Hey guys,my 240 is getting worked on by my buddy whom works with me on our cars replaced the fuel filters, oil replacement with synthetic, hoses, new primer & just installed a new battery & glow plugs BUT STILL NOT STARTING....

It wants to kick over AT ANY SECOND THOUGH!! There's a tiny bit of smoke when we lift the oil cap.
*My buddy said he's been reading tons of posts/threads & MercedesSourse but he's drawn conclusion the engine is putting out medium compression from posts or the Valve timing or timing chain
*Personally I do not believe it is lower compression especially knowing tear down ahead.
The car ate up oil as I know a seal leaking but not this fast asthere was minimal oil on the dipstick but still a tad left & heard diesels use fuel when oil is out but I have 3/4 of a tank & NO SMOKING OR STEAM came from the engine when it turned off, oil had & pressure currently is reading 3 & coolant has been perfect. Cold smoke coming out of the exhaust which is is good!?

I put fuel injector cleaner in & a tad oil treatment & the car ran BEAUTIFULLY, day of breaking down was running like butter, best yet with 230 miles then 5 minutes from home began to lose power & shut off on the highway.

WHAT do you friends, from experience & readings believe this is??

WHAT do you RECOMMEND I do or take a look at?
Hey guys,my 240 is getting worked on by my buddy whom works with me on our cars replaced the fuel filters, oil replacement with synthetic, hoses, new primer & just installed a new battery & glow plugs BUT STILL NOT STARTING....

It wants to kick over AT ANY SECOND THOUGH!! There's a tiny bit of smoke when we lift the oil cap.
*My buddy said he's been reading tons of posts/threads & MercedesSourse but he's drawn conclusion the engine is putting out medium compression from posts or the Valve timing or timing chain
*Personally I do not believe it is lower compression especially knowing tear down ahead.
The car ate up oil as I know a seal leaking but not this fast asthere was minimal oil on the dipstick but still a tad left & heard diesels use fuel when oil is out but I have 3/4 of a tank & NO SMOKING OR STEAM came from the engine when it turned off, oil had & pressure currently is reading 3 & coolant has been perfect. Cold smoke coming out of the exhaust which is is good!?

I put fuel injector cleaner in & a tad oil treatment & the car ran BEAUTIFULLY, day of breaking down was running like butter, best yet with 230 miles then 5 minutes from home began to lose power & shut off on the highway.

WHAT do you friends, from experience & readings believe this is??

WHAT do you RECOMMEND I do or take a look at?

Any other input greatly appreciated!!??

What is the nozzle hookup size for compression test??

As far as compression testing - there's a current thread on the HF compression tester and most of us have had OK luck with them for the money. They have an appropriate adaptor to use the glow plug hole which is usually easier.

Remember that these Diesels have sort of the same requirements as any engine in order for it to run. In an Otto-cycle engine you need compression, fuel, and spark (at the correct timing). Sort of the same with Diesels except "compression" and "spark" are pretty much the same. So as long as your injection timing hasn't changed, you need to be sure that fuel is getting to the injectors and that compression is still at an acceptable level even if it's not like a brand new engine. The thread I mentioned above has some typical values.

Now that I've said that I'll tell you what I have to do after the fuel system has been opened (for example, after replacing the filters) on mine. Some of the guys will spit up blood on this and they have a point, but this works for me. I've tried all of the bleeding procedures, etc. but I have to start it the first time by spraying a SMALL amount of starting fluid into the intake and intermittently spraying a TINY amount of the spray until the engine catches and runs (you'll hear it). It generally takes 30 seconds or so. From then on everything is fine and it works like it should. I think it's likely that you have a bit of air someplace in the fuel system where it simply can't be and I've never been able to fire mine up except as described.

CAUTION!!!! I am NOT recommending this process, just telling you what I have to do. DO NOT put the engine under any strain (for example, putting an automatic trans in D) while you use this to make the engine run. One of the guys says that he can do this with WD40 instead of starting fluid but I haven't personally tried that - might work fine.

Diesels do NOT use oil if they're out of fuel. Diesels with a TON of oil leaking past the rings may burn some oil as it is drawn up past the rings. This story comes from the old Detroit Diesel 2 cycle engines but they have a completely different fueling systems and are not at all like our old Mercedes'. These engines were unique in many ways including the fact that all it takes to make them run backwards is a reverse-rotation starter - the engine itself will run either way.

