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Been trying to fix a coolant leak that has reappeared after fixing it once before in my 2003 530i. The leak is coming from either the coolant pipe or the heater inlet pipe. It's hard to tell because they are right next to each other near the front of the block but the failure mode is the same as the first time it started leaking - slowly loosing coolant for a few weeks until the one day the coolant just starts pouring out, down along the block underneath the intake manifold.
Within the last year I had replaced the coolant pipe and the heater inlet pipe after finding that they had both rotted away inside the block, which required digging out the rotted plastic from the ports that they connect to. I'm pretty sure I used Rein OE parts. Been having a slow leak over the last few weeks and yesterday the coolant just started pouring out down the side of the block, so I parked it and pulled the intake off to see what was up. Removed the heater inlet pipe since you have to remove that first and the plastic is fine but I'm questioning the o-rings. They look a little marred up and I'm hoping that this is the problem, though I'm not sure how that would happen in the short time it's been installed.
Other things that I've noticed that might be relevant: Coolant seems to be wanting to come out of every possible place. Both bleeder screws (I have the brass ones) have coolant residue caked on there and I can see evidence of coolant being sprayed on nearby components. The cap also keeps leaking even though I've replaced it with a brand new OEM one. I also had the aux pump leaking a few months back, which was the first sign of leaks after I had replaced the pipes the first time.
I'm wondering if there is some condition happening where there is too much pressure building up in the cooling system, which might be why I am seeing leaks in so many areas. If that is possible, what might be causing it? Blockage in the radiator? I replaced the radiator, hoses, t-stat and pump a few years ago and there aren't that many miles on them. Wondering if anyone has had experience with leaks coming from various places even though the parts are relatively new.
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This is the heater inlet pipe o-rings.
59728240491__07F7C361-F55B-47A7-AB8D-707ED82BBC96.jpg
There seems to be some roughness to the surface of the first one, but they seem to be sitting proud of the pipe and I can't really imagine coolant pouring out at the rate I witnessed, especially with two o-rings there. When I say pouring, it was a steady stream, not necessarily like when you remove a radiator hose. I'll pull the other pipe off next but there's lots of rain in the forecast, so maybe not for a couple days.
Last edited by Atomistic; 12-06-2019 at 03:08 AM.
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This is unusual. Once the pipes are installed and they seal initially, they usually don't fail in such a short time.
How well did you clean the bores before installation? maybe there was residue from old pipes? I use a plumber's copper pipe cleaner (small round wire brush on a handle) to clean mine before installing.
You are correct to use only OEM quality pipes. you can also buy the o-rings separately.
I use a gutted thermostat housing when when I install these pipes to test before installing intake. After pipes are in, I install gutted thermostat, fill with coolant or distilled water and pressurize to <20 psi, then look for leaks.
Your comment about excessive pressure is interesting. I would keep expansion tank filled well under the neck of the tank. If you thought there might be excessive pressure, I would test coolant for exhaust gasses and/or do a compression test.
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Probably not the issue but while they're open, check the insides of the ports for casting burrs. The port for the water pipe that fits behind the t-stat on my '99 (M52TU) had one that was so sharp it would have easily sliced an O-ring. Also check the pipe ends for roundness.
Artifically Aspirated
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And lube the o-rings before you push the tube in.
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Originally Posted by effduration
That's a great idea to pressure test before putting everything back together. I'll have to consider that. I did use some fine sandpaper in an attempt to get all of the residue out. I do notice that the port itself seems a little marred up, too. I'll try to post a pic of it, but probably won't get under the hood for a couple of days. I've never sent any fluids out for testing, but I read about people doing this to diagnose things. Might give that a shot.
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Good idea! I will pay close attention to the port. At first look it actually seemed a bit rough... not exactly a perfect surface. Maybe that's the problem.
