Driving home last night in the '80 300TD, heard a snap & every working dash light came on. Then the temp started climbing steadily & pegged at 120C+. Luckily I was about a mile from work & got it to our parking garage. Coolant was sprayed everywhere in the engine bay on the passenger side, and I saw just a strand or two of the alternator belt still hanging on. Some coolant then started pooling on the ground. Couldnt really tell even with the flashlight where that was spilling out from, but I'm guessing that was whatever was left in the system.

Now, all the belts were due to be replaced, so shame on me (the alt started squealing yesterday, silly for me thinking I had more time). But has anyone had this belt actually shear off while driving & take the lower radiator hose with it? I'm hoping that's what happened, but it'd be nice to know if that makes sense given the layout of everything.

Yikes, that may not be so lucky. Could end up being the most expensive mile you've ever driven... I would make sure the engine still turns over by hand, and that the cylinders still have compression, before spending any money on it at this point.

__________________
1998 E300 turbodiesel

America's Rights and Freedoms Are Not The Enemy!

Something similar happened to me about a year ago. Alternator bearings had been howling for awhile but I chose to ignore it. Bad move. One day, the alternator seized which caused the drive belts to literally SMOKE.

Had the car towed home then replaced BOTH the alternator and the belts. When you hear the sound alternator bearings begin to sound like rocks in a washing machine, time to replace.

You'll just have to look.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

x2 ^^^

When the engine has a failure SHUT IT OFF!!!!! Walk home or call the tow truck, especially if it's overheating! You may be due a head gasket, or worse...

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

I had my belt snap at 75mph in my 1987 300D this spring. I got her safely off the freeway and parked before the temp hit 120.

After replacing the seized alternator, and the shredded belt, I'm G2G.

You're probably hosed. the coolant probably burst/cracked something when you severely overheated the engine.

__________________
RenaissanceMan Labs: where the future is being made today.

Garage:

2017 Chevy Colorado Diesel (nanny state emissions)
2005 Volvo S40 T5 AWD, 77k
1987 Mercedes-Benz 300D turbodiesel, 4 sp auto, 156k - 28.7 mpg
1996 Tracker 4x4, 2 door, 16v, 3 sp auto. 113k - 28.6 mpg

WARNING: this post may contain dangerous free thinking.

Sounds like you have a blown head. The coolant is coming out due to extreme amounts of pressure. The alternator belt turns the water pump, so you had no coolant circulating.

The proper thing to do would be to pull over, open the hood, and turn the heat on in the car while the key is in the number 2 position (engine off).

Sorry but it looks like you have some engine work to do now.

Dkr.

There is a blowoff valve on the expansion tank, which is supposed to open befor expensive stuff pops. If turns smoothly by hand (not hydrolocked) and runs smoothly when checked after cooling, it's probably OK to fill up with coolant, fix belt and any leaks and call himself lucky. If it runs rough or produces white smoke when filled with coolant and hot, it's at least a blown gasket and checking the head for flatness and cracks.

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

Member adriel may have a TD head still for sale.

__________________
CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

Unlikely you damaged the engine. Cast-iron heads don't warp like the aluminum heads on later engines (1986+ 300D's). Look it over in the morning. Most likely, the relief valve on the expansion tank just released (~16 psi?).

Yes, the alternator in my 1985 300D seized (jammed bearing) soon after I got it and burned up the belt(s). Actually might have been just 1 belt on when I bought it (didn't know these engines then). I left the car on the side of the road since a co-worker stopped. I returned after work and tied a nylon rope tightly (barrel knot) so it turned the water pump/fan and drove 2 miles home. Another time, a large metal plate popped up on the freeway and cut off both alternator belts. I came back after a 3 hr class and drove home 10 mi, watching the gage. It got to ~105 C, so probably OK. Ambient was ~50 F.

__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Thank you all, I know it wasnt the right move to keep it running; my first goal was to get it off the highway safely, so getting it the extra 2/10-3/10 mile to my office & a safe place to park it didnt seem like too much to ask. As noted, I may pay dearly for that decision.

Appreciate the input & will get the chance this weekend to fully assess the damage.

My neighbor told me about a time he had a flat tire out on the freeway. He was attempting to change the tire when a supposed "good samaritan" pulled over and asked him if he needed help.

Next thing he knew, the "good samaritan" pulled a gun and ORDERED him to get into HIS car. He complied (they say NEVER NEVER get into the car with a criminal because they are planning on transporting you somewhere to do some very bad things). He begged the guy to let him go; the perpetrator told him he would let him go only if he promised he wouldn't tell the police about the incident. He promised to not call the police so LUCKILY, the perp let him go.

So......bottom line, IMHO, you did the right thing. Your personal safety comes FIRST. Getting the car to a safe well-lit populated area where there are plenty of witnesses is first and foremost. Fifty years ago people were generally a lot nicer than they are nowadays. Nowadays, you have to watch your back AT ALL TIMES.

First thing now you need to assess where the coolant was leaking from.

The thing is, if the belt snapped, it may not have been turning for a long while before it snapped.

If the alt light came on, and you immediately pulled over, you may be fine... if the light came on, and you kept driving until the temp spiked, then decided to continue to work, you may have blown the head. It is good liquid was still in he motor when you got there, but if it is leaking out the head/block gasket, it may have hydro locked and broken things.

I promise you, the 617 can destroy the head if overheated... I have two that are cracked badly from it. Both are turbo, so, that makes a bit of difference, but look carefully for signs.

Good luck!

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Many years ago, I pulled out of the parking area of the local crags after an afternoon of rock climbing when my alternator/ water pump belt snapped. The coolant temp slowly rose as I drove so I would pull over, shut engine, pop the hood and let it cool for 15 minutes and continue to drive while watching the temp gauge like a hawk, pull over and let it cool before the gauge got into the red area. I drove all the way home (about 15 miles) like that. I did not have the tools to change the belt with me nor did I have AAA back then. This was not a W123 diesel but an aluminum head turbo diesel. I did have the heat on full blast to help with heat removal. No damage to the engine after I got home and changed the belt.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

w116 300sd 1979,

2 weeks ago, after pressure washing my engine, my dash lights came on while driving on the freeway. The car began to overheat and the temp gauge needle made it to the red. Drove for 1 mile before getting off the next exit. I discovered the 2 alternator belts (fan belt) came off and tangled themselves around the fan clutch. Some belt pieces were left tangled around the tranny cooler line. Good thing the new tranny line is wire wrapped.

Earlier this year one of the alternator belts came off the pulley and severed the tranny hose line, also while driving on the freeway. Replaced the tranny lines, filled the tranny with tranny fluid and it drove like nothing ever happened.

I'm happy to report that after replacing the tangled belts, my w116 is still running like nothing happened.

I have to check those damn belts regularly. The belt tension gauge I use is terrible.
Going back to the old school "push down with the finger".