Dan

I'd not use starting fluid as primer. wd40 will work for priming a dry pump with no risk. Starting fluid is very dangerous to your engine.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

When you remove the fuel filler cap does it make a "whooshing" sound? Fuel filters fresh?

I had a 240D that sat for 20 years do the same thing. Crank and crank and not turn over. I had to take the top of the injection pump delivery valves off and clean out the delivery valves. Then it fired up no problem.

"day of breaking down was running like butter, best yet with 230 miles then 5 minutes from home began to lose power & shut off on the highway."

Good news is the symptom above does not indicate a compression problem. Probably fuel related. Sorry but I gotta ask...does it have known good fuel???

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Engine dying out the last time used is not glow plugs or compression in general. There has to be something stopping an adequate supply of fuel at least at some small pressure available in the base of the injection pump. Or the engine just will not start.


Possibilties most likely are plugged in tank fuel filter, Weak lift pump, constantly open relief valve. Also if the engine is using a lot of oil the crankcase pressure might be shutting down the injection pump shut off valve.


A sudden failure of a fuel line is unusual as well and then you would only be getting air or so much air no fuel is available to run on.


I also never take it for granted the fuel is good.

Just re read your post. I see you said there was a small amount of oil remaining on the dipstick. At speed I hope you still had oil pressure but many times people do not observe that.









Anyways perhaps a compression check is in order because of what was observed. I am as guilty as the next guy in not checking my oil level every time I fill up with modern cars.








On these older 123s there are good enough potential reasons to check it at every fill up. The 240d does have a tendency to consume more base engine oil at highway speeds anyways.



This particular post is just to be kept in the back of the mind as a possibility. It sounds like you changed it to synthetic oil after the event. So can you remember about how much oil came out while doing so?

Was the power loss sudden/immediate or gradual? How long did the slowing down take? Any odd sounds?

Look in the air cleaner housing for obstructions.

What fuel injector cleaner was used?

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Your comment about there being a 'little bit of oil on the dipstick' is troubling. It kind of sounds to me as if you know you ran it out of oil but don't want to admit it to yourself. If so, there could be serious internal damage. If it runs out of oil, it won't use fuel as a substitute. How much oil did you have to add to get it to the top mark on the dipstick and did you observe low or no oil pressure when it stalled? In any case a compression check is in order.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Sounds like you lost prime in the IP between the elements and the injectors during your return trip.
Probably due to an small air leak in one or more of the connections that were opened when you replaced the primer pump and fuel filters.


I just went through loss of prime on the IP when I replaced the three old brown plastic hard lines with new clear plastic hard lines on my 1978 W116 300SD.
(6150704332 lift pump to fuel filter head inlet, 61507204032 fuel filter head outlet to IP inlet, 615005632 IP outlet to fuel filter hollow bolt/air bleed/return to fuel tank).

The primer pump only fills the IP to the level of the base of the elements.
Air in the metal hard lines between the elements/delivery valves and the injectors needs to be purged.


I see you did replace hoses, did you renew the fuel hoses to the primary clear fuel filter?
Does the new primary clear fuel filter have brass reinforcements?
Did you renew the o-ring and crush washer on the fuel filter hollow bolt?
Did you renew the crush washer for the new primer pump?
These are common air incursion points.
Also, old plastic hard lines get brittle and tend to develop cracks at the barbed end of the metal fittings.

To get fuel to the injectors:

1) Disconnect the hard lines at the injectors (17 mm flare wrench), and loosen the nuts on the hard line brackets (8 mm wrenches).
2) Unplug the glow plug harness (to save battery charge).
3) Use the primer pump to purge the air from the clear plastic hard lines.
4) Crank 30-45 seconds, wait 10 minutes to let the starter cool off, repeat until fuel dribbles out of the rearmost metal hard line.
Be patient, and take your time...you don't want to fry your starter. (I watched some Netflix shows between the cranking sessions.)
5) Tighten the hard line fitting (17 mm) on the rearmost injector.
6) repeat step 4) and step 5) until each of the remaining injector hard lines are reconnected. They fill from the rear to the front (ie 4, 3, 2 and then 1).
7) Re-tighten the injector hard line brackets (8 mm).
8) Reconnect the glow plug harness.

Glow twice for 45 seconds, depress the accelerator pedal and crank the engine.
She should start right up.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022