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One of my mechanic buddies said this as well. Will do that when I get the new parts. I'm going to actually replace both pipes even though they are pretty new. The OEM one looks a bit more uniform from the pictures on FCP. Mine looks kinda strange in the pic I posted. Looks like the pipe itself has a bunch of fibers at the end from a poor casting or however it's made.
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Is there a way to test the radiator for blockage? And if there is blockage, would I be experiencing overheating or any other symptom?
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new radiator about 100 from reliable online vendor, if in doubt, replace it! Cheap insurance IMO
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Can't argue with that! I'm going to go ahead and take this advice.
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I just finished the same installation of heater pipes. I found leaks after I put the entire manifold back on, OMG!! When they were re-installed the second time, I bolted them down and saw a weeping drip from the straight pipe. I unbolted it and the weeping stopped. It appeared as thought the OEM pipe was cocked a little bit somehow. So my fix was lubricate the o-rings and block with Pool and Spa o-ring lube and gently push them in place. Bolted them down and it started weeping again. I used a flashlight a tiny mirror to ensure the o-ring wasn't sticking out somewhere and it wasnt. I was baffled thinking these pipes were made wrong. Strange enough I left it over night with the pipe in the block unbolted and when I returned to it in the morning the pipes were now against the block kinda like they settled where they needed to be without binding. Easily bolted them up and no leak no. Cant explain it but I am not complaining.
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Wow I'm pretty stoked to hear from someone who has had the same problem. I'm almost tempted to leave mine unbolted overnight and hope I get the same result! I just ordered some OEM BMW pipes because I've read that they might be more reliable. They were probably 3 times as expensive, but I'm desperate at this point. I didn't lube the o-rings the first time, so I'll definitely do that this time. Did you also have coolant leaking from other areas like the cap and bleeder screws? Seems like my coolant just doesn't want to stay in. I'm even considering changing over to waterless coolant to ensure that the pressure is not a factor.
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I can't really picture where this attaches to the engine from memory. But you mentioned there are two things, very close to each other, that could be the culprit? Can you stick something between them to help determine? Something like a plastic putty knife? You could cut/shape the knife to better fit the area. The idea would just a simple "blocker" between the two items.
Or, can you wrap some putty around one of the fittings to test?
Those o-rings look quite flattened?
Check out a product made by Mercury Marine (also known as Quicksilver) called Perfect Seal (I'm sure others make this type of thing). It's a sealant, but it never hardens. It's pretty neat stuff.
Last edited by DennisG01; 12-10-2019 at 08:44 AM.
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I would get a lower pressure radiator cap from German auto solutions. The stock cap is set to 29 psi, which is too high for most of the US. I believe it puts a lot of unnecessary strain on the cooling system.
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I considered this as well, but wouldn't that make it so that the cap would release coolant whenever the pressure builds up and therefore require frequent topping off? Additionally, the coolant leaks out of my brand new cap as it is. It also is coming out of the two bleeder screws. I may give it a lower bar cap a try because I'll try anything at this point. My new pipes arrive tomorrow and I'll be putting it all back together this week. I'm also planning on replacing the coolant with waterless Evans coolant once I confirm that the leaks are fixed, at which point I think pressure will no longer be a concern. I'm still on the fence about that, but I've already bought and received the Evans coolant.
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Yeah, I think the o-rings look pretty flat for how old they are, but maybe that's just what happens after 6 or 7 months. I think I will be using some kind of compatible silicone sealant to assist the o-rings when I install the new pipes like you suggest. The two things that are close to each other are the two pipes: one is the heater inlet and the other is the return pipe. They are oriented vertically one right above the other and require that you remove the top one before you can remove the bottom one. It's super cramped in there when the intake is installed and even getting an inspection camera up in there was difficult (and also did not reveal anything, unfortunately)
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Curious at what miles that you devloped the coolant leak at the plastic pipe/O-ring area?
My 2006 X5 3.0i with 133K miles: the plastic pipe is still OK, no leak (yet)...
