Diesel Fuel Injection System Help Desk

**mbeige** · January 2nd, 2008 07:35 PM

Hello,

I replaced the glow plugs the first time since I got the car in 2004, so I don't know when they were last done. One had a slightly broken tip and the others had a mix of bad and good so it was timely. I heard Beru is better but harder to acquire, Bosch makes up for it with availability though. Either way it's a win-win situation. When it gets hot it's actually hotter than it is there, so the temperature fluctuations are rather broad. Once it's cold it gets really cold too, last week it was down to the 40's (degrees Fahrenheit, which is roughly single digit Celsius readings). Still not a problem with my car.

By the way I meant to ask you, what do you think of Monark versus Bosio nozzles for the OM617.952 engines? There were several versions of the Monark that were released. See related thread here:

http://www.mercedesshop.com/shopforu...d.php?t=207859

Also one more thing, the non turbo versions of the OM617 that use the series type glow plugs can be upgraded with the parallel type glow plugs. Have you heard of this? I'm pretty sure a lot of MB owners there that have 1979 and older cars would love to get their hands on a kit like this installed on their diesels. My friend who has a 79 300TD recently had the kit installed but one problem was the availability of the "fast" glow plugs. Here they cost $12.xx while the turbodiesel versions (smaller but also fast glowing) cost $10 at the local Autozone. Rewiring has to be done for the parallel type but that's not so difficult. See what he did here:

http://www.runboard.com/bmercedesben...sinc.f5.t13234

I did not notice any transverse shaking at that engine speed, perhaps it's due to the large air cleaner mounted high on the engine bay allowing for a pendulum effect? Those air cleaner mounts could have been designed better though. Doesn't the "rack dampener pin" at the back of the injection pump dampen the vibrations? This device was only found on the turbocharged engines though. Maybe the non turbo versions had the vibration, something I have never experienced having only owned the turbodiesel models, a 1981 300TD-T and a 1983 300D both US version turbodiesels.

I recently graduated here so I plan to work full time already, so I can get my wife over.

My field is completely different from anything automotive.

**Dieseldude** · January 2nd, 2008 09:58 PM

Monark was quite popular here a few years back. They seem to just have vanished. I can't give you any feedback on Monark nozzles as we haven't tried them. The MB thread you sent me was very informative...... many fine points for Monark.

This is the first time I hear of the parallel type glow plug upgrade. I'm sure this system is better the the old series type plugs. Does this upgrade kit include a small control box?

You are correct on the rack damper. However, adjusting this damper doesn't always solve the shaking problem. Sometimes the injection pump and governor need an overhaul.

I recently graduated here so I plan to work full time already, so I can get my wife over.

My field is completely different from anything automotive.[/quote]

It is always good to be with family. I hope you can soon get together.

Thank you for the diesel threads...... very good topics.

Bye,

Dieseldude

**mbeige** · January 3rd, 2008 03:27 AM

The upgrade kit may or may not come with the updated control relay, depends on how much "control" you want on the system. At least that's how they did it. Their key feature is the purple wire that is responsible for maintaining after-glow once the key has been turned and the engine started. This allows the glow plugs to still be used for an amount of time after the engine has started, so it can provide better starts and somewhat better fuel economy too, by avoiding unburnt fuel going out the exhaust.

You're right, the rack damper can only do so much. Of course it helps to have new mounts and shocks installed to get the most out of it, and perhaps even pop testing each injector to check for even distribution.

There was one guy in Florida who has installed an intercooler from a Saab (Blackstone is what it's called) and he cranked out the governor on the injector pump and adjusted the wastegate to get higher boost, plus an EGT probe on the exhaust and a boost gauge tapped into the intake after the turbo. On the thread I gave you his name is MTUpower, which I think also refers to a high output diesel engine was it? Here is the link by the way:

http://www.schumanautomotive.com/for...?t=5373&page=3

If you can get access to the updated glow plugs for the OM61x series of MB engines I'm sure a lot of guys from the MB Club of the Philippines would want to get them installed on their cars.

Since I will be there January until March, we should meet up. I frequently pass by your facility and have always been fascinated with what or who is inside since I got my w123 300D

By the way when I had my car's valves adjusted on its birthday, they used a bump starter. I need to get myself one of those so I can do my own valve adjustments

I already have the (expen$ive) Hazet 14mm wrenches!

**Dieseldude** · January 3rd, 2008 03:41 PM

[quote=mbeige;984614]The upgrade kit may or may not come with the updated control relay, depends on how much "control" you want on the system. At least that's how they did it. Since these are fast-heat / low voltage plugs, a timer contoller is important for limiting voltage application time. Applying 12v for an extended time will zap the plugs.

Their key feature is the purple wire that is responsible for maintaining after-glow once the key has been turned and the engine started. This allows the glow plugs to still be used for an amount of time after the engine has started.... The purple wire is probably a dropping resistor for afterglow. A timer will also be needed to cut off the voltage though.

You're right, the rack damper can only do so much. Of course it helps to have new mounts and shocks installed to get the most out of it, and perhaps even pop testing each injector to check for even distribution. From my experience, a pump and governor overhaul will correct the engine shake.

