My 83 300 D was overheating recently. 205K miles. It would go to the danger zone at idle with the A/C running. (95 degrees ambient.) I removed the radiator and took it to the radiator shop. The coolant was clean, showing no visible sign of corrosion. The shop told me it was 38 percent blocked. They cleaned it and reassembled it for 65 bucks. It runs 1/4 of the gauge cooler now with the old thermostat. Have you tried running your car without the thermostat to see what effect it would have on your temperature? Also, in a perfect world, all replacement parts are as good as new ones AND new parts perform as they are supposed to. We do not live in that world. Your new radiator may be bad and that would really confuse the issue.
( I hate to suggest that but it is possible.) Good luck

Another off the wall thought.
What kind of shape is the condenser in front of the radiator in? Is it clear? This could prevent air from flowing through the radiator. How much clearance is between the fan and fan shroud?
Unfortunately, the water pump in the E320 decided to start leaking on Friday the 13th. This would not be so bad if I did not already have the 300D torn apart. The wife is real impressed. Anyway, when I started the disassembly of the cooling system on the E320 I found that there was severe pluggage on the air inlet side of the radiator. Also, for the past few months I have heard some "bearing" noises coming from the front of the engine. Not only does it look like the noises were coming from the water pump but the fan clutch bracket bearing is shot too. I have been working with Phil (thanks mercedesshop.com) to get these parts in here the first of the week. The wife thinks I should go get a new Honda . If anyone wants to see or can post a pic of a plugged radiator email me and I will send the pic.

[Edited by engatwork on 07-15-2001 at 10:06 AM]

__________________
Jim

In the previous post engatwork mentioned some pics, he has emailed them to me, so I put them up for the benefit of everyone. If you would like to see his pics and comments you can traverse to:

http://12.96.14.5/engatwork.htm

thanks to engatwork for sharing the pics and comments, they are a big help to newbies such as myself.

If for any reason you want and can not get an OE part in FastLane, call me, I'll get you all the OE parts you can handle. I do understand wanting it NOW!! however, I can usually get it to you by the next work day.

Your Partsman is watching and listening

Phil

What about the ALDA and boost adjustments made in your previous postings (back in June). Could any of these be contributing to the problems you now face?
Almost sounds like an overfueling condition.
Good luck with this.
Mike.

240Joe: Excellent link. It’s interesting to note that the thermostat(s) in my 117 V-8s use a thermostat with a small air bleed hole already drilled into them. They a bit more sophisticated, with a ball bearing in a cage to act as a check valve. However, the later 617 diesels are (supposed to be) self venting.

Brrrrs: I’m glad it worked out for you, but this new radiator is functioning well, as far as I can tell. A note about running without a thermostat though: It is not advisable to do this on these cars, as the thermostat does not act as a simple gateway. It has a dual function, one of which is to simultaneously close the bypass as it opens up to admit cooler water from the radiator.

Engatwork: That’s not that off the wall at all. I actually cleaned out the condenser when I had the radiator out, since it was so easy to access and ‘back flush’ it with the garden hose. If your wife wants a Honda *real* bad, take her to a wrecking yard to look at the ones that now look like wadded up balls of tinfoil. Just don’t let her see the bloodstains if she’s squeamish though. (Yes, I’m warped, - and proud of it.)

Jeric: Good job.

Partsman: I’ll keep you in mind. But remember that the bottom line is a significant factor.

Mskulik: Good call. I did not adjust the boost pressure yet, and I did try turning the ALDA back to where it was originally, but to no avail. Same problem.

Thank you everyone once again! I have been out sick since Thursday, so I have not been able to do anything else to the car since then. I am going to check the IP timing, but I am going to do it in conjunction with installing new injectors, which I should have back from the rebuilder in a few days. The ones in the car are probably original with 200K on them.

Someone with a lot of professional experience also sent me an e-mail about modifying the thermostat that sounds interesting. It just seems to me that the thermostats should not *need* to be modified, but if it works…well, you know. I just do not want to mask a problem if that’s what it would do. I’d rather solve the basic problem, if there is one.

I’ll let you know what happens.
RTH

This is a fascinating thread, and as I followed it there were all the things I thought of here except maybe one.

The self bleeding effect you are thinking of is caused by the small bleed hole drilled into the flange of the thermostat. I have seen some of these with a one way valve arangement on them, but I think it was Japanese.

Here is a though though, If the bleed hole is covered by the rubber gasket, it ain't gonna work, and you will have air always.
and...

CHANGE YOUR RADIATOR CAP! (if you haven't )

If nothing else, take out the thermostat and see what temp you run, should be very cool indeed!

__________________
Ed
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"

This is an interesting thread.

I think everyone has covered about everything so we are in a noon-linear situation ...

1. Something is clogging a passage somewhere
2. Its a sensor issue
3. Its a gauge issue
4. Its still a thermostat issue
5. Its a pressure issue
6. There's air in the system

What I would do (even though I process little in the line of profound knowledge):

1. Take current thermostat and drill five or six small holes in it to allow flow during all conditions
2. New cap
3. Check inside of all hoses and at inlet/outlets for obstructions
4. Check gauge ... I don't know enough about IR testing systems and where to shoot to know if there is direct correlation between temps shown on gauge and in the area where fluid is flowing
5. Pop hoses a bit while engine is running

Lots of luck ... I really will be interested in seeing how this is resolved.

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

Judging from the post dates RTH has given up. What was the end result? We're all anxious to know.

I've been searching the site for info on cracked heads and preasure in the coolant system. Check out these threads.

Preasure in the coolant system when cool is a bad omen. My guess is that the head casket has a one-way leak between the combustion chamber and coolant system. This will preasurize the coolant and heat it up.

Strange cooling system problem

__________________
-Mike
'87 300TD 304kmi (RIP)
'95 Toyota Camry Wagon 125kmi