170SD Diesel engine help

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s2ksimon
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170SD Diesel engine help

Post by s2ksimon » Tue 15 Jul, 2014 3:56 pm

Hello,

I have a 170SD that has been running well for some years, until a few days ago when it decided to stop as I drove away from my house.

I suddenly lost power, looked in the rear view mirror to a cloud of white/light blue smoke. Stop and started it a few times with the same issues - ended up getting a push home. Tried to start it the next day and it just turned over and over - as if there was no fuel.

Jumped on Google and based on the symptoms it sounded like I had air in diesel system. So I bled the diesel pump and filter with no change, then I cracked open the injector hoses while cranking the engine - now it starts on what sounds like 2 cylinders - with a huge cloud of white/light blue smoke out the back, and throttle down or it will die on idle.

I recently had it serviced where they replaced the fuel filter and fitted some new fast start glow plugs, I have only driven it twice since then and filled up with diesel on the way home last time (it was low but didn't run dry).

So now I am stuck on what to try next.. any tips on what to check?

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Mercmad
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Re: 170SD Diesel engine help

Post by Mercmad » Tue 15 Jul, 2014 9:39 pm

It sounds like the diaphragm in the pumps governor has failed . it's held in the end of the injection pump and normally never gives problems . They reasonbly inexpensive and considering it is 60+ years old it has done well.

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Tony From West Oz
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Re: 170SD Diesel engine help

Post by Tony From West Oz » Tue 15 Jul, 2014 9:46 pm

Check fuel supply (done)
Check Fuel Quality - Many diesels have driven off from the servo and within 100km have stopped with water in the Injector pump. Pump some into a glass jar and check for water, smell - like diesel (not petrol) and clarity - should be crystal clear, if not it is contaminated.
Check filters (does yours have the pre-filter and main filter?) Generally, filter blockages are first noticed when under full load, not at idle or low RPM.
While it does not seem related to your issue, I will include: Check Glow Plug operation. & Check Air filter (usually gives reduced power and more black smoke)

I hope this helps,
Tony
Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

'83 W123 300D 325000km (Wife's car Josephine - sold).
'84 W123 300D replaced good OM617 912 with OM617 952 and enjoyed having good acceleration for the first time since first driving a 300D in 2002 - became engine and trans donor for 300CD Turbodiesel conversion. Now parted out.
'86 W124 300D sold (Wife's old car - sold )
'85 W123 300CD, 275 000km (Fatmobile) rebuilt turbodiesel from previous Fatmobile transplanted into 280CE (occasional tourer)
'99 W202 C250 Turbodiesel (my darling Wife's car - Sold)
'98 W202 C250 Turbodiesel (my car - Sold)
'06 Ssanyong Musso Crew Cab 2WD Ute (OM662 diesel and Auto Transmission)

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s2ksimon
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Re: 170SD Diesel engine help

Post by s2ksimon » Thu 17 Jul, 2014 10:47 am

Thanks Mercmad & Tony,

I did check the pre-filter and while it had some black particles in it (looked like paint flakes, that I cleaned out) it didn't look like it would impede the fuel flow. There isn't much to the air filter on this engine, it has the required oil in it.

I was assuming the glow plugs are working, the filament on the dash lights up as expected - I will pull them out to confirm operation.

When I was bleeding the fuel it smelt and felt like diesel, I will fill up a jar as suggested.

I will look up the diaphragm in the OM636 workshop manual that I am lucky to have (followed its guidance to bleed the pump etc), from a quick look around on Google it might be a task I send the car back to the mechanic for.

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s2ksimon
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Re: 170SD Diesel engine help

Post by s2ksimon » Mon 28 Jul, 2014 10:26 am

Update on the problem - I had incorrectly assumed the fuel filter was changed when the car was last serviced, opened it up to drain some fuel and it looks like it could be the original filter - the metal caps on the top and bottom of the element had started to disintegrated, filling the filter with rusty gunk.

Ordered a new filter and crossed my fingers this would solve the problem - I now have the car running on 3 cylinders. On the cylinder closest to the driver there is no change to the engine if I crack open the injector line, unlike the other injectors where I crack the line to bleed and the engine misses or doesn't start. What was also different was unlike the other injectors where I get diesel bleeding out, on this injector I get diesel shooting out when I crack the line - it appears there is no or little diesel getting past the injector. I still have lots of smoke, white/grey colour.

