Thermostat

[Partscarver]

Just changed out the apparently failing (never got above 60C mbz unit) stat. Installed a new cheapie chinese from napa $26.00.
Question my temp gage now reads about 90C and the car seems to run as or more strong than before..

However halfway into a ten mile run I stopped to check for leaks or whatever and the no start problem surfaced again.

Before the car ran cool and stops and starts were not to much of a problem, just now and again after a short run it might not want to start, but a few (two to three) tries and all would be well.

Tonight it was well and truly warmed up and there was no way it was going to start until it sat for ten or so minutes then it starts.

I checked the shut off valve for vacuum leaks no leak down on a cold engine.

Is the injection pump so worn that it wont make pressure when hot guessing here.

Any idea's?

thanks in advance for your thoughts

1983 300sd 238K 617

[compress ignite]

1.ONLY use MERCEDES branded Thermostats!
[You don't want to "Cheap Out" on MB Filters OR Thermostats]
2.If you've got a "Hot" engine AND the Starter Rotates it...
(Faster than Ruuuuum,Ruuuuuum,Ruuuuuum)
MOST LIKELY YOU'VE GOT A FUEL supply problem...
A.K.A. Clogged:
Fuel Tank Screen (Bottom of Tank) due to FUNGUS Infestation.
Fuel Filter(s) Due to FUNGUS infestation.
3. STARTRON is your solution.

Star Tron Enzyme Fuel Treatment - Star Tron Diesel Additive

Throw an 8oz bottle in the Tank and in 2 days the problem will Vanish.

[compress ignite]

If However you're describing a No Rotation of the Starter condition...
@ 238 K Miles that Bosch unit needs to be opened up and cleaned of ALL
the Carbon buildup from the Brushes!
New:
Bushings/Bearings
Brushes/Springs
Etc.
May be called for.

Those Bosch Starters are "NO Recycle UNITs" A.K.A. Rebuilds ARE JUNK!!!

Proper maintenance of those older starters can get you 400K out of one.

These guys can supply you with all the parts you need:
Wagner Alternators and Supplies, Inc.

[compress ignite]

@238K "Zomebody" would have had to be running STRAIGHT H2O through it!

300K for that model Bosch I.P. is about Half Life.

[Partscarver]

Starter was spinning fast and fine
so i'll get some startron down at westmarine

[toomany MBZ]

90 C is normal.

[DieselPaul]

A lot of the US parts stores rate their thermostats for benzes in Fahrenheit and they end up being hotter than OEM. OE is 80*C a lot of American thermostats are 185*F which is closer to 85*C. I went through this on my SDL. I bought one from the dealer it was only like $25.

[Partscarver]

Learned something today.

On the ignition switch housing there's a cam operated vacuum valve that can stick open or partially open, and when its failing even partially the engine often will not start or start and run but not at full power.

Proved this today by removing the vacuum line from the shutoff valve.

The car started at the first touch of the key and ran at full power, responsive to driver input.

Though a pain to shut down, the apparent vacuum leak was the cause of all my no start, low power, slows.

Who knew, and the replacement part is available!!

.

[charmalu]

This is what you ae talking about? Last picture. $27.00
1983 Mercedes-Benz 300SD Sedan - Steering System - Page 3


Hope it is not the vacuum shut off valve. pricy $160 +
1983 Mercedes-Benz 300SD Sedan - Fuel Injection - Page 1


Here is a good thread on replacing the vac shut off valve, and how the gaskets go. Also a link I posted in post#9 that THEGEARS did with pictures of how the lever connects inside the IP.

http://www.peachparts.com/shopforum/diesel-discussion/324079-85-300d-shut-off-valve-replacement-two-gaskets-one.html

Charlie

[Partscarver]

yep either gummed up and not fully operating or leaking bad
will try to clean in place and then check hoses

thanks for the parts list

J N