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Last edited by TheTailor; 12-11-2019 at 12:23 AM.
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If the cooling system is working properly then the OEM cap should be no problem, I mean it did come from the factory like such. Getting a lower pressure cap to fix a over pressure problem is just ignoring the real problem.
Over pressurizing can be caused from a series of issues like a clog somewhere in the system, failing thermostat, failing water pump, failing head gasket or failing expansion cap. None the less the cooling system should be diagnosed before you toss $ at it orrr just go big and replace everything at once.
Once you get everything sorted then a lower temp cap would be beneficial.
As for the O-rings, I would take a pair of calipers and make sure they are the proper dimensions (use realoem to confirm the correct #'s).
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Three words of advice: Cooling system overhaul
Do it all and you should only have to do it once (every 80,00-100,000 miles).
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I agreed you have to fix the problem. How many other cars have radiator cap pressures this high. GAS makes the lower pressure cap for a reason and I have had them on 4 BMW without any issues for 4 or 5 summers. Again I do not live in a super hot climate.
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Ah, OK, now I understand better where you are talking about. The o-rings also look nicked up - and it doesn't take much, at all, to make for a leak. I'm betting that all you need is properly seated, new o-rings (on both pipes, of course). Using that stuff I mentioned (instead of silicone spray) can only make things better, though. Probably not (shouldn't be) necessary, but it can't hurt, either.
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I had to replace the plastic coolant pipes last year.
I was pulling into the parking lot at work when I saw steams bellowing from under the hood.
I think the car had 194k miles on it at the time.
When I removed the pipes, or what was left of them, they were completely disintegrated at the engine head.
I replaced them with OEM pipe from the dealer, but when installing them, one of the o-rings got pinched and leaked.
I replaced all the o-rings with new ones, and used a little bit of dielectric grease .
So far, so good.
Looking for an E39 belly pan , passenger front inner fender liner …
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I received the new pipes a couple days ago and installed them earlier today. I found that there was still quite a bit of residue from the original set of pipes that had rotted away, so I guess I hadn't done a thorough enough job cleaning those ports the first time. Although I paid a lot more for the OEM pipes, I feel a bit more confident now that I've been able to compare the quality of the two. Simply replacing the o-rings and cleaning up the ports more may have resolved this, but this may be one of the repairs where I recommend OEM parts as opposed to OE like Meyle, Victor Reinz, Rein, etc.. I've only driven it a couple of miles so far, so I can't say for sure that the leaks are gone, but it's not leaking at the moment. Additionally, I never really understood how to properly bleed these engines and it's probably because my auxiliary water pump never worked and I wasn't aware of it's role in bleeding. Over the course of the last year I've developed leaks everywhere, starting with the pipes, then the aux pump, then from the bleeder screws and cap, and finally the pipes again. It may be possible that I had air in the system because I wasn't bleeding it correctly (I assume due to faulty aux pump), and the cooling system was producing too much pressure, therefore blowing out of every possible part. When the aux pump started leaking badly, I replaced it and the leak moved to the next weakest point.
So, today when I put it all back together, I did the bleeding procedure with the engine off and ignition in position 2 and the pump started circulating, which is something I've never seen it do before when bleeding. It was so strong that when I fully removed the bleed screw coolant shot up a few feet. The process went pretty quickly to where I was satisfied that the air was out, heat was hot and there were no leaks. The whole process seemed to go just like it should, whereas in the past, I bled it with the engine running and was never confident that I had done it properly.
There was, however, some residue that I don't think I could get off without risking marring up the port surface even further. It seems like there are some corroded areas of the metal that are pitted and the old pipe material is stuck in those recesses. I'm not sure if that pitting is due to some reaction with the wrong coolant or whatever, but I hope that the new o-rings are able to deal with it. The photo that shows this is taken with a flashlight aimed at an inspection mirror, so it's kind of hard to really see what's going on. I spent at least 30 minutes with some 500 and 400 grit sandpaper and my finger putting light pressure. That stuff is really baked on there. If it leaks again, I'll expect that it's because I need to clean it even more.
