How much coolant loss is normal

[cyberman]

I'm definitely losing coolant, slowly. Filled to max line (about halfway up the radiator) and I'd guess it's going down a notch every 500 miles. I put in dye and can't find the leak with a UV light. There may be some indication of steam out of the bleeder since there is a little build up of dye, but that may be some slop from filling. I noticed threads mentioning replacement of the plastic bleeder with brass - is this the reason why? Note everything coolant-related has been replaced including the radiator and water pump, thermostat housing, etc.

I'd like to pressure test, but that means buying a $55 adapter in addition to the tester and it may be more cost effective to bring it to the Indy, but I have to wonder if such a slow leak will show up that way - any thoughts?

Off topic, I joined the BMW CCA as we have a local chapter and it's active. Going to a social tonight at an outdoor eating venue and a scenic ride Saturday. I'm wondering if I'll fit in. Some of the profiles on the site show ordinary enthusiasts with older cars, but there are many with gobs of money who love the dealer. I hate the dealer, but will keep my mouth shut. I'm wondering if I'll have the oldest car in the group and if they'll think it's an old piece of junk and if my bad luck holds I'll break down on the scenic ride.

[pine1000]

You can borrow a pressure tester from most local auto parts stores like Advance Auto for free (as long as you return it). I used one to find a slow leak in my cooling system.

[cyberman]

Thanks didn't think of that, but what are the odds they have the BMW adapter? I'm looking at an adapter on Amazon, says:

• Applicable for 1988-2005 BMW except new 3, 5, and 6 series

That's pretty specialized for AutoZone, but I'll take a whack. Why does BMW make everything hard? Why can't all the automakers just standardize these things? Before I traded my Suzuki, a control arm needed replacing and it turned out it was the same part used in a Toyota Corolla. That's smart thinking. Everyone has to reinvent the wheel.

pressure tester adapter.jpg

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Update: FCP Euro lists the adapter for $30. Hmm... I'll buy it and then borrow an AutoZone tester.

Attachment 679544

[Schreier]

I second the cooling system pressure tester. It's sometimes a hassle finding the exact right coolant cap for the testing rig, but it's well worth it. I did this during my own cooling system replacement, and found that I hadn't secured the coolant hoses to the heater core properly!

Also the heater core is an element that could leak, and you wouldn't necessarily be able to tell by poking around from under the hood: https://www.pelicanparts.com/BMW/tec...eplacement.htm

Are you noticing any residue around the coolant overflow tank?

As for the BMW club, give it a shot. I don't go to their regular meet-ups, but only because of a lack of time, and I do run into them at other events around town. If they are like mine, they are a mix of older and newer cars and generally are good folks who love all of them.

[BimmerBreaker]

Zero amount is normal

Pressure test it. Harbor freight sells a pressure testing kit with a bunch of caps including one that fits BMW for about $60

Also NEVER use a brass bleed screw. Its designed to be softer than the expansion tank it screws into. Would you rather strip a $5 plastic bleed screw or use a brass bleed screw to strip the $60 expansion tank?

[delvec]

I went to Autozone a couple a months ago for a loaner pressure test kit. It comes with the BMW cap in the kit.

[cyberman]

Are you noticing any residue around the coolant overflow tank?

There's a little line of dye around the top seam of radiator about from the bleeder screw location to the corner next to the reservoir. Again, maybe a little spillage from when I introduced the dye. It's very hard to get off since it's hardened in the crack. I'll get in there tonight with my UV flashlight and an inspection mirror.

Also the heater core is an element that could leak

I know, my worry... But the job doesn't look that bad as long as I can get new bushings. Also, nice opportunity to delete that heavy knee bolster. I've also got a new heater solenoid - so if all else fails, another winter project.

I went to Autozone a couple a months ago for a loaner pressure test kit. It comes with the BMW cap in the kit.

Thanks, but don't trust my local AutoZone and already order the adapter. Hell, what's another $40 towards this project - just a drop in the bucket.

Zero amount is normal

Pressure test it. Harbor freight sells a pressure testing kit with a bunch of caps including one that fits BMW for about $60

Also NEVER use a brass bleed screw. Its designed to be softer than the expansion tank it screws into. Would you rather strip a $5 plastic bleed screw or use a brass bleed screw to strip the $60 expansion tank?