There was one guy in Florida who has installed an intercooler from a Saab (Blackstone is what it's called) and he cranked out the governor on the injector pump and adjusted the wastegate to get higher boost, plus an EGT probe on the exhaust and a boost gauge tapped into the intake after the turbo.
Adjusting the pump and turbo for higher HP settings is easy, and more power can be extracted from the engine. The question however is: Can the engine handle this condition? As a Bosch service dealer, we never modify pump settings as this can lead to premature engine failure. Pump calibration specs are determined by both Benz and Bosch to give optimal engine performance and service life.

If you can get access to the updated glow plugs for the OM61x series of MB engines I'm sure a lot of guys from the MB Club of the Philippines would want to get them installed on their cars. The glow plug upgrade may be good. However, plugs have never been a big issue here since they don't fail too often due to our warmer weather.

Since I will be there January until March, we should meet up. I frequently pass by your facility and have always been fascinated with what or who is inside since I got my w123 300D. Good, let's meet up when you get here......

By the way when I had my car's valves adjusted on its birthday, they used a bump starter. I need to get myself one of those so I can do my own valve adjustments
What is a bump starter? I may have a need for this tool too.

**mbeige** · January 3rd, 2008 07:04 PM

A bump starter taps onto the emergency start terminal on the front passenger fender and the + side of the battery if memory serves. When you depress the button it activates the starter via bypassing the ignition switch. That way when doing a valve adjustment you don't have to cycle the pre glow system via bypassing it altogether using the bump starter. It's like a joystick with a long cable and a button for the thumb to rapidly press it so the starter will turn the engine as you get the correct alignment prior to adjusting the valves.

You definitely will benefit from it if you do a lot of valve adjustments. Saves not having to use the power steering pump pulley bolt as a means of leverage, and avoids crawling under to access the 27mm crankshaft pulley nut to turn the engine.

You're right the glow plugs rarely fail there but it's also good to have the convenience of faster starts rather than wait each time for the engine to start.

Curious when you say overhaul what exactly does that entail? Does it mean recalibrating the small camshaft inside the injection pump, does it mean replacing bad parts (plungers, seals, delivery valves, etc), or simply adjusting the timing?

Finally one thing I really am interested in are the new Bluetec MB diesels. What do you think of them? I understand the glowing cycle is much faster so there's no more waiting time but I've heard about the "gap" on Mercedes Shop referring to the glow plugs maybe (or similar devices on the newer engine)? Or was it tap?

Anyway thanks for this small discussion, when we meet I'm surely going to enjoy having a talk with you.

**mbeige** · January 3rd, 2008 07:49 PM

I found a very nice thread about somebody doing an engine rebuild on his 1980 300SD. All I can say is that's one heck of a project! You might enjoy reading it bit by bit

http://www.benzworld.org/forums/w116...locked-up.html

**mark_t** · January 3rd, 2008 08:15 PM

Sir,

Ang ganda dito! i have always been interested in diesel engines.

Studied automotive mechanics got certifide to get started, unfortunately i

can't afford the pay of an entry level mechanic. Got a family to take care. Ended up

somewhere else.

But I will be back!

**Dieseldude** · January 4th, 2008 03:47 AM

Hi Mark T,

I'm glad you are benefitting from our helpdesk.

And even if you have ventured onto another field, what is important is that your interest is there.

I also took the circuitous route during my younger days and ended up specializing in this field which was my first love from the very beginning.

You will also be back someday.

Feel free to post your questions anytime.

I wish you success.

Dieseldude

**Dieseldude** · January 4th, 2008 04:13 AM

[quote=mbeige;984945]A bump starter taps onto the emergency start terminal on the front passenger fender and the + side of the battery if memory serves. When you depress the button it activates the starter via bypassing the ignition switch. Is the swtopicsitch contactor heavy duty? Is it supposed to energize the starter solenoid just like the ignition switch?

Curious when you say overhaul what exactly does that entail? Since these 617s are about 20 - 25 years old, a complete pump teardown may sometimes be necessary, especially on high mileage cars. Worn out parts will have to be replaced. This could be an expensive.

Finally one thing I really am interested in are the new Bluetec MB diesels. What do you think of them? I understand the glowing cycle is much faster so there's no more waiting time.... To tell you frankly, this is the first time I've heard of Benz's Bluetec technology. Where can I get more info on this topic?

Anyway thanks for this small discussion, when we meet I'm surely going to enjoy having a talk with you. It's always good to hear from you.

**mbeige** · January 4th, 2008 06:14 AM

Yes, the bump starter bypasses the ignition switch and links the starter with the battery via the terminal on the passenger fender. Remove the cover and you'll see three attachments. My mechanic tapped the forwardmost screw which is presumably the starter, and the other end of the bump starter was on the + terminal of the battery.

The Bluetec of MB is pretty new. You can find useful links on Google, information is out there. One thing you might really want to look up is "Diesotto" which is another MB invention that combines the fuel economy of diesels and the compress-ignite feature, together with the otto engine's spark ignite. The key is variable compression. At start up the compression is low, and the spark-ignite is used. When it's already running, some mechanism increases its compression and the spark plugs shut off as far as I know. I think the engine developed is 1.8L with the fuel economy of a compact car but with 200+HP on a full sized S-class (it's used on the F700 Concept car by MB). It's really interesting! Mercedes-Benz.tv has links to it, with accompanying videos. Enjoy!

It's always good to hear your insights too!