Buick Rendezvous 3.6 coolant filler neck

[Raden]

While investigating a coolant leak, I found the plastic filler neck on the pass side of the engine bay has cracked and is leaking. When removing it for inspection, it basically crumbled and is no longer usable. I was hoping to use some JB weld or something, but it's not an option. Calling GM, they say the part is discontinued and no dealer in North America has stock. There are no aftermarket parts listed for it. The closest wrecker listing a 3.6 is in the southern states, no way to check if the part is still available and im in Canada. Not sure what to do.

Anyone come across this issue? Some other aftermarket part that I can use as a substitute?

 

[TollKeeper]

I ---think--- this might solve your problem.. But cant guarantee..

https://www.autozone.com/collision-body-parts-and-hardware/coolant-filler-neck/p/dorman-coolant-filler-neck-902-680/821536_0_0?cmpid=LIA:US:EN:AD:NL:1000000:IEN:19489353526&&CATARGETID=120054150001289641&CADevice=c&gclid=CjwKCAjwg-GjBhBnEiwAMUvNWwMaocwPafLi0oiDeK4Vd2bJD6uXrcvJH3gqKAwS4LOSzOhaq743BRoCDDkQAvD_BwE&gclsrc=aw.ds

 

[Raden]

Its close.
Part looks more like this ⏬. The red outline is what broke off into many many parts. Sits here in the engine bay ⏬. Might have to get creative though as I can't find anything to replace it. I ordered a filler for a 2006 Buick Allure with the 3.6. Suppose to arrive tomorrow. Hope it works. If not, im out of ideas.

 

[TollKeeper]

It appears this is the closest you are going to get..

2005 Buick LaCrosse 3.6

https://www.autozone.com/collision-body-parts-and-hardware/coolant-filler-neck/p/dorman-coolant-filler-neck-902-305/20106_0_0?cmpid=LIA:US:EN:AD:NL:1000000:GEN:19502231967&&CATARGETID=120054150001287652&CADevice=c&gclid=CjwKCAjwg-GjBhBnEiwAMUvNWxIt5bHM_90O8SF66fZQXkmBiIz7j3HfGIkAVU4TlkT0E6D8V-EigRoCg-MQAvD_BwE&gclsrc=aw.ds

 

[Raden]

So after playing with a few filler necks, this is the best set up I could find. First, thanks TollKeeper for the suggestion. Unfortunately, the OD on that filler neck you suggested, was a smidge too wide. Despite trying to heat the hoses with a heat gun and use dish soap, I just couldn't get the Buick hoses on. Next I tried Dorman 902-2133 which is the filler neck for Buick Allure 2008-05, Buick LaCrosse 2008-05, Chevrolet HHR 2011-06. The hoses fit. Because the OE filler neck had a small bend in it and Dorman 902-2133 does not, using this product now puts a small bend in the hose instead. But not enough to concern me. Using this product also means you need to change your pressure relief cap. The cap I used is AC Delco RC85. Its 1 psi lower than OE which was 16psi. After the Rendezvous being down for almost 6 weeks looking for parts, I don't care about the 1 psi drop and thus far, has not affected the cooling system.

 

[Jazzyf]

So after playing with a few filler necks, this is the best set up I could find. First, thanks TollKeeper for the suggestion. Unfortunately, the OD on that filler neck you suggested, was a smidge too wide. Despite trying to heat the hoses with a heat gun and use dish soap, I just couldn't get the Buick hoses on. Next I tried Dorman 902-2133 which is the filler neck for Buick Allure 2008-05, Buick LaCrosse 2008-05, Chevrolet HHR 2011-06. The hoses fit. Because the OE filler neck had a small bend in it and Dorman 902-2133 does not, using this product now puts a small bend in the hose instead. But not enough to concern me. Using this product also means you need to change your pressure relief cap. The cap I used is AC Delco RC85. Its 1 psi lower than OE which was 16psi. After the Rendezvous being down for almost 6 weeks looking for parts, I don't care about the 1 psi drop and thus far, has not affected the cooling system.

I am having the exact same problem. How long did this solution last for you? Did you experience any further problems? Thank you for your assistance. I have been looking at salvage yards and can't find any Ultra models to replace the discontinued part and it has been sitting for so long.

 

[TollKeeper]

He has not been back on the forum since that post above about his replacement part.

 

[Raden]

I am having the exact same problem. How long did this solution last for you? Did you experience any further problems? Thank you for your assistance. I have been looking at salvage yards and can't find any Ultra models to replace the discontinued part and it has been sitting for so long.

Sorry, I didn’t get a notification that anyone had replied. To answer your question about how long it worked — it's still functioning, but recently I’ve been having issues with the cap on hot days.

