You will never start a 606 without glow plugs in sub freezing temps - PeachParts Mercedes-Benz Forum

Chris W. · #1 01-16-2016, 09:08 AM

This is my opinion based on the following. I have one GP out right now. When I start the car in the morning when the temp is below freezing, it starts on 5 cylinders. It runs for 10-15 seconds before the dead cylinder starts to fire, and then it fires intermittently for another 15 seconds or so before it settles down and runs normally. It knocks a bit on that cylinder as it burns up all the unburnt fuel it accumulated during this time.

So if it takes 15 seconds of the car RUNNING to get a dead cylinder to _start_ to fire, I maintain that there is no way that just cranking alone with the starter will ever start your 606 unless you have most of your GP's in operation. I have started with 2 dead GP's also, but then it runs super rough, of course, on 4 cylinders until those dead cylinders start to fire.

I have not had the opportunity to observe this situation with a cold engine in warm weather to see how soon a dead cylinder will start to fire. My GP's always seem to fail in the winter...

Rgds,
Chris W.
'95 E300D, 457K

pimpernell · #2 01-16-2016, 09:16 AM

Quote:

Originally Posted by Chris W.

This is my opinion based on the following. I have one GP out right now. When I start the car in the morning when the temp is below freezing, it starts on 5 cylinders. It runs for 10-15 seconds before the dead cylinder starts to fire, and then it fires intermittently for another 15 seconds or so before it settles down and runs normally. It knocks a bit on that cylinder as it burns up all the unburnt fuel it accumulated during this time.

So if it takes 15 seconds of the car RUNNING to get a dead cylinder to _start_ to fire, I maintain that there is no way that just cranking alone with the starter will ever start your 606 unless you have most of your GP's in operation. I have started with 2 dead GP's also, but then it runs super rough, of course, on 4 cylinders until those dead cylinders start to fire.

I have not had the opportunity to observe this situation with a cold engine in warm weather to see how soon a dead cylinder will start to fire. My GP's always seem to fail in the winter...

I would tend to agree with you. I was able to start my 96 e300d with one plug out at around 28 degrees, and got the exact same results you did. If 2 plugs are out, I think it would be a crap shoot if the engine fired up.

97 SL320 · #3 01-16-2016, 09:30 AM

A 6 cyl prechamber enigne with 5 working GP is more or less like a 5 cyl with 5 working GP except for more drag from the non firing cylinder.

In theory it could start on one GP like a single cyl engine however the compression drag from the other 5 cyl would be too much for the single cylinder to power. This is where having all cyl in cold operation helps , while each cyl is down on power, the all contribute something or the starter would need to remain engaged until other cylinders start to fire.

Wodnek · #4 01-16-2016, 03:07 PM

My 93 E 300D had all 6 glow plugs working, and it will not start below 0 unless it is plugged in. I truly believe the 606 is more cold blooded than the 603. My 87 300TD, i rarely plugged in when i had it. It always started right up, and after 15 seconds, was ready for the road.

Now days, I run an 05 and 06 CDI. It is weird having a diesel with no cord to plug in to. it was -10 monday morning of last week, and it started right up, i have to admit, i was worried. It was no more than 4 seconds of running a bit rough, and it was ready.

Now, our power stroke diesel in the truck, it's a 7.3, and i have never plugged it in, not once and it always starts. it does shake the truck violently for about 30 seconds though.

mannys9130 · #5 01-16-2016, 06:32 PM

Agreed.

These prechamber diesels won't start nicely without glow plugs even at 50 F. You'd need to crank for probably 30-45 seconds to start it. Prechambers SERIOUSLY sap all the heat from the combustion chamber. The increased surface area allows the head to absorb all the heat and the flow plugs become critical. Even AFTER starting in extremely cold temps, once the plugs cool off in a non after glow car the engine will run a bit rough until the piston and pintle ball start to warm up.

JB3 · #6 01-16-2016, 09:10 PM

Aside from glowplugs what weight oil is the OP running?

5w or 0w 40 makes an amazing cold start difference.

For me it was an inability to fire up at 20 degrees down to reliable starts in negative temperatures, same glow plugs

Chris W. · #7 01-17-2016, 08:28 AM

I'm running 15-40 Rotella non synthetic, year round. Where I live we don't get single digit or below zero temps very often, so I don't switch during the winter. I agree that dino oil gets pretty thick in cold temps, but assuming my GP's are working the car starts right up on those few days when we do have really low temperature.

