83 240D Howling at startup. - PeachParts Mercedes-Benz Forum

123boy · #1 08-06-2019, 04:50 PM

Looked around for anything on this topic, found nothing.
When I start my 240D, it fires up, runs for second or two, then makes a "howling" type noise. Just once. Then the noise stops, doesn't happen again (until next startup) then runs normally. Just one "howl" (not sure how to describe it).
Wondered if any members experienced anything similar or might know where or what the noise is? BTW, this happens when the car isn't moving. Before it's in gear and rolling. As mentioned, one "howl" and that's it.

97 SL320 · #2 08-06-2019, 06:02 PM

Could be a loose belt to the alternator. When the battery is drained to start, the alternator is under high load for a bit to recharge it. Once the alternator is up to speed and battery charges a bit, the load drops and belt stops slipping.

Mike D · #3 08-06-2019, 07:24 PM

Check for loose starter bolts.

123boy · #4 08-06-2019, 10:11 PM

Thanks for the tips. Alternator belt is new and tight. Battery is fully charged. I'll check the starter motor bolts, but the "howl" seems to happen after the starter has "done it's thing" and is completely out of the picture, so to speak.
Odd noise for sure. I've never heard anything quite like this noise.
My worst fear is that it involves the vacuum pump. Although, that unit pulled a nice steady 20psi on the gauge when I checked it.

Diseasel300 · #5 08-06-2019, 11:21 PM

Maybe catch a video clip and upload to YouTube to show what it's doing? Are you sure it isn't the overrun clutch on the starter howling?

97 SL320 · #6 08-07-2019, 06:19 AM

Quote:

Originally Posted by 123boy

, but the "howl" seems to happen after the starter has "done it's thing" and is completely out of the picture, so to speak.

I've had this happen with starters that have worn bushings and / or when the " plastic washer on the commutator side that acts as a friction brake when the starter drive isn't engaged so the armature does not spin down forever " gets covered in brush dust / oil and causes a chatter. The effect is similar to a clutch / brake lining that has thick sticky dry grease on it.

123boy · #7 08-07-2019, 12:37 PM

Thanks for the starter info. I'll have to pull it and thoroughly check it out. Recent purchase. Cars been sitting a few years. 200K on the odometer. Not much info available from seller. Belonged to a father and the "kids" were selling it. Seems fairly well taken care of. Starts right up, no smoke cold or when driving. Not a cream puff, needs a bunch of tlc. Been lookin for something like this (older Mercedes) for a while. My 1st diesel. Paid $900. Havin a ball!!

Frank Reiner · #8 08-07-2019, 04:17 PM

Quote:

Originally Posted by 123boy

Looked around for anything on this topic, found nothing.
When I start my 240D, it fires up, runs for second or two, then makes a "howling" type noise. Just once. Then the noise stops, doesn't happen again (until next startup) then runs normally. Just one "howl" (not sure how to describe it).
Wondered if any members experienced anything similar or might know where or what the noise is? BTW, this happens when the car isn't moving. Before it's in gear and rolling. As mentioned, one "howl" and that's it.

123:

Before rushing into any parts removal, consider having another person perform the behind-the-wheel starting operations, while you listen around the engine for a few start cycles. By listening from different places, you may be able to determine the locus of the "howl". Candidates are: alternator, steering pump, water pump, starter motor, A/C compressor clutch bearing, and (if manual transmission) throwout bearing.

97 SL320 · #9 08-07-2019, 06:18 PM

Whenever I get a car with miles / time I always pull the starter / alternator and take them apart for inspection / brush - bearing replacement / lube. This minimizes surprises down the road.

Given the car was sitting for a while, the starter drive / solenoid might be slow to retract causing the noise.

123boy · #10 08-07-2019, 07:47 PM

Once again, excellent advice from all and thanks to all for responding. Noise seems to be coming from the general vicinity of the starter. Maybe the simplest test would be to remove all 3 belts and fire it up? No "howl", gotta be a belt driven accessory.....easy enough to narrow down from there. No belts and a "howl", pull the starter.
Also neglected to mention, I've driven the car a "fair" amount since purchase. Nothing too crazy, around the neighborhood, after doing various maintenance procedures. No noises, no howls. Just the one howl on each and every startup. Burned about a quarter tank of fuel all in all.
I'm likin the "starter theory" more and more.....
Thanks again. New here and this forum is really great! You guys have been a big help. Gettin ready to adjust the valves......

Mike D · #11 08-10-2019, 08:07 PM

Any progress on this issue?

123boy · #12 08-11-2019, 10:21 AM

Thanks for checking back with me. Life keeps gettin in the way of my newfound love and passion......an 83 240D lol!
Hope to "sort it out" in the next couple days. I'll definitely post my results.
This is a great community. Really. Can't tell you how much I appreciate you following up.
Also, absolutely, cannot believe how hard I've "fallen" for this car. Kinda scary..haha.
Probably a few folks on here that can relate?

123boy · #13 08-20-2019, 08:22 PM

Wanted to give a quick update about the "howling" (some might say it sounds more like a "quack"). Anyway, got a lot of irons in the fire with this 240D right now. A glow plug issue just reared its ugly head a couple months before the northeast winter settles in. Tires and brakes are "in the works".
The "howling" seems to have disappeared....for now. Never pulled the starter (checked bolts for torque) and tightened belts.
I did have the glow plugs out and checked them with the glow plug relay/system, 2 out of 4 inoperative (glow plug light was working, then quit suddenly). A new batch of Bosch are on the way. Doubt that could make any difference in the "noise"...but, ya never know.
Def wanna pull the starter, check the bendix, etc. clean and lube and also pull the alternator for inspection/basic maintenance. Oh yeah, and a valve adjustment, of course!
Gotta get ahead of these other basic issues before I look for the "quack". Appreciate the responses and I'll keep updating as the work progresses (if anyone gives a crap...lol) Unfortunately, gotta work for a living, too (who doesn't?...sure does cut into my Benz time)
Plan on using the car to commute to work (about a 30 mile round trip). I work a 4/10's shift, so 16 days/month. Fantasizing about using about a tank of fuel per month to my job and back. That would be super cool...heh heh.
Thanks guys (and gals?)....PC, now....thanks people! Ya'll are the BEST!!

Usaguy · #14 08-26-2019, 07:08 PM

few tips:

get a reamer and ream the carbon in the prechamber. excessive carbon can cause premature failure and seize the plug in the prechamber

check the glow plug relay that it puts out 12V on all relay pins and check the wiring from the relay to the plugs for continuity

starter bolts on diesels can be very tight.

123boy · #15 09-03-2019, 11:32 PM

Well, the howl (quack, squawk, honk, etc) is back. Just one "honk" on startup only. Then no more while driving or anything else with the engine running. New set of Bosch glow plugs today.
Glow system is working great! Car starting and idling great, too. Had some set backs with "normal life" last few weeks. Gonna go after the "squawk" with a vengeance, now.
If I can figure out how to do it, I'll take a video on startup, capture the sound and post it here. That's a big "if"....