Dumb question no 2 million and three

[Lippyp]

I need to take my radiator out so I can sort out my electric fan setup properly. Its an auto with the in rad cooler. My question is do I just undo the tranny cooler lines and plug them with a bolt or something whilst the rad is out? Also when I refiot it do I need to refill the cooler somehow or just run the engine and top up the transmission the usual way? Will it refill the cooler if I do that or is it likely to airlock and cause me problems later on? I can't take it out for a drive as its currently not road legal here.

I am replacing the nasty bodged on small four bladed electric fan that only covers half the rad with a fabricated aluminium shroud and a larger 8 curved bladed two speed fan (from a Volvo 850 T5 actually!) and an adjustable electronic thermostatic controller in the bottom hose to operate it rather than the curreent manual switch in the cab that requires me to keep a constant eye on the temp gauaghe. To be fair its never come close to overheating but I'd like a bit of extra assurance and automatic operation.



New fan

[68gmsee]

Just remove the lines and if you have some plugs to prevent the fluid from leaking out of the radiator then you can do that. Make sure you capture all of the coolant and transmission fluids that drip out. I have removed the radiator off old cars and trucks to have them rodded out or various other reasons with no problems.

Hook everything back up, refill the radiator warm up the engine and top of coolant and check trans fluid level. It's really that simple. You could tape up the ends of the trans lines if you want.

[Lippyp]

Thanks for that. I'll see if I can dig out something to plug over the cooler stubs. I've Just been out to measure up so I can nip out and buy some aluminium sheet to build the shroud out of and the new fan is an exact fit top to bottom so its gonna cover a fair old chunk of the radiator. As my 350 is sat back in the six cyl position theres plenty of room in front of the engine. The existing fan is only a 12 incher whereas the new one is around 16. My radiator is a three row. I've also measure the ID of the bottom hose to be about 45mm, does that sound right? The reason I ask is thats where the fan controller/t-stat will be going. it looks like this

[71tahoe]

I see hose from the cooler line to rad. You could just use a longer piece to connect the 2 lines.

I'm not sure about the lower hose size but 45mm could be a little small. It might be 1 3/4" but 2" seems more likely (51mm)

[Classic Heartbeat]

You also want to put the controler into the upper hose on the radiator, not the lower. That will reflect a more accurate temp reading of the fluid inside the radiator. When the thermostat opens up the hot water from the engine will flow from engine to the radiator via the top hose. The cooler water flows from the radiator to the engine via the lower hose, so the water in the bottom hase is always cool. (Unless you have a heating problem) WES

[Lippyp]

I keep reading conflicting reports on this, the reason I've been told to put it in the bottom hose is that if you put it in the top hose the fan is likely to be on pretty much all the time regardless of whether it needs to be not as its always gonna be in a stream of super-hot water, same with putting it in the head or inlet manifold. If you are travelling at speed then the ramair coming in the grille should be enough to cool the radiator adequately as its likely to be way more airflow than any fan can pull. If the temp sensor is in the bottom hose then it measures the coolant when it is re-entering the engine so if the radiator isn't cooling enough in the airflow then the fan comes in.

If you look at most late model cars they tend to have the temp sensor low down on the outlet side of the rad.

[68gmsee]

Originally Posted by Lippyp

I keep reading conflicting reports on this..... If the temp sensor is in the bottom hose then it measures the coolant when it is re-entering the engine so if the radiator isn't cooling enough in the airflow then the fan comes in......If you look at most late model cars they tend to have the temp sensor low down on the outlet side of the rad.

Makes sense to me, but I would check with the manufacturer to see what they recommend. Then make sure the temp gauge in the instrument cluster is fairly accurate and monitor the engine temp that way.

[piecesparts]

It is up to you, BUT I would put a sensor in a spot that would turn the fans on when you need them, not when it is too late. My electric fans are driven from a sensor that is in the intake manifold of my engine. That way I am sensing the hottest part of the engines coolant (right by the T/stat) and it turns the fans on when the temp is at 180 degrees. I do not like the fan switches that have the sensor that fits into the hose connections or through the fins of the radiator, it is just my taste, I guess, but it also lends to leaks and inefficiencies in operation. My late model GM engines have the sensors in the coolant flow by the water pump.

[mclairmo]

My Flex-a-Lite Black Magic electric fan has a probe built in to the plastic shroud that measures the temp of the outside surface of the radiator core fins. I then have a dash mounted temp guage with the sender in the head. I've adjusted the fan so that it turns on when my temp guage is around 180 degrees and all works well.

[Lippyp]

The sensor setup I'm looking at isn't one that fits in a hose via the end or in the fins as I also have had bad experiences with those in the past. This is a proper setup whereby you cut a section out of the hose and this then fits in the gap like a hose joiner with the sensor screwed into it.

With regards to top/bottom hose what I'e been told is you use a different set opf temperature settings dependant on location, so in the bottom hose it operates at a lower temp than in the top hose. I guess though thats the same if you put it in the head, it needs to tuyrn the fan on at a slightly higher temp than if its in the bottom hose. I'm open to ideas really, I'm also gong to be swapping the stock intake for an edelbrock performer eps thats sat in my garage so I will have a spare hole in the intake for a temp switch which would be a neater option.

[68gmsee]

In my experience the engine is not going to get ruined by a few degrees up or down. Most engines these days have a t-stat that's 190-195 degree range and my 68 had a 190 t-stat for couple of years before I changed it.

If the fan control is adjustable, I'd place the sensor where it's most convenient or recommended. The main problem would be if the sensor were to go bad or is defective, but a reliable temp gauge would let you know if it's overheating.

[71tahoe]

It's also probably a good idea to put a sensor where it will always be covered with coolant. I've been told air contact gives incorrect readings and these systems aren't normally equipped with overflow bottles.

[piecesparts]

The fan controller (SPAL Fan PWM)that I used on my DD (91 Silverado--350 with TBI) allowed me to use a factory temp switch, or I could install their sensor. All I had to do was to find the wire from the switch that had the variable voltage and then splice into it. I did that, using the one from the intake manifold on the engine and it works real well.

[Lippyp]

Originally Posted by 71tahoe

It's also probably a good idea to put a sensor where it will always be covered with coolant. I've been told air contact gives incorrect readings and these systems aren't normally equipped with overflow bottles.

Thats another reason given for using the lower hose, if you've got no water in that then you've pretty much gonna have cooked the engine anyway!

I'm intending to fit an led somewhere on the dash to show when the fan is working and a manual overide switch, it may be overkill but at least then I have the option of switching it manually if the temp sensor fails. I have a friend thats running this setup in his 2.9L 24V cosworth engined Ford Capri and it works well for him (he's currently trying to work out how to squeeze the current modular V8 from a an 07 Mustang that he bought on a whim from Ebay into the thing, man thats a wide engine!) , its a well made unit thats used a lot by racers. I only have the factory temp gauge but that seems to have been fairly reliabe if not that accurate.