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  #46  
Old 09-22-2013, 01:46 PM
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Injector Heat Shields

Injector Heat shields for the 617 engine are Part# 617 017 03 60 and $2.00 ea.

1983 Mercedes-Benz 300SD Sedan - Fuel Injection - Page 1

Injector Heat Shields for the 87 300TD are part# 601 017 00 60 and $1.25 ea.

1987 Mercedes-Benz 300TD Wagon - Fuel Injection - Page 1

One has a 10mm hole and the other a 7.5mm hole and either will work in either engine.

I also found them for $1.10 else where..........


These things are a one time use.


The heat Shields for a VW Rabbit will also work.

Charlie
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Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

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  #47  
Old 10-19-2013, 01:12 PM
deniss's Avatar
'84 300SD W126/OM617
 
Join Date: Apr 2006
Location: Central NJ, USA
Posts: 452
Well I'm taking this preparation a step at a time -- today I adjusted the valves. Every one of the valves was tight -- I couldn't get a feeler gauge into any one of them before adjustment.

Now it seems that I need to re-adjust rack damper bolt and idle, since I adjusted those some time before I did the valve adjustment, and now there seems to be a little dip in the idle after letting go of the throttle.

I believe next up will be professional injector cleaning/test and most likely nozzle replacement for each injector -- I'll let the diesel injection shop decide when I get to it.

The shop I'm going to try here is Garden State Diesel, which is a Bosch-certified diesel injection shop. They quoted me $20 per injector for testing, and if nozzle replacements are needed, they told me they waive the testing fee in that case. We'll see how it works out.
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  #48  
Old 10-19-2013, 06:11 PM
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You should really do a compression check. If it is not strong you may be squandering your time and money to some extent. If strong then pursue the other possibilities.

Your valve adjustment may have helped and you do not know it yet. This is required before a serious compression check anyways.
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  #49  
Old 10-19-2013, 06:58 PM
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Because your valves were so tight....I would suggest in about 200miles and some freeway driving to recheck them...
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  #50  
Old 10-19-2013, 11:00 PM
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'84 300SD W126/OM617
 
Join Date: Apr 2006
Location: Central NJ, USA
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I'm wondering how much this matters, but... I left valve clearances a little on the loose side when I did the adjustment -- meaning the feeler gauge would slide in with just a slight bit of friction, not totally loose but not metal-against-metal either.

I adjusted rack damper bolt and the idle adjustment screw when the engine was at operating temp.

One observation I made was it takes an extra crank or two for the car to start after the adjustment. Maybe I gotta give it a little bit of time.

I wound her up to about 3,600 RPM on the freeway today, and she purred pretty nicely, felt smoother with less vibration. (I generally cruise at 2,800 RPM on the highway).

Maybe doing a compression test would be a good idea. Can it be done through the glowplug ports? And how do I deal with the injection pump getting fuel everywhere as it cranks (guessing I would need to disconnect injector lines?)
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  #51  
Old 10-20-2013, 01:07 PM
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Tie the shut off so no fuel is delivered during the compression check.
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  #52  
Old 10-20-2013, 04:47 PM
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'84 300SD W126/OM617
 
Join Date: Apr 2006
Location: Central NJ, USA
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Alright, I did the compression test using Harbor Freight compression tester for diesel engines. I used the glowplug holes for this test and removed all glowplugs at once.

Here's what I got:

Cylinder 1: 340 psi
Cylinder 2: 340 psi
Cylinder 3: 320 psi
Cylinder 4: 340 psi
Cylinder 5: 340 psi

I did about 8 cranks per cylinder. From watching the gauge as I cranked, I think the initial value (from first crank) was around 200 psi for each cylinder but climbed to 300 pretty quickly - I think by 3rd or 4th crank.
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  #53  
Old 10-21-2013, 01:03 PM
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Good enough readings to pursue other things to some extent. I would tackle the fuel system to make sure it is not draining back when off for quite a time. A test might be to have someone pumping the primer pump and keep pumping it when you try to start the engine cold.