Thanks, I could live with a pint every year. And bleeder screw - when I was bleeding the system, that was my question - is it stripped or not tightened enough? Hard to tell and wish I could find a better alternative.

[BimmerBreaker]

just a drop in the ocean

Fixed that for you based on how much money Ive watched you spend

[cyberman]

One other thought on this: there's always the possibility of a head gasket leak. I hooked up INPA and never saw such perfect smoothness - all four cylinders ran at 65 and 66 consistently with coolant temp at 30 deg. C and in the past the readings always smoothed out eventually by operating temp, but now the readings are perfect at well below it. Now, I suppose there could be a tiny internal leak still, but that thing is ticking like a little clock.

[pine1000]

I've rented tools from autozone a few times and they are actually pretty good quality. They have been at least on par with harbor freight and it's a free rental.

[Vintage42]

I'm definitely losing coolant, slowly. Filled to max line (about halfway up the radiator)....

This post made me look at my coolant. In 2015 at 42,000 miles, I had every part of the cooling system replaced. I must have added coolant since then, because I have an empty 16 oz. water bottle marked BMW 50/50, but can't remember. I never think about the coolant.
Today at 51,000 miles, I found the coolant was at the very bottom of the reservoir. So I made some more 50/50 and brought the level up to Max. I looked at the hoses and engine with an LED spotlight and everything is dry.
On my 2008 Forester, I do watch the coolant because its engine can have head gasket leaks, and the coolant does drop less than an ounce per thousand miles. However, its engine is also dry, and four years ago at 50,000 miles I did have the entire cooling system replaced, and the head gaskets replaced with multilayer steel, preemptively as the OE composite gaskets that came out were still perfect.
My experience with the Z3 and Forester is that a small amount of coolant use or loss may be normal over time.

[z3forlife]

Or this could be just a slow burping of air left over from the cooling system swap ?

[Pat Gautier]

Having just done this myself, I opted for a aluminum t-stat housing and they are prone to leakage. If you did same and have a small leak it could be obscured by the pulleys and such on the front of the block. You would have to look from underneath.
As to your question on BMWCCA, i have been to local events in two different states and I’ve seen all types. Pristine classics and beaters plus the high-dollar just off the showroom. Probably a bit clicky but usually you can find someone you can relate to.


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[Vintage42]

... I opted for a aluminum t-stat housing and they are prone to leakage. If you did same and have a small leak it could be obscured by the pulleys and such on the front of the block. You would have to look from underneath...

I used OEM plastic parts. And with a short 1.9, with no fan on the engine, and the intake crossing over the radiator permanently removed, there is about 9 inches clear space between the engine and radiator for viewing the pavement or any leaks.

[cyberman]

This post made me look at my coolant. In 2015 at 42,000 miles, I had every part of the cooling system replaced. I must have added coolant since then, because I have an empty 16 oz. water bottle marked BMW 50/50, but can't remember. I never think about the coolant.
Today at 51,000 miles, I found the coolant was at the very bottom of the reservoir. So I made some more 50/50 and brought the level up to Max. I looked at the hoses and engine with an LED spotlight and everything is dry.
On my 2008 Forester, I do watch the coolant because its engine can have head gasket leaks, and the coolant does drop less than an ounce per thousand miles. However, its engine is also dry, and four years ago at 50,000 miles I did have the entire cooling system replaced, and the head gaskets replaced with multilayer steel, preemptively as the OE composite gaskets that came out were still perfect.
My experience with the Z3 and Forester is that a small amount of coolant use or loss may be normal over time.

Funny, a thread reminded me to look at tire pressure recently, which led to another $200 expenditure for a super-quiet air compressor. But, I agree a small amount is expected over time, if nothing else, the steam will go right through the rubber, just as air gets lost from tires. The technical term for it escapes me (no pun intended).

it's a free rental.