The quality of the OEM part is noticeably better than the aftermarket part.
IMG_3165.jpg
The o-rings on the aftermarket part seem to have been seriously deteriorated over the last 6-9 months.
IMG_3164 2.jpg
There was quite a bit of residue in the ports from the original pipes, so this seal was probably compromised. Even after using a wire brush and sandpaper, there was still a bit left. See the recessed pitting in the port. This made it difficult to get it all. Not sure why it's pitted.
IMG_3166.jpg
Installed. Running good so far.
IMG_3167.jpg
Last edited by Atomistic; 12-15-2019 at 01:05 AM.
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I would be HIGHLY surprised if those pieces started leaking again. There's probably only two things I would have also done, but they are really minor things - really just a different way of doing things. I would have finished up the sanding with a Scotch-Brite pad to really smooth things out. Second, I would have used a non-hardening sealant (like that PerfectSeal) as that would have guaranteed to fill in any remaining gaps and also to expand/contract with things over time.
BUT... I really think what you did is going to fix it. As far as any remaining rubber in the aluminum pipe... I've always thought that if you do a thorough job of sanding things... anything that still remains has earned the right to stay there and won't be a problem down the road
WOW! Did I miss that? That aftermarket part (the deteriorated o-rings) was only in there for 9 months?!?!
Maybe it would be a good idea to do an cooling system flush (Blue Devil, for example) and refill with good stuff - just to be sure. Especially if it hasn't been done in a while and/or you don't know the whole history of the car. I'm not convinced that BMW coolant is the "best" as I've been using other stuff for 100K miles (based on my Indy's recommendation/esperience). BUT, the BMW coolant is a "known good" product and, in the end, isn't a whole lot more expensive.
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Rein is not OEM, I think.
Best is to get genuine BMW pipes, costing a bit more but much more reliable.
These pipes have specs down to 1/10 of a mm, so even 1/10 mm off (such as O-ring a tiny smaller than factory), it will leak.
Also, the factory O-rings last some > 150K. Aftermarket O-rings, who knows where they were made, can crumple under heat in < 1 year.
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This thread is very helpful, and proves that factory parts are needed here. I just finished this job (with help from this thread), and will contribute some tips specifically for the M52TU engine ('99-'00):
- The throttle body has to be removed only to access the manifold support bracket hidden behind. While you're there, disconnect the positive leads attached to the starter solenoid. Now you won't have to remove the positive jumper terminal on top of the manifold. Of course, disconnect the battery first.
- The electrical distribution rail for the fuel injectors must be removed to access all 9 manifold retainer nuts. This is a PITA due to the small metal retainer clips that must be completely removed from each terminal. Use needle nose pliers and a small screwdriver to detach and extract each clip. Upon re-installation, simply reattach each clip and push the rail back into position until you hear the clips "click" on each fuel injector plug. See image below:
fuel_rail_clip.jpg
- I used 2x4 lumber to help support the manifold after pivoting it up and away from the cylinder head as illustrated below:
manifold_raised.jpg
This also makes the intake gaskets accessible for replacement. Protect the rear center bulkhead against damage from the manifold by placing a thick towel over the part of the manifold that contacts the bulkhead. Better yet, remove the bulkhead (for more room too).
- Located at the rear, the vacuum line feeding the secondary air pump pressure regulator will likely break when manipulating the manifold. Have miscellaneous sizes of vacuum hose on hand to mend.
Also:
This is a good opportunity to address any other issues discovered along the way. In my case, I replaced leaking power steering fluid hoses (from reservoir) and the intake cam position sensor (leaking oil internally).
Jack the car up high and place on jack stands. Why? To help save your back! After several days of this work, your back will be hurting from all your contortions.
This job is very time consuming, requiring patience and much attention to detail especially during re-assembly.
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