Of course the person pumping should mention that the pressure to pump is increasing before you try to light it off. If it is much easier to start then recondition the lift pump and generally check the fuel system. There are valves in the lift pump to prevent back flow of fuel for example that may be leaky. Of course if no increase in the effort to prime with the finger pump the relief valve on the injection pump is not working well or perhaps the primer pump is marginal or fuel is being partially fed back through the lift pump.

What you want to be sure of is that the moment you start cranking that there is adequate fuel spraying. Not some form of delay causing inadequate fuel or little at all at that time. Actually cheap to examine this area as well.
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  #54  
Old 10-21-2013, 01:42 PM
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'84 300SD W126/OM617
 
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Quote:
Originally Posted by barry12345 View Post
Good enough readings to pursue other things to some extent. I would tackle the fuel system to make sure it is not draining back when off for quite a time. A test might be to have someone pumping the primer pump and keep pumping it when you try to start the engine cold.

Of course the person pumping should mention that the pressure to pump is increasing before you try to light it off. If it is much easier to start then recondition the lift pump and generally check the fuel system. There are valves in the lift pump to prevent back flow of fuel for example that may be leaky. Of course if no increase in the effort to prime with the finger pump the relief valve on the injection pump is not working well or perhaps the primer pump is marginal or fuel is being partially fed back through the lift pump.

What you want to be sure of is that the moment you start cranking that there is adequate fuel spraying. Not some form of delay causing inadequate fuel or little at all at that time. Actually cheap to examine this area as well.
Does "lift pump" and "primer pump" refer to the same thing? I have the new style Bosch primer pump, which has been installed by the MB dealer back in 2007.

In general, when you pump the primer pump with the metal injector lines fully installed, the flexible return lines on the injectors will recirculate the excess back to the injection pump, right?
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  #55  
Old 10-21-2013, 07:57 PM
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Quote:
Originally Posted by deniss View Post
Does "lift pump" and "primer pump" refer to the same thing? I have the new style Bosch primer pump, which has been installed by the MB dealer back in 2007.

In general, when you pump the primer pump with the metal injector lines fully installed, the flexible return lines on the injectors will recirculate the excess back to the injection pump, right?
The Hand Primer screws into the top of the Fuel Supply/Lift pump. The Hand Primer has no Valve in it. This means any problems with the Valves in the Lift Pump have nothing to do with the Hand Primer.
I think what is confusing is that if you look up Hand Primer some internet Sellers show the Fuel Supply/Lift Pump with the Hand Primer attached as an assembly.

Pumping on the Hand Primer does not force Fuel into the Fuel Injection Lines or the Injectors.

The Elements inside of the Pump take in a small amount of the Fuel supplied from the Fuel Supply System that is circulated through the Fuel Injection Pump Housing.
The Elements create that high pressure that overcomes the pressure needed to open the Injector and cause it to spray/inject the Fuel.
The Fuel that returns from out of the Injectors is Fuel that was squeezed past and lubricated the Injector Nozzle Pintel and that goes back to the Fuel Tank.

In the mean time the larger volume of Fuel inside of the Fuel Pump Housing is circulated through the Fuel Injection Pump Housing; cooling the Fuel Injection Pump Housing and out past the Fuel Pressure Relief Valve and ends up back in the Fuel Tank.

In the pic is one Element from an MW Fuel Injection Pump (where the High Pressure for Injection is created); missing at the bottom is the Plunger as the Plunger is still in the Fuel Injection Pump.

The Arrow point to the hole where the Fuel enters the Element.
If I remember correctly the highest Fuel Supply presser is 18 psi pushing the fuel into that hole.

When the Element Plunger comes up it covers that feed hole and traps the Fuel inside and keeps pushing Fuel through the Fuel Injection Lines until the pressure is high enough to overcome the Spring (opening/Pop Pressure) in the Injector lifting the Injector Nozzle Pintel and injecting the Fuel into the Engine.
Attached Thumbnails
Glow plugs test OK but hard starting below freezing-mw-pump-element-1-feed-hole.jpg  
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  #56  
Old 10-21-2013, 08:00 PM
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I am not sure what is at this site. In My notes I have it as

Fuel Injection Pump training
Index of /docs/Bosch/Bosch_Pre-Tech_Diesel_Service_Training

There is more than Mercedes Fuel Injection Pump stuff at this site.

