Need help with radiator hose issue.....

[CrazyOneToo]

Hello Z4 fans, Today I was changing my OFH gasket on my 2007 3.0 Si but when I removed the radiator hose off of the OFH unit an Oring and
a small plastic ring came out and I did not see how they came out.
Any chance anyone knows how they go back in?

The pic below with the yellow highlight shows where I'm talking about.
The Oring seems almost to big to fit inside the hose connector but there was no leak before removal.

-

[elerner61]

I changed both my upper and lower radiator hoses two months ago so this is from memory. I think the O-ring goes on the radiator fitting and the plastic (rubber?) ring goes inside the fitting on the end of the hose. If you want to confirm, take the other end of the hose off from the radiator (taking care not to dislodge the same two rings) and see how those are fit.

Also, if those are your original hoses you may want to think about replacing them (as well as the coolant reservoir). BMW cooling system plastics are known to have a working life of roughly 10 years. One overheat encounter can warp your head and then you've got a German flower planter. Edit: Just looked at your sig and see you own 3 of Munich's finest...never mind.

[Steeler]

Originally Posted by CrazyOneToo

Hello Z4 fans, Today I was changing my OFH gasket on my 2007 3.0 Si but when I removed the radiator hose off of the OFH unit an Oring and
a small plastic ring came out and I did not see how they came out.
Any chance anyone knows how they go back in?

The pic below with the yellow highlight shows where I'm talking about.
The Oring seems almost to big to fit inside the hose connector but there was no leak before removal.

-

This pic may help show where one of the rings sit in the coupler.

[CrazyOneToo]

Originally Posted by elerner61

I changed both my upper and lower radiator hoses two months ago so this is from memory. I think the O-ring goes on the radiator fitting and the plastic (rubber?) ring goes inside the fitting on the end of the hose. If you want to confirm, take the other end of the hose off from the radiator (taking care not to dislodge the same two rings) and see how those are fit.

Also, if those are your original hoses you may want to think about replacing them (as well as the coolant reservoir). BMW cooling system plastics are known to have a working life of roughly 10 years. One overheat encounter can warp your head and then you've got a German flower planter. Edit: Just looked at your sig and see you own 3 of Munich's finest...never mind.

Yeah I removed the hose to look at the other end but that didnt help much.
I see no way of getting the oring back in there without it being bunched up.
I assume it was placed inside there originally by a machine that compacts it to insert it.
I bought another hose anyway. Didnt want to chance an overheating situation. Thanks

[CrazyOneToo]

Originally Posted by dbarton62

This pic may help show where one of the rings sit in the coupler.

Thanks. I removed mine from the radiator and see no way to reinstall it properly enough that I wouldnt worry about it going bad while driving.

[chinhminhdo]

I'm tempting to replace the radiator hoses, both upper and lower, on 2004 Z4. Is it something I can do by myself? Google youtube and see no video. Thx

[CrazyOneToo]

Originally Posted by chinhminhdo

I'm tempting to replace the radiator hoses, both upper and lower, on 2004 Z4. Is it something I can do by myself? Google youtube and see no video. Thx

Yes, they have a clip ring that pops up then they pull straight off.

[Efthreeoh]

Originally Posted by chinhminhdo

I'm tempting to replace the radiator hoses, both upper and lower, on 2004 Z4. Is it something I can do by myself? Google youtube and see no video. Thx

I've not removed radiator hoses from your specific model, but I have from the E90 and I also own a 2008 Z4 Coupe with the N52 (engine) and a '05 E46 330i convertible with the M54 (engine). That means I'm indirectly familiar with the parts we are discussing. I've been turning wrenches on BMW for 30+ years. I'm assuming a few things, that you have a M54-equipped Z4 Roadster. So, my experience is relevant here because BMW has been using the same over-engineered coolant hose connectors since the early 2000's, meaning my 2006 E90 uses the same style coolant connectors as your 2004 Z4. I posted a DIY over in the E90 DIY subforum on how to replace the coolant hoses on an N52-equipped E90.

dbarton62 posted a good pic of what the connectors look like from the inside, look at them closely and notice the indexing slots. After a few years of service, the connectors get stuck in place on the radiator hose bibs. The connectors are indexed to the bibs, which means you can't twist the connectors to break the friction that develops between the two parts. All you can do is wiggle the connectors up and down and left and right to try and break the friction. That doesn't work sometimes. Others have sprayed penetrating oil into the connectors to assist in chemically breaking the friction. That seems to work on occasion. I've not tried that method personally, but if your hoses are stubborn to remove it can't hurt to try.

So as CrazyOneToo explained already, the female side of the connector has a spring clip that pulls up to an open position (you don't have to fully remove it). Just use a flat-blade screwdriver to lift it from its locked (down) position. Once the spring clip is unlocked, then wiggle the female side (hose side) of the connector up and down and left and right to break it loose as you pull it away from the radiator. Do not try and rotate the female connector on the bib because you'll just break the indexing tabs on the bib (male) side of the connection. If you do that, then a new radiator is in order.

Hope this helps.

[elerner61]

Some patience may be required. My upper hose came right off but the lower one was very stubborn. It required quite a lot of wiggling, pulling and conniving before it yanked free.