BMW cooling mystery!

Factual Questions
1

I’m posting this on The Dope also, as I anticipate less than timely and helpful results from the “proper” forum, as outlined in my old thread about other message boards sucking ass. Feel free to look it up. Any way, here we go…

1989 BMW 325i (e30), 186k miles, ran pretty good considering the hard life its had. It broke a rocker arm, but instead of just fixing that, I decided to swap the head with a good one (I just happened to have sitting around), replacing the head gasket (guy who gave me the car years ago suspected it was bad, but I’ve been driving it for a while with little/no problems) at that time.

Anyway, the job went pretty smooth and got it all back together, but the cooling system ain’t right! I’ve tried to bleed it 15 different times and ways, but it still gets hot. I’ll fill up the system, bleed it and it will run correct for about 5 miles, heat blowing nice and hot. Then, the heat starts to get cool and the temp gauge will slowly creep up. Done this over and over with no success. Shut the car off, open the bleed screw in the thermo housing and you got steam. I’ve had the hoses off this thing several times before and never had this problem. Always bled and worked like a charm. Well, duh! Its got to be the head gasket/head repair gone wrong!

Here is the mystery part: Where is the water going? (only using water right now to test for leaks and problems. Once I had everything correct, I was planning on going with 50/50) System holds pressure, not getting water in the oil, no Old Faithful steam geysers or obvious leaks. Is it somehow getting out the exhaust as steam? Wouldn’t that eventually get into the oil? Wouldn’t it run like doo-doo?

I guess I know the obvious answer. My head gasket installation has gone wrong, but that’s the answer I don’t want to hear. I ran a compression test, and although not super, the figures are higher than before the head swap, and consistent on all six holes. Am I missing something else? Is the water pump crummy and not circulating enough? If so, how did it work before? Or does it just take forever for coolant to get through all those tiny holes in the new head gasket? I reject that as an answer!

Bad mechanic, stumped! Ignorant technician, befuddled! Sometimes I think I don’t deserve a BMW.

Thanks, Usual Suspects!

2

My guess is that it’s you’re not filling it up with water all the way. If there’s pockets of air in the cooling system you’ll get wonky things happening with the temp gauge and cabin heater.

If it were my car, I’d do two things. First, hook you’re pressure gauge up to it and see if it holds pressure over night. Click and Clack might even recommend doing hooking it up when the car is hot since cracks that show up when the block is warm might close when it cools back down. Either way, I’d leave it on for hours or a day since that’s how long it might take for a leak to show up on your gaute.

Second, if it’s not leaking and you’re not getting white ‘smoke’ out the tail pipe, I’d assume it’s never getting filled properly. Squeeze the hoses as you’re filling it. Run it with the cap off until the t-stat opens and it’s circulating and see if the level drops. Each time you drive it, after it cools, open it and see if you can top it off and see if maybe it eventually stays put. On top of that, I’d poke around on the internet and see if other people with my car have had similar problems.

Or, you just have another bad gasket.

3

Instead of driving the car to warm it up just let it sit and idle with the cap off. Bleed as you would normally and keep topping it off even after the thermostat seems to have opened. Do this until it is completely warmed up and not taking any water. If the water in the radiator is not getting as hot as the water in the engine you may have a bad thermostat or installed it wrong somehow. You need to fill it as you bleed it.

4

I agree it probably would. But if coolant is mysteriously disappearing just after the head & its gasket have been replaced, it’s awfully tempting to believe it’s found a way out the exhaust pipe.

I’d look at removing & reinstalling the head, with a new gasket.

(Note that this is based on the assumption that you really are losing coolant.)

5

My first Porsche was a 924, which was liquid-cooled. It was overheating and losing water. Turned out to be a warped head.

6

I agree with Joey about not getting it full. I spent over 40 years in the industry and this was by far the most common thing guys would run into after draining a cooiling system. The system is holding pressure so chance are it is not leaking. Use the filling technique I suggested above.

7

Have you kept track of how much coolant you’ve put in the thing? That could disprove the “simply not full” theory.

I’d second HoneyBadgerDC’s suggestion of letting it idle without a cap and topping off as needed also keeping a close eye for the telltale exhaust bubbles in the coolant. Also, are you filling it directly into the radiator, or into the reservoir? One small possibility is if you’ve got a leak in the overflow line, the thing could be puking out coolant only when you’re driving, which you might conceivably not notice. If the coolant level in the radiator isn’t going down while idling with the cap off, try putting the cap back on and idling it some more. Hopefully if you can get it to overheat in the driveway you can see where the coolant is going.

Otherwise, unfortunately not all headgasket issues are accompanied by billowing clouds of smoke out the tailpipe so that’s a very distinct possibility. A compression test would probably be my next step.

8

I recall once from Click and Clack - that the engine (or the cooling compartment) was higher than the radiator - thereby the air trapped in there had no chance of getting out even if you followed HoneyBaggerDC method. Please check into this - and if this is indeed the case - then jack up the front of the car until the radiator cap is the highest point in the water loop and maybe run it for a few minutes.

