Our '89 744 Ti has a rubber bushing that holds the pusher fan thermoswitch in the rad sidetank. That bushing is rotten now and needs to be replaced. I'm hoping the dealer will have one in stock so I can get one tomorrow (Monday) otherwise I guess the car is down until I can get one on Tuesday either through the dealer or Auto Value can bring one in for me.

If ya ask me the whole thing looks to me to be a pretty flakey design. I see in the 700/900 FAQ that one way to prevent the thermoswitch from popping out again is to basically tie it down with a cable tie wrapped around the side tank.

The thing is I'm probably just going to transfer a nice 2 speed puller e-fan setup from my old 240 that we aren't using anymore into the 740 and I'm wondering if it's necessary to keep the extra pusher fan in there. The e-fan hardly ever kicks on in the 240, even in the mid summer so I'm wondering if I would ever need the pusher fan. The 240, however, doesn't have A/C and the 740 does.

So the bottom line is I'm not sure if I really need that pusher fan or not. Does A/C make that much of a difference to the demands on the cooling system ? And wouldn't a 2 speed 16" e-fan more than compensate for the loss of the pusher fan ? Also consider we don't use the A/C much and the car is seldom driven in heavy stop 'n go traffic with or without the A/C on.

I really would be just as happy to plug that hole off permanently and forget about the pusher fan and just rely on the 2 speed 16" e-fan I'm going to take out of the 240.

Thoughts ? Comments ?

Has anybody found an easy and reliable way to plug that hole off in the rad side tank off ? How did you do it ?

Thanks,

Roj

I'm surprized this hasn't been jumped on yet...if your 740 has AC it will add additional load to the car's cooling system, not always directly - though I'm sure it could be argued. But AC systems usually have the condensor on the front of the rad and that decreases the cooling capacity of the rad...so they use a larger rad.

The rest of your post is confusing and I'm having a hard time figuring out...are you adding a pusher and puller to the same setup? If that is really what you are thinking about, then stop...go outside and get away from the exhaust fumes . Honestly, what would be the point of having a pusher on one side and a puller on the other? It's a binary option, you either push or pull.

Actually craig, the 740s had a puller on the back of the rad (ie. the mechanical fan off the water pump) and an aux pusher fan in front of the whole rad/intercooler/condensor.

Roj is asking if a good two stage electric puller in place of the mechanical fan would be good enough to remove the pusher.

One way to find out! I can't comment directly, but I know when the A/C was working in my 242, the temperature was above normal ALL the time, even on the highway. I think this was due to an older rad, and lots of crushed fins on the condensor blocking flow. It's all now on my garage floor.

If the 740s have the electric compensated temperature gauges, be careful, apparently you don't get much warning before an overheat.

Air conditioning is for americans and sissies.

and redblocks don't care about getting slightly overheated

- R

air conditioning is for people who fear if they put their window down, they'll never get it back again!

(god bless you AC!)

They had a bushing/grommet down at Valentine's so I picked one up there. I have now installed it. Boy, what a tight fit getting that thermoswitch back in there. Had to use some soap and really push hard to get it to slide in. Guess that's a good thing as it should be just as hard or harder to get it to pop back out.

As an extra precaution I ran a cable tie through the rad fins, around the side tank and in between the two spade terminals on the thermoswitch and tighetned it down so now that thermoswitch cannot pop back out !

The replacement bushing/grommet I got had a Volvo part number, etc, on it so was genuine Volvo. The one I pulled out did not have those things so was most likely a third party probably made by Scan-tech or whomever makes the third party replacement rads for those cars. I'm hoping the OEM Volvo one holds up better than the one that was in there. The rubber was really broken down.

I'm probably going to take the belt/clutch fan out of that car and replace it with the 16" two speed e-fan setup I installed in my old 240. Once I do that I think I'll disconnect the pusher fan but I'll leave everything in place until I'm convinced it's not needed at which point I'll likely take it right out.

Does anybody know what temperature that pusher fan thermoswitch is supposed to kick in ? I'm wondering if it may still be useful to use in a warning light circuit after I install the 2 speed e-fan system.