Mysterious loss of coolant....looking for ideas please

[redwagon]

So I'm looking for a list of things to check.......I'm currently losing coolant at a rate of about 2-4 ounces every 100-150 miles. Essentially if I top it off at the lower mark on the expansion tank indicator, after 100 miles or so it has sunk down so the top is flush with the lip of the tank.

1. I pressure tested (cold/cool engine) and no loss of pressure at 15psi.
2. Looked for stains and cant find anything anywhere of significance.
3. Its not getting worse, a stable rate of loss so far.
4. Only cooling related issues- water pump was replaced about 5K miles ago, and a couple weeks ago I replaced coolant and inspected for any indications of leaking. The 04 ZHP has about 64K total.

I'm thinking perhaps to pressure test when its hot, but that would entail hooking up the pressure tester when cool and getting it hot I assume?
The coolant tank cap is original AFAIK, might replace that but I dont see stains around that. Hoses all look good and no evidence of leakage, but I know at some point soon I know I need to do the major cooling system overhaul, but I want to know the offending part first.

What else to do?.......I dont want to have a small leak suddenly turn into a gusher at a bad time for obvious reasons so trying to get to the bottom of this.

Tim

[ZHPRegistry.net]

The cap is a REAL possibility. When the car is fully warmed up, how tight are the rubber hoses when you try to squeeze them?

[zj96sc]

what does your oil look like?

[telijah]

Your plan of action seems pretty spot on. You'll want to check things while hot as you know, thats when things start expanding and such. The concerning part is you cannot find the signs of the leak, which is likely like it was suggested to check your oil. If coolant is getting into your oil, it may not be a cheap fix.

[danewilson77]

On my old 325i it would only leak when hot. I had these same indications. I think it was due to crack swell when warm. Would the crack below hold 15 psi when cold?.....dunno.

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/DSC02730sz1200-1.jpg

[kayger12]

I'd be taking a hard look at the cap and expansion tank.

[Sockethead]

My 325 coolant loss was due to a cracked head. I could tell that's what it was because the coolant smelled like exhaust. there were no other tell tale signs...

[LivesNearCostco]

In your case did the exhaust also smell like coolant?

Edit: Right before I bought my car, we discovered a very slow coolant leak from one of the radiator end-tanks. But this was at 135,000 miles, so it's not likely to be the cause at 64,000 miles. Still I suspect it was similar to that ET crack... something small that only seeps when hot. Mine was diagnosed because there was dried coolant on the side of the radiator. You could only see it from under the car with the plastic undertray removed.

[Newjack]

I'd be taking a hard look at the cap and expansion tank.

+1
It may have cracked somewhere underneath the expansion tank so you wouldn't necessarily see it. Also a very common failure on the E46.

[ranger]

+1
It may have cracked somewhere underneath the expansion tank so you wouldn't necessarily see it. Also a very common failure on the E46.

Yep - I had that happen with my 325.

[Sockethead]

In your case did the exhaust also smell like coolant?

No... it appeared that the cracked head was actually pushing exhaust into the cooling system. My case was extreem.
There are two dye tests: one tests for exhaust in the coolant tank and other tests for external leaks using dye and an ultraviolet light... I never priced any of these out...

[Hornung418]

My coolant light came on again...The only thing I replaced was the thermostat gasket. I'm not really sure where I need to begin. I'll be getting a pressure test next. It's much slower than the one previously...I have put almost 500 miles on the engine since the fix. I swear to god if this is a head gasket I will have no idea what on earth I need to do. Not gonna be a fix for the winter.

[redwagon]

Thanks for all the good thoughts, ideas, and validation! You guys are great.
The oil and coolant both look and smell great, and no excess steam from exhaust etc. Hoses all look good and feel good. I'll get a cap and get out the inspection mirror and maybe borescope to look around the expansion tank which I agree is a likely offender...and perhaps start collecting parts for the cooling system overhaul. As well as pressure test hot. I really dont want to start shotgunning the problem, ie its best to find the smoking gun and then expand the scope of repair rather than just replacing pieces until its fixed.
Keep the ideas coming-
Tim

[aurelius]

1. Tank
2. Temp sensor in lower radiator hose

[aurelius]

Here's a leaky temp sensor in the lower cooling hose:

http://i1125.photobucket.com/albums/l584/aurelius3/Random%20BMW%20Pics/tempsensorleak.jpg

[Sockethead]

Here's a leaky temp sensor in the lower cooling hose:

http://i1125.photobucket.com/albums/l584/aurelius3/Random%20BMW%20Pics/tempsensorleak.jpg

Looks like a simple o-ring replacement on the temp sensor would fix that instead of replacing the whole sensor, yes?

[danewilson77]

Ooo...I have those o-rings. I can throw one in an envelope...

[redwagon]

Might be interested.....need to find some time to work on things a bit more!

[danewilson77]

Might be interested.....need to find some time to work on things a bit more!

OK....lemme know.

