Author Topic: black plastic coolant pipe - anyone have issues w/ new part & o-ring leaking? (Read 12851 times)

Cobra Jet · « **on:** December 30, 2008, 08:39:25 AM »

My engine was previously rebuilt back in the beginning of 2008 (Jan-Mar time frame). All of the parts used were all brand new parts.

The one part I am now having an issue w/ is the black plastic coolant "pipe" that is inserted into the driver's side of the engine block. The part is pictured below, the photo source of this part is courtesy of bimmerparts.com:

When on the REALOEM website, the part is referred to as the "connector", BMW part # 11531714738 ($14.17 per REALOEM). The O-ring for this part is listed as BMW part # 11531709157 ($2.28 per REALOEM).

The connector pipe on my M42 is seeping at the main flange where it is inserted into the engine block. My M42 also has had the complete "mess under the intake" deletion when the engine was rebuilt, so I have very few hoses remaining, I've checked all other possible areas of where coolant can leak and all of those areas are completely dry. The coolant is seeping past the flange and puddles onto the engine block right below the connector pipe.

I'm not sure if the replacement O-ring for this part has failed or if this part is just a bad aftermarket reproduction part. I'm thinking it may be made by a company called "URO", as where the part was originally purchased, that vendor only lists a "URO" coolant connector pipe.

Has anyone experienced a new part failure, specifically this coolant connector pipe and if so, what was the brand or who was the part manufactured by?

My current thinking is that the part is made w/ inferior plastics and the plastic flange & tubing where it meets & goes into the engine block has warped due to heat off the engine block, causing coolant to seep past the O-ring and flange... This could be BAD if an unsuspecting M42 owner does not take notice to any coolant seepage in this area, as it is kind of hidden by the intake, other hoses & the oil can. If you have replaced this part recently, I would certainly check that area of the block and look for any coolant stains or small puddling under the pipe.

Looks like I may be replacing this part w/ an original BMW connector & O-ring from the local BMW Dealer.

JP 91iS · « **Reply #1 on:** December 30, 2008, 01:32:47 PM »

When I put a new one in, I remember it being difficult to press that end in nice and flush. Maybe you accidentally left some small pieces of plastic in the hole that had broken off of the original pipe. I had to dig out a couple big chunks that stuck in the block.

Cobra Jet · « **Reply #2 on:** May 23, 2009, 11:42:59 PM »

just an FYI and update:

I purchased a brand new coolant bypass pipe and O-ring from the local BMW Dealer and finally had a chance to install it last night w/ my best friend's help.

Once we had the leaking bypass pipe out, we were able to compare it to the new BMW manufactured part.

The "aftermarket URO" piece is similar in design, however, where it fails is due to the mold and cast process used in the manufacturing of this part. The part is poorly molded and where the flange is (where the o-ring gets installed over it), this area is problematic. The flat surface of the flange has excess plastic flash scaling on it and is not a 100% smooth mating surface once installed into the engine block. Whatever mold URO uses to cast their part, it is crude and leaves multiple defects on the final part, therefore the part is not 100% flawless like the original BMW part.

Basically, when replacing the coolant bypass pipe, DEFINITELY buy this part from your local BMW Dealer (or buy a genuine BMW part) - it's not worth the hassle of having to replace this part months later and it would be detrimental to your M42 if you did not catch a leak from this part... We all know what happens to an M42 head if coolant leaks go undetected or is overlooked.

///m42 sport · « **Reply #3 on:** June 04, 2009, 10:35:59 PM »

whats the price difference?

Cobra Jet · « **Reply #4 on:** June 12, 2009, 10:06:05 AM »

Quote from: ///m42 sport;73061

whats the price difference?

Less than $3-$5.... trust me, it's not worth the "savings" buying this part as an aftermarket reproduced part... Go directly to the Dealer (or order from your local Dealer online).

gearheadE30 · « **Reply #5 on:** June 13, 2009, 02:10:17 PM »

Yeah, when I bought that pipe in a panic at the stealer after it exploded, it was only like $45.

///m42 sport · « **Reply #6 on:** June 21, 2009, 05:47:08 PM »

well my dealer was obviously jacking up the price...asking $100+. I was in a hurry and went with whatever worldpac was selling.

qualicas · « **Reply #7 on:** June 22, 2009, 10:02:48 PM »

That part would have been injection molded. To make the O ring groove the mold would have had a couple of slides built into it. The slides are supposed to seal off and leave just a witness line. Obviously, you part had plastic flash
from not sealing properly or injecting with too high pressure. You could have just trimmed off the flash carefully and it would have been fine. I've got one of these on order so I'll have a look at it when it arrives. (I'm in the plastic molding business and I make some parts that seal with O rings so we watch those areas carefully.)

spanish_pants · « **Reply #8 on:** July 28, 2009, 03:57:43 PM »

I just replaced this today along with the rest of the hoses and i had the same problem.
I noticed the old pipe sat nice and flush with the block, while the new one would not sit flush no matter how much i jiggled or pushed. When i put the two bolts back on it seem to help push the pipe closer to the block. No leaks so far though.
BTW, the old pipe was still in great shape. I couldn�t say the same for the rest of the hoses.
The new pipe was from the dealership.

DesktopDave · « **Reply #9 on:** July 28, 2009, 04:08:41 PM »

I have to do this before the summer ends...y'all are making me worry! I haven't been in a BMW dealer in a decade...might have to bite the bullet.

You can be sure I'll let them know that their cars are uglier than ever...after they quote me a price on the part.

Cobra Jet · « **Reply #10 on:** July 29, 2009, 01:50:41 PM »

Quote from: DesktopDave;75968

I have to do this before the summer ends...y'all are making me worry! I haven't been in a BMW dealer in a decade...might have to bite the bullet.

You can be sure I'll let them know that their cars are uglier than ever...after they quote me a price on the part.

Don't worry about it - it's simple enough to replace.

I'm really surprised that some of you are paying more than $30 for the part directly from BMW - let alone nearly $100?

Print the page from REALOEM, it has the part # and the price - bring it with you to your local BMW Dealer. I paid under $30 for the part directly from DeSimone BMW here in NJ....

BlackBMWs · « **Reply #11 on:** July 30, 2009, 09:35:36 AM »

:eek:

Just replaced mine, listed as a MTC replacement, $10.83 at EACTuning. I noticed it did not sit perfectly flat on the aft side of the pipe connector on initial installation. After carefully bolting it in, it did move in, but has perhaps a 1MM gap between the flange and the block.

I'm under the hood again this weekend with a broken thermostat bolt, the intake manifold is still off, so I'll check again... Easy to pull back off... :cool:

iamcreepingdeath · « **Reply #12 on:** July 30, 2009, 09:22:14 PM »

oh poop! i just bought this part from pelicanparts.com and i am going to install it. Is the one from Pelican any good or is it crap?

BlackBMWs · « **Reply #13 on:** August 02, 2009, 04:37:38 PM »

So, I confirmed that mine isn't sitting perfectly flat either. .5 to 1mm gap on the aft side of the flange. The block is clean and free of obstructions and the o-ring seems to be seated O.K. There isn't any excess plastic. Im thinking that the piece isn't perfectly straight to seat properly. hmmm... Now I wonder about the quality of the plastic.

I did put everything back together and it runs just fine with no leaks. I'll keep an eye on it.

gearheadE30 · « **Reply #14 on:** August 03, 2009, 06:47:03 AM »

Mine's not quite perfect either, but as long as the o-ring is seated, it won't be a problem. The plastic flange doesn't seal to the block or anything; it's just there to provide a little extra strength.