w115 240d help
 

hi all and happy new year ( i posted this in the vintage section as well, so please delete if inappropiate mods )
over the past 21 months ive been slowly restoring a w115 240d auto.
Mostly fixing rust issues., so firewall and floors have been repaired ( even had to pull dash out )
replaced windscreen shields , rebuilt auto transmissions

however now comes the motor , it blows smoke and the diesel blow by is a problem
so my options are to repair/rebuild the motor
or a swap
Id like to keep the original transmission in it , as it has just been rebuilt
so im thinking a om617 ( non turbo ) in keeping with the diesel theme. and there are plenty of w123 300d in my area ( the turbo never came to my country )
or
convert to a petrol motor, and something like an m130 or m114
the w115 has those two firewall to chassis strut braces , so i dont want to remove them and compromise the integrity/strength of the body.



Thanks for any feedback

check the air line running from the throttle body to the injection pump, if its cracked anywhere, replace it with std vacuum line.
also see if the vacuum pump output line is pushing oil into the intake. that line should be clear, never black.

adjust the valves.

If you change motors the simplist is a 300d na. It should bolt right up to your tranny and the oil filter and battery will be in the correct place for you. I did one of these and it makes the car much more drivable with the extra cylinder especially with the automatic transmission.

Good luck with it.

Will a w123 300d na motor fit ? these are plentiful in my area..

There are a lot of similarities between the early 123 motors and the 115. The motor was changed around 1980 or so. notably the oil filter and ac compressor came to be mounted differently. I have not done that swap so cannot speak in detail.

For a "straight" swap you need to source a pre-'76 N.A. OM617.910.

The engines used after '76 MY (W123) are the OM617.912 and other variants which have the oil filter mounted up high on the side of the block. An oil filter by-pass or conversion plate would be required.

ANY of these engines will require a modification to the engine shut down as the MW series injection pumps are used which use a vacuum system as opposed to the "Gorilla knob" manual shut-down and start type.

Something like this ?
https://www.doomsdaydiesel.net/product-page/om617-oil-filter-relocator

Yes to the link you provided. Good luck!!!

I own a W115 240d 4 speed (now restored). I experienced similar symptoms to you which I was able to drastically reduce without a rebuild.

1) Perform an AUTO RX engine oil treatment (2 bottles). A quick google search will highlight that there is no safer way to remove sludge, carbon deposits or varnish from your motor internals, allowing for reconditioning of seals. It takes 5K miles for a treatment to be completed so make sure you follow instructions precisely.

During this time, I treated the fuel system with:

2) A Liqui Moly Diesel Purge (2 bottles).

3) Followed by Chevon Techron fuel additive (diesel). I use two consecutive bottles at first followed by one before every oil change.

IF Auto Rx does not solve your oil consumption/ blow by, then your only option left is to use Engine Restorer. This metallurgical chemical compound bonds to worn cylinder walls to undo damage due to past neglect.

Given that these cost <$150 combined, I highly recommend you attempt to rejuvenate the original motor vs. attempt a swap. I can assure you none of the above are snake oil and all of my 65 horses never rode better!

Nice looking car you have there Nacho. What country are you in? I'm guessing Australia?

- Peter.

Yes in Australia.
the w115 3.0 om617 never came to australia. However the w123 300d did , so there are a few around

If it were me I'd keep it original, but your's to do with as you wish. It would give it a bit of a power boost with that extra cylinder. But there'd be less space to get in there if you ever have to do stuff.

- Peter.

Maybe the motor just needs some TLC

Gorgeous car. Hope you have more luck with it than I'm having with my 81 at the moment.

