i searched from your other thread. Anyway, thanks Henry for linking the two threads.

I am not an expert with this engine but generally what Henry is talking about can catch you out. No. 1 piston is at TDC twice in an engine cycle and you can be 180 degrees out. When your rotor is lined up with your no. 1 plug lead, are the valves on No6 at the point of opening and closing? If its No. 1 then you are 180 out. If you have sparks happening at the leads and fuel then that would seem most logical. Being EFI I geuss the next question is if the injectors are opening. If you sprayed some aerostart down your intake and got a kick, that might be a shortcut to tell you if it is ignition or fuel.
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Wed 04 Jul, 2018 9:53 pm

Thankyou, I will check on this. So you're saying that upon reassembly I may have put the sprockets in one revolution too early? I shudder to open the engine up again, as I'm entirely a novice, but if it's a potential way to avoid it costing me more shiny pennies I will check on the valve position and rotate the shafts if necessary. I honestly admit it gives me a mental blank, becuase surely if the TDC on the balancing wheel and the camshaft notches and the rotor line up, it should be a winner... I guess it will come to me as I look into it. Thankyou both for all your help so far! :)
Last edited by ledmeter on Wed 04 Jul, 2018 9:59 pm, edited 1 time in total.

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Wed 04 Jul, 2018 9:59 pm

Lol, I have to see what a 'Dernburg Wagon' is.
So just to clarify, the valves should be poised at #6 cylinder if the point is on lead #1.

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Henry Schuman » Wed 04 Jul, 2018 11:18 pm

As CraigB stated if you put it all back the way it was then it Should run.
We guessed for over a month on another no start a while back and the guy had just run out of Go Juice :banghead:
Put some fuel down the breather and it should at least backfire or try to start .
You have quite an accomplishment at this juncture as the M110 engine is truly one of the Hardest Heads to remove much less get it all back together .
I don't see how you could have gotten it out of time if you did not move the engine crank shaft position from tear down.
I have seen that the chain get on the wrong side of the intermediate gear in the housing and cause one of the camshafts to move the wrong direction and it can bend the intake valves but lets hope this not the case.
A couple of things to do after you try the fuel down the air intake is to pull the plugs and Check Compression ,the Valves may be tight .
Line everything back up to TDC and insure that the Rotor is pointing to number one wire on the cap! It has been more than a few years since I tore the Head off one of these and I just don't recall the direction of rotation on the cams nor distributor however I will find out .
Here is a pic of the 'Dernburg Wagon
http://www.seriouswheels.com/pics-1800- ... 24x768.jpg
It was the worlds first all wheel drive and all wheel steer back in 1907

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Thu 05 Jul, 2018 12:47 pm

This is the positioning when balancer is at TDC and rotor at #1. Have I got one of the camshafts in a rotation early perhaps?

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Bartman4800 » Thu 05 Jul, 2018 1:28 pm

The camshafts both rotate ONE turn for every TWO rotations of the crankshaft.

If you have the Crankshaft at TDC on the balancer (did you have the balancer off?), and both markings on the camshaft are up and aligned with the markings on the bearing cap, it cannot be wrong.

Bart
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by CraigB » Thu 05 Jul, 2018 1:39 pm

Thanks Bart, That is nice and clear, and i assume if say you move the crank one of those revolutions then that makes no difference (ie. pistons etc all back in the same position).

So I would now at TDC for no. 1, ie no confusion when those cam marks are lined up - just look at the rotor and the cap and see if the rotor is pointing to where No. 1 lead is and see that lead is to No. 1 piston. You have probably done that already, but if those spark plugs are sparking it has to be when and where they are sparking or fuel. Also check all the plug leads going to the correct firing order, sometimes easy to mix up.

I know that is simple and I don't want that to sound condescending when obviously to do that head you have excellent understanding - but so many times over the years i have scratched my head, worked myself back to the basics and usually found a silly error.
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Thu 05 Jul, 2018 2:40 pm

Hi, and thanks again everyone for the input.
I did have the balancing wheel off for cleaning and painting (and also because my thread repair man managed to blow a piece of bolt into the water system and I had to disassemble to extract it) but it went back on in the correct position as there;s a locator dowel. When at TDC the #1 piston is at the top, I checked by removing the spark plug. The rotor points to lead #1 and all leads have been installed in the correct position and firing order. The distributor rotates clockwise and all leads have been checked (twice).

I will try to get some aerostart but to be honest I find it a little tricky as the car is 40 min walk away. The auto supplies shop is 30 min the other way so I tend to put these things off... and the car has a flat battery from cranking, I just walked home with it to charge it overnight so I am totally spent for the day ;) Tomorrow I will walk it back up the hill and put it back in. I've added pics of where cylinder #6 cams are on TDC with sprockets aligned and rotor on #1. Please let me know if these are totally wrong? But it looks as though #6 is about to be depressed (like me lol) on the right hand camshaft, as shown in the photo.
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by CraigB » Thu 05 Jul, 2018 4:33 pm

If that is bang on tdc for that photo, that doesn't look right to me. I am assuming the crank moves in a clockwise direction and the two cams but i don't know if that is correct. If that is the case, at tdc, and i am pretty sure the inlet valve is on the LHS of motor, then it should be about to open and that looks like it has just closed. If it is anticlockwise rotation then that looks ok but then the exhaust valve should have just closed. If that is No.1 tdc and it turns clockwise looking at the motor, then that inlet cam lobe we can see clearly I think should be other side of that rocker and exhaust lobe should be like a mirror and just past the rocker.