So my theory is a particle from the failed filter made it through to this injector and is impacting its operation - I have to go and get a deep socket to get the injector out for a look, from what I read I will most likely need to take the injector to a specialist - and possible take them all out to be matched.

Does this sound plausible?

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Grumpy
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Re: 170SD Diesel engine help

Post by Grumpy » Mon 28 Jul, 2014 12:07 pm

For what its worth from a very ex diesel mechanic in a past life. :)
1/ White smoke normally indicates raw atomised discharging coming out the exhaust. Not partially burnt, but not burnt at all. ie. no combustion what so ever.
2/ Reasons for this - a)= low to no compression b) = water in the combustion chamber c) tip burnt off injector, therefor no atomisation occurring, very important for pre-combustion chamber heads.
It is hard to image a particle getting though the injection pump to the injector. If one element was over delivering fuel, it would knock like buggery and possible idle faster than normal.
My 2 bobs worth.
Kel
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Tony From West Oz
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Re: 170SD Diesel engine help

Post by Tony From West Oz » Mon 28 Jul, 2014 6:12 pm

s2ksimon wrote:Update on the problem - I had incorrectly assumed the fuel filter was changed when the car was last serviced, opened it up to drain some fuel and it looks like it could be the original filter - the metal caps on the top and bottom of the element had started to disintegrated, filling the filter with rusty gunk.

Ordered a new filter and crossed my fingers this would solve the problem - I now have the car running on 3 cylinders. On the cylinder closest to the driver there is no change to the engine if I crack open the injector line, unlike the other injectors where I crack the line to bleed and the engine misses or doesn't start. What was also different was unlike the other injectors where I get diesel bleeding out, on this injector I get diesel shooting out when I crack the line - it appears there is no or little diesel getting past the injector. I still have lots of smoke, white/grey colour.

So my theory is a particle from the failed filter made it through to this injector and is impacting its operation - I have to go and get a deep socket to get the injector out for a look, from what I read I will most likely need to take the injector to a specialist - and possible take them all out to be matched.

Does this sound plausible?
I recommend that you take it back to where you had it "Serviced" and demand that they repair it. They should have replaced the filter and the filter failure has caused this problem.
Take the old filter with you as proof.

Regards,
Tony
Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

'83 W123 300D 325000km (Wife's car Josephine - sold).
'84 W123 300D replaced good OM617 912 with OM617 952 and enjoyed having good acceleration for the first time since first driving a 300D in 2002 - became engine and trans donor for 300CD Turbodiesel conversion. Now parted out.
'86 W124 300D sold (Wife's old car - sold )
'85 W123 300CD, 275 000km (Fatmobile) rebuilt turbodiesel from previous Fatmobile transplanted into 280CE (occasional tourer)
'99 W202 C250 Turbodiesel (my darling Wife's car - Sold)
'98 W202 C250 Turbodiesel (my car - Sold)
'06 Ssanyong Musso Crew Cab 2WD Ute (OM662 diesel and Auto Transmission)

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s2ksimon
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Re: 170SD Diesel engine help

Post by s2ksimon » Mon 11 Aug, 2014 6:04 pm

Update - had the car towed to a local diesel specialist, checked the fuel, injectors, pump etc - compression test showed the problem is with 3 & 4 cylinders. They suspect either the head gasket has given way between these cylinders or piston issues.

As the diesel specialist only works on the diesel components, I am now on the hunt for a mechanic in Melbourne who would be capable to take on this job - or I might get it towed home and take the head off to confirm the exact damage. I think I could tackle replacing the head gasket if that is the issue.

Tony - the mechanic that serviced it last has retired and shut up shop.

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Mercmad
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Re: 170SD Diesel engine help

Post by Mercmad » Mon 11 Aug, 2014 11:45 pm

The head gasket failure is a very very unusual problem. Were the tappets checked?
These engines are very sensitive to incorrect tappet clerarances.
Removing the head is easy,these engines were designed to worked on by the owners but when you get it off you will see cracks in the head surface around the ports etc. This is completely normal and they can be ignored. (I gave way a head a couple of months ago which was crack free...) .
http://youtu.be/SahH9zmTQu8

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s2ksimon
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Re: 170SD Diesel engine help

Post by s2ksimon » Tue 12 Aug, 2014 12:49 pm

Nice video Mercmad, thanks for the advise on cracks - I adjusted the valve clearance in the past, perhaps I got it wrong? I followed the manual - which indicated TDC on cylinder 1 was when the valves for cylinder 4 "cross over", don't have it in front of me right now but I think it stated as the inlet valve is closing and exhaust opening. Think it was .20mm and .15mm and then I followed the firing order.

