reyxlp

Recently I had the temp gauge run as much as two notches above normal. 100F+ outside in bumper to bumper traffic. Temp back to normal whenever I could reach highway speed again. A/C on the whole time blowing cold with no problems.

TB service done just a couple of months ago, presumably reducing the odds it's thermostat and/or waterpump related. Tozo advised fan clutch was likely culprit so I read everything I could find about fan clutch.

(1) Car off and cold after sitting overnight, turned fan by hand. Car off and warm after running up to normal temp, turned fan by hand again. Felt no difference in resistance.

(2) Turned car on after cold from sitting overnight, tried newspaper into fan blade toward center of fan, could not get fan to stop. Not sure how thick I was supposed to roll up the newspaper or how hard to push it into the fan (especially after reading one post about someone's fan blades blowing apart sending shrapnel flying during this test -- I wore safety glasses and was partly ducking for cover lol) but fan seemed entirely unaffected and started chopping little bits off the newspaper, I was afraid to push it.

(Electric fan turns on when you turn on A/C.)

If I understood correctly what I've read, this confirms the fan clutch is failing? Should turn more freely when cold than hot, and also failed newspaper test?

But also-

Some owners say the running hot at no/low speed is normal on a 100F+ day and even by design, as long as you stay out of the red. While others say they were able to resolve it and always have normal temp even no/low speed on hot days by replacing the right part(s)-- fan clutch, pulley, electric fan, converting mechanical to electric, thermostat, water pump, and/or using a "better" brand of one or more of these parts that has not actually failed, etc.

So I'm also wondering how much time/money to put into this issue if it's going to keep happening no matter what I replace, because it's working the way it is supposed to, as uncomfortable as it makes me to ever see a temp gauge even a hair off spec.

Appreciate the latest word on all this from anyone willing to share their experiences -- thanks very much!

tommygogh

Don’t really know much about overheating of an d2 since I live in the Netherlands, but when replacing the timing belt I destroyed the fan clutch and since then it is stuck in the ‘open’ position. I see no problem of that, if the car cools down to much in the winter then the thermostat will close and prevent over cooling.

jfrahm

As far as I know if the fan clutch is too tight it's either clutched up because it's warm (doing it's job) or maybe it's a bad part like that run of (Meyle?) units that were like that all the time.
If it's too loose, spins too easily when hot, causing overheating with AC on a hot day or in traffic, it's usually lost the heat transfer fluid inside.

reyxlp

Thanks! Parts on the way (Behr/Mahle)...

jfrahm

OK but it sounded to me like your fan clutch was not limiting cooling?

reyxlp

The car def starts to run hot if I turn the A/C on at temp on a hot day while parked, and then temp goes back to normal when I turn the A/C off-- just tried that couple of days ago.

But you think I might have a different issue?

Still a D2 newbie but figure it can't hurt to replace, either way, since seems like a common failure part and mine still has the original.

jfrahm

I dunno, maybe the fan clutch is weak but if so I would expect you could stop it with the newspaper.

Be sure to lube or replace the fan support bearing and lube or replace the tensioner roller and belt idler.

reyxlp

Recent TB service with all new rollers, idlers, tensioners, incl serp + related -- newbie question but that should have included the "tensioner roller and belt idler" you mentioned, right?

And I had already bookmarked your fan clutch WYAIT posts on the support bearing on the other forum so thanks for those!

So taking another look at everything, I realized this morning the coolant level cold was only a bit above the minimum. I had checked it several times since the temp gauge started running hot and it always looked about halfway between min and max but I hadn't checked it cold.

Decided to top it up to the max line cold right before driving to work. When I got there, 99F out, parked and idling at temp with A/C on and temp held at normal. Didn't have time to test more than a few mins so I'm not sure yet but now wondering if I just didn't have enough coolant for 100F+ days, even though it was above the min mark cold.

Will test more over the next few days before doing the fan clutch.

Worst case, I have a new one on hand now for when it does go, and maybe one of the last -- was told by FCP per their supplier one of the last left in stock and now discontinued by Behr, but maybe that was just salesmanship.

jfrahm

Good question, I would say normally the TB service and serpentine belt would not include a fan support bearing or serpentine belt tensioner. Just doing the serpentine belt tensioner roller is a bit of a hack, utilizing an idler from a Hyundai 2.7L rather than replacing the whole tensioner just to get a roller that's not pooched.

jfrahm

2003 Audi S8 fan clutch test
I tested my fan clutch, getting gas at 90F and the car fully hot from AC and traffic (gauge reading normal) I flipped the fan as hard as I could.
If I had one blade straight up 12 noon and I flipped the next one around, it'd get to noon and stop. Could get it no further. That should be 1/8 of a turn? I'll try it cold sometime when I remember.

*Update* tested cold, 65F and car sitting overnight. I was able to flip the fan and get 1.5-2 blades of travel in testing.
65F overnight cold - About 60-90 degrees of rotation. 1.5 - 2 blades of travel if flipped with my left hand as quickly as I could
90F stopping for gas hot - 45 degrees or 1 blade of rotation.

My car seems to stay in the normal range an the gauge in traffic on hot days, or at least I have not noticed worrisome gauge movement. 125K miles, original fan clutch as far as I know.