PHIL928

When I bought the car, about 8 months ago, the PO let me know that the fans weren't working well (the original ones) and he gave me a pair of sharkblades with to fit.
The problem with the original fans was that they would melt and then blow the fuse. Pretty nasty.
So after upgrading to the sharkblades almost immediately, the problem persisted. They also started rattling slightly after a few days. I left it because I thought that something may be clipping the fans. I took the fans out and made sure nothing was clipping them, but there was nothing.

The rattling progressively got louder until it was louder than the engine itself.
At this point the fuses stopped melting, which I was pleased about.
However I took them out a couple of weeks back because the rattling was driving me crazy and it was a bit embarrassing to drive with that noise.
Oiled the bearings and made sure everything looked alright on the outside. The rattling PERSISTED.

So I reckoned: bearings!

I have also been battling an overheating problem and yesterday when I drove back I hit a bit of traffic and the temperature went up to about half way between the last white line and the red. When I got home I realised that one of the fans was turning very slow compared to the other one.

Today I took the thing apart and found that the wires had burnt off of the internal rotor! What the hell? (see picture) The other one was fine so only one must be rattling. So not the bearings then and this explains why it was only able to turn at a minimal pace.

Does this mean that my fan controller is bust and that it is sending an overdose of power?

Or could it be something else?

Thoughts and help would be appreciated!

P.S. I was careful when I took the thing apart, so it was definitely not damaged during the disassembling.

Dean_Fuller

I would guess the rattling is the motor itself bouncing around in the casing. I would bet the bearings that center the motor inside the casing are gone....atleast the one to-wards the brush end.

If you could swing it I would call Roger at 928Rus for new motors. I tried to fix mine without luck but you may be better at it.

I think the melted wires are a result of the motor seizing when the center bearings are not doing their job .

PHIL928

That could be true, but I am kind of persuaded that it might not be that because I noticed that it only made the rattling when there was actually power being supplied (tested through turning the ignition to almost on and the fans coming on due to the AC position) as soon as the power was let go of, the rattling would stop even though the fans would still spin for another few seconds. But you might be right.
Yeh I definitely will give roger a call, does he have replacement motors for the Sharkblades? Or just the stock fan motors?

Cheers for your reply!

Alan

Have you tested your voltage when running?

The fan controller cannot provide too much power (at least not for the stock fans) unless the system voltage level is too high?

What are the specs for these fans and are they wired up as designed

Alan

fraggle

If you cooked a set of sharkblades (928 specialists), your motor is running WAY hot. You've warped the housing. I know because I did this as well.

The fuses melting suggest you've got a power draw problem or resistive contacts at the fuse.

If the housing warped and dragged on the fan, it would probably draw extra current, further making a mess.

The root cause of ALL the issues may be the fan controller, but the overheating is causing more problems as you go on.

Even the stock fans shouldn't met the fuses. The melting fuses is a result of a problem, not a cause.

Alan

When correctly sized (fuse rating) fuse bodies melt (vs blow) then this is solely a problem with the fuseholder or fuses only - it does not indicate anything particular about the rest of the circuit.

To be clear there may be other problems - but there may also be no other problems - functional problems elsewhere (like poor/slow operation) may also be solely caused by these fuseholder issues... (but maybe not).

Higher current loads than normal can expose such a fuse/fuseholder contact issue - however it is a fuse/holder issue and oince present will lead to lower total circuit currents (not higher current) as it deteriorates further.

To fix it you must solve the fuse/fuseholder issue - once present it will only get worse without remedies to the connectivity issue, regardless what you do elsewhere in the circuit.

Yes I know this seems completely counter-intuitive - but fuses/fuseholders melting usually has nothing to do with excess current (when the correctly rated fuse is installed). It is most commonly due to water damage on the fuse panel - these fuses are the most suceptible to damage as a result.

Poor quality fuses with crappy ratings and/or poor terminal materials can also be a cause, fuseholder damage due to corrosion (water/humidity) and/or physical abuse (including aggressive cleaning or too many insertions) can also be a cause.

However here it seems unlikely the fuse issues caused this fan problem and its unlikely that the fan problem directly caused the fuse issue.

If the fuses are working OK now without attention its likely only because your fan current consumption is much reduced due to the winding damage. I think you still need to address the fuseholders - likely with replacement parts.

It also seems likely your fan motors are rattling themselves due the the winding damage causing irregular impulse action.

Are you sure there was no way this damage was mechanically caused?

Alan

DR

Hi Alan,

Agree 100%.

That picture is very informative as to the cause of the rattling sound... now I would like to figure out what caused the winding breakages.. something mechanical/physical...or electronic/heat related.

Phil,

Sorry you had this problem, if you would, please send me the original high rez version of that pic if you have one. I would like to forward it to Spal to get some feedback from them before making any suggestions.

Although at first glance it almost looks as if the wires of the winding were melted in two, or got so hot and soft they failed/broke. But, I am not an electric motor expert and would like more feedback.

OH, more pics of the install if you have them might help. Also an accurate time frame they were installed, mileage would help too.

IIRC, of the 2 or 3 I know of that had this rattling issue, all of them were S4 type systems with prior factory fan "issues"....although yours is certainly the extreme of the others I saw or heard about.

Again sorry this has happened, but your info just might be exactly what is needed to solve this mystery so we can take steps to prevent it from happening to others...no matter if it is factory or aftermarket fans. I do know almost every factory S4 fan connector I have ever looked at was "toasted" and most were pretty darn scary looking.

