I'm still trying to find the leak in my coolant system. I bought a hand pump to pump up the system to check for leaks. Unfortunately, I can't get my coolant system to pressure long. I pump like crazy but the system never pressures. I can't find this leak. It is very aggravating. Usually in my experience, I look at a car problem like this as obvious. You immediately see the problem.

I took the tank off and the first hose and filled it will water. There is no leak there.

The leak must be huge for the system not to pressurize. Anybody got more ideas on how to find this puppy?

 

It is no waste of time to replace the plastic pipe and thermostat housing, as it needs to be replaced eventually anyways. Maybe just get a expansion tank to be on the safe side.

My more than worthwhile tip if you do it DIY: buy some silicone lube paste for the o-rings. All the horror stories about the pipe being hard to insert into to the block - gone. Also remove the intake manifold. And use some of the lube sparingly on all the hoses to have them flush on easily.

 

Just a crazy thought, have you tried the hand pump on another vehicle to make sure it works properly?

If your gauge goes up and immediately down, and it's not pushing any water out, the leak is above the water line. Either you have a leak at the expansion tank or the pump adapter is not sealing to the tank.

 

Clean the wet areas as much as possible. Spray parts you can not reach with brake cleaner and allow it to dry completely. Get the car up to operating temp. Feel the lower radiator hose to make sure the thermostat is open. Open the bleeder screw to make sure there is no air trapped in the system (as soon as you see coolant, close it). Put fresh cardboard under the car while it is in the air and with a good flashlight, look for the leak. Everything connects at or near the t-stat housing. Likely culprits are the water pump, water pipe, t-stat housing and all the hoses that connect at the housing. The intake pipe and wiring harness will need to be removed. Mark the connections as many are similar and two are the same.

My son and I had a leak on the passenger side. First we did the water pump as we could see a leak at the weep hole. After everything was back together, we started it up and were frustrated to find that the water pipe was also leaking (just behind the water pump). My opinion is that just like all BMWs of this time of life, the cooling system simply needs a thorough going over. Most BMWs usually lasted closer to five years back then. I am of the once and done mentality. So, I recommend you do the pump, water pipe, t-stat and housing, expansion tank and hoses. Then you can rest assured for the next 10 years you will be trouble free. Otherwise, every year or so you will be going through this same process of trying to find the mystery leak. Bite the bullet once and be done with it.

BTW, the job is not that bad once you put it into "front end service mode" and remove intake piping, wiring harness and the five 10mm's holing on the intake manifold.

 

I can put my hand on the hole coming into the lid, and pump and it shows a pressure. However, that is a good idea of something to try. What I can do is seal the expansion tank up and see if it will at least pressurize the tank.

 

I agree with this. I started out just planning on doing that and followed someone's advice to find it first. So I have been trying to follow that first. However, I have spent enough time on this that just doing the work, I'd be done already. I could replace the pipe, water pump, T-stat and be done with this. 96% that the problem is one of those things and 3 years from now in the middle of no-where I know it won't be one of those things. Do you recommend replacing the hoses as well? I looked at a full set of silicon all the way around from China for $70

 

I trust ECS sourced products. They have a few different cooling system refresh kits. I would pick up one of those. The kits do not have all the hoses so you may need to get them separately. I think you are smart to just do the entire job.

 

One more thought, you may want to pick up a new tensioner wheel and water pump pulley. Either or both may be bad and you'll probably need to wait for parts. Let me know when you get ready to start. Since I just did it everything is fresh in my mind.

 

Does it make more sense to replace those "instead" of the water pump. I would think the water pump should go to 100K I think those are the parts that fail first. The pump is one of the most expensive parts. So are you saying you replaced the hoses?

 

I have no bleeder screw. I have checked and checked. I don't know if the OEM original didn't have that or what but I don't have it.

 

We did not do the hoses. We simply grew tired of ordering and waiting for parts. If I were to do it all over again I would.

 

There is an ultraviolet dye that my mechanic added to my coolant and then used a light and glasses to find my leak.
He showed me a leak on my T housing with me wearing the glasses.
It was very easy to see. I spent 3 months trying to find the leak.
My T housing was in terrible shape.
I don't know where he got these tools but they should be available.

 

minidd99 is totally correct on this check. When my customers come to me with a coolant leak which aren't obvious to find, I normally add the UV dye first ($20 kit includes the UV light and a bottle of dye). Then I'll use the pump to try to force out the coolant then check for leaks. It also helps if you already know where all of your cooling components are, namely: T-stat housing, water pipe, water pump, coolant exit hose to radiator, radiator, entry hose back to T-stat housing. Also check your auxiliary coolant pump if you have an N14. Looks like you've already confirmed the reservoir still holds, but that feed line joint right below the reservoir is also a point of failure. Coolant piping to and from the cabin don't normally exhibit problems, but you may check those, too.

If the above application can't find your leak, you have a bigger problem to deal with and I hate to speculate. Those would be leak through head-gasket, leak through oil/coolant exchanger (common failure too since the gasket seals can crack, but you should catch your engine oil to smell differently or change color, in worse cases, it'll become milk shake), and lastly, coolant leak through turbocharger's cassette if there's a leak there. If that's the case, you'll just lose coolant through the turbo, I don't see this being common, though.

Hope the above helps. Happy motoring.

 

Ok this is what I did/found. I pulled the panel over the oil reservoir so I could see the water pump clearly. Water pump definitely not leaking anything. I do see that the water pump friction wheel could need replacement soon as well as the belt. (62K).