I had a bad experience with their fuel pressure test set - nothing would fit the schraeder valve. But as long as I have my FCP-supplied adapter, I should be good. Not sure what to do with it - long term test? Look for liquid? Just verify if pressure doesn't decline? How to check for head gasket leaks (internal)? It's a new world to me.

Having just done this myself, I opted for a aluminum t-stat housing and they are prone to leakage. If you did same and have a small leak it could be obscured by the pulleys and such on the front of the block. You would have to look from underneath.
As to your question on BMWCCA, i have been to local events in two different states and I’ve seen all types. Pristine classics and beaters plus the high-dollar just off the showroom. Probably a bit clicky but usually you can find someone you can relate to.

Mine's new plastic. What you said about the chapters is what I'd guess. Every group has clicks - that's just human. I find as I get older and move to a new place, its harder to find friends. Locals have all the friends they need, sometimes going back to childhood. Likewise, people who've been in a group for a long time establish their friend circle (click). So, my expectations are low, just hoping for some interesting conversation.

I used OEM plastic parts. And with a short 1.9, with no fan on the engine, and the intake crossing over the radiator permanently removed, there is about 9 inches clear space between the engine and radiator for viewing the pavement or any leaks.

My intake tube is deleted but I still have both fans. With the dye marker - I did get a neat inspection mirror set on Amazon cheap and am impressed with it: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 Those magnets picked up a lot of stuff during my overhaul, stuff I could definitely never pick up any way. The lighted mirror isn't too useful since the lights glare at you when the mirror is positioned to reflect to you, but I may figure out a way to deflect their light a bit. So, maybe UV light plus mirror will tell me something. The plastic coolant tube on the side of the engine under the manifold really worried me when I put it in because it seemed to cock at an angle and did I get all the old o-ring debris out? The only way to inspect it without taking the intake off again is with a mirror. And, if it is a slow leak there, I'll live with it since its cheaper to replace coolant, even over the long haul than to get into that nightmare again (remember the sliced injector o-rings?)...

[Vintage42]

... I did get a neat inspection mirror set on Amazon cheap and am impressed with it: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 ....

I wish I had found that thirty years ago. I have accumulated everything in the set except the light, but it's a rag-tag collection of junk that probably adds up to more than the cost of the set.

[BimmerBreaker]

Rubber hoses should not allow coolant seepage. Rubber is not porous in that way

Silicone hoses, however...

[cyberman]

Rubber hoses should not allow coolant seepage. Rubber is not porous in that way

Osmosis: see https://www.tirereview.com/why-do-ti...ss%20of%20air.

It's pressure and temperature dependent: the air molecules slowly migrate from higher pressure (inside the tire) to the atmosphere. Same principle as permeable membranes using in water filtration, albeit much more slowly. Likewise, and it would be so miniscule as to be barely measureable, same principle applies to rubber hoses containing steam. The air would migrate and to a much much lesser extent even the larger water molecules. But, I shouldn't have mentioned it - too small to consider.

[cyberman]

Pressure test it. Harbor freight sells a pressure testing kit with a bunch of caps including one that fits BMW for about $60

To finish this, I finally got around to pressure testing as the dye didn't tell me anything. BimmerBreaker was right and I should have listened. The adapter I purchased from FCP Euro, while they said it would fit, didn't. I looked at the fitment and they actually listed no specific models so I think their application algorithm got messed up. However the $250 "loaner" from Autozone did have an adapter that worked. Same thing is available from Walmart for $150, but I'll just buy the Harbor Freight kit if I ever need it again.

Now, I bitch when threads are left incomplete and future readers waste time reading them with no solution. So, to review, after installing everything cooling-related new, I had a slow loss of coolant. I put in dye, but was unable to home in on it. Today, I set up the pressure tester and brought it up to 20 PSI (maybe a tad high, but in testing I learned to push things a little to ensure they'll work under normal conditions).

After fooling around with my UV light and a mirror, I couldn't see any leaks on that back pain in the ass plastic fitting that started my whole escapade. That took a while and by the time I got back around to the front I spotted my first and major leak. It was from the hose clamp on the small heater hose that runs from the PITA fitting in the back and heats a plate attached to the intake manifold. It was dripping badly, and in the dark under a UV light the puddle under the car glowed a fluorescent green, like Mr. Spock's blood. There were some tell-tale splatters glowing on the nether parts of the engine where the sun doesn't shine and perhaps I missed them when I checked.

