W115 74 240D Glow Plugs Question - PeachParts Mercedes-Benz Forum

RonjonJD · #1 02-28-2023, 03:30 PM

Hi, All

Last year I bought this 1972 W115 220D as a little cruiser. I love the car and it reminds me of my uncles 240D that he used to take me around in as a kid in the 1970's

The previous owner had installed a later model 240D motor into it.

On the dash I still have the saltshaker glow plug indicator mounted and so assumed that the car still had the series style loop type glow plugs in it. After some reading and watching vids from mercedes source . com about glow plug reliability and efficiency, I decided I should upgrade my plugs.

But when I popped the hood and looked around I noticed that the glow plugs in the car looked new, had wires (which look new) going from one plug to the other, and without a final ground wire going to the block. So now it seems its got the parallel style plugs in it. But how is the saltshaker indicator still working in my dash? Everything I've read says that if you upgrade your plugs the dash indicator stops working.

Anyone got any thoughts?

Thanks
Cheers
Ron
Zuid Holland
1974 W115 22D w 240D motor. Hellgreen.
Aka 'El Pimiento.'

vox_incognita · #2 02-28-2023, 05:18 PM

I guess you can leave the salt shaker as it is (operating). It is bypassed when the starter motor is energized anyway.
The ballast resistor (if there) on the firewall under the hood however should be by-passed by all means.

https://www.hanshehl.de/tipp14.htm

I'd check the supply voltage to the plugs too...and Amps if you have DC clampmeter.
It is a good idea to install an inline 50A or 60A fuse just in case.

RonjonJD · #3 03-01-2023, 09:01 AM

Quote:

Originally Posted by vox_incognita

I guess you can leave the salt shaker as it is (operating). It is bypassed when the starter motor is energized anyway.
The ballast resistor (if there) on the firewall under the hood however should be by-passed by all means.

OK thanks I'll take a look! I was confused because from everything I've read, I thought the indicator was disabled when the pencil type plug upgrade is done.

https://www.hanshehl.de/tipp14.htm

Quote:

Originally Posted by vox_incognita

I'd check the supply voltage to the plugs too...and Amps if you have DC clampmeter.

I'll do that as well. I don't have a clamp meter but I do have a pretty good volt meter with probes. So I hope that can give me a good enough reading to do the check you suggested.

Quote:

Originally Posted by vox_incognita

It is a good idea to install an inline 50A or 60A fuse just in case.

Yes I plan on doing that as well, plus adding a safety kill switch for the car electrics overall under the hood. It sits for long periods and the battery can get drained so the switch will come in handy!

Thanks for the tips

gmog220d · #4 03-01-2023, 12:27 PM

I'm curious to see photos of this engine install. What engine reference number is stamped into it? Where is the oil filter? If it's up top then was the body brace cut to make room?

My '74 came to me with pencil glow plugs installed. The installation also includes a relay control box, and the resistor filament in the salt shaker was replaced by a small light bulb. When I engage the glow system that light comes on and then goes off when it is time to start the engine, like a later car works.

Are you sure you have a resistor strip in the salt shaker? Does it take time to glow brightly, or does it light up bright immediately? If it lights up immediately you might have a glow setup like mine that includes the control relay.

It seems like I've read about folks leaving the resistor strip in place when installing the pencils without a relay, but I don't know for sure.

RonjonJD · #5 03-01-2023, 02:38 PM

Quote:

Originally Posted by gmog220d

I'm curious to see photos of this engine install. What engine reference number is stamped into it? Where is the oil filter? If it's up top then was the body brace cut to make room?

My '74 came to me with pencil glow plugs installed. The installation also includes a relay control box, and the resistor filament in the salt shaker was replaced by a small light bulb. When I engage the glow system that light comes on and then goes off when it is time to start the engine, like a later car works.

Are you sure you have a resistor strip in the salt shaker? Does it take time to glow brightly, or does it light up bright immediately? If it lights up immediately you might have a glow setup like mine that includes the control relay.

It seems like I've read about folks leaving the resistor strip in place when installing the pencils without a relay, but I don't know for sure.

Quote:

Originally Posted by gmog220d

I'm curious to see photos of this engine install. What engine reference number is stamped into it? Where is the oil filter? If it's up top then was the body brace cut to make room?

My '74 came to me with pencil glow plugs installed. The installation also includes a relay control box, and the resistor filament in the salt shaker was replaced by a small light bulb. When I engage the glow system that light comes on and then goes off when it is time to start the engine, like a later car works.

Are you sure you have a resistor strip in the salt shaker? Does it take time to glow brightly, or does it light up bright immediately? If it lights up immediately you might have a glow setup like mine that includes the control relay.

