Tips for starting a OM616 in cold weather - PeachParts Mercedes-Benz Forum

schickm · #1 09-25-2015, 02:53 PM

Hello everybody,

I've got a 76' 240D with about 190,000 miles on it. I'm taking a trip across the country stopping along the way to camp, which means no plugging in the block heater.

This morning I had a little trouble getting the car started after overnight lows dropped to about 40F. After the glow indicator on the dash stayed lit for about 15s we'd try and start it. It'd crank a bit, but never actually start. We repeated this process 2 or 3 times and then pushed the car over into the sun to let it warm up. After sitting for about 15mins, we tried it two more times and got it running the second attempt.

From what I've read on the forums these cars should start without block heater assistance until the temps get down to the teens. I've read people recommend cycling the glow plugs 2 or 3 times until you try and start it. Should I be concerned about this draining my battery? The battery is fairly new, but certainly not new-off-the-shelf.

I'm always starting with the idle adjust at high, but would pressing the accelerator past that high-idle point help or hurt for starting?

A few more details about the car:
- I'm running 10-40 dino oil (not syth)
- just did valve adjustment before the trip
- remanufactured bosch starter just installed along with new flywheel (old wheel was all eaten up)

Should I switch to synthetic? Okay to begin adding it as I refill the oil along the way? Or do I need to do a full oil change? Driving across the country I'm consuming about a quart every 300m anyways...

thanks for reading!

barry12345 · #2 09-25-2015, 04:24 PM

Can be other things but the glow plugs may be the old style and aged. New pencil plugs with the correct diameter mounting thread are still available.

If you have the old style series glow plugs you will see curly wires between some of them. These tend to be resistant dropping wires. Too much heat energy then does not get to the pre chambers. It is lost on the jumper wires.

Installing the new pencil type plugs since they are no longer in series requires some rewiring of their hookup. Most people that have done this conversion have thought it really improved things.

I was also wondering if the car was starting with no actual glow plug cycle. Usually your engine would not in my opinion at the temperatures you quote unless in very good condition. It is possible though as well.

A preliminary test just in case you have one glow plug shorted out. Get a glow cycle going and measure for each glow plug heating up with hopefully a laser guided type temperature reader.

A base oil actual consumption rate of 300 miles per quart puts this engine somewhat into the fairly worn category condition. Have a look for oil leaks or the vent line from the vacuum pump having oil in it. Both these problems can drop the base oil level quicker and make the engine seem like a heavy oil user when it really is not.

tyl604 · #3 09-25-2015, 05:21 PM

Try a lighter weight oil like 5W - maybe it is 5w-15? Do not quite remember.

schickm · #4 09-25-2015, 05:49 PM

barry12345: The engine definitely has the older style glow plugs in it. I'm planning on upgrading to pencil once this trip is over. Engine is fairly worn, has a decent amount of blowby (the oil cap dances and then topples off when I run the ol' oil cap test)

I'll pick up a laser temp reader and make sure each plug is heating, probably a good tool to have in the kit.

The vent line from my vacuum pump is pretty black, not sure if that's from old oil or current. Guess I'd just pull the line off and look inside?

The engine had some leaks coming from the valve cover seal and oil cap, but Ive since replaced those and now have no visible oil leaks!

barry12345 · #5 09-25-2015, 06:23 PM

I really do not think that vent line should be black. There is a chance that at some time in the past the pump diaphragm leaked and was replaced without the individual cleaning out the line. Otherwise it exhausts the clean air to enable the vacuum pump to develop vacuum.

A totally intact diaphragm cannot leak oil from the mechanical lubricated supply into this line.

You are already into your trip it seems so I realize how difficult it is to deal with these things or to even check them out.

Mxfrank · #6 09-25-2015, 06:32 PM

The oil youre using is a bit thin- is it Diesel rated? I used to use synthetic in cold seasons with my '79.

Ive recently come to the conclusion that its critical to seal the engine envelope..valve cove gasket, oil pan, the oring on the dipstick, front and rear mains, breather grommet, oil cap, etc. If the engine isnt sealed, you can be drawing huge volumes of oily air through the crankcase.

