Fan Ate Coolant Hose: A Cautionary Tale + Question

[jlevie]

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?

Correct, that hose is attached to the engine at both ends as is the fan, so movement of the motor doesn't affect fan to hose clearance.

As I said earlier, remove the alternator/fan belt and check for play in the fan and water pump.

[StereoInstaller1]

The 'Bad motor mount eating hoses" is on early models and is the lower hose.

As JLevie said, it is likely a fan clutch issue

[Earendil]

Thanks for all the information and clarification. New hoses come Friday along with the clip. With the belt off I'll give the fan blades a stern prodding and see if there is any play. I'll report back this weekend with the results!

[StereoInstaller1]

When you get your clip, you will see a tiny clamp off to the side. That clamp is for the CID wire. Hardly anyone gets it right, be one of the few!

Luke

[Earendil]

When you get your clip, you will see a tiny clamp off to the side. That clamp is for the CID wire. Hardly anyone gets it right, be one of the few!

Luke

Someone should probably put together a list of things that a PO likely broke off and never fixed. One of the greatest mechanical benefits to E30 meets is getting to look at other M20 engines and finding all the things they have that your car probably should. I'll be sure and get the CID wire put in place :)

[E30Gus]

I had this same problem with a new fan clutch so I took maybe 5mm off of the end of the hose so I would have more clearance on that 90Deg bend. I don't have that hose bracket so I used a ziptie to hold it back a little bit more. My fan blades were not all completely straight which I think was the main contributor to this issue. I eventually got tired of worring about this hose getting eaten and put in an electric fan.

[bangn]

lol @ some of the replys in here.

Its because that clamp that attatches to the hook above the camshaft gear was missing. Mine was also missing, just use a fat cable tie to hold it back so the hose just touches the bracket, but not enought to clamp down on the hose. There will be a 6mm hole in that bracket.

[Earendil]

lol @ some of the replys in here.

Its because that clamp that attatches to the hook above the camshaft gear was missing. Mine was also missing, just use a fat cable tie to hold it back so the hose just touches the bracket, but not enought to clamp down on the hose. There will be a 6mm hole in that bracket.

Perhaps you missed the part where I said that I've never had the bracket, and my car has been fine for 7 years. The bracket might have prevented it, but something else with the system changed to cause that much damage to the hose that fast. While I suspect it was a defective hose that swelled up into the fan, it could also be that the fan pushed back into the belt.

Note in the picture how the belt naturally sits away from the fan by half an inch. Either the hose moved forward, or the fan moved back.

[Earendil]

Update, as promised.

I've replaced all front hoses, and added the required clip. I've also seen three M20 engines since this all started.

In looking at the three other M20 engines I determined a few things:

• None of them had this black clip, none of the owners new it existed.
• Two of them had their fan shroud installed, and I was able to verify that the shroud would not have prevented this particular fan-hose contact.
• All of them had a similar distance between blade and hose.

While taking three random 25 year old engines and using it as a baseline is iffy at best, it did give me something to work with.

What I was able to verify on my own engine:

• Removed alternator belt and fan: Water pump spun free without noise or vibration.
• Blades were attached to fan clutch tightly.
• Fan clutch spun without noise or vibration.
• Fan clutch might have some play, however it allows the blade tips to move laterally no more than a single mm. After that mm I have to start forcefully bending the blades back. Getting the blades to make contact with the hose took significant force.
• The black clip I installed did not actually move the hose much further back from the fan blades. The reason for this is that the blade contact point is at the bend in the coolant hose. Moving the hose back thus did not actually change the hose position, just made the bend a little tighter.
• As a final measure I cut a few mm off of the hose as others suggested, and snugged it up. I now have a tiny bit more room to play with.

I think I'm going to have to chalk this up to a defective/failed hose. It probably swelled up and into the fan. This would explain why when I popped the hood immediately after the car started overheating that there was a good gap between the blades and the hose. As soon as there was a leak in the hose all system pressure went to zero, and the hose deflated. That's the only thing I can figure.

Here is what the new hose and fan look like. You'll note the location of the CID wire :up:


Full Resolution.

Thank you everyone for your suggestions and help. It gives me some peace of mind, and hopefully it'll help someone else trouble shoot the same problem.

[rodpaine]

Good that you got it back in position. I'd only add that this potential problem can cause a hose to swell and move. I've seen it on several 528e cooling system hoses that were way over due being replaced.
FWIW,
-Rod

[jeffnhiscars]

Good that you got it back in position. I'd only add that this potential problem can cause a hose to swell and move. I've seen it on several 528e cooling system hoses that were way over due being replaced.
FWIW,
-Rod

Call me a cynic but I find it amusing that Gates, who has been making hoses since they first discovered fire, has only recently revealed its "research" and solution to short hose life (not that it would be in their interest to keep this under wraps...<cough....cough>) especially when galvanic corrosion has been known to ship builders for hundreds of years.

Next they will be telling us that Pinto gas tanks explode.