- Peter.

this has been 12 months at least ( i even scrapped a series 1 w114, which had way too much rust )

I do have another few questions
where can i get the bozio or monark injectors for the om616?
is there a vacum pump repair kit ?
and can the injection pump be rebuilt or best to source one from another model ? ( like a w123 )

monarks - google "5 cyl 617 diesel engine fuel injector diy rebuild kit". buy it. should work with 616 except you use 4 instead of 5. check with retailer though. use penetrating oil overnight when needed to break things loose, don't screw up the balancing and lapping, and torque things properly.

vacuum pump - get mity vac and troubleshoot and replace rubber hoses with pelican parts kit or elsewhere. may need new diaphragm.

replace, not rebuild, injection pump, if it cannot be ungunked easily. it is one of the most robust parts in the car but very complex and not DIY friendly.

-Henry

thanks , cant seem to find anyone with the injectors... mercedesource has them , but shipping internationally is a challenge at the current moment

Ah, gotcha. That's who i was suggesting ... good luck.

-Henry

Bosio nozzles
 

https://kermatdi.com/i-926-mercedes-early-om-616-617-nozzle.html

I would suggest replacing the nozzles only after performing the steps in my previous post unless the car is running terribly.

I'm with Screwdriva.

If these engines were poorly maintained or never driven aggressively, the rings and pistons get very built up with carbon which increases blowby and decreases compression. Swapping a W123-spec 5 cyl. engine in can be done, but isn't 100% bolt-in. Doing anything you can to make sure the crankcase is venting properly, the internals of the engine are clean, and the fuel system is operating properly should come before deeming a OM61x engine worn and in need of rebuild.

Auto-RX is not available in my country.
So I will give the diesel purge a try first.

ive got fresh oil and filters in , and adjusted the valve guides.
also put in some diesel fuel injector cleaner in the fuel tank, although not sure if its made any difference

nachoman I'm not trying to be critical but thought you would want to know...valve guides are not adjustable only replaceable. The adjustments made are to the valve clearance between the sliding surface of the camshaft and the rocker arm often referred to as a valve adjustment.

Since AutoRx isn't available you could try a ring soak with a solvent like SeaFoam.

Put clean quality oil, get it hot and push it hard. Go full throttle uphill and let it coast downhill repeatedly, this may free up mildly sticky rings. It won't free a completely stuck ring.

Good luck!!!

Sorry , you are correct ( i get my terminology mixed up )

No need to apologize...keep up the good work...get that thing hot and push it!

Auto-RX wasn't available here either. They ship internationally. I'd suggest ordering 3 bottles. It's worth the trouble to get it.

Diesel purge is a great first step.

Ok and here is an odd question
when i stand back and look at the front / rear of my car , it look that the drivers ( remember we drive on the opposite side of the road :D ) is leaning..
is this the shocks, springs or rubber bushes etc causing this ?

I had the same problem. (I'm based in London and was raised in Sydney)

I recommend starting with the front and rear sub frame mounts, then sway bar links and the rear differential rubber mount. Use OE Mercedes rubber parts only - yes, still available and lasts 2-3X longer than the Chinese garbage out there. If you don't know when these parts were changed, then the new rubber will really transform the car. I'd wager the rubber has long since dried up and crumbled to bits.

If that doesn't solve the problem, then replace your shock absorbers. Bilstein Heavy Duty are the best bang for the buck.

When you are done, you will have the best handling Mercedes model ever manufactured. It's unlike any other model they made.

So an update on progress.
installed new rear sub frame mounts
the lean is gone now

did the diesel purge... no noticeable difference , except the idle was higher but that was fixed with some adjustments to the throttle linkage assembly..

Handling wise and ride wise , it is quiet and smooth , so no complaints there.
engine wise , it needs more power !!! :D

No it doesn't. Need more power that is. The rest of the world needs to take a chill pill. Nice to hear it's coming along. I'd love to have one of thes old squares. They appeal to me more and more the older I get.

- Peter.

