Starter delay in cold weather.........??? - PeachParts Mercedes-Benz Forum

MarkM · #1 12-29-2006, 08:54 PM

When the weather is warm, and when I turn the key to start the car (after glowplug cycle), the starter immediately engages.

As the weather turns cooler (30's F), there is a very slight hesitation after I turn the key before the starter engages.

When the weather turns freezing (20's and below), there may be up to a 5 second delay after i turn the key before the starter engages. No click first, just total silence for a few seconds, then bang, the starter starts.

At first, I figured it was a faulty solenoid on the starter, so I replaced it with a brand newsolenoid, and the problem remains the same.

Note that when I first got this car a year ago (84 300 TD wagon), it did the same thing in cold weather. Thinking that it was the starter, I replaced the starter with a relatively new one that I took out of my previous 300D. And the car did the same thing. Thinkin that this may just be a coincidence that the solenoid on both starters were faulty, I replaced the solenoid the other day. Still does the same. So the problem is definitely not with the starter.

I checked the electrical diagram for the starting circuit, and the only other possible problems could be poor electrical connections (battery, ground strap, connection block on passenger wheel hump), or the neutral safety switch (transmission interlock), or inside the ignition switch itself.

The hesitation will occur when I am in park and in neutral, so I dont believe it is the neutral safety switch.

Tommorrow, I will clean electrical connections (especially ground strap and connection block) and see if this fixes the problem.

Anyone ever had this problem, or have other suggestions?

Thanks,

Mark

JimmyL · #2 12-29-2006, 08:58 PM

I have that exact problem with my '85 wagon. I was sure thinking either the solenoid was sticky or the bendix would stick when the grease was cold. I'm really stumped with your problem with all that you have done......

MarkM · #3 12-29-2006, 09:18 PM

What you said is exactly what I was thinking.... bad grease in the solenoid that gets "sticky" when cold. So when I put in the new solenoid, instead of using regular silicone dielectric grease, I used synthetic bicycle chain lube...lighter than grease but still very tenacious.

I can't imagine this problem is specific to the wagons...I belive the starting system is exactly the same in sedans and wagons.

A possible hint (not wagon specific)....I work with the previous owner of this car, and a few years ago, I helped him adjust his valve clearances. To jog the engine I attached the aligator clamps of my push button tool to the two connectors in the connecting block just forward of the battery on the wheel hump, and when the ignition switch was on, I could not jog the engine like this...it just wouldnt work like in my own car. So we had to rotate the engine by hand with a socket on the main pully bolt. So maybe there is a bad connection there!?!?

My sticky solenoid theory is out the window...now I am thinking of a carbonized connection that when cold will not conduct (maybe wet and frozen?), but when the ignition key is turned, voltage is applied, the connection heats, dries, then bang...the thing starts.

I read previously that a bad ground strap connection can cause many subtle problems, and it is a regular maintenance job (cleaning ground strap connections) that most of us ignore (myself included). The strap is certainly located where it gets wet (bottom of engine, drivers side).

So first thing tommorrow morning out in the cold, I will clean ground strap connections, (as well as the connections in the block on the wheel hump).

At this point, I'm betting on the ground strap. What is the "bendix" you mentioned in your post?

Mark

kerry · #4 12-29-2006, 09:22 PM

This problem has been reported repeatedly in the past. I used to have it on my 85TD. Even bought a new starter in an attempt to solve it. I never installed it and the the problem has gone away. No idea what was causing it but i had precisely the same symptoms which got worse int he cold. Once it even failed to start at all around 0 degrees. No problems in over a year now.

MarkM · #5 12-29-2006, 09:30 PM

Now I am determined to figure this out....I will be dreaming of this tonight!

I have never had a failure to start, but I have had several "anxious moments" with this. Last year when morning temps were below zero, I turned the key and it was a full 10 to 15 seconds of absolute silence before the starter jumped to life!!!!

I will report back tomorrow.

Mark

JimmyL · #6 12-29-2006, 09:33 PM

Quote:

Originally Posted by MarkM

Now I am determined to figure this out....I will be dreaming of this tonight!

I have never had a failure to start, but I have had several "anxious moments" with this. Last year when morning temps were below zero, I turned the key and it was a full 10 to 15 seconds of absolute silence before the starter jumped to life!!!!

I will report back tomorrow.

