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In checking around after my low coolant light came on, I noticed coolant residue spattered all around the water pump pulley. Closer inspection revealed that the water pump pulley has been rubbing a hole in the lower rad hose. There is nominally about .025" clearance between the pulley and the hose at rest.

As background, I replaced the lower rad hose about 6 months ago with a Gates 21658. I also replaced the thermostat housing with the newer style (since old style was not available).

It is not readily apparent to me how to solve this problem.

Is the Gates hose shaped a little wrong? Did I possibly install the hose incorrectly? Would the BMW OEM part be the right way to go?

Thanks,
Joel

Do you have this bracket in place to keep hose away from pulley?

Hmmm...Never seen that before. So I guess that should fix the problem. What does it bolt to? And who carries it?

Thanks!

Gee,
I don't have that either on my 84 633.
I guess I need to get me one of them boogers.
--Ken

my 4/87 635 hasn't got one of those. And I reckon if the hose is good, it doesn't need one. On L-jet cars there is a similar part (you may need it because the hose run is different...) and it is a PITA because it is yet another thing that gouges into the soft parts of your wrist when you are working in that area.

The bracket attaches to one of the small bolts that attaches the upper timing cover to the lower timing cover. This bracket also goes rusty and often just breaks off in your hand.

If you really want to lash the hose in place at this location I'd suggest making a small L shaped bracket in stainless steel (with a slight return) and then use a zip tie round that and the hose. This arrangement will have the advantages that you will be able to unhook it when the system has no pressure in it, and if you do it right it won't be trying to remove all the skin from your wrist whenever you are working on the car.

BTW there are at least three different versions of the lower hose to the radiator, so be sure that you have the right one.

cheers

I got the hose replaced last week, and the OEM BMW hose was definitely a different shape than the Gates hose. The Gates had a longer fat section at the water inlet housing that was causing the interference issue. I had also ordered the clamp for the hose, as pictured, but the one that arrived was plastic (not metal), and I could not figure out how to attach it. So I left it off, and it seems to be OK without it.

After all that, the water pump decided to start leaking a day or two later. So I went ahead and ordered a new one along with a radiator (pinhole leak) and some heater hoses. Hopefully this will stop the leaks....

Thanks for the help!

So I got 125 miles out of the car before another bright light lit up! It was the exact problem you are describing. Imagine my surprise when I saw coolant had shot out all over my engine compartment.

Pressing the hoses, I saw the split in the hose where the pulley was rubbing it. Crap. I'm so tired of draining and refilling the coolant in this car.

Time to order more parts.

I don't see that bracket either. I think I'll go for the OEM hose as well.

JoelR wrote:In checking around after my low coolant light came on, I noticed coolant residue spattered all around the water pump pulley. Closer inspection revealed that the water pump pulley has been rubbing a hole in the lower rad hose. There is nominally about .025" clearance between the pulley and the hose at rest.

As background, I replaced the lower rad hose about 6 months ago with a Gates 21658. I also replaced the thermostat housing with the newer style (since old style was not available).

It is not readily apparent to me how to solve this problem.

Is the Gates hose shaped a little wrong? Did I possibly install the hose incorrectly? Would the BMW OEM part be the right way to go?

Thanks,
Joel

Mine only lasted 125 miles. I ordered the OEM hose and that stupid metal doo hickey for good measure.

Why the heck would those exacting German engineers design such a goofy system with little to no clearance? Sigh...

About 3 weeks ago I had a lower rad hose split by the pulley. It was a Gates hose that had been on the car for 3 years. I replaced it with a used BMW hose of unknown age and have since replaced it with a new BMW hose. There seems to be about 1/2" clearance between pulley and hose so it is a worry. Even the old BMW hose had a mark made by the pulley at one time. I am going to buy one of those brackets with my next parts order.

Anybody have the bracket PN handy?

jacko wrote:Anybody have the bracket PN handy?

Clamp 11531268751. - $2.28

This was for my 1984. They had multiple listings by year of car.
The OEM hose was $23

I ordered it from BMW of Monterey, CA since they are very close to my house and I was hoping to get the part ASAP! What bugged me was that they charged a minimum $14.95 for shipping!

Of course that made me order a bunch more stuff so that I wouldn't be paying 5x the cost of the part for shipping. ðŸ˜

So my new BMW OEM hose arrived today and I put it in the car in all of 20 minutes. It's a lot better than the Gates that was in there before.

Upon examination, I realized that the Gates hose has the taper from the end on the wrong side! The taper needs to be on the side closest to the water pump pulley to prevent contact.

The BMW hose has the proper taper resulting in about 1/4" clearance between the hose and the pulley. Also the BMW hose has a extra re-enforcement layer on the bottom of the hose where it connects to the Radiator itself. So overall, worth the extra bucks.

Here's a picture of the Gates hose. You can see it was making good contact. Good in a bad way.

Alpinacsi wrote:Do you have this bracket in place to keep hose away from pulley?

I was looking on my car today and I am not totally sure where this part goes.
Is it mounted on one of the bolts for the thermostat housing?

THis happened to me, too, with new hoses. First I knew of it the power steering failed and the battery light came on.

Obvious really: coolant spraying all over the ps pump and the battery!

Learning point from this for me is not to take the cold installation position of the hose as being the same when the bugger gets hot.

Yes, I have got the hose bracket in place but it's not the answer to all of your gouging worries, it's careful installation that's the key.

at risk of stating the bloomin' obvious, if you have a good static clearance, yet the pulley still chomps into the hose, then #1 chief suspect is... (drum roll...)

the engine mountings .

OEM mounts can fail or go soft (oil in the RH one....) and when combined with a manual gearbox, I think the engine moves around quite a lot.