Good luck

9

I know its getting full. Gone to great lengths to make sure. Jacking the nose waaay up, rigging up an extra hose that sticks up about 2 feet with a filler at the top, etc. etc.

As for your second point, see my previous rant about “other internet sites”. I am a member of 2 BMW sites and get shit for responses.

The rational side of me knows I’m gonna have to redo the whole job. :frowning: But for one final test, I’m going to pour actual anti-freeze into the block and try this again. I predict I’ll be smelling it out the exhaust.

I’ve runs gallons of water thru this thing at one time or another. :smack:

Why I’m stumped (not really, I think I know I fucked up the gasket install) is that it will work correctly after bleeding the system for a few miles, or a long while in the driveway, then get hot without leaking on the ground!

Its gotta be going out the exhaust then, but why isn’t there water in the oil or oil in the water?

Did a compression check. About the same as pre-head removal, and consistent on all 6 holes. Its kinda low, but the car has a lot of hard miles.

I’m slowly coming to term with the fact I’m a shit mechanic, and need to do every job 2-3 times before getting it right.

10

Try filling it as suggested, and don’t stop filling it until hot water is circulating through the radiator. You might be filling it,blowing it out and then filling it agian, just be patient even if it takes 30 min.

11

Because the leak is directly into the cylinder. A small leak might not even show up on a compression test, but will still blow exhaust into the coolant.

If you fill the radiator to the top, and run the car, do you see bubbles coming out of the top of the radiator? If so, that’s a good indication you have a bad head gasket.

12

This is true. Standard procedure is get the front end high. But the e30 has no radiator cap, so you need to use a bleed screw.

I came up with a crazy way to create my own “high spot”. I used an extra radiator hose, turned straight up, coupled it to the original one hooked to the thermostat housing and filled from the top. This way, I’m able to fill from either side, making sure its full. (I installed an “open” thermostat for this test, so water flows through the entire system freely)

With this set-up, I can pour water into the radiator side, and water will eventually come all the way up the other hose and pour out, and also the other way around. Then I hook the hose up, top off and seal. It will run like this for a long, long time!

Problem is, the junction I used was stinkin’ PVC and eventually failed under pressure! :smack:

I was hoping I had actually eliminated all air pockets and succeeded, but I think I’m fooling myself. I think I just added extra water and allowed it to run longer before boiling out enough water to get hot. :frowning:

13

I’m too embarrassed to admit I’ve been trying this a couple hours a day for over a week now! :smack:

I’m such a dork.

14

No radiator cap, but not seeing bubbles out of the bleed screw or overflow tank (where you have to fill from).

Like I say, I’m gonna dump some anti-freeze into the block and I bet I’m gonna smell it coming out of the exhaust, confirming my (our) suspicions of a bad gasket installation.

I wanna get Overhauled!

15

Oh, so I missed on the first readthrough that you’re using straight water. Have you tried using coolant since you’ve had the car back together? You can get away with running straight water on some cars, but on others the coolant routinely runs hotter than 212F and so you get steam in the system, which creates all the same problems as having air in the system. Also, with a suspected head gasket problem, if just straight water is getting into the cylinders it’ll be basically undetectable-- it’s the antifreeze that makes the smoke visible (and smellable).

If you haven’t already given that a try, I’d strongly suggest you drain the water out and refill with the correct antifreeze mixture before you bang your head against the wall too much more.

16

Wished I’da thought of it first. :wink:

Gotcha Ya! :smiley:

17

Solved! One stupendously egregious installation error. :smack:

As easy as the e30 is to work on, I’ll toss one bitch out there: The Satanic Exhaust Manifolds.

18

Not trying to embarrass you, but what was the smack-worthy installation error? Other home mechanics want to learn from your pain.

19

Ditto, we want to hear the dirt! Congrats on your find!

20

Agreed!

You need to share your find with the rest of us.

I have an E46, and I have found two sites helpful. Both I am sure you have found, but for those that haven’t, I’d recommend bimmerforums.com for a good place to start.

You CAN get snarky answers, but on a car as old as mine, often the problem has been seen and posted about a few times over the years. It also has many DIY videos posted on YouTube by enthusiasts. Some are of course more helpful than others.

One thing I have a very hard time doing (but recommend) is reading the wikipages for your car. It is scary to read all of the things that can and will go wrong with your BMW, but there are many things that an average mechanic can do that can save you an amazing amount of heartache, not to mention money.

The other nice thing I find is that BMW, more than any other high-end car brand, seems to get kids in their late teens-early 20’s who both love to tear their car apart, and fix it right, and sharing their steps with others. If you can get through the static, and net-speak (“ur” - for your, “u” - for you etc.) you can find some good info.

Glad to hear you solved your problem.

I eagerly await the find/explanation.