Mark

Mark, the only thing better than knowing that there are other folks out there who have the same problems is having them fix it and tell you what it was......

My wagon is not a daily driver, plus we don't have just a whole lot of cold weather. But I get a half second delay even when it is in the 50's.

JimmyL · #7 12-29-2006, 09:26 PM

The bendix is the starter gear that meshes with the flywheel. It pops out to mesh with ring gear, then retracts after engine starts. I'm assuming that is how these work.

**edit**
I just went out and looked at the starter I have laying in the garage. There is also a ground strap from the solenoid to the starter housing.
Replacing your starter should have taken care of this, though. Interesting info about the terminal block for the wiring. hmmmmmm........

MarkM · #8 01-04-2007, 11:16 PM

I previously described the sympton as a delay in actuation of the starter after you turn the key....he colder the weather, the longer the delay. Even in mild weather, there is a slight but noticable half second delay, but in very cold weather, the delay is sometimes as much as 10 seconds!! The symptom is usually thought to be a faulty starter solenoid....it behaves as if the solenoid is gummed up, and the gum gets thicker with cold weather.

In the last post, I described how my car had this symptom and I proved that the starter solenoid was NOT THE CAUSE..see that post for further discussion.

The neutral safety switch is not the cause, verified by "jumping" the contacts to the leads from that switch, completely bypassing that part of the starting circuit, and the car still had the starter delay.

All indications were that the cause was the electric portion of the starter switch. I just replaced that switch on my car tonight, and voila, absolutely no hint of a delay!!! Solved! Done!

I took apart the old switch, and inside there was a lot of heavy oil lube...not white grease or similar non flowable grease, but messy heavy flowable oil. I don't think the increase in viscosity of this oil with cold weather is the cause, though, because there is no freely sliding switch component that would explain the symptom. What I DID see inside the switch was that two of the several contacts (relay type contacts) were severely carbonized, and one of those carbonized contacts had a lot of oil on it. The remaining contacts were nice and clean.

I don't have enough technical knowledge about current flow through carbonized contacts to explain why variation in temperature would cause delay in current flow, but I suspect that the symptoms (delay start) have something to do with attraction of moisture to the carbon, freezing of the moisture in cold weather, high resistance of the contact point, insufficient current flow to engage starter solenoid when first contact is made, but after the contact heats up, current flows.....maybe someone else could explain this phenomenon.

The bottom line is that the common delay start symptom is absolutely, positively caused by internal malfunction of this switch....seems to be bad contacts. This switch is easily opened by pressing the three tabs and sliding the internals from the metal case. It would be very easy, I believe, to repair the switch by cleaning out the oil, cleaning the contacts, re-lube with better grease, and reasemble. However, you can get a new switch for about $30 through Phil with Fast Lane. My own experience is that once contacts are severely carbonized, even when you clean the contacts, the carbon problem reoccurs quickly. Therefore, given the price, I think the new switch is the better option.

Note....in order to gain access to replace the electric switch, it is best to remove the entire ignition lock from the car with the switch attached, and then replace the switch. This procedure is really very simple and easy (you do need to remove the dash cluster and the footwell trim panel)....easier than trying to get your hands into the dash an unscrew the three screws that attach the electric switch to the ignition lock housing.

Procedure for removal of the ignition lock is described in detail in other strings on this site...note that Diesel Giants writeup says that you need to unbolt and lower the dash as you extract the ignition lock in order to provide enough clearance....this is NOT the case...you just twist the lock housing as you extract it and it comes out no sweat.

Another note, you can only remove the harness plug from the back of the switch if the ig. key is in position 1...there is a little gizmo that holds the plug in there when the key is turned to OFF.

I can post a pdf of the Mercedes manual procedure for ignition lock removal if anyone would like,

Regards,

Mark

kerry · #9 01-04-2007, 11:21 PM

Well done. A longstanding mystery solved. Any speculation on why the problem magically disappeared on my 85 TD?

pawoSD · #10 01-04-2007, 11:24 PM

Out of both of our cars, only the '83 has had a "turn the key with no sign of starting" issue. It was the solenoid on the starter...and it was when the engine was hot! Right off the freeway, went into the bank for 5 mins...came out, turn key, no go. Hit it with a wrench from the trunk...

tried again, voila, started right up. Has never happened again, hot or cold. Weird.