I'd wager that (hose and bracket notwithstanding) most people who have this failure have manual gearboxes/old engine mounts rather than autos with new engine mounts....?

What says the assembled brain trust?

cheers

songzunhuang wrote:

jacko wrote:Anybody have the bracket PN handy?

Clamp 11531268751. - $2.28

This was for my 1984. They had multiple listings by year of car.
The OEM hose was $23

I ordered it from BMW of Monterey, CA since they are very close to my house and I was hoping to get the part ASAP! What bugged me was that they charged a minimum $14.95 for shipping!

Of course that made me order a bunch more stuff so that I wouldn't be paying 5x the cost of the part for shipping. ðŸ˜

Brucey wrote:at risk of stating the bloomin' obvious, if you have a good static clearance, yet the pulley still chomps into the hose, then #1 chief suspect is... (drum roll...)

the engine mountings .

OEM mounts can fail or go soft (oil in the RH one....) and when combined with a manual gearbox, I think the engine moves around quite a lot.

I'd wager that (hose and bracket notwithstanding) most people who have this failure have manual gearboxes/old engine mounts rather than autos with new engine mounts....?

What says the assembled brain trust?

cheers

I hadn't thought of that Brucey.
However, my situation doesn't match up to the theory as I have an automatic. In my case, even at rest and cold the hose was only millimeters away from the pulley. I recall wondering about the clearance, but since it wasn't touching I didn't worry about it. Wrong assumption there.

Now with the OEM BMW hose, I have about 1/4" clearance (still kind of close) but I also took care to pull it away from the pulley before tightening the hose clamp. For double protection, I slightly rotated the lower radiator mount clockwise before tightening the camp so that the tendency will be to pull the hose away from the pulley. The theory is that when it's hot it'll soften and twist away from the pulley.

Who knows if this will make a difference, but I'll watch over it closely now.

songzunhuang wrote:So my new BMW OEM hose arrived today and I put it in the car in all of 20 minutes. It's a lot better than the Gates that was in there before.

Upon examination, I realized that the Gates hose has the taper from the end on the wrong side! The taper needs to be on the side closest to the water pump pulley to prevent contact.

The BMW hose has the proper taper resulting in about 1/4" clearance between the hose and the pulley. Also the BMW hose has a extra re-enforcement layer on the bottom of the hose where it connects to the Radiator itself. So overall, worth the extra bucks.

Here's a picture of the Gates hose. You can see it was making good contact. Good in a bad way.

Spooky , I had it's twin.
I too replaced it with a genuine BMW item ,It had the retaining clip / bracket fitted anyway and I added a loose zip tie down lower to keep slight tension on the hose in the opposite direction to the pulley. Just checked it and so far so good .

Well this is a head scratcher. The only place to mount the OEM clamp I received from BMW is the lower bolt on the cover for the distributor. In that location it would actually serve a function to keep the hose away from the water pump pulley.

But all is not well. First, you can't really clamp down tight on that bolt as it'll probably crack the plastic of the distributor cap. Also the slot on the mounting hole for the clamp would be facing up, meaning that if it wasn't tight gravity would cause the clamp to fall off the bolt. So this doesn't seem like a good place to mount it.

So where else could it be mounted? Nothing on the thermostat housing makes sense and the engine lift bracket is too far away for the clamp to have any affect I am stumped.

For people who have this clamp in their cars, where's it attached?

Btw- Day 4 and 200 miles after installing the factory hose, I am seeing no issues with clearance and everything appears to be functioning well.

IIRC the bracket mounts to one of the M6 distributor housing bolts, i.e. one of the bolts that holds the part (that the distributor cap bolts onto) onto the rest of the engine.

cheers

Brucey wrote:IIRC the bracket mounts to one of the M6 distributor housing bolts, i.e. one of the bolts that holds the part (that the distributor cap bolts onto) onto the rest of the engine.

cheers

Wow, I guess the only place that made sense to me was correct. Guess I'll give it a shot. It's tight in there.

eh? You've been talking about bolting it to the distributor cap. This is not what I meant.

cheers

Brucey wrote:eh? You've been talking about bolting it to the distributor cap. This is not what I meant.

cheers

Oh I see the difference. I was reading and responding to fast on my phone. This forum is a bit challenging to navigate on a phone sometimes.

Anyhow, I see that you were talking about the distributor housing and not the cap now. Ok, another exploration item for this weekend.

Well I have looked several times and now I have replaced the distributor cap for another ailment. I still can't figure out where to mount that bracket. So far it's been a few hundred miles and I have kept a close eye on that hose to water pump pulley clearance. It still looks good/same.

For now, I give up on that bracket. It's going in the spare parts bin until a later date. I'll remain vigilant on the clearance.

Brucey wrote:IIRC the bracket mounts to one of the M6 distributor housing bolts, i.e. one of the bolts that holds the part (that the distributor cap bolts onto) onto the rest of the engine.

cheers

Brucey - an age old mystery has been solved and you were correct. Again.
While replacing my thermostat housing this weekend, I saw something curious and dug out that bracket (Clamp 11531268751. - $2.28) from all those months ago. With the thermostat housing out of the way, I could see how the clamp would mount and help to hold the radiator hose away from the pulley. Hmmm.

I did find it odd that the opening of the clamp for the fastening bolt faces up when installed. That means if it ever loosened, it would just fall off due to gravity. Seems like the slot for the bolt should face down. Here's the clamp installed. It does help a little, although I have to bend the clamp a bit or it doesn't even make contact with the hose. So, it's good to get this installed so that I don't have another errant part to lose. Lol!