Email is p928sp@928gt.com

Thanks,

Dave

PHIL928

Alan,
That makes a lot of sense, I'll pull the fuse panel this weekend and check the fuse holders. I am pretty sure the rattling was caused by the irregular impulse action (as you put it so well)
I checked the voltage with one of the 928 diagnostic computers that a friend has, and the voltage was fine at around 12.5 +- 0.2 constantly
So should I order a replacement motor, install it and all should be well?
On the TOP of my to do list is the radiator because some fool re-cored it with copper (probably advised to do so by his mechanic...)
So basically the fans need to run at max speed the whole time to keep the car cool, and at that its only about 90C anyway. This may have added to the strain on the motors and acted as a catalyst.

By mechanically caused failure, what do you mean?

Fraggle, how did you go about stopping your motors from running too hot? I remember mine being so hot that I was not able to touch them. But they hadn't visibly warped. Is it due to the fact that the fans are running at full speed the whole time?


Thanks again guys!

PHIL928

Dave,
It's interesting to hear that others had a similar problem because I just called a guy at Spal and he said that he's never heard of this? I guess they don't always know what's going on...
I'll email you the pics and the kms done etc.

Cheers.

FredR

Phil,

I have these fans fitted and touch wood I have no problem with them at all [both hands grasping the wood in my head].

The stock fan motors do no fare to well here probably because the extreme heat dries out the grease. I kind of figured that the SPAL fan units would be relatively cheap to replace if they fail. I did intend to buy some spare units but 4 years on still hanging in there. I reckon if you get 5 years out of fan motor here you are doing OK.

The first thing I would ask is- how is the fan kit fitted in your 928? In this respect I mean how did you configure the air inlet bridge?

I did not purchase my kit from Dave because he did not have them in stock at the time and I needed something urgently. I then had to start from scratch to make the base SPAL kit fit- it took rather a lot of work. I had to trash the stock fan shroud to be able to use the stock inlet ducts. I do not think Dave's kit has these and the owner therefore logically has to do what I did- Have you done this? If this bridge piece is not there air will effectively by pass the radiator, things will heat up and the fans therefore may not get the air blast they normally should get in traffic. If that is the case then it may explain why you are overly hot in that zone.

Another point to note is that the fan system is controlled based on the coolant temperature measured- the fans ramp up as the temp increases. As you doubtless understand, the fans only have cooling value at standstill/ v low speed , after that natuiral air flow takes over. However, when the a/c system is switched on the fans default to full load both fans I believe so, over hear, given we use the a/c more or less all the time- our fans get a relative hammering.

As the fan motors are DC driven, the load consumed by the motor is governed by the voltage applied and the mass of air moved [at higher temps less mass flow]. The only issue I noted on my kit was that where I interfaced with the original wiring I used a domestic 15A screw connector- the plastic shroud of this melted so I just left it.

With all the measures I have taken the temp needle sits just short of the last white line during summer and when working the engine hard it moves to a needle's width past the last white line. A stock system sees the needle on the redline when cruising at ton plus speeds. In short it is not adequate for our air temps IMHO.

Trust the above helps. If you want to see what my engine bay looks like it is located somewhere in the long post asking people what their engine bay looks like- perhaps a search will locate it easily. I do not have access to this pic at the moment- the lap top it on is down.

If I can think of anything else I will let you know but I suspect Dave's kit is not the root cause- just the victim of something else not quite right here.

Regards

Fred R

DR

BTW, did you send the pic to the person at Spal already? If you already made contact there be sure they have that pic too. The more people we talk with hopefully the better the response will be.. (fingers crossed).

Got the e-mail and pic, thanks!

Dave

Alan

By mechanical - I mean something impacting those wires and ripping them off - from the picture it seems rather unlikely - is it clear to you that they melted through?

Alan

fraggle

I fixed my heat issue by rebuilding my motor. I had a headgasket problem and a poor connection (my fault, bad crimp) to one of the fans + fan amp required a rebuild = mega HEAT.

Now, no more heat problems, though I still have some rattle due to the last catastrophic event before my motor lunched. I plan on going in there this winter and taking care of it.

ALSO - the fans (either STOCK or sharkblade) only have two speeds based on heat sensor feedback. It is not infinitely variable.

They BOTH should always run at the same speed.

They BOTH go full blast when you turn on the AC. This happens even if your AC system is pretty much completely removed, as mine is. My compressor won't turn on because the condenser is missing, but the switch still enables the fans.

I've had to debug the living snot out of my system because I missed the bad crimp the first two dozen times I went in there - it was intermittent enough I could rarely catch it, too.

ALSO - natural airflow will not keep an 87+ cool under full throttle, the fans MUST be working correctly. One fan will work OK at a 60-70mph cruise. Slower and there isn't enough flow through the idle fan, faster and you'll be creating too much heat to get rid of.

That dark mark on the armature looks like heat damage, there may have been a short in your fan and it ended up being the fuse instead of the ones in the CEL.

Keep us posted!!

GregBBRD

DC motors will turn either way. If the fans were wired so that they "blew" air towards the radiator, the air would "bounce" off the radiator and then interfere with the incoming air...which would make the fans both rattle and overheat.

Mrmerlin

I was wondering when the new fans were put on possibly the shaft was driven further into the fan body and thus contacted internal parts that made the wires shear off.
Was the rear portion of the fan shaft supported whjile the new fan was tapped onto the shaft?
Did you test the fans to see if they are pushing or pulling? did you fit new connectors to the fan motors?
did you verify that the fan fuse is a tight fit in its fuse holder?