I need the forum's input on manual engine cooling
 

I have this idea that I think would be great, but I want to get the forums input first. Its to manually cool the engine with a mist of water being sprayed across the radiator. The idea occured to me when my temp gage goes up to about 100C. I live in the desert and so its around 105 here and my car gets really hot, especially with the a/c on. So I came up with the idea to disconnect the windshield washer nozzles and attach a fine tubing the length of the radiator and run it acoss the top of the radiator before the fan. The tube would have tiny holes in it for the water to come out. The windshield wiper tank would be filled with distilled water and the windshield wiper motor will of course be disconnected of course, so when I press the button that sprays the water a thin mist will br produced right in front of the radiator and the fan will act as a dispersion mechanism that will disperse the mist to cool the engine. Anyone have any input on this idea? Or has anyone tried this?

This would work, the turbo guys do it with intercoolers, but I'd be more tempted to use other means of cooling first. ( your idea of using distilled water is a good idea to prevent mineral build up. )

In order to take some of the load off the A/C, make sure the heater valve shuts off water flow. Feel the heater hoses, ( careful,might be very hot ) if they are as hot as the uper rad hose, you have water flow that needs to be stopped.

On my 97 SL 320 I added a valve to the heater water supply. The stock system has a valve on the outlet but the heater core has small bleed line. This allows hot water to circulate and bring heat into the cabin. Something you want to avoid is to completely isolate the heater core as expansion of water might cause to burst. ( not likely but possible )

The added valve is a good quality plumbing type 3/8" pipe thread ball valve coupled to a 3/8" pipe 6" long cut in half. A 3/8" pipe is just over 5/8" OD making it a good fit for either 5/8 or 3/4" hose. I think it is a bit of a stretch for our metric hose but a little bit of carb cleaner spray on the hose ID does the trick. I add a heater valve to all of my cars / trucks. It makes a huge difference on the ones that don't have AC.

My SL also has / had heated windshield washer tank and heated wiper park location. While both of these have a thermostat, taking them out of the loop made for less chance of leakage.

Another thought would be to install well a guarded heater core under the bumper but in the air flow. This would help a bit but I'm not sure if it will make enough difference.

Is the A/C condenser / rad clear of leaves and bugs? Take a look between the condenser and rad for any clogs.

Air flow across the condensor & radiator is very important in cooling & a/c operation.

Does your car have 1 or 2 fans on the condensor?

Do you have them running on high speed with a/c operation?

I have 2 fans and when I turn the ac on the fans come on at med or low speed. but once the temp rises to 105°C the high speed fans kick in. I know that I can disconnect the 2 prong temp sensor to the engine block and have them always running at high speed (over cooling would not be an issue as the normal outside temp where I live is triple digits 100°+), but I am not sure about the effect of the electric fans constantly running. my condenser and radiator were both replaced less than 6 mos ago, and I serviced my electric fans by taking them apart and cleaning them and greasing the parts that created friction with electric grease and they work great.


97 SL320, my heater core is disconnected, so no coolant runs to it. I have a ball valve in place of the aux water pump as I didn't need that either.

On cars in HOT areas, I would suggest allowing the fans to run on high speed with a/c operation as well.

Are you running 100C with the A/C off too?

Ismalley,
For what it is worth, I live in the Palm Springs area. I had Jim Forgione make a special resistor that turns on the dual aux fans at 90C My car always runs in the 85-92C area. yes, the fans are on most of the time but like you I have a guy who rebuilds motors quite reasonably. In October, I simply pull the added resistor and return to normal operation.
Anziani
'93 320CE
'95 E420

Ps2cho, not 100 with ac off, only when its on.

Aziani, how much was the resistor?

They are $79 + shipping. Here is his site: K6JRF Auto Page

Anziani

Bought the resistors at radio shack for $1.40. I have the 1k ohm resistor, but what do the different ohm numbers mean? I.e., 5 ohm, 1m ohm, 100k ohm, etc. They had a lot to choose from. How do the xx ohm numbers correspond to the temp at which the high speed fans turn on? Thanks.

You need specific resistor values for the engine temperatures you want. That is why I suggested Jim Forgiones page. He has the values figured out and has put together a "harness" that snaps on to the exisitng switch.
Anziani

You can also just wire a switch in parallel across the temp sensor that kicks the aux fan on high speed.

On my 91 300TE, I threaded a wire from the temp sensor through the firewall to the console, and installed an extra Rear Overhead Light switch there. I turn the fan on high whenever I want :-)

added the resistor across the temp sensor, fan cuts on at high speed around 90°C. Problem solved. Thank you all for the help and input.

Back in the 6os, stock car racers would increase engine cooling by running tubing from the water pump around three sides of the engine bay and then back to the radiator. I don't know in how much increased area a stock water pump could effectively work for everyday use, but it might be worth a try.