[JohnnyGraphic]

At your mileage, it would be wise to consider doing a full on cooling system refresh. I did mine at 70k and thought my system was leak free. Wound up finding that I had a smidgen of coolant leaking from the weep hole on the front the of water pump. Since the coolant leaks down to the backside of the pulley (and is completely covered by the pulley), it would fling all of the coolant off and it wouldn't show any obvious signs of a leak. The only way I found out, was when I pulled the pulley and the water pump. Saw the signs of the coolant leak then.

27862785

Johnny

[Meric]

My dealer qouted me $177 just for the expension tank part.

[aurelius]

ECS Tuning sells a Meyle expansion tank for $50. I think their free shipping threshold is $75.

[danewilson77]

My dealer qouted me $177 just for the expension tank part.

Cough, cough.

[LivesNearCostco]

But that's Canadian $, which today means about... $171 USD. Tell the dealer the ET is made of plastic; plastic is made from oil; Calgary is near the Canadian tar sands; ergo the tank should only cost you $60 CAD. Ignore the fact that the tar sands need to go to a refinery somewhere then be shipped to Germany then have the ET shipped back to Canada. That kind of reasoning is too complicated. Should be... near raw materials, gimmie discount!

On the other hand, all the Alberta oil patch money might be driving up prices in your neck of the woods.

[Meric]

ECS Tuning sells a Meyle expansion tank for $50. I think their free shipping threshold is $75.

I'll go with oem I don't want to deal with it again. Thank you aurelius i think im going to get the oem one from the ECS. :)


Cough, cough.

Yes i know :) I asked 3 times just to make sure. :D



But that's Canadian $, which today means about... $171 USD. Tell the dealer the ET is made of plastic; plastic is made from oil; Calgary is near the Canadian tar sands; ergo the tank should only cost you $60 CAD. Ignore the fact that the tar sands need to go to a refinery somewhere then be shipped to Germany then have the ET shipped back to Canada. That kind of reasoning is too complicated. Should be... near raw materials, gimmie discount!

On the other hand, all the Alberta oil patch money might be driving up prices in your neck of the woods.

They probably wont change the price :D

[aurelius]

Worth reading. How to remove the expansion tank without breaking anything:

http://blog.bavauto.com/10737/bmw-m54-radiator-coolant-expansion-tank-removal-how-to-e46-x3-x5/

[danewilson77]

Worth reading. How to remove the expansion tank without breaking anything:

http://blog.bavauto.com/10737/bmw-m54-radiator-coolant-expansion-tank-removal-how-to-e46-x3-x5/

Idk if that's a help or not. Disconnect hoses then pull up?

What am missing that makes this easier (less hard)?


HTC Thunderbolt+TT

[echo46]

Yea, be careful removing the expansion tank. Be patient and just try to wiggle and gently but very forcefully pull off the hoses at the top of the tank. Then you may need to gently tap the bottom of the tank with a socket and rubber mallet to get the thing loose. Oh and be ready to get coolant in your face. I also had an issue when I went to put the new tank in. The top hose did not correctly fit so I had to get a replacement Behr tank.

[danewilson77]

Here's another option...

http://www.zhpmafia.com/forums/showthread.php?5738-BMW-E46-330i-ZHP-Expansion-Tank-Removal-Made-Easy

[MrMaico]

Here's another option...

http://www.zhpmafia.com/forums/showthread.php?5738-BMW-E46-330i-ZHP-Expansion-Tank-Removal-Made-Easy

+1 That's how I did mine. After I had the tank and frame out I hit the connection of the two with some WD40 and it popped right apart. Like Static mentioned though, the top screw is a little tough to get at.

[danewilson77]

Got this kit last week...for $10.00. it kicked that lil screws ass.

http://www.lowes.com/pd_338552-22328-85232_0__?productId=3387782&Ntt=torx&pl=1&currentURL=%2Fpl__0__s%3FNtt%3Dtorx&facetInfo=

http://i1015.photobucket.com/albums/af278/nicee46/Maintenance%20and%20Misc/099198852324xl-1.jpg

[echo46]

Nice

[Meric]

Question. I'm still not sure if the leak is from the expension tank. Do I need to take off the airbox and then see whats what? Is that the only inspection style?

[kayger12]

Question. I'm still not sure if the leak is from the expension tank. Do I need to take off the airbox and then see whats what? Is that the only inspection style?

Yes and no. A lot of times the expansion tank will only leak when the system is pressurized- so when the engine is off and you take the air box out, you still may not see any leak.

Ditto for the tank cap, which is another common failure item.


Droid X. Tapatalk. Use it.

[danewilson77]

Jack up car... Remove splash panel, and look "up" at cooling components for white residue.

Another way to identify leaky cooling components.

HTC Thunderbolt+TT

[3ZHP]

I had a similar problem last year about this time of the year. i was working crazy hours and couldn't afford to be without the car so I did the Dealer rout. They did the pressure check and found a bad water pump. Once they found it, they let me into the shop to talk to the tech. He had everything off the front of the engine right down to the water pump were you could see the trickle from the vent hole under pressure. Note the only way he found it was to remove the belts and the pulley.

This was one of the greatest experiences I have ever had with a dealer and I never paid more the the $70.00 quoted for the check. I told them I had just done the same job on my Wives 325Cic a few months earlier and could do it my self. They said no problem and buttoned up the car and put the new parts in my trunk. I preceded to do the job myself the next weekend with the help of my son.

