Low Coolant Level Warning

[BeamMeUpSeattle]

Back under the car, low coolant level warnings two days in a row and it looks like it’s coming from the water pump and thermostat I just replaced 10k miles ago!

[pbonsalb]

What brand did you use? I did this in 2021 along with the turbos, turbo water and oil lines, belts, pulleys, pan gasket and rod bearings. But the car has had only light use since — under 15k miles. I would have to search around to see the brand I bought but think it was Continental.

[BeamMeUpSeattle]

Continental. I can’t tell where it’s coming from. I wanna drop the subframe again…so much work! But maybe I do the turbos and make it worth it.

[pbonsalb]

Maybe it is just a hose that connects to the pump or thermostat? An inspection camera might show the source.

[BeamMeUpSeattle]

My inspection camera is worthless lol. I took the subframe down. It’s this hose IMG_3225.jpgI bought the repair kit and changed it with the water pump. I suppose the hose being constantly wet from my oil leak compromised the hose’s structural integrity so…I just got all new houses but I need to fix the oil leak! Trouble is I’m just not sure where it’s coming from. I’m wet all down the front and above the oil pan gasket. I guess I’ll do the valve cover and oil filter housing again. I think I may have made the leak worse doing those jobs the first time…but I was just starting out. I know my way around a little better now…fingers crossed. I would love to do the turbos now too but for another day. I’m gonna keep this car for ever!

[pbonsalb]

I remember a short 45 degree hose that was hard to buy. Not sure if that is the one leaking for you. I bought some off brand like Uro and it did not fit well. Can’t remember whether I forced it into place or found another hose and adapted it, but at 13 years and 150k miles (my 08 when I did the work) and a hot twin turbo engine bay, I wanted to change everything I could find parts for.

It took me a while to get the front of my engine oil free. I did the valve cover gasket, oil cooler gasket, the oil cooler hose o-rings, the oil filter housing gasket and there was still oil. Turned out to be the crimped upper end of the U shaped oil cooler hose was dripping and getting on the fan and all over the belt and front of the motor. Easy fix but took me a long time to find it.

I did the pan gasket when I did the turbos and did the rod bearings since I was in there.

[BeamMeUpSeattle]

Found the leak - a short 45deg hose, thanks PB!IMG_3273.jpgIMG_3259.jpeg
I think I also found the oil leak. It was the lower camshaft sensor. There are two? The lower one’s oil trail looks very incriminating.

[pbonsalb]

Don’t use the Uro repair hose for that short 45. It is too tight. There must be another brand or take the hose to a friendly auto parts store and ask them to let you visually look for one in the hanging stock that you can cut that short section from. Measure the pipe OD first and bring a tape measure.

hope you found the oil leak. I found a few suspects and removed and resealed parts and maybe that helped. But it was that U shaped oil cooler hose you see between the engine and the radiator/fan assembly on the driver’s side that was the problem. The upper crimp was leaking. If your hose is dry at the bottom of the U shape, then that is not your problem.

[BeamMeUpSeattle]

I do too!!! I’m almost back together but ran into two reassembly issues. The first was the steering universal joint bolt was jamming on the spline…I torqued it from the top with many extensions and did not notice steering bolt was not seated all the way until putting the axels in and had very limited movement on the steering range…saw my bolt sticking out and was banging against the fire wall…read the manual and it said to re-tap threads. So I did and the tap would not go…so I got better light in there and I was tapping against the splines!!! Dang idiot! So I got that sorted but made some metal shaving out of a few splines…luckily the universal went on without binding. Ok second idiot thing and I’m still dealing with it. I did not replace the bolts on that support plate like they tell you to and the torque is pretty high: 56Nm with 90 deg angle so the threads do get stretched a bit. Well…they were all seated and the last bolt to get the 56Nm never made it…it just started spinning. Now it won’t come out. I’m drilling and drilling. Got cobalt bits and was making progress until I broke the bit in the hole and it’s stuck. Dang
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[pbonsalb]

I can’t remember the steering shaft design. Some have a chamfer for the bolt that locks the shaft to the coupler and some have a bolt that goes through a hole in the shaft. I don’t think any are set screw style. I often have trouble getting the shaft and coupler back together because the splines do not want to match up. Sometimes I wire brush, sometimes I have used a mini angle file to clean splines. Opening up the pinch gap always helps but can be a pain in the limited space.

Cobalt is great but brittle. You need a good assortment and should start small and go up one size at a time. Always use oil. Messy when drilling above you. I recently bought a bolt buster type induction heater. It can help but is not a guarantee for frozen or rusted bolts, and of course you are always tempted to try first without heat and sometimes you stop on time and sometimes you don’t.

