2007 E70 3.0si Upper Radiator Hose Question

[SmartSolution]

It appears there are two versions of the upper radiator hose on the N52 E70. First one made up to 2009 had a small vent tube connecting to the main vent hose that goes from radiator to expansion tank. The second one made from 2009 onwards eliminated that vent tube. They both have same part numbers though and I just received the latter(from 2009) from my order. My question is can I make the conversion to the 2009 and later version without any adverse effect on the cooling system? To do that I would have to order the straight through main vent hose as well. Thanks!

See diagrams below:
Up to 2009


From 2009

[Falkon]

You may be better served going to the dealer to get first hand explanation/education about the difference and if this is suitable for your car and, if those are the only required hoses to change if you plan on making the swap.

Alternatively, if my understanding is correct that your car is previously configured with the vent tube hose; how about you cut the new "ventless" one at a similar location as yours, install the 3-way plastic piece with secure clips from your original hose and, connect everything up as you had it originally? And voila! you are once again compliant with original configuration.....

Please keep us posted with your findings.

[SmartSolution]

Originally Posted by Falkon

You may be better served going to the dealer to get first hand explanation/education about the difference and if this is suitable for your car and, if those are the only required hoses to change if you plan on making the swap.

Alternatively, if my understanding is correct that your car is previously configured with the vent tube hose; how about you cut the new "ventless" one at a similar location as yours, install the 3-way plastic piece with secure clips from your original hose and, connect everything up as you had it originally? And voila! you are once again compliant with original configuration.....

Please keep us posted with your findings.

Thanks for your input Falcon! I await response from thebmwpartstore.com on whether they carry the original version I have with any explanation tomorrow. I may also stop by the dealer as you say to get first hand info.

On cutting, the way it broke off renders the 3 way connect useless because the plastic connector broke off in a way that can't make another secure connection.

[Falkon]

I wish you the best of luck.

Also, you may want to ask them to look up the part number for the 3-way connector to see if they are used in other areas of the vehicle so making it more likely that they will have it in stock. If you are in luck, you could as well purchase it and go with the plan of putting back your car the same way it was originally configured.

The car's cooling system is a critical system and it will be sad if you get misled to try to reconfigure it differently and something else fails; this could be costly.

[ard]

Originally Posted by SmartSolution

Thanks for your input Falcon! I await response from thebmwpartstore.com on whether they carry the original version I have with any explanation tomorrow. I may also stop by the dealer as you say to get first hand info.

On cutting, the way it broke off renders the 3 way connect useless because the plastic connector broke off in a way that can't make another secure connection.

Did you provide them with your VIN? As they are a BMW dealer, they should have looked up your VIN for that part.

(I believe they are in internet storefront operating out of a BMW dealership...like getbmwparts.com, etc)

[SmartSolution]

Originally Posted by ard

Did you provide them with your VIN? As they are a BMW dealer, they should have looked up your VIN for that part.

(I believe they are in internet storefront operating out of a BMW dealership...like getbmwparts.com, etc)

They are indeed a dealer but while the rep said via email that the part matches the vin he couldn't clarify accurately how it all works.

This morning I made a visit to a local bmw dealer and the parts adviser did clarify that yes, BMW did delete the extra vent hose. They now provide the upper hose in conjunction with either a straight through expansion tank to radiator vent hose or a small cap to block the midway junction connector on the pre2009 vent hose. I opted to get the cap.

[Falkon]

Okay good luck, I hope it all works out well for you in the end.

So they are saying that you could make the direct swap and block off the original vent hose with no consequence.

How does the excess coolant vapour pressure get relieved then? Is the Coolant Expansion Tank Cap equiped with a pressure relief device? I can see how that could be a reasonable substitute for the vent hose function, if indeed it is.

If not, does it mean that in an elevated engine temperature operating condition and/or engine overheat situation, the only solution would be for the weakest part in the cooling circuit to burst? This would be highly undesirable/ unpredictable and could be costly except if there is a known intentional weak link designed into the system by BMW.

Please do well to clarify the above with them. Inquire to know what were modified, if any, when the vent hose was "deleted"

[SmartSolution]

Originally Posted by Falkon

Okay good luck, I hope it all works out well for you in the end.

So they are saying that you could make the direct swap and block off the original vent hose with no consequence.

How does the excess coolant vapour pressure get relieved then? Is the Coolant Expansion Tank Cap equiped with a pressure relief device? I can see how that could be a substitute for the vent hose if indeed it is. If not, does it mean that in an engine overheat situation, the only solution would be for the weakest part in the cooling circuit to burst? This would be highly unpredictable and could be costly except if there is an intentional known weak link designed into the system by BMW.

Please do well to clarify the above with them. Inquire to know what were modified, if any, when the vent hose was "deleted"

Yes they said a direct swap to block the original vent connector has no consequence. However, I didn't get too technical and deep with the questions of which you raise good ones. I just trusted that the engineers had their reasons for changing it up and that it should work fine.

[bmrboi2]

I experienced the same thing when I did the radiator swap. The hose from the expansion tank to the top of the radiator and the radiator hose, I just plugged it and proceeded with the install.

[lt2mc]

Hey All, Can anyone add some details here regarding the elimination of the "extra" vent line? I just replaced my electric coolant pump about 1500 miles ago, and replaced my upper hose with the 2009 2 piece version. Today however, I found my expansion tank now has a crack and is leaking. My questions are; 1) with the new vent line, do I need a different type of expansion tank cap? 2) could the expansion tank crack be a coincidence, ie how prone to failure are they? Thanks in advance.