This might be stating the obvious but you understand the 4 cycles? No. 1 on tdc and gets spark to fire that compressed fuel, piston goes down and then comes up with exhaust valve opening to let it out and then as it comes back down again the inlet opens to suck fuel in, then back up to compress and go bang and do it over again. You have indicated you can see where the piston is so just rotate and see if that pattern is there. Word of caution is that i think those motors if not timed properly can bend valves and I hope that hasn't happened. Always good to turn motor over by hand first because you will feel resistance on that sort of thing.

I am not very familiar with your motor though.

Random thought - its not possible to swap the cams or cam wheels is it? Would that explain marks lining up but valve timing wrong?
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Thu 05 Jul, 2018 6:19 pm

left hand side from driver's perspective? or from mechanic's perspective? I am assuming inlet valve ought to be on the side that inlet manifold is on. That would mean left from driver's perspective I guess.
Which piston are you talking about? #1?
The crankshaft rotates clockwise, as does the camshaft with the chain over the top of it, and the other camshaft turns counter-clockwise. They turn inward toward each other if that makes sense.
I am not able to turn the engine while looking at it, because the radiator and fan are in the way, so I have to go under the car and do it bit by bit. I will have a think about the cycles until I can see it in my mind.
The engine is mostly being turned by hand at this stage but there have been numerous slow crankings while the battery flattens. It is admittedly quite hard to turn by hand.
It is possible that the guys who cleaned up the cam box might have taken the shafts out and not put them back in the right place. A nightmare looms on the horizon as I realise I may have to undo so much of my work!
I don't have a way of seeing the engine while it's being turned so I guess I will have to uninstall things in order to turn by hand from the top.

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Thu 05 Jul, 2018 7:02 pm

I've been studying the image and conclude that the shafts themselves are in the right place. However the sprockets were removed and I'm uncertain as to whether they are keyed in different places. I imagine, for the sake of the assemblage efficiency in the factory, that they are the same sprocket right and left, with the same keying, and i imagine that very hopefully indeed :)

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Christo C » Thu 05 Jul, 2018 7:06 pm

When you’re talking engines the general convention is: viewed from the mechanic’s perspective i.e. the front.
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by ledmeter » Thu 05 Jul, 2018 7:24 pm

Upon further imagining, I'm now imagining that the sprockets do need swapping over. Anyone else think that's a good idea?

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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Henry Schuman » Fri 06 Jul, 2018 7:21 am

I would like to see a pic of the Cam Timing Marks on your engine but the pictures you posted does not show those but if you are sure the Marks are lined up on both sides and the Ballancer is on Zero and the Distributor is pointing to number one and you have a good Blue spark and you are sure the Valves are adjusted right about all is left is FUEL.
Again try putting some Gas,Petrol or whatever yall call it down there down the intake and see if it will run.
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Bartman4800 » Fri 06 Jul, 2018 9:44 am

Here is a blurb with pictures of the cam timing marks on the camshafts

http://mbci.mackuz.ovh/mb/index.php/war ... aft-timing

Everything on these engines start from cylinder #1 being at TDC (the cylinder closest to the cooling fan)
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Bartman4800 » Fri 06 Jul, 2018 9:54 am

Here is a blurb with pictures of the cam timing marks on the camshafts

http://mbci.mackuz.ovh/mb/index.php/war ... aft-timing

Everything on these engines start from cylinder #1 being at TDC (the cylinder closest to the cooling fan)

But as CraigB has described above: there are 2 possibilities with cylinder #1 in TDC:

1 (correct)- it is in its compression stroke; both valves are closed and the spark plug is firing (rotor sitting opposite to the notch in the distributor)
2 (incorrect)- It is in its exhaust stroke; the exhaust valve is open and about to close, and the intake valve is about to open (rotor sitting opposite to the notch)

If all is in option 1 your engine will run providing it has fuel
If all is in option 2 your engine will never start

Hope this clarifies things

Bart
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by CraigB » Tue 10 Jul, 2018 11:20 am

Thanks for pics. Disregard some of my comments - I had assumed like a lot of double OHC that the chain went over top of both cam wheels. That means that at your pic of tdc, inlet is about to open and we can't see it but hopefully exhaust lobe is on the other side and just closed. Its all pretty logical once you get your head around it and if you google how 4 cycle engine works you should be able to relate that to what is happening with the motor. We have been describing how marks can be deceiving and that's why i like to get my head around it all and go back to basics to check.... before turning engines over and risking valve bending.... but I think you are ok. So back to the original fuel suggestion for me too.
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by AMG » Tue 10 Jul, 2018 12:38 pm

Gotta say, this is where you must have a copy of the factory service manual to use as a reference.

Bart provided an excerpt of the manual, but really, this is one key area when yo must absolutely have a factory service manual at hand, on pdf or a proper hardcopy.

There are so many diagrams and details, that it can be confusing, but use bart's link.

here it is again.

http://mbci.mackuz.ovh/mb/index.php/war ... aft-timing

Once you have established that the cam timing is correct, make sure the distributor rotor is on #1 cyl mark.

Then check the electrical connections for the fuel pump and D-jet if you have it.

the Reference library section of the forum contains all the info you need for troubleshooting djet as well.
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Re: Rebuilt top end on '73 280E - won't start! Help me please!

Post by Henry Schuman » Wed 11 Jul, 2018 12:17 am

Well it has been nearly a week since we heard from this guy so with all the info posted about his problem he must have either got her going or Blew it UP ??????if
I hope it's running like new but it would be nice to know if he got it going.

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