It’s a plastic reservoir cap, not an inline metal one. According to ChatGPT, it’s likely going through more heat stress/ abuse and should ideally be replaced yearly. I had noticed some minor hose collapse after use and mild boiling in the reservoir on longer drives in hot weather previously, but nothing serious until yesterday.

I had a violent boil-over on the highway and pulled over immediately when the warning light came on. As soon as I stopped, the push cap for the passive reservoir blew off, sending coolant everywhere. So, clearly had a major steam bubble caught in the system somewhere. Once it stopped bubbling, I unscrewed the upper cap, refilled both the filler neck and the reservoir, and drove home without further issues.

This morning, I opened the upper cap again and found it was completely empty. Strangely, as soon as I removed the cap, coolant started flowing into the filler neck from the smaller top hose.

So I’m not really sure what’s going on. Does the metal cap perform some function that the plastic cap doesn’t?

Unfortunately to date, this is still the best set up I can find. Ill be moving to another province in a few months and dont want to deal with an out of province inspection on the Buick.. so best plan it to keep band aid ing it till its time to sell or it dies. But if you found a better solution, would be great to hear.

The engine and transmission are still strong runners, so its a shame to toss in the garbage because of a stupid $30 filler neck. But do to lack of vital parts, not sure what else to do.

 

[Tollmandot]

car-part.com , they will ship

 

[G-84390]

car-part.com , they will ship

I just had the same problem, car parts.com does not carry the part

 

[G-173769]

Sorry, I didn’t get a notification that anyone had replied. To answer your question about how long it worked — it's still functioning, but recently I’ve been having issues with the cap on hot days.

It’s a plastic reservoir cap, not an inline metal one. According to ChatGPT, it’s likely going through more heat stress/ abuse and should ideally be replaced yearly. I had noticed some minor hose collapse after use and mild boiling in the reservoir on longer drives in hot weather previously, but nothing serious until yesterday.

I had a violent boil-over on the highway and pulled over immediately when the warning light came on. As soon as I stopped, the push cap for the passive reservoir blew off, sending coolant everywhere. So, clearly had a major steam bubble caught in the system somewhere. Once it stopped bubbling, I unscrewed the upper cap, refilled both the filler neck and the reservoir, and drove home without further issues.

This morning, I opened the upper cap again and found it was completely empty. Strangely, as soon as I removed the cap, coolant started flowing into the filler neck from the smaller top hose.

So I’m not really sure what’s going on. Does the metal cap perform some function that the plastic cap doesn’t?

Unfortunately to date, this is still the best set up I can find. Ill be moving to another province in a few months and dont want to deal with an out of province inspection on the Buick.. so best plan it to keep band aid ing it till its time to sell or it dies. But if you found a better solution, would be great to hear.

The engine and transmission are still strong runners, so its a shame to toss in the garbage because of a stupid $30 filler neck. But do to lack of vital parts, not sure what else to do.

Thank you for responding back! I have not quite found a solution. It is terrible to not find this one part that we need. I was wondering if someone could remanufacture it or 3D print the part especially since it is discontinued. I no longer have the filler neck piece to see if there was a way to scan it. especially since it is just a cracked part😵‍💫 You seem to have the best solution so far. I am going to see if my mechanic might have a suggestion but he has been unable to find a replacement since the Ultra model is so hard to find even in the wrecking yard. It is so frustrating our car has been sitting there for a few yrs now because of this one part and we had just changed replaced ransmission before hand as well. Did you ever try finding a metal cap that fit the filler neck part you used to see if there was a difference?

 

[Raden]

Thank you for responding back! I have not quite found a solution. It is terrible to not find this one part that we need. I was wondering if someone could remanufacture it or 3D print the part especially since it is discontinued. I no longer have the filler neck piece to see if there was a way to scan it. especially since it is just a cracked part😵‍💫 You seem to have the best solution so far. I am going to see if my mechanic might have a suggestion but he has been unable to find a replacement since the Ultra model is so hard to find even in the wrecking yard. It is so frustrating our car has been sitting there for a few yrs now because of this one part and we had just changed replaced ransmission before hand as well. Did you ever try finding a metal cap that fit the filler neck part you used to see if there was a difference?

Honestly, after changing out the plastic cap for a new one and making sure the system was properly burped, I haven't had any issues post 7500km of driving. I think either the cap was worn, possibly defective from the start or, I failed to get all the air out of the system. maybe both. Unfortunately, because of the threads on the filler neck, only plastic cap AC Delco RC85 will fit. Rather than your Buick sitting for years more, I would giving Dorman 902-2133 a try. With the exception of that one over heat (which again I think was cap or bleed failure, not the Dorman part), I've put about 20,000 km total on the part and its held just fine. My only recommendation, is to change the cap yearly. Which is no biggie Its completely accessible and costs $5.