So, I brought the pressure back to 20 PSI, and waited, dealing with a squable between a feral cat I've befriended and a neighbors cat who kept crying that he wanted in since it got pretty cold by this time. By the time I got back to the car, it had lost pressure again. It turned out I had leaking on both big radiator hoses going into the thermostat housing, albeit much more slowly and solved by tightening the hose clamps. I tightened the rest of the hose clamps I could reach and it's holding for now, but TBD what tomorrow morning will bring.

What happened? My past experience tripped me up: Last time I tightened a hose clamp on a new hose was maybe the early 80's. Since then, the wall thickness has increased and a softer compound is used. Thus, I didn't know how much tightening was needed. In spots where I knew it would be hard to reach after assembly, I closed my eyes and tightened to what I thought may be overtightening. I feared I was literally cutting right thru the rubber with the sharp edge of hose clamps, which I confess I've done decades ago trying to fix an old hose with extra tightening. But, I left the exposed hose clamps less tightened. And sure enough, they were under-tightened but "mostly" held initially.

With a 50 degree drop in temperature the rubber naturally contracted a bit, but I also know from a class in deformable body mechanics (no jokes..), the when put under compressive stress, all materials will deform and its initially at a higher rate, and in this case, "deform" means the rubber compresses under the hose clamps and, to some extent, flows out a bit from under the clamp. That extent is tiny, but it does occur and would contribute to a loss of compression too. Everything gets worse under pressure, deformation and leaks are no exception. Add time and temperature, and eventually a slow leak will get worse. I knew it was worse when I checked the last couple of hundred miles of coolant losses and the pressure test just added to the faults and made them obvious.

Now I still don't have a good feel for it. But the hose clamps definitely needed tightening as they were easily tightened. I just have to develop a better "mechanics feel" for this as I could find no torque recommendations on hose clamps. Lessons learned:

1. Tighten the hose clamps more than I did initially (admittedly a personal conclusion). Don't go crazy, but don't wimp out either.
2. Go back after a thousand miles (300 - 2000) and retighten clamps, especially if any loss of fluid is detected (maybe ignore losses in the first few hundred miles to allow for system self-bleeding).
3. Control paranoia, it's probably not a bad new water pump or a bad new radiator, and, my worse fear, a leaking head gasket.
4. Dye is great, it will tattletale leaks where the traces can be seen, but nothing beats pressure testing!

[saneesh8]

Those water pipes are the worst . Please see https://www.bimmerforums.com/forum/s...-DIY-with-pics

[cyberman]

Those water pipes are the worst

Thanks, I did everything coolant-related this summer, including the water pipes. The only thing remaining is the heater valve/solenoid which I have in my stock. So, this morning I found pressure dropped overnight from 20 PSI to 19 PSI and noticed (or renoticed) a puddle directly under the water pump, as well as on the inside side of a belt near it. So, before I return the pressure tester, I'll jack it up and see what's going on from the underside. I'll post findings here later.

[cyberman]

Long term testing commence! No evidence of leaks than what I found yesterday when viewed from underneath so it's all buttoned up and we'll see if there are no losses over time.

Aside(s): Next job, fix the door rattle - it's coming from the bottom when the window is down and the top when it's up, on the rear side of the door. Regulator? And a couple of cheap 5.25" speakers for the kick panels, just to hold it at bay until we dive into a complete audio restore. In 1972, late in the evening when the garage was quite (no gas customers), I used to read the JC Whitney catalog. It was thick with plenty of goodies and I remember all kinds of molding one could attach to the doors to keep dents at bay. I can't remember the terminology, "bumper guards", "door guars", whatever. If I can find 4" stuff, I can extend the line from the side cowlings back to the door handles and most of my dents would be gone (covered). Not sure if it would look weird though. Nowadays that stuff is hard to find. This site has a few items such as this: https://www.brandsport.com/trmg-99ct-02-01.html but that's even weirder than plane black I was looking for. The problem is mostly in the width, plenty of narrower items though.