My car since buying it has been running hot while on the freeway going up hills. It typically cools right back down on the down hill, but I often have to babysit the temp gauge while on road trips and one of these days I'll forget to look and will cook my motor.

I put a new thermostat in, when I first bought the car, and also bought a new OEM water pump, and I'm suspcious of my fan clutch, but I don't know how to remove or test it. My fan shroud is also shredded and I would like to replace it, and while I have the shroud and clutch off, I would like to replace the water pump for good measure. Anyone know what the part number is, and a good place to buy a new fan shroud?

I couldn't seem to figure out how to get the fan off though, and I imagine that I need some special tools, one of the other threads I read mentioned you could make the "clutch nut wrench" but with out dimensions or some sort of print, I'm not quite sure what to make.

Is there a way to test the radiator to know if it is getting adequate flow? Would it be worth the $100 to take it out and have it flushed, or would it be cheaper in the long run to just buy a replacement?

1984 300D TURBO 149K
PULL THE TOP RADIATOR HOSE OFF, LET ENGINE COOL, FILL HOSE WITH WATER, YOU HAVE AIR IN ENGINE,

Thanks for your reply, and the yelling all caps response, but no, I don't have air in the cooling circuit, I can pump the hoses, top and bottom with no gurgeling or purging.

Heat car up to 100c or so, pop hood, depress stop lever. If the fan turns for more the a couple seconds after engine stops, you have a bad fan clutch

__________________
VegStew
1983 300SD 70,000 WVO Powered miles
1990 300D In driveway with Head Off - Cracked

Sounds easy to evaluate, now all I need to do is get the car running again so I can test the fan clutch

(O.K. I'll put on the BC / gsxr Hat)

What is "Running Hot" on your Water Temperature Gauge ? (in Degrees "C")

Have you tried to clean the "fins" of the Radiator and Condenser of ALL the
accumulated junk that's built up in there over the last 18 years?

If the Radiator has a "Cool" spot right in front of the Viscous Fan Clutch;
(caused by "Junk" obstructing the Air Flow in either the Condenser or Radiator)
The Viscous Fan Clutch WILL NEVER ENGAGE...It needs Heated Air-Flow to engage.

'Burping these engines (of Air Pockets) Almost Requires Standing it on it's
Rear Bumper and Shaking it.

You have to fill the block with the Upper Radiator hose (Quick) and then
Elevate the Front [On Ramps?] and run... cool down.... fill... run...cool down
...fill...Etc.

__________________
'84 300SD sold
124.128

The clutch is held on the water pump pulley flange by a bolt that takes an 8mm hex bit. There's just enough room in an 87 300D to slip in an 8mm hex key down the middle of the clutch and set a deep 10mm socket and breaker bar over the long end of the hex key. There should be more room in a 2.5. The water pump pulley will spin with the bolt so you need something like -



to hold the pulley. If you're lucky, your water pump will have a beefy rib on the snout allowing you to wedge a locking pin though a hole in the pulley against the rib. I've only seen this beefy rib in 603.97 water pumps. 603.96 water pumps have a small rib that isn't enough to hold a locking pin when I've tried.

My money's on the radiator but member swogee has replaced every part of his 87 TD cooling system except the block which he's descaled and deoiled but he still has cooling problems. Regardless, I'd replace the radiator if it doesn't have a metal sleeve inside each radiator hose fitting or is more than 5 years old. Clean the condenser core well while the radiator is out.

Sixto
87 300D

On a long uphill I will run all they way up to the 120ºC line unless I slow down to below 50mph, and during the summer (I work in a town named Mojave) even on the flat and level with the AC on I will often have to run the heater with windows open on my way home from work to not get to teh 120ºC line.

I'll get to the 120ºC line even when ambient is 70ºF outside if I'm accelorating hard or going up long freeway hills

I haven't checked this, but I will tonight when I get home and clean out the radiator fins with compressed air and water

I have a steep driveway, I filled the block via the hose, and then connected and burped the hoses and ran 10 minutes and filled again, and then checked it again the next day after work. Is that adequate, or should I consider one of those pressure fill setups?

Thanks for you help and rapid responses!

Got a new hard injector line and now have the car running/idleing ok. Ran the car up to 110º C and shut her down and the fan still spins freely, so I'm now going to try to focus on repairing the fan clutch. I took a video of the car running and at the end, shut the engine down and spin the fan by hand. You can see it on youtube here:

http://www.youtube.com/watch?v=4QohSp4j70s

Now to find a thread discussing how to repair/replace the fan clutch.

Got the failed hardline replaced (used) and ran the engine. Drove it hard up a hill and once I got the temp to 110º C. I pull over to the side of the road and hit the stop switch. The engine died and the fan just kept freewheeling. So it looks like I'm no onto rebuilding or replaceing the fan clutch. Need to buy some tools and find a few threads on the fix. I'll post on here how it goes. I also took a video of the engine running and at the end of the shut down, you can see the fan continue to spin. See the video here:

http://www.youtube.com/watch?v=4QohSp4j70s

Based on what I saw in your video the fan clutch doesn't appear to be that bad. That is actually a reasonably quick stop assuming your engine was up to temperature. My SDL was spinning for 6 seconds after stopping the engine prior to the replacement clutch install.

That being said, replacing the fan clutch can be done with the radiator in place. I've done it before on a 90 300D but I left a decent amount of flesh behind. It's much easier to do with the radiator removed.

Takes about 5 minutes once everything is out of the way. You'll spend way more time pulling/installing the radiator. Would be a good time to go ahead and clean the radiator anyway.

__________________
Joe

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1980 300SD - 495k miles - 'The Ambassador'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

It takes about 20 minutes of actual road driving to fully warm up the engine.
(You want to have the thermostat fully cycle through All Three Positions.)
[AND run the Heater to cycle the Heater Core in the mix]
Then you've got to let it sit and cool off enough so you don't burn yourself
opening the Tank.
[This system Should Be Self "Burping",There is a small metal line that runs
side to side in the engine compartment and connects both sides of the cooling
system...it may be impaired]

You'll want to replace the Fan Clutch with an OM 606 Fan Clutch
(Much Cheaper) #606 200 01 22 ($109.34)
AND a New Plastic Bladed Fan # 606 200 01 23 ($56.14)
(Less weight on the belt drive system and the Water Pump Bearing)
AND new Bolts to connect the two # N914020-006017

__________________
'84 300SD sold
124.128

I was under the assumption that the clutch would totally lock up and not spin at all? Not true?

I ran the car for about 15 minutes, and I live at 4,000 feet so when I ran the car up to the top of the hill that I have to drive over everyday to get to work, (6,000 feet) the temp gauge was reading over 110 degrees C. Its a good idea to run the heater, I didn't think of that.

Thanks for all your help, where is your favorite place to buy parts online? Also, do you know of a good thread that details the fan clutch removal process? I figure once I have the Radiator out, I will have it boiled, flushed and tested.

I also have a new water pump to put on, as well as a new fan belt. I need to order the fan pully tool and other specialty tools to make the job go easier. I tried it before, just "winging it" and wasted a Saturday on the job, and still never got the clutch off. This time, I want to be prepared with the process and tools so I can do it quickly.

Any good simple ideas for capping the Tranny cooler lines? Since I just drained and refilled the tranny 3 weeks ago, I'm not keen on wasting all the new fluid. Any simple ideas cap the lines?