Note: I have also been told after I used OEM that Stewart water pumps are the best replacement for BMW. http://www.stewartcomponents.net/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=BMWHPWP

This is only one of the reasons why I so highly recommend Ganley BMWs service department. These guys are fantastic.

Good luck and check for my water pump replacement DIY in the maintenance section.

[redwagon]

Hey just an update to my original thread.........
Amazingly my leak stopped. No coolant loss in the last 400 miles. Also, I purchased the adapter so I can pressure check my system and it holds pressure. Ugh.....I also bought all the parts, but without knowing what the guilty part is I dont want to tear into things. So I'll just monitor closely for now and when I have a spare weekend will just dive in and replace all I can......
BTW, good post earlier on the slight leak from the water pump. My pump was replaced about 20K ago, so hopefully thats not an issue.
Tim

[Meric]

I hope mine is just the expension tank... Still has to pay $177 just for the tank.

[danewilson77]

I hope mine is just the expension tank... Still has to pay $177 just for the tank.

Wut?

HTC Thunderbolt+TT

[Meric]

My leak problem. lol I hope it's just the expension tank

[das boots]

Meric...what are you symptoms or how do you know you are loosing coolant fluids? Just inquiring.....

[az3579]

You're getting bent over on the price of that expansion tank, Meric. :eek

[danewilson77]

You're getting bent over on the price of that expansion tank, Meric. :eek

That's what I was trying to get at...I guess.

[Meric]

Meric...what are you symptoms or how do you know you are loosing coolant fluids? Just inquiring.....

Right now i dont think its the expension tank. The leak is coming from right side of the car right beside the front passenger side tire. (approx) I got the low coolant light came on, on the dashboard. I see water spills on the ground too. Also put fluid at the dealer they said yes the coolant level was low but i didnt do any inspection. Is it just the hoses?


You're getting bent over on the price of that expansion tank, Meric. :eek

Haha i earn more than that in an hour. But yes it hurts me to pay that much money on that stupid plastic tank.

[danewilson77]

Temp sensor oring?

HTC Thunderbolt+TT

[das boots]

Right now i dont think its the expension tank. The leak is coming from right side of the car right beside the front passenger side tire. (approx) I got the low coolant light came on, on the dashboard. I see water spills on the ground too. Also put fluid at the dealer they said yes the coolant level was low but i didnt do any inspection. Is it just the hoses?

Haha i earn more than that in an hour. But yes it hurts me to pay that much money on that stupid plastic tank.

Can you provide pics of the area(s) in question?

[LivesNearCostco]

+1 to what Dane said, temp sensor O-ring or lower radiator hose connector. Lesser chance is plastic end tank on radiator. Otherwise the only source or blueish fluid over there is the windshield washer reservoir!

[Meric]

Will post a picture of the leak and no its not the windshield washer. I got the light came on, on the dashboard. It's the coolant. Is it hard to replace? Orings? or Hoses?

[danewilson77]

Will post a picture of the leak and no its not the windshield washer. I got the light came on, on the dashboard. It's the coolant. Is it hard to replace? Orings? or Hoses?

Nothing over there is tough to replace, unless it's tia radiator.

HTC Thunderbolt+TT

[Newjack]

Will post a picture of the leak and no its not the windshield washer. I got the light came on, on the dashboard. It's the coolant. Is it hard to replace? Orings? or Hoses?

It isn't very hard to change out the temp sensor if that is where the leak is. You might just want to throw in a new lower radiator hose depending on the age of the one you have in currently.

Correct me if I'm wrong but I'm pretty sure the temp sensor comes with a new a new o-ring. They are $30 from pelican parts. Again I don't know the age or mileage of your cooling system, but if its old you might as well just get a new lower radiator hose and temp sensor.

http://www.pelicanparts.com/cgi-bin/smart/imgdsply.cgi?pn=13621433077-M9

[Meric]

Nothing over there is tough to replace, unless it's tia radiator.

HTC Thunderbolt+TT

xD Again my dad says if it was the radiator car would overheat real fast but i drove 200km yesterday (I know shouldnt do) Temp needle didnt even move an inch from the normal position.


It isn't very hard to change out the temp sensor if that is where the leak is. You might just want to throw in a new lower radiator hose depending on the age of the one you have in currently.

Correct me if I'm wrong but I'm pretty sure the temp sensor comes with a new a new o-ring. They are $30 from pelican parts. Again I don't know the age or mileage of your cooling system, but if its old you might as well just get a new lower radiator hose and temp sensor.

http://www.pelicanparts.com/cgi-bin/smart/imgdsply.cgi?pn=13621433077-M9

I dont think PO ever changed anything on the coolant its probably aged out. Car has 107k km on it.

[Meric]

http://img825.imageshack.us/img825/6831/img0571wg.jpg
As you can see right side of the car.
http://img683.imageshack.us/img683/2800/img0572zb.jpg
http://img32.imageshack.us/img32/9413/img0573jz.jpg
http://img69.imageshack.us/img69/6978/img0574u.jpg
under the car.