Learn me on loop style glow plugs + manual trans shifter bushings (240D)
 

Hey Folks,

1st Question

last week my 72 220D (240D swap) stopped glowing. I figured it needed plugs and replaced all four of them with new Bosch loop style plugs. The Bosch loop style plugs in the motor did not seem that old. One had a completely broken loop.

After replacing them the car was starting reliably. I know there is an upgrade but do not mind the amount of time it takes to glow. In comparison my 82 240D starts in the blink of an eye. I realize it has the pencil style plugs.

This morning was our first "cold" morning in SEPA (about 50 out). I pulled the know out and let it glow but the motor seemed to be cranking for a while - say 20 seconds while trying to start.

On a morning like this my 82 240D will start in maybe 1 second. Basically as soon as soon as the motor turns its firing.

Is this normal for a OM616 with loop style plugs? Do i need to be glowing it longer than just what the salt shaker shows? I haven't done a compression test but did adjust the valves last weekend and the motor runs pretty much flawlessly. Will start immediately after sitting for a week in the garage. Does not leak much if any oil and honestly hasn't burned a drop of oil in the 1k miles I've put on it since acquiring. It does not shake really at all unless the AC is on.

2nd Question

The shifter (4 speed manual) rattles horribly going down the road in all gears at a certain rpm. There is also ALOT of play in just the 3 - 4 gear positions side to side.

I checked under the car and the bushings look to be in good shape down there. What am I missing that could cause this?

Thanks!

The bushings should be snug at each and of each linkage- R, 1-2 and 3-4. If they're not snug, you can have play there.


The input levers on the side of the transmission can loosen and have play. If you take the linkages off (one at a time if you lose track of things like I do) the input levers should have a definite center (neutral position/disengaged) detent where you don't feel any play. If there is some, tighten the cap screw, its a 6 or 7 mm, IIRC. If you find yourself tightening it a second time, mcmaster carr has some loktite that wicks into threads, try applying that. Don't take the cap screw out, it's very hard to get back in with the transmission in place.



There's round hole through each of the 3 output levers of the shifter underneath. IIRC a 16 penny nail fits snugly and fixes all 3 in the neutral position. If you lock the output levers in place and it's still sloppy, maybe your problem is the shifter. Be careful, springs will pop out when you take it apart.

When one of the loops is burn it breaks (opens the circuit) and all the rest of the Glow Plugs cannot function.

An upgrade to the Pencil type glow plugs also changes the electrical circuit and when one Glow Plug goes bad the rest of the Glow Plugs can still work. And that is an extremely good benefit.

The next benefit is the Pencil Glow Plugs get hotter faster and people have side their engines start easier and faster. That means less stress on your starter and battery.

Note that your loop in the loop type plugs can burn through due to carbon bridging of an individual glow plug; usually the one a head of the one that burned. It can burn in the cylinder causeing the issue becuase your Injector is not spraying properly or the injector pop pressure is way low (things happening in the combustion chamber when they are supposed to or in the case of the spray in the manner they are supposed to happen).

If someone would post one of those online sites for you to view the service manual there is a good description of how the glow plug system works in it. The loop types have several variations of systems.

Get an ohm meter, put one lead on the ground strap, the other on the first plug, note the ohms, if infinity, change that plug, repeat on the rest...

Or RIP em out and get a set of pencil upgrades if you can find them and rewire for pencils.

Here is my experience regarding the time required to glow a 220d:
https://www.peachparts.com/shopforum/diesel-discussion/317520-possibly-dumb-question-about-glow-plug-use.html

Twenty seconds is a long time to crank. Certain fuel supply issues can delay starting as well. I almost would bet you have not checked for reasonable valve clearances. In todays world many people take it for granted they are self adjusting or not important.

I always like it when the really cold weather starts. There are multiple glow plug responses. Yes they frequently are the problem.

If you do not have a decent volume of fuel spraying when you hit the key. It cannot start until a supply builds. If for example air must be purged first or for some reason the initial supply of fuel is at a substandard pressure to the injection pump.

All too many times people just think the car is old. The reality is it has never been properly serviced for perhaps a dogs age. In general this is a very cheap thing to do yourself.

Today a lot of commercial service establishments would not know how. To many current working mechanics they are a blast from the past.

This is just one reason to properly check out the fuel supply system in good weather. It improves reliability and extends the life of the starter and battery.

Especially when you heavily over discharge the battery when attempting to start. The average modern car battery really does not like that at all in my opinion. When you have series loop lugs.

Carry a small meter and some item so you can bypass a burnt out glow plug. I have had a couple of diesel engines that just would not start hot or cold without some glow plug function. Otherwise they appeared normal. I never trouble shot that particular issue either.

I'm only answering Q #1. I think you need to examine your cables. I have often found that Benz cables corrode internally, and that lead mesh ground cable underneath fail after corrosion. Replace the cables!
On W123 chassis cars, I reroute the ground directly to the rear of the engine block using a 12mm bolt and a marine style connector that attaches the cable to the battery using a wing nut. See below from O'Reilly's:


https://www.oreillyauto.com/detail/b/super-start-4986/battery-accessories-16452/battery-terminal---universal-17657/b63cd76af39a/super-start-battery-terminal/sk7203/4742317?pos=5


Additionally, clean the battery posts and the starter connection. Plus, use the right oil. I use a Mobil 1 0W-40 which is always on sale at Walmart.


I learned all this by experience. The charging system and the battery are your friends, take care of them especially on these diesels.

Heck, make sure your battery is good under load. Check your motor oil. If its too thick for the weather, it makes it tough to crank...
Also try glowing the plugs twice before starting, especially in cold weather.

Best of luck. And what others have opined...