leif.anderson93

I would recommend a 50/50 mixture of Zerex G05 and distilled water

SWCDuke

Make sure you remove the block drain plugs. You'll have to loosen the "boomerang" ignition wire shields to access. Use a 6-point socket on a half-inch drive breaker bar. Put some torque on the bar, then shock it, and they should come loose.

If no coolant flows out you'll have to dig out the debris with a tool.

The viscous fan clutch on my '88 MBZ is inop. According to a thread on the MB Shop Forum the reservoir can be refilled with silicon fluid that you can buy at hobby stores. Since I only drive the car in winter, and it has two pretty powerful aux. electric fans in addition to the mechanical viscous clutch fan, repairing it is not a big priority.

Maybe OE Corvette fan clutches can be similarly rejuvenated at home. They had to get the fluid in there when it was manufactured. There are also pros that can restore them. They usually advertise in the NCRS Driveline.

Duke

After38Years

Thanks Duke,
I'll stash the original for the time I want to be super original. In the mean time, the replacement is on its way so I can enjoy the '66 when the weather cools down (soon would be good!!!)

Vipergtrs

All this talk of clutches can someone tell me what effect on cooling will running without a clutch?

GTOguy

A clutchless fan will run at engine speed, with no slippage. Therefore it will pull more air and cool better at slow speeds and in traffic than a clutch type fan. It has a much more parasitic affect on the engine at freeway speeds, when a fan isn't needed because it cannot freewheel like a clutch type fan. So, a clutch fan cools better at low speeds, and costs fuel mileage and horsepower out on the open road. Properly working clutch fans work in both situations well, as do quality flex fans, which change blade pitch with RPM to reduce drag.

GTOguy

Edit: a fan WITHOUT a clutch cools better at low speeds and costs fuel mileage and HP on the open road! Moving too fast here!

After38Years

Towing a trailer in summer, I once had to rig a strap to lock the fan blades to the water pump shaft of a seriously overheating Olds 88. Worked great, but sounded like a street sweeper when it was at idle. As soon as I got to an auto parts store I got a new clutch. You would not be happy with a clutch-less system (no experience here with flex fans).

Also, power to drive the fan rises exponentially with engine speed, so you could begin to sacrifice 10 - 15 hp at high engine speed.
http://johnmaherracing.com/tech-talk...e-cooling-fan/

After38Years

Got my new fan clutch from LIC yesterday, installed this AM. Outside temp 88 degrees. Drove around until normal temp reached, then parked in driveway with idle set to 800 rpm and watched it climb back up, touching yellow when I shut it down. New clutch appears to be working well as it makes maybe half a turn after the engine quits. Took it for a ride around the neighborhood at 25 - 35 mph and temp came back to normal.

It's too hot to proceed with draining/flushing, etc. I will go over the seals to be sure they are all installed. I'm done for the day. I deserve a beer.

Update: Looking at the assembly manual, I don't see any radiator seals. Is this correct?

JohnZ

Radiator seals were only used with air conditioning (C60); easy-to-install and low-priced insurance (GM seal across top of radiator to hood and foam pipe insulator seals to fill the gaps between the front of the radiator and the radiator support).

After38Years

Thanks John, I also note the large rectangular opening in the shroud near the upper radiator hose connection at the radiator. That appears to be as built, but it is a large opening.

JohnZ

That's the airflow path to cool the alternator.

After38Years

Decided to lock the fan to the water pump with some chain and zip ties. Also stuffed some foam in all the cracks I could see between the radiator and the shroud. Outside temp 88 degrees F.

Idling at 800 rpm, came up to the 210 degree mark, then proceeded to climb to high 230's before I shut it down. Difference this time is that it took quite a bit longer to reach the yellow range on the temp gauge, (verified by IR gun).

Fan blades extend between 3/4 and one inch out of the shroud. Don't see any way to reach the half in/half out recommendation. Fan is original 5 blade.

Next step is to drain down far enough to examine the thermostat. Perhaps stuck partially open....

Mr D.

I would really like to see a picture of that.

Mr D.

Well while your throwing Guess ***** at this problem why not just remove the T-Stat and see what that does for you.

Back in the 70's I has a 69 Stepside with 327 and I removed the T-Stat for what reason I don't know. However, I do recall the temp gauge never moving after that and the heater not blowing hot air in the winter.

After38Years

No picture available since I removed it after the test. Picture one link of a light duty chain similar to what was used on swing sets - sort of a twisted figure 8. Ran one of the water pump flange bolts through one end of the chain link, then ran a zip tie through the other end of the chain link and around one of the fan blades at the hub.

Worked, but breaks the zip tie keeper tab when the engine is shut down or accelerated.

856666

Don't forget to check the heat riser on the exhaust for sticking

Phil

After38Years

It appears to be working but I can wire it open to make sure...

After38Years

Pulled Thermostat, put it in a pan of water on the stove and watched it operate properly, starting to open at about 175, fully open at about 180.

Heat riser valve operates freely, but wired it open to check.

Result: Still Overheating at idle.

One thing that seems a little odd is that the air coming off the fan is thrown out radially, there is almost no feel of airflow off the axis of the fan. Since the fan is original, I assume that is normal...

According to the rebuilder, the radiator is a DeWitts reproduction of the original Harrison. I'll check the radiator flow next, but have to wait for a new petcock to arrive as the current one's handle is now spinning free when I try to open it.

65tripleblack

It would be helpful to everybody here if you post a picture of your radiator, fan, shroud. We can verify if your rad is a DeWitts, or not, We can also see whether or not the fan is the right one, if it's not installed backwards, and its orientation fore-and-aft.
Thank you.

You stated early on that your timing was properly set. Please give us numbers. At 700 RPM idle with VAC disconnected and plugged. At 700 idle with VAC connected. The WOT and "all-in" number is important, but doesn't apply to this situation.

After38Years

Thanks 65tripleblack, not sure if this pict will provide all the answers. Fan is about 3/4 inch out of the shroud. Not sure how to show if the radiator is a DeWitts. Timing check will have to wait as I've got to monitor the beer wagon at the community picnic this PM (someone has to do it )

Question: Holley 4160 - is the vacuum can connection to the carb suitable for full vacuum?