Rgds,
Chris W.
'95 E300D, 457K

babymog · #8 01-17-2016, 08:58 AM

603s are great in the cold, I've started as low as -18 outside with nothing other than the normal glow cycle, ... if all is in good shape (good battery, good glowplugs, good compression, good (preferably group-IV synthetic) oil ...).

An interesting point, my '93 300SD manual states that it is not necessary to pause and glow a warm engine, proceed directly to the start position. It works, no significant extra cranking. On the '87 I still wait, although they have the same head/injectors/prechambers/glow-plug relay, I will eventually check to see if Mercedes changed the glowplug P/N between the early "afterglow" and later "afterglow" 603s.

mannys9130 · #9 01-17-2016, 12:49 PM

Quote:

Originally Posted by Chris W.

I'm running 15-40 Rotella non synthetic, year round. Where I live we don't get single digit or below zero temps very often, so I don't switch during the winter. I agree that dino oil gets pretty thick in cold temps, but assuming my GP's are working the car starts right up on those few days when we do have really low temperature.

Rgds,
Chris W.
'95 E300D, 457K

Check the temp of your refrigerator and your freezer. Put a small amount of that 15w-40 oil in there and let it sit for a few hours. Tell me if you think it's actually going to be able to be pumped or if it'll be good at lubricating.

In Tucson we get extreme summers and winters. 110* summer, 20* winter mornings. I run Rotella 5w-40 synthetic year round. If you check the owner's manual, you'll notice 5w-40 is recommended for all temps possible, and it the preferred grade of oil. 5w-40 will seriously improve your cold starting abilities, and when you do the fridge/freezer test you'll see why.

babymog · #10 01-17-2016, 01:09 PM

Agreed, put in a bit of Mobil 1 Extended (a Group IV synthetic) in there also.

It isn't just the lubrication and pumping, the slow crank is because of the very thick oil creating so much drag on the bearings, extra power necessary to turn the oil pump, drag on the rings, etc. Takes much more power just when the battery is the least efficient and the engine needs heat and fast cranking most.

carl177 · #11 01-17-2016, 11:16 PM

I Second that above. I for one use Mobil 0-40 European Formula down here in Florida Based on what the Mobil one website recommends for the 95 E300; I have seen 102 steady on the temp display and the oil gauge seems up there and happy.

You may want to try that and it may help out further on you cold starts.

Hope this helps out Chris.

Respectfully.

Sent from my  using Tapatalk

mannys9130 · #12 01-18-2016, 12:31 AM

For some reason, everyone with a diesel Mercedes thinks they need 15w-40 oil. Leave that for the semi trucks. 5w-40 is a much better grade. It doesn't sacrifice anything yet it lubricates better quicker from cold regardless of temp, and is still a 40 grade when hot. It's common sense to me after becoming knowledgeable about oil grades and lubrication systems.

babymog · #13 01-18-2016, 11:08 AM

If you're talking dino oil, a 5W-40 is largely an SAE5 oil with viscosity modifiers. These viscosity modifiers are fragile, don't shear well, and don't protect things like cams as well as heavier basestocks will, I do not recommend a lower than necessary basestock in a dino oil.

One thing that my diesel loader reminded me of this weekend: even with everything else healthy, a tired starter will not crank fast and will consume lots of power. A good starter is essential in the bitter cold.

KarTek · #14 01-19-2016, 06:11 AM

Quote:

Originally Posted by Chris W.

This is my opinion based on the following. I have one GP out right now. When I start the car in the morning when the temp is below freezing, it starts on 5 cylinders. It runs for 10-15 seconds before the dead cylinder starts to fire, and then it fires intermittently for another 15 seconds or so before it settles down and runs normally. It knocks a bit on that cylinder as it burns up all the unburnt fuel it accumulated during this time.

So if it takes 15 seconds of the car RUNNING to get a dead cylinder to _start_ to fire, I maintain that there is no way that just cranking alone with the starter will ever start your 606 unless you have most of your GP's in operation. I have started with 2 dead GP's also, but then it runs super rough, of course, on 4 cylinders until those dead cylinders start to fire.

I have not had the opportunity to observe this situation with a cold engine in warm weather to see how soon a dead cylinder will start to fire. My GP's always seem to fail in the winter...

Rgds,
Chris W.
'95 E300D, 457K

I agree as well. The GP relay went out on my car and it wouldn't start at 50*. I had to pull the connectors off the relay and use a jumper wire to apply power to each GP wire in turn, for about a minute each before I jumped in and finally got it to start.