Anyway, that is to remember for next time and now you have some trouble. I don’t exactly recall how the aluminum plate is attached to the subframe, but think there are basically nuts welded into the subframe to receive the bolts. Hopefully you can access it and hold it in place to remove the bolt. If not, you may have to remove the subframe. It might be a good idea since the aluminum plate comes off periodically for projects and even if you could remove the welded nut and hold a loose nut in place while you tighten the bolt, that will be a pain over time. Welding a new nut in place is the ideal fix.

If you can get this bolt out somehow, you could also drill a new hole nearby and install a rivet nut into the subframe. You would want to do it right so it can handle torquing over time. Maybe a steel one. And maybe even tack welded to help hold it. For steel you need a quality rivet nut tool.

There is always something. I am in the process of doing rotors and pads on my F90 M5 with 68k miles. Each front rotor has 2 retaining bolts and on one side, 1 of the 2 stripped. I tried pounding a torx into the chewed up hex hole but ended up having to drill it out. And yes, a cobalt bit broke in the hole at the end. Cobalt is brittle so I hammered it a little with a pinch and was able to break it up a little and push the parts through the thread hole. Fortunately, I had nearly drilled out the bad bolt and the hub is only about 1/2” thick. Your situation is worse with a broken bit in a hole that is not yet drilled through.

Let us know how it turns out.

[BeamMeUpSeattle]

Thanks Pb for the help and encouragement, I dropped the subframe which was a little tricky with the support frame attached but extensions and a universal coming in from the wheel well got me to the top bolt on the engine support bracket. I left a jack on the front jack point so I didn’t have to mess with power steering banjos or power steering and transmission line support brackets. After dropping and gaining access from the top I cut the bolt flush with the welded nut to minimize drill length and started drilling from the top with my smallest bit and got through! I was a bit off center. Graduated sizes and eventually started hitting the broken bits and was at a stand still. Took a finish nail counter sink and pounded it in the hole I had made and pushed out the broken bits!! Then I was in a loop of drilling from the top and bottom as I was still breaking bits I think because I was hitting both the nut and the frame and the two different point of connection was causing extra stress. Well, at some point I had taken enough of the bolt off that I was able to pound it out. I would say about 1/8 of the bolts thread were compromised after I retapped it. You all are gonna judge me but I was in a time pinch and what I ended up doing was staking a second bolt on top of the first and securing there with steel enforced epoxy. I looked at welders and rethreading options (which I bought) but needed to get the car to the alignment shop so…that was my quick fix. I torqued to 56Nm and only went 45deg on all 6 bolts…probably not the best but the pain of drilling out a bolt is is not good either. The torque wrench recorded around 100Nm after the 45deg angle. What do you think of heli-coil repair kits?
IMG_3388.jpg IMG_3393.jpg IMG_3394.jpg

[BeamMeUpSeattle]

Just in time

[pbonsalb]

The torque you reached is probably fine. I usually just go by feel and don’t do the angle for the stiffening plate. I don’t have personal experience with helicoil though I did recently buy a kit. I have used rivet nuts before and have welded nuts in place before.

Looks like you went to a dragstrip. How did it go? I never ran our wagon. It had a JB4 on 93 pump and I was guessing it might do 105.

[BeamMeUpSeattle]

We were at Pacific Raceway doin laps! Well I wasn’t, my daughter was. This car is slated for her and we used it in their level 1 drivers class so she could get a feel for the limits of the car. It was so great, I would recommend it to anyone. I was a little nervous about the car performing having come off the jack stands the day before but zero issues and I’ll also like to report no oil leaks!!!!
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[URO Parts]

Found the leak - a short 45deg hose, thanks PB!

Looking into this, which part number is this?

[pbonsalb]

Looking into this, which part number is this?

I have a parts order from Autohausaz from 5 years ago when I changed the turbos and pump and thermostat on my 2008 BMW 535xi with N54 engine and think this might be the part:

URO Parts Coolant Hose; Pump to Inlet
P/N: UR-11537558522RPR

If it is a short 45 or 90 degree, I recall it was so tight that either I really had to stretch it or I could not use it and salvaged a similar size/shape from another hose.

[URO Parts]

^ Thanks for the part number!

BMW p/n 11537558522 is actually only listed to fit 2007-2013 3-Series and 2009-2016 Z4 with N54: https://parts.bmwofsouthatlanta.com/...pe-11537558522. Our repair kit 11 53 7 558 522RPR is listed to fit the same 3-Series and Z4 models, and only cars with MANUAL transmission for following models: 2008-2010 BMW 135i, 2007-2010 335i, 2009-2010 335i xDrive, 2007-2008 335xi, and 2009-2016 Z4 sDrive35i.

We'll have to do some research to figure out why BMW says p/n 11537558522 isn't compatible with any 5-Series cars, as Pbonsalb confirmed.