Via Google I can see a few other posts around for OM636 motors with gasket issues, with some people using reinforced copper gaskets with apparent success. Elring OM636 gaskets seem readily available online, will hold off ordering until I pull the head and confirm the issue - and as there at 76mm and 76.50mm gasket versions.

You don't happen to have a exhaust manifold that goes with the head you gave away? Mine cracked at some point prior to my ownership and has an ugly weld, it is a different design to the one in your video.

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Re: 170SD Diesel engine help

Post by Mercmad » Tue 19 Aug, 2014 2:39 pm

I gave away a rolling chassis and all of the 170D parts I had when i moved to the new workshop. You could grind down the weld and then get it sandblasted then ceramic coated to hide the repair.

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s2ksimon
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Re: 170SD Diesel engine help

Post by s2ksimon » Tue 26 Aug, 2014 11:27 pm

The head is off, as suspected the head gasket had failed between cylinders 3 & 4:
gasket.jpg
Here is what it all looks like (prior to a good clean), I can see marks on the pistons that look like the valves have hit at some point - advice on what I should do apart from the original plan of cleaning and replacing the head gasket?
head.jpg
block.jpg
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benedict
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Re: 170SD Diesel engine help

Post by benedict » Wed 27 Aug, 2014 11:38 am

Simon,

Not the best news but certainly not the worst-case scenario. All looks pretty good otherwise. Are you going to get the head overhauled or just repair with a new gasket?

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s2ksimon
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Re: 170SD Diesel engine help

Post by s2ksimon » Wed 27 Aug, 2014 11:57 am

benedict wrote:Simon,

Not the best news but certainly not the worst-case scenario. All looks pretty good otherwise. Are you going to get the head overhauled or just repair with a new gasket?
My neighbor recommend Head Hunters in Dandenong, I am planning to get them to look at the head.

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Re: 170SD Diesel engine help

Post by benedict » Wed 27 Aug, 2014 7:18 pm

Given the age, they (or anybody) might be calling on you or parts if required. Not sure there will be too much stuff available in the aftermarket world for an early 1950‘s Benz. John Green might be able to assist with parts-I'm sure he'd be familiar with this engine.

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s2ksimon
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Re: 170SD Diesel engine help

Post by s2ksimon » Sun 07 Dec, 2014 9:24 am

Long story short - car is running again! Slow process but got there in the end.

Onto the next task, I wanted to get the front windscreen and rear window rubber seals replaced (current seals are brittle and have shrinked/cracked in the corners). Ordered new rubber and had a guy come out from one of the larger windscreen replacement companies - 2 hours later the rear window is out and he has gone to do some research on how to refit.

Getting the window out involved a lot of cutting as there is a urethane bead between the rubber and the car. The car metal is in good condition with no rust (car was re-painted prior to my ownership and must have had the glass out - perhaps they reused the old rubber) I have been looking on the internet on how to remove the old urethane (it is fairly stiff and looks like I just cut it down from what I have read on some sites, then apply a new bead).

Can anyone recommend a installer in Melbourne (bayside area) who is more familiar with this type of install?

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markb
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Re: 170SD Diesel engine help

Post by markb » Sun 07 Dec, 2014 3:42 pm

Not sure if it is still the same guy (I think his name was Peter) operating this company, but try Amergency Windscreens based in Boronia, but is a mobile service:

http://www.truelocal.com.au/business/am ... cy/boronia

My family used him for many years and I even had him do a replacement screen for me on my Austin Healey Sprite, which was not that easy....
Current Fleet
1985 C123 280CE Midnight Blue (230k Klms..back to a daily,city commute cruiser again (2010-.)
2013 Mazda CX-5 Grand Touring AWD in Metropolitan Grey (2017-...)
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1972 W108 280SE 3.5 White (2002-2003 project)
1971 W108 280SE 3.5 White (1999-2006 Unmolested original & sadly missed)
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