It seems like I've read about folks leaving the resistor strip in place when installing the pencils without a relay, but I don't know for sure.

Thanks for the reply. The car definitely has the resistor strip in the salt shaker. It’s slow to glow and also emits heat. The engine has the oil filter up high and to the front and right of the engine engine block. Here are some
Pics. (Plugs and overview of engine bay)

I also plan to remove all the wiring and connect the glow plugs to a separate high amperage starter solenoid/relay, and a 50a fuse with a separate push button for pre-glow on my dash as a few others have done. It’s a much more reliable setup.

vox_incognita · #6 03-01-2023, 03:22 PM

Beru Glow Plug conversion kits did not include the relay (only GP and wires). Bosch kit had a relay which people often did not bother with.

Methinks the engine has original oil filter setup under the IP with the plastic mesh full-flow and the big cylindrical cotton gin bypass flow filter.

The push/pull starter/preglow knob is sturdy and reliable enough. I'd keep things simpler.

gmog220d · #7 03-01-2023, 07:23 PM

Thanks for the engine pics, RonjonJD. I see that your engine still has the pneumatically governed injection pump, so this engine is likely an OM616.916 like the car came with originally, and as such would have come with the oil filter mounted down low, under the IP. I was curious to see if it was a later engine with the later style IP (not pneumatic).

I have wondered about the possibility of retrofitting the earlier style oil filter setup onto a later OM616. This would make it possible to install a later engine into a W115 chassis without having to cut the brace from the body to clear the top mounted oil filter housing, and also without using a remote oil filter setup.

Anyway, this is a side issue not related to the purpose of this thread. Thanks again for the pics.

To be on topic, I agree with vox_incognita's suggestion that you keep using the gorilla knob for operating the glow plugs. It is a pretty tough switch, and I'm not sure I've heard of one failing.

Also, the filter you describe as being on the front corner of the engine is for fuel. The oil filter is accessed from below the car.

RonjonJD · #8 03-01-2023, 09:13 PM

Quote:

Originally Posted by gmog220d

Thanks for the engine pics, RonjonJD. I see that your engine still has the pneumatically governed injection pump, so this engine is likely an OM616.916 like the car came with originally, and as such would have come with the oil filter mounted down low, under the IP. I was curious to see if it was a later engine with the later style IP (not pneumatic).

I have wondered about the possibility of retrofitting the earlier style oil filter setup onto a later OM616, thereby making it possible to easily install a later engine into a W115 chassis without having to cut the brace from the body to clear the top mounted oil filter housing.

Anyway, this is a side issue not related to the purpose of this thread. Thanks again for the pics.

To be on topic, I agree with vox_incognita's suggestion that you keep using the gorilla knob for operating the glow plugs. It is a pretty tough switch, and I'm not sure I've heard of one failing.

Also, the filter you describe as being on the front corner of the engine is for fuel. The oil filter is accessed from below the car.

Thanks for the info! The car (a 74 220D) definitely had a 240D motor put into it. I’ve got the receipt from the original owner for the work. It does ok for the most part but it’s got some blow by and the oil cap jumps a bit when you open it while running. I plan on putting another motor in sometime soon. Likely a full rebuild of a turbo version.

I’ve mostly had petrol cars including a 71 BMWtii, an 85 535i, a 635i, 2 pre 74 Porsche 911’s and a few other fun toys. Worked on them all myself, including a ground up on my 73 911s. This is first diesel passenger car I’ve owned aside from my 80 series Landcruiser I recently sold before moving from Australia to the Netherlands. Having fun learning this car.

Cheers!

RonjonJD · #9 03-03-2023, 07:25 PM

Quote:

Originally Posted by vox_incognita

Beru Glow Plug conversion kits did not include the relay (only GP and wires). Bosch kit had a relay which people often did not bother with.

Methinks the engine has original oil filter setup under the IP with the plastic mesh full-flow and the big cylindrical cotton gin bypass flow filter.

The push/pull starter/preglow knob is sturdy and reliable enough. I'd keep things simpler.

I just had a look and I think the oil filter is up high just behind the battery. It’s got a green painted cap on it.

vox_incognita · #10 03-03-2023, 08:24 PM

The oil filter canister (red circle) is under the Injection Pump :

The setup consists of a plastic mesh full-flow filter and a big cylindrical by-pass filter :

https://www.peachparts.com/shopforum/diesel-discussion/312434-w115-om616-oil-pre-filter-rinse-reuse-replace.html

The plastic mesh should be cleaned and re-used until ruptured.Both must be present in the canister. If you have access to aftermarket ones (Mann-Hummel, Hengst or Knecht) get a couple more. They're getting harder to get nowadays. The big (bypass one) are still available...God only knows until when.