MarkM · #11 01-05-2007, 12:15 AM

Quote:

Originally Posted by pawoSD

Out of both of our cars, only the '83 has had a "turn the key with no sign of starting" issue. It was the solenoid on the starter...and it was when the engine was hot! Right off the freeway, went into the bank for 5 mins...came out, turn key, no go. Hit it with a wrench from the trunk...

tried again, voila, started right up. Has never happened again, hot or cold. Weird.

Absolutely!!!! The most common cause of a delayed start after turning the ignition is a faulty starter solenoid. Hey, I pulled the starter and replaced the solenoid! I assumed that would fix the problem! The perplexing thing is that there is not much difference in symptoms to distinguish an ignition switch fault from a starter solenoid fault. However, when the starter solenoid is at fault, you often get some kind of noise from the starter (click, flutter, etc.). But with the ignition switch problem, after you turn the key there is NO sound anywhere, then all of a sudden, boom, the car starts. The other kind of unique characteristic to the ignition switch problem is the very clear correlation between longer start delay and colder weather...I lived with the several-second delay all last winter, then when weather got warm, the car was almost normal...only a split second (but noticable) delay all spring, summer and fall...and the car always starts. Then with the onset of colder weather again, the delay is more pronounced again. A bad starter solenoid will not likely correlate with cold weather that way.

Another distinguishing characteristic is that it seems the faulty ignition switch delay problem can persist for many months or years, and never result in a no start condition. On the contrary, when a starter solenoid starts to "act up" you can be pretty sure that you will soon (days or weeks at the most) have a failure to start condition.

Bottom line is that it is VERY EASY to distinguish between a faulty starter solenoid and a faulty ignition switch by a TEST: if your car exhibits the delay problem, turn the ignition to the "run" position, then "jump" the contacts in the connecting block on the passenger side wheel hump forward of the battery (jump one of the big screws to the small screw)....if the delay occurs, you know its not the ignition switch because you bypassed it...thus, the problem is likely the starter. If there is no delay when you jump the contacts, but there is a delay when you start with the ignition switch, then you know you have the ignition switch problem.

Mark

JimmyL · #12 11-24-2007, 08:02 PM

I had almost forgot about the starter delay as we haven't had any cold weather yet. Went to go somewhere in the wagon today and had my 2 second starter delay again.
I really need to replace the electrical portion of my switch this winter. Just not looking forward to dash removal again.....
Mark, I am still appreciative of your fine investigative work last winter. A job truly well done, and another example of helpful folks on here.....

I'm guessing this is the part?

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=27R1AUDQC28H16YA6N&year=1985&make=MB&model=300-TDT-001&category=M&part=Ignition+Switch

MarkM · #13 01-04-2007, 11:34 PM

Other than that, I can only suggest that since the delay start symptom is not the result of a specific, discreet, irreversable failure (e.g. something breaks)., but instead due the gradual buildup of carbon, and several related factors: number of starts, age of vehicle, presence of cold weather, humidity, and so forth, there will likely be variations in the occurance of "clinical symptoms". Perhaps in your car, you had a little carbon buildup only to be reversed when the contact arced and blew out some of the carbon (self cleaned).

Mark

compress ignite · #14 01-04-2007, 11:51 PM

Kerry,

I've had and old, wisened (and decrepit) starter "remaner" tell and show me
on the '84 SD's starter the incredible carbon buildup over 20 years of use.
Then he blew out the components (and bead blasted one or two) , reassembled
and said,"No new parts...Well not for another 200k miles".
Heat affects all the built up carbon , which acts as an insulator.

So, The inverse is also correct.
Cold "Shrinks" the heavily carbonized contacts away from each other,just
enough to reduce electrical transmission across the gap between the
contacts(until they "Warm Up" enough) to close the gap.

leathermang · #15 04-02-2008, 03:52 PM

Quote:

Originally Posted by compress ignite

Heat affects all the built up carbon , which acts as an insulator.
So, The inverse is also correct.
Cold "Shrinks" the heavily carbonized contacts away from each other,just
enough to reduce electrical transmission across the gap between the
contacts(until they "Warm Up" enough) to close the gap.

I think I am going to take this with a does of Buckminsterfullerines... ( one of the seven allotropes of carbon ) ... I am glad they did not know that carbon acts as an insulater when they put those carbon brushes into your starter.....