Also the Governors that are attached to the rear of the Fuel Injection Pumps are listed separately. So you either have to visually identify; or sometimes the Governor has a number plate on it.
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  #57  
Old 10-21-2013, 11:59 PM
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'84 300SD W126/OM617
 
Join Date: Apr 2006
Location: Central NJ, USA
Posts: 452
That's a wealth of information about how the IP works -- thanks for taking the time to explain, and now I know what/where the lift pump is.

Both the primer pump and the lift pump have been replaced on my car about 5-6 years ago (or roughly 60,000 miles ago) by the dealer in the process of troubleshooting a fuel leak.

Recently when I was under the car replacing the oil pressure sender, I noticed a very slight wetness around one of the mounting bolts of the lift pump, so I tightened that particular bolt ever so slightly.

But I think since my lift pump has been replaced fairly recently, the theory about the lift pump being a culprit in hard starts is fairly unlikely.

I will say, though, that my fuel economy has gone to pot over the last couple years. Oil consumption has been pretty low, so maybe IP timing has deteriorated with timing chain stretch or maybe my injectors are really worn, or both.
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  #58  
Old 10-22-2013, 12:42 AM
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Just because parts are only five to six years does not mean they are functioning properly. It does increase the chance they are but the test is so simple. Plus some thing or things are not up to snuff as you have issues with the car.

Also some parts of the fuel supply system where not replaced remember. Because of your declining fuel milage the injectors may be checked. If bad enough they could impact starting as well.

Before that though since the car is a daily driver still I believe. After a run check your wheels for temperature. A dragging caliper or two could pull the fuel milage down. Another easy and cheap test. A dragging caliper heats the wheel and is not that uncommon. A simple comparison test from wheel to wheel. Always wet the tip of your finger in case you have a really hot wheel. Usually when that hot though you will smell it as well.

I do not think the additional chain stretch in only 20k could in itself be causing all the newer grief. Does the car still accelerate well? If a lot slower than it once was it could be a lack of adequate fuel now. Or at least less than you had once.

Getting the cheap stuff out of the way with simple tests is cost effective usually and you learn things that you will use in later years. No fun on the wallet taking a car in for paid service anymore. To add to the misery there are probably fewer and fewer mechanics still up to scratch on these older engines. You are somewhat fortunate though as there are some clues present. A 617 engine getting inadequate fuel will be actually harder on fuel. Perhaps not as bad as yours has become but a symptom not to be ignored as something is causing this. Personally I hope it is also impacting the ability to cold start easily as well. A not unreasonable assumption in my opinion.

Last edited by barry12345; 10-22-2013 at 12:53 AM.
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  #59  
Old 10-22-2013, 12:57 AM
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'84 300SD W126/OM617
 
Join Date: Apr 2006
Location: Central NJ, USA
Posts: 452
You're right, Barry - your arguments are definitely sensible.

The car is generally very peppy. There hasn't been any decline in power at all in the 7 years that I've owned the car. I generally take it easy on her, but sometimes if I must accelerate briskly, she will take 3,600 RPM in stride, and I won't see smoke pouring out the back while doing it, either. Turbo still boosts to 10 psi (I inherited a boost gauge from the previous owner).

I haven't replaced my main fuel filter for quite a while, although I've replaced the pre-filter several times. I'm not sure if a fuel filter will effect fuel mileage that much, but I will definitely do that.

For backflow, just pump the primer pump before a cold start and see if there's an increase in pressure?
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  #60  
Old 10-22-2013, 05:18 AM
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You pretty much have it. Oddly enough poor fuel pressure does hurt fuel milage. At first I assumed it just limited fuel. Too many owners reported they had noticed an improvement in fuel milage just by changing their fuel filter. This led me to believe the injection pump applies more equal fueling to all the cylinders when the base fuel pressure is better.

Do the primer pump test as I described earlier with someone helping. It can indicate issues or clear them from suspicion. Best again it is a free and easy test.
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