So here is what I did. I brought my compressor up to 15-20 psi delivery. I used the lid that came with the pressure test kit put cut about 3 inches of line and I simply used my compressor. That allowed me to put in a lot of air and I can quickly see that the leak is the first T-connector that the expansion tank hooks too. That is actually where I saw water coming out originally as well but since that was a sealed unit, I figured that was a figment of my imagination at the time. The part that goes up to the turbo and connects to a metal tube that feeds the turbo is where it is leaking. However, this part seems to have "everything attached to it".

It is this part right here and I would say my failure is similar except I just hear and feel air there. I don't actually see it severed.


This is my car: https://www.realoem.com/bmw/enUS/par...&q=11537645832
Anybody know how to get the plastic piece or do you have to buy the whole thing? I may have other leaks but this one is massive and has to be fixed first.

I found this https://www.ecstuning.com/b-genuine-...e/11537645832/ but this part is expensive having to buy the whole thing.

 

You have no other choice but to get that part. I don't see other aftermarket makers producing this part. There are instances I see other forum members discussing about changing out the joint coupling where one of those ends connects to the bottom of the coolant reservoir. But if you have any cracks along the T-joint, you're out of luck, must replace that entire part.

When you mentioned that you feel air coming out of that part, that's because your coolant level isn't all the way filled. It's supposed to be filled with coolant.

 

Thanks.
Hmm, if air can come out, what would keep fluid from coming out? Is this some kind of stop-valve (auto bleed) there that lets air out but not coolant?

My thermostat housing has no bleeder valve. So at this point, I'm not sure how I could even fix this without installing a new thermostat anyways??

 

So I took a look at that. I agree that the tensioner doesn't look great. However the water pump pulley is buried right up against the body. There looks to be no way to get to those screws without pulling the engine.

 

Thats the part: https://www.ecstuning.com/Search/Sit...h/11539845352/

If we com across an aftermarket version we will let you know.

 

Thanks. Does this "new" part have a valve there to let air out without letting out liquid? I can see it has raised plastic and where it might have some kind of air outlet in that gap that is intentional.

Also, does this install require some kind of copper washers/gasket--maybe up by the supercharger?

 

I wonder if just using JB-Weld makes more sense...
It looks like a terrible design with plastic glued to plastic there right next to the very hot supercharger.
I've put JB Weld on mufflers before with hundreds of degrees. It changes colors and continues to hold.

Every-time you change the oil, you flip the expansion tank over putting strain there.

 

I cannot see that part as I am working remote, so i can look at it up close, but it looks like its just the way its manufactured. Dont see anything that would be a air inlet.

The cooper washer are here for the turbo and the hallow bolt.

Hollow bolt
https://www.ecstuning.com/b-genuine-...119905973~oem/

2x washers: https://www.ecstuning.com/Search/Sit...54__ES2673526/

https://www.northamericanmotoring.co...6&goto=newpost

 

Thanks. Ok. I thought that might be there. That likely needs to be replaced as well so it doesn't start leaking there from reusing the compressed copper washer.

 

Your T-stat has way for by-pass. So if the car is sitting still for a while, your coolant could have settled at the lowest places and coolant can be low enough so as you blow air into it, air naturally stays in the higher part of the system. That joint where you feel the air come out could just be part of this systemic effect. i'm not sure unless I know exactly how much coolant is left in your car.

In regards to getting the water pump and the friction wheel out of the bay, please don't pull the motor, that's an overkill. All you really need to do is have the motor supported by a floor jack, then remove the passenger side motor mount. By then you will be able to jack the motor up and down, that'll grant you enough space to access those bolts.

Another tip: as you will need to remove the pulley wheel before you can unbolt the water pump, you can use a strap type oil filter wrench and strap the pulley then go undo those 3 bolts to get the pulley off.

Here's a list of tools I find helpful for working that side of the motor:
1. strap type oil filter wrench: https://www.homedepot.com/p/Alltrade...-203125064-_-N
2. Extended length 10mm ratchet wrench: https://www.northerntool.com/ and look up item #13874

Hope this helps.

 

I'm still not following you though. If the system is not "air tight", how can it be water tight? When you are pressure testing the radiator system (or any system for that matter), you are using air to simulate the water (coolant, oil) pressure.

...

I just took a mirror and looked at this part and I can actually see the plastic is cracked there. It goes about half way around...so it is not as bad as the picture above. Every time you disconnect the expansion tank and pull it back, it is THIS point exact point where all the strain occurs. There has to be a better way to change the oil and get the expansion tank out of the way.

 

Air has a much less density than water. In your case, you already have a major leak or several according to some of the statements you made. In this case, as long as the system is not completely sealed and open to atmosphere, then no matter what air you pump into the system, air will tend to travel up above the water level. If the coolant level in your system is currently under that pipe which has a leak, then when you pump air into the system, air will come out of that hole. This is also how the bleeder location works. At operating temperature in a sealed state, all of the fluids will be pushed past the bleeder screw location, making it the highest spot where air can accumulate. And so when you're filling up coolant and bleeding it off for air pockets, that's where it'll exit.

The place where that T-joint breaks according to your previous finding, its height is pretty near the bleeder screw location, that's why I suspect where all the air will be, even if you pump air into the reservoir. Now, if you were to fill the reservoir full with coolant and then pump that air, you may then see coolant seeping out along with the air you pump.