Is your pneumatic injector pump diaphragm holding vacuum? Both the diaphragm and the hard plastic (not rubber vacuum) hose are key to proper operation and fuel delivery. If you need to replace the hose from the plenum to the IP, use PEX pipe, not a rubber vacuum line. The rubber line will flex a bit and can cause "sawing" effect in your idle. You'd need 6mm inner diameter PEX and a heat gun to properly get it on the barbed fittings. The heat gun helps with making a permanent bend in the pipe as well a couple inches above the IP, to match the stock pipe shape roughly. It's not necessary, but is much neater this way.
If your diaphragm isn't holding vacuum, it needs to be replaced. Until then don't bother making any adjustments to the linkage.
Other than this, you're not going to get more power from that engine. It's not a muscle car, nor even a fast car. Treated right though, it will outlast you. IMO, the 4cyl W115s handle better than the 5cyl ones, probably due to the extra 300lbs in the 5cyl sitting on the same suspension as the smaller engine.
Learn how that transmission shifts and it will be a great car, with plenty of power.

Phil Forrest

Thanks Phil
my next step is to look at some bozio or monark injectors.
the glow plugs have been replaced as well..
as for injection pump , my mechanic advised this is a very expensive thing to repair , considering the 240d wasnt sold in huge numbers in Australia.

Have you replaced the IP oil?

Phil Forrest

Hi Phil
to be honest i dont know when the oil inthe IP was replaced...
engine oil was replaced around 3 months ago

You should have a red plastic cap (or formerly red due to 50 years of exposure to everything in the engine bay) on your injector pump a few inches aft of the injector lines. Unscrew the cap and stick in a small diameter vacuum hose attached to an aspirator tank on a handheld vacuum pump, like a MityVac.
Suck out all of the old oil which will probably smell like paint thinner and be a nasty black color.
Once you get this fluid removed, find the fill-level bleeder bolt in the side of the IP. This bolt takes a 14mm hex socket and has weep holes which should become visible after you unscrew it about 3mm. You'll find the bolt about halfway down the side of the IP. Don't unscrew it completely, just enough that you can see a weep hole in the shank of the bolt near the head and the sealing ring.
Use a funnel and pour in a couple ounces of clean motor oil until you can see it dripping out of the weep hole in the bleeder bolt. Tighten up the bolt snug.
While you have the red cap out of the IP, clean it with some decent solvent like fresh diesel or brake cleaner. Make sure the vent holes are clear in the cap, then replace and run your engine.
This process needs to be done with every oil change but since you're rescuing this car, you may need to do it once every few hundred kilometers because your IP will be sloughing off old crap inside with the fresh oil and cleaning itself as it runs.
While you are at it, you may want to rebuild the lift pump, if you haven't already. It's an easy rebuild and there is a great kit available from a guy in the UK with the exact o rings and gaskets you need. This rebuild will prevent fuel from leaking from the lift pump into the IP.

Phil Forrest

I took the red cap off
but couldnt see any oil in there ... is that normal ?

There's only a few ounces in the sump at the bottom of the IP. You won't ever see it and will have to use some kind of suction device like a mityvac with aspirator tank, to get the old stuff out. There is a sump drain plug but it can be hell to get loose and then back in properly.

Phil Forrest

So another update
things are not going so smoothly...

Took it to my mechanic, who ran an injector and fuel line cleaning solution through it about a month ago.. They also fixed the air conditioning ( just a regas) , perfect for the hot Australian summer.

It was driving fine , but my driving is mostly city based , where the stop/start traffic is common and speeds dont go over 80km/h ( or 50mph )...

however , the last two weekends , ive need to drive along the freeway to visit horse stables/yards. this involves a drive of over 90 minutes with speeds around 100kmh (60mph). and with low gradient rolling hills..

The car struggled to climb and hold speed ( actually went backwards by over 30kmh ) and temp gauge was rising steadily... got brief respite when descending.... got to my destination and noticed the crank case vent pipe had blown off and could see a lot of oil vapour coming out of the breather outlets... It fees like it really laboured going and maintaining that sort of speed

Is this the telltale sign of worn engine and blowby ?

