OM602 Odd starting - PeachParts Mercedes-Benz Forum

dieselbenz1 · #1 11-07-2017, 09:07 AM

Well we are hovering around -5 to +5 degrees F for the past week or so the other day I had a no fire on the first crank. I re glowed still nada so immediately re glowed but this time instead of a 4 second crank I could detect a weak even fire so I continued to crank for 30 maybe 40 seconds before she would run on its own. Oh yeah she was smoking strongly with the diesel smell. What was odd to me was the even slow fire pattern and of course the amount of white/ grey smoke.

I was running 15-40 Dino, GPs about 3.5 yrs old, filters and hoses 3.5 yrs old with about 20 k kilometres so nothing out of the ordinary. Well I had a few hours yesterday so changed oil 0-40 synthetic in preparation for the cold weather, went through GP system all reading similar .7 ohms, dressed GP contacts, was about to do a purge and change filters but stopped. I've had mixed results with running purge so instead I thought I'd do a health check of the fuel system. Having extra pre filters but no clear hose I installed a prefilter on the return line as Funola may have mentioned before in another thread. Yup a bit of frothing was visible she's sucking air. Bypassed fuel heater no change! Bango bolts all firmly tight but every hose clamp slightly loose retightening fixed the air ingress issue. This morning may tell how she will start but when I took her for a spin last evening no more slight haze at night in the rear view mirror.

dieselbenz1 · #2 11-07-2017, 11:59 AM

A little disappointing this morning it was 11 F so it started right up on first crank. But I did notice when the after glow cut off there was no change in engine noise. It used to chatter more the instant after glow went off mind you that's when it's colder out. The smell of diesel is still present but the smoking has been reduced significantly.

moon161 · #3 11-07-2017, 01:38 PM

61x people are hating on you right now.

Maxbumpo · #4 11-07-2017, 01:39 PM

Why don't you use the cold start procedure in the owner's manual? Allow a full glow, hold accelerator to floor, crank until engine firing enough to sustain running once the starter is released, and slowly back off the pedal so engine RPM doesn't get too high or stall out.

Has this odd cold start behavior just started suddenly, developed slowly over time, or has it always been like this?

Did you de-water your fuel tank with a treatment of an additive? Winter or summer fuel in the tank?

My last input would be check the condition of your injectors if they have 100k miles (160k km) or more on them.

vstech · #5 11-07-2017, 04:26 PM

Quote:

Originally Posted by moon161

61x people are hating on you right now.

Why? 0C temps are nothing for a 61x motor...

dieselbenz1 · #6 11-07-2017, 06:20 PM

Quote:

Originally Posted by Maxbumpo

Why don't you use the cold start procedure in the owner's manual? Allow a full glow, hold accelerator to floor, crank until engine firing enough to sustain running once the starter is released, and slowly back off the pedal so engine RPM doesn't get too high or stall out.

Has this odd cold start behavior just started suddenly, developed slowly over time, or has it always been like this?

Did you de-water your fuel tank with a treatment of an additive? Winter or summer fuel in the tank?

My last input would be check the condition of your injectors if they have 100k miles (160k km) or more on them.

Yes this behaviour just started our first cool spell. I did follow the procedure right after I noticed a no start with out the slightest hint of a fire or kick. Glow once glow then a second time petal to the metal still no real kicks but a hint of even weak firing just like trying to bleed air out of the system. I could see the rpms come up ever so slowly until it would finally self sustain around 450-500. I run additives (anti gel, lubricatiation, enzyme) but my method to dewater is run the tank almost empty just before the cool weather. My guess is we've had winter diesel for a while but I never know. Injectors were rebuilt several years ago along with all fuel lines replaced. This problem was a tiny amount of air through hoses likely metal lines shrunk hoses expanded not sure but a quarter turn on the clamps fixed the issue as was noted by observing the filter in the return line being froth free.

Maxbumpo · #7 11-08-2017, 09:50 AM

Simply running the tank dry doesn't de-water it, there will still be water in the bottom. One must use an additive like Heet that absorbs the water into the fuel so it is carried out of the tank and burned.

Diesel911 · #8 11-08-2017, 11:28 AM

I would do the testing on a tank of pure diesel fuel. If your problem clears up it is your alternative Fuel that is the issue.

What do people put in alterative Fuel to winterize it?

Diseasel300 · #9 11-08-2017, 12:12 PM

Did I miss where the OP is talking about alternative fuels? He's talking about pump diesel in this thread.

Air in the system will sure cause problems starting. I'd check the glow plugs to make sure you don't have one going flaky on you. A cold cylinder will sure cause some diesel vapor in the exhaust until it warms up.

How much mileage is on the engine? If it's getting up there, it could be down to lower compression causing a harder start/incomplete combustion in the cold. At 0F I'd expect there to be some smoke and roughness anyway, regardless of how tight the engine is.

moon161 · #10 11-08-2017, 12:43 PM

Quote:

Originally Posted by Diesel911

What do people put in alternative Fuel to winterize it?

Heat/antigel/solvents as required.

dieselbenz1 · #11 11-08-2017, 12:47 PM

Simply running the tank dry doesn't de-water it, there will still be water in the bottom. One must use an additive like Heet that absorbs the water into the fuel so it is carried out of the tank and burned.

Agreed a small amount of water will likely be present. Having grown up in frigid climates it was always ingrained on us do as I had mentioned above. Now in sub zero temperatures you never let your tank go below 1/3 empty as a further precaution to prevent freezing. Heck when dating 50 years ago first thing the girls would do is check your fuel gauge and force you to fill up in those temperatures. I never did like the idea of using emulsifiers but would rather determine if I have a problem then deal with it. When I was living in south east Asia 90% humidity and 30 degree plus C temperatures BMW dealers would offer specials to drop the gas tanks and spray on an insulation to help control condensation. Those cars had constant problems with water perhaps the cold helps in that regards?

Just over 250 km no miss as with a bad glow plug or 2 upon starting, I know that rocking feeling. I did have one lowish cylinder 330 from memory the rest closer to 390. I'm fairly confident the small amount of air was the issue just waiting on cold temperatures again. Seems like extreme temperatures brings out the problems.

I was about to try alternative fuel when or a purge when I thought what will that prove if I don't even know if the fuel system was sound so putting a window into the return line made diagnostics quick at least in this case.

dieselbenz1 · #12 12-30-2017, 05:07 PM

I'm still having issues starting so I've run several compression tests but not sure what's going on. With the engine at 80 d C 1 through 4 are all close to 390 psi 5 is 360. With the engine at 20 d C again 385 for 1 through 4 but 5 is 330. Now at negative 22 d C 1 through 3 360 psi 4 at 280 and 5 at 210 psi.It starts fine above 0 d C and the exhaust smells normal. Below 0 d C down to neg. 20 it starts sputters but the colder it is the more white smoke it generates and a strong diesel odor. Could the head be shifting with temperature? It runs strong when engine temp reaches 45 d C and warmer without smoke or odor. Just wondering what the next steps should be?