'89T fan clutch engagement - Toyota Nation Forum : Toyota Car and Truck Forums

bosco659 · 07-19-2005, 09:34 PM

I have an '89T with a "problem" that the clutch on the fan engages too often (just needs to be relatively hot out and the clutch in the fan becomes fully engaged). It is annoying as it is quite noisy when this happens and robs power at lower engine rpms. This problem began after I installed a Koyo aluminum rad a year or so ago (not the stock replacement but the bigger 1JZ spec rad that also fits the MA70 MKIII).

The engine is healthy, tuned to 12:1 AFR, engine coolant temperatures are well within spec (about 185 to 195 degrees F, on an Auto Meter gauge , factory gauge ok as well), EGT's are good and there are no signs of overheating or head gasket problems. The factory fan shroud is in place, the thermo viscous hub or fan clutch was replaced with a brand new one from Toyota and no change was noticed. Cooling system has been power flushed many times and still no change to the frequency and duration of the fan engagement. I've tried to remove the bottom half of the fan shroud, the engine undercover and it consistently engages very frequently. The rad is perfectly clean with no blockage. Condition worsens with the A/C running but that is understandable.

Any ideas on what may be causing this? The only thing that I could think of is that the fan does sit physically closer to the rad since the rad core is about 50% thicker, and since aluminum is a great conductor / dissipater of heat, the proximity of the thermo viscous hub to the face of the rad causes frequent engagement.

Any ideas or experience on how I might remedy this. Just a note that I don't want to ruin any cooling effieciency in the process as the car runs cool (within spec) at 140 km per hour, A/C on in 95 to 100 degree F weather.

Any thoughts would be appreciated.

Thanks,

Vic

ahmedootie · 07-19-2005, 11:26 PM

I'd wait for Jeeves or Bgreiger to answer this question, but as for a solution, I'd go with an electrical fan...I am actually going to the yard tomorrow to pick up a set of DSM fans...on www.supraforums.com they said that this was the best stock swap, for electrical fans, which don't take any power at any RPMs and don't make the car sound like a semi

Jeeves · 07-20-2005, 01:15 AM

Depending on where you live, electic fans can be disasterous. Where I live, they're horrid. Cars die all the time with them. It's just too hot and electrics don't flow near enough.

Keep in mind, that 89 is now 16 years old. Fan clutches do go out, I think that it happened around the time that you put in the radiator is just a coincidence. Simply pull it off and replace it with a new one. You can't really repair them.

bosco659 · 07-20-2005, 07:34 AM

Jeeves, as per my post, brand new one installed 1000 miles ago. Any ideas?

***bgrieger*** · 07-20-2005, 08:10 AM

Vic, I still have no idea. Like I said at the TN meet, I can't say mine comes on any more frequently since installing the rad, but I only had last season to try it out and then parked it for upgrades....I haven't driven it this year in the kind of heat we've been getting for the last month or more, which may well have something to do with it. Last summer was colder than normal, and this one is record setting already. Perhaps the fan shroud is a little different on the 87 (do you have the 2 electric aux cooling fans or the single?). Mine also does not have the lower half ring around the fan that clips onto the shroud, but is otherwise intact.

Other differences I can think of: I don't run a Toyota thermostat (Canadian Tire Fail Safe). Now Rupinder and Marino got a lower temp thermostat from UAP (83 degrees I think) so I found out talking with them last night. That might help you keep the fan activity down for very little money and time.

Bob

Jeeves · 07-20-2005, 10:22 AM

1) I didn't see that, you had a lot of seemingly unrelated info in your post, my bad.
2) No real solution. I'd say live with it or since you're up north try going to electric ones. My fan clutch I know locks more than it should, but it's not that big of a deal to me.

Sorry.

bosco659 · 07-20-2005, 05:55 PM

"you had a lot of seemingly unrelated info in your post" - just trying to demonstrate that the engine is healthy and not overheating. I also tried to include sufficient information so I wouldn't have to reply to posts asking if I had tried to remove the fan shroud, flush the system etc...