Vapor is normal, blowing the breather off isn't. It does indicate blowby. It probably gained some power when the breather disconnected relieving crankcase pressure. Blowby can be worn out rings and/or pistons OR it can be stuck/clogged rings. The real test is a leak down test.

I'd try chemically soaking the rings, using something like AutoRx, then run synthetic oil. Get it hot and run it hard.

The power loss could be fuel related such as poor fuel or clogged filters.

How high did the temp go? How steep and long was the grade? Dropping speed w AC on on a steep hill is normal in a 240D.

Good luck!!!

G'day!

A] I second Auto-RX - and would follow instructions to the letter. It removed blowby entirely on my 300D but didn't on my 240d. It did improve compression in both vehicles though.

B] I would also recommend you use Liqui Moly MOS2 15W40 in the injection pump (and in the motor after Auto- Rx treatment completion)

https://www.youtube.com/watch?v=rh0PtXwZo_Q

C] Bosio injector nozzles sold here:

https://kermatdi.com/i-904-bosio-mercedes-late-om-616-617-single-nozzle.html

D] Injector Rebuilder here (I'd get your lift pump rebuilt too, and purchase the OFV spring):

https://dieselfuelinjector.guru

E] My W115 restoration journey here:

http://www.peachparts.com/shopforum/diesel-discussion/398899-w115-owner-advice-needed-buying-1976-240d-6.html

Unlike most car engines. Every horsepower that engine can produce will frequently be needed.

Three issues very common to the 616 cars. Have someone push the accelerator pedal to the metal. It has been there before. Have a look at the same time the linkage is getting the arm on the injection pump to the stop.

Close off the return line from the relief and overflow valve.Huge difference or no difference the spring tension in the valve will need a tension check or there are other issues.

As the timing chain stretches with use over the years. This naturally retards the injection pump timing. Wise to also check the timing chain as well for too much stretch.

Going up a pretty good long hill. Even with a perfect engine and a manual transmission. If you lose speed. For example catch up to the car ahead and slow down. In general you cannot gain the lost speed back.

A reasonable test in my mind is to find the 0-60 time of this model. See if your car can do it. If it can the checks probably will not be required. If not they should be done.

Engine worn too much? The na engine should be a managable swap. fortunate for you perhaps many might have come with manual transmissions in Australia. You also want the rear end from the vehicle that has had the 5 cylinder.Maybe they even exported the five speed manual transmissions to there?

It may just be me but I preffer the way the 616 handles over the 617 cars. I find that I have to drive them and that may be part of the appeal.

the hill isnt a high gradient ( between 5 and 10% ) , but it is long...
the temp was getting close to 100. usually it sits around 80 when travelling on the flat plains.

oil pressure was all the way up , but when i turned off the freeway and came to intersection for a stop, it dropped down to 2.

the aircon was not on at all during these long drives.

Manuel transmission mercedes are very very rare in Australia... after 1970 most mercedes were automatics.
The om617 was available in the w123 here , and only in automatic variant

Those temp and oil pressure changes are normal.

Be sure not to lug it. Keep the motor singing a happy tune. The fan is vital if the speed is not too high.

My first long trip , i did lug it as I was stuck behind a truck and couldnt get enough lane space to overtake as traffic comes up fast..

Ive also thought about switching to an electric fan ( puller type ) ... Water pump is new as well

Lugging it may have been half of the extra heat generated and it is tough on bearings. Downshift and rev it instead.

its automatic , wont downshifting make it worse by increasing revs ?

Downshifting will increase the rpm's in an automatic or manual. Avoid over revving by looking at the dots on the speedometer, e.g., three dots on the speedometer is the maximum RPM for third gear.

The automatic transmission should shift 3 times, 1-2, 2-3, & 3-4 as it is a 4 speed.

Good luck!!!

no. There is a device which will limit fuel if the revs get too high. If going slowly the fan is needed to pull air through the rad. At highway speeds usually the air coming through will be sufficient to cool it without the fan. That is why some cars use clutch fans which will pull more air through the rad.