Fan Ate Coolant Hose: A Cautionary Tale + Question

[Earendil]

I did not think this possible, but I have just discovered that the fan can eat a coolant hose if provided the right circumstances. I'm still not exactly sure what all those circumstances are, but I have discovered at least one factor, and if there are more I'm hoping the community can point them out.

Now for some pictures. Note that this is the fan and hose at rest, without modification.






A few things to clear up about what happened:
The hose in question is only 9 months old, but has lived on the car for 9 months without issue. In fact I just replaced my coolant pump last month and inspected all the hoses at that time, there wasn't a scratch in it. A couple weeks ago I had a tech inspection for a track day. They didn't see a problem, and in my pre-inspection I didn't find any marks.

I take my baby out on Pacific Raceways last weekend for four 20 minute sessions and had no issue, HOWEVER I'm sure the fan started eating the belt at this time. A couple times I popped the hood open with the engine running and heard nothing strange.

The hose held together until I started driving home from the track, and then bam, 3 miles away from the track a bic pen sized hole appears and half my coolant is immediately gone.

What I have discovered is that my car is supposed to have this:
11-53-1-714-433 "Hose support, to lifting bracket".
I intend on adding this.
BUT, I've owned this car almost 7 years, this is it's 3rd track day in 3 years, and it has never had this problem before. I'll add the bracket, but it bothers me a little that this only just reared its head. Maybe a lack of supporting bracket plus a defective hose? My last track day was also the easiest on my car, as it was raining all day and this was my first time on this particular track. The car saw some high revs and I have no doubt that the engine was working good, but the braking G force was minimal.

Anyway, if you don't have that bracket on your car, you might consider picking it up! :up:

[jlevie]

The most likely cause of that failure is a bad water pump or bad fan clutch.

[Earendil]

The most likely cause of that failure is a bad water pump or bad fan clutch.

Would the result of either of these being bad be play in the fan? Because at blade tip there is maybe one millimeter of play forwards and backwards, no more. Not enough play to cover even half the distance to the hose.

[Ryann]

Cause of issue is a missing fan shroud imo.

[Earendil]

Cause of issue is a missing fan shroud imo.

Could you explain that one? It might be hard to tell in the picture, but the hose was hit directly on the side, not from below. The fan shroud I have in my garage would not have prevented this in a direct manner. Maybe an indirect one, or I have the wrong shroud?

[Ryann]

I can't really explain myself other than had your fan shroud been attached to your radiator I don't think what happened could've happened. The fan won't pull air properly or evenly without it on there anyway.

[redhatpat]

There's also a plastic ring that's supposed to go around that hose and pull it in tight to the valve cover to keep this from happening. I can't see it in your pics.

Same thing happened to me when my water pump went bad and I didn't have that plastic ring in place.

#3 in this pic: http://realoem.com/bmw/showparts.do?...67&hg=11&fg=35

[e34_spangler]

Had this problem your fan clutch is going out cause the fan to be able move towards the coolant hose I fixed thst now it runs great!

Sent from my SCH-I535 using Tapatalk 2

[Earendil]

I can't really explain myself other than had your fan shroud been attached to your radiator I don't think what happened could've happened. The fan won't pull air properly or evenly without it on there anyway.

I don't recall why I don't have my brand new fan shroud installed. I've had it for two years. I want to say it didn't fit my radiator well. In any case I've never had a problem with it overheating at idle. When I replace the hoses I'll look into installing it again.

There's also a plastic ring that's supposed to go around that hose and pull it in tight to the valve cover to keep this from happening. I can't see it in your pics.

#3 in this pic: http://realoem.com/bmw/showparts.do?...67&hg=11&fg=35

I believe that is the part number I listed? In any case, I do not have that piece, and have one I believe to be that piece already on order. I'm hoping that prevents it from happening in the future.

Had this problem your fan clutch is going out cause the fan to be able move towards the coolant hose I fixed thst now it runs great!

Did you fan blades exhibit lateral movement (forward and backward) with the bad clutch? Mine doesn't budge, and the fan clutch is still clutchy.

Thanks everyone for the tips so far. Hopefully by combining a few of these it won't happen again.

[Cinnabar325is]

I know my hose was millimeters from being chopped by my fan until I added that same plastic bracket you mentioned. I found a mint one in a junkyard. The hose is still close to the blades, but I'm not worried about it hitting.

On a related noted, my fan blades do rub on my spark plug wire/distributor cap cover. That's annoying.

[jlevie]

When you go to replace the hose, take the alternator/fan belt off and check for play in the fan and water pump.

[jeffnhiscars]

Definitely check for wobble due to a worn water pump or fan clutch and while the shroud will making cooling more efficient it has no bearing on why the fan is hitting the hose. I'd also check motor and trans mounts since either being soft could allow more engine movement than normal, especially on track days.

My fan was just barely making contact with my new hose at the same spot after a TB & head swap. I had a new retainer (it was cheap) & water pump so everything was to spec. I wound up trimming 1/4" off the end of the hose so it would slide further on to the housing and that gave me just enough extra clearance to eliminate the problem.

[e34_spangler]

I don't recall why I don't have my brand new fan shroud installed. I've had it for two years. I want to say it didn't fit my radiator well. In any case I've never had a problem with it overheating at idle. When I replace the hoses I'll look into installing it again.



I believe that is the part number I listed? In any case, I do not have that piece, and have one I believe to be that piece already on order. I'm hoping that prevents it from happening in the future.



Did you fan blades exhibit lateral movement (forward and backward) with the bad clutch? Mine doesn't budge, and the fan clutch is still clutchy.

Thanks everyone for the tips so far. Hopefully by combining a few of these it won't happen again.

Yeah dude my fan move back and forth just enought to hit the hose

Sent from my SCH-I535 using Tapatalk 2

[long tall eta]

could a bad motor mount cause enough engine movement from tourque for the fan to contact the hose.
just a thought.

[Earendil]

I'd also check motor and trans mounts since either being soft could allow more engine movement than normal, especially on track days.

could a bad motor mount cause enough engine movement from tourque for the fan to contact the hose.
just a thought.

When searching the internet for probably causes I came across this one. Since I have newly installed condor motor mounts and they are still tightly in place, I don't think motor mounts are contributing to anything.

HOWEVER, I do not understand how motor mounts could cause this issue. Both the fan and the hoses are connected to the block/head and only to it. They should move in unison, right?

Fan hitting the radiator? Yeah, totally a symptom of motor mounts, that one makes sense to me.

I don't recall if it was since my previous track day, but I remember now that I installed new fan blades (but not clutch) last summer. I suppose it could be a hair wider. I'll have to try and verify that as well. Otherwise I guess it's just a bracket and new hoses for now, and keep a careful eye on it.