The plugs may not be the problem-with this sort of oil consumption, your compression could be low. What I would suggest is to do three consecutive glow cycles before attempting ti crank. And get some of these problems looked at when youu can.

leathermang · #7 09-25-2015, 06:50 PM

Quote:

Originally Posted by Mxfrank

.... What I would suggest is to do three consecutive glow cycles before attempting ti crank. And get some of these problems looked at when youu can.

THE FSM has a chart showing the glow plugs getting hotter up to one minute in the on position. They do not say turn off and back on... just leave it on for a timed 30 to 45 seconds and see if that allows it to start.

Upgrading to the later pencil type plugs.....and doing a plug hole reaming to be sure no carbon is blocking the effectiveness of the plug operation would be advisable.

As your engine wears... it is common to use higher viscosity oil to fill the extra space where the bearings are worn away.... be sure to use Diesel rated oil.... I use straight 40 wt Delo 400... a pretty standard oil for our diesels...

charmalu · #8 09-26-2015, 12:48 AM

I haven`t delt with these older style Loop type Glow Plugs, but from what I
understand is, if one burns out, the rest are out also. Like the old style
Christmas Tree lights back in the 50`s.

Up grading to the pencil type large plugs as Berry mentioned is the way to go.
Here is what pelican shows.

1976 Mercedes-Benz 240D Base Sedan - Ignition - Page 1

If you are going to be in camp grounds, maybe take along one of those Honda
generators for your Block heater. They are really quiet.

Charlie

sent from my pos computer

mannys9130 · #9 09-26-2015, 01:11 AM

If it's cold out, 5W-40 synthetic oil is a must. Anything thicker than that is too thick. I use Rotella T6 5W-40 even in the dead heat of Tucson summer. The parasitic loss to pumping oil is VERY evident between 15W-40 and 5W-40.

Other than that, you absolutely should switch from series gow plugs to parallel. Ream the holes when you do. Clean all of the electrical connections related to the glow plug system.

If you can boil a big pot of water over a camp fire and slowly pour it over the engine block, it'll warm up the engine a bit. If your engine has the mostly solid aluminum intake, you can take a burning piece of firewood and run it along the body of the intake to warm up the air and intake.

The name of the game here is to get as much heat into the engine as possible, and make it as easy for the engine to crank as fast as possible.

leathermang · #10 09-26-2015, 07:44 AM

Pouring hot water on the block is very dangerous....
First of all... it is totally ineffective... because you have a water jacket between where you can pour water and where the heat has to be for it to have any help.. that is the Cylinder Walls ....
and you put enough to possibly do any good you would be taking a chance on cracking the block. There are some things like the injection pump which are so close tolerance that the FSM warns about things like spraying it at a car wash...

barry12345 · #11 09-26-2015, 12:14 PM

I think one suggestion is valid. Or worth consideration. A cheap generator if you know the block heater works.

Mainly because on a trip you have few cheap options. No tools and probably no access to parts like the special new glow plugs.

interzonearts · #12 09-26-2015, 03:52 PM

I wonder if using starter fluid would not be a valid option if you wanna get started in cold.

leathermang · #13 09-26-2015, 04:00 PM

Yes... on the starting spray..... while the engine is turning over... meaning you need two people to do it correctly.... spray 3 seconds of spray into the intake tube with everything in place.. like the air filter...
Approved by moderator WHunter for anyone feeling skeptical and about to post that it will blow up the engine......not enough BTU's to harm it..... but well may start it....

mannys9130 · #14 09-26-2015, 06:11 PM

Pouring boiling water on the engine is way less dangerous than Ether in the hands of a novice. There's no way pouring boiling water will ruin anything. It will add just enough heat to help. You know, where I'm from in Boston it gets cold enough that a cup of boiling water tossed in the air will flash freeze into snow.

I would not use Ether even myself because I have a tendency to over due things and I would not want to crack a prechamber. I think the other suggestions listed are much safer and should be used first before reaching for the ether.

leathermang · #15 09-26-2015, 06:13 PM

Manny, you are completely wrong.