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I have been driving my 97 328iC and had no issues. Yesterday I park it in the driveway. I come out and the car is leaking coolant. I can't see where it starts but it's dripping off the the bottom pulley. It's not running but dripping. Car has 173k miles on it and if the coolant system was upgraded I have no idea. I do know the thermostat is aluminum. Where should I start?
Member
likely water pump shaft or bad tstat housing gasket
Member
Make sure you do not drive it till it's fixed, you will over heat and warp the head. Use AAA to get a tow home or a shop. You cannot limp the car home.
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I'm lost
Just gotta keep looking. Could be as simple as needing to tighten a hose clamp.
Hate to throw parts at a problem without narrowing it down first, but if you don't know the history of the coolant system, wouldn't be a terrible idea to just refresh everything now. WP, t-stat, housing, rad, expansion tank.
smokes at gas stations
You can add some UV dye to the coolant and use that to trace the leak.Originally Posted by B328iC
Or, if the whole cooling system hasn't been serviced in a while then it might be time for a full refresh for peace of mind.
Member
Yeah like me replacing two idlers and the water pump to find out the squeal was a crappy belt I bought three months ago .
But I agree if the system had not been serviced in a while change the water pump and thermostat at the same time as well as what ever else u can afford while you are in there .
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How does the dye work? I think this might be a good place to start as it might help me find the starting place of the leak.
shade tree mechanic
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Usually no need to add dye. OEM coolant is blue and the dried spots can be easily found when there are leaks
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smokes at gas stations
The dye reacts to blacklight. Add it to the system and let it run through for a short period and then visually inspect with the light to trace the leak. But again, if the whole system itself hasn't been serviced in years then its probably time for a full overhaul.
Member
Op, do not be too worried. You can keep your fan clutch and radiator and possibly your coolant hoses. You just need new clips, a new rad cap, a new bleed screw, coolant, thermost and thermostat gasket/o ring, as the case may be. This is half an overhaul and costs you around 60 bucks in total. But the labour can be extensive for an amateur. A seasoned mechanic will get in and out within an hour at most and he would not be hurried.
Inspect your fan clutch when hot and cold. Then inspect your hoses, are they slightly compressible even when hot? Then remove your belts and turn your water pump by hand - does it turn smoothly or does it feel rough (bad bearings) ? If all this is ok then you can get by with half the overhaul. This is assuming that your pump and pump gasket is not the source of the leak here.
Half overhaul is done at 50k. Full overhaul which includes the pump and hoses and fan clutch, is done at 100k. All this assumes you are using oem material for everything.
Radiator should be pressure tested once a year and if it holds pressure need not be changed.
Whenever coolant is changed, a forward flush and backflush should be done with running water from a hose. The backflush also helps to keep the radiator channels clear of blockage. Cabin heater must be fully activated during this process.
The system needs to be bled whenever coolant is changed or hoses removed, and that includes activating your cabin heater.
If your car has truly behaved itself all this while, then during a full overhaul, spring for prestone's coolant flush with chelating agents that helps to break down and remove corrosion. Use it after a full flush - you can even drive around with it for a day and reflush and refill with oem coolant the next day. Always nice to leave a dedicated flushing agent overnight.
I'm lost
You start off by saying he might not need to do everything with some guidance on how to determine if a couple things really need to be replaced. Then go on to say a full overhaul (which includes those couple things) should be done at 100k. He/She is at 173k, with no record of the cooling system being serviced.
OP I don't know your financial situation. I really value my peace of mind so I'd recommend taking this time to just go through and do a full refresh. There's nothing worse than fixing one thing and a couple months later having to go back and address something in the same system. Not sure if it's BMW's engineering or what but I've had to do that multiple times on my E36 and E70. E70 expansion tank started leaking, did the quick and dirty repair and only replaced that, 3 months later the WP started growling. 1 month after fixing that the tensioner started squealing.
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I was giving him all the information he needed for him to decide what was best to do based on his instinctive understanding of what his car was up to.
Though I showed him how to test and thus possibly avoid doing some of the stuff, the long list I later produced might well stoke his sense of prudence to do all of it at one go. Sometimes people don't know how complex something is until you list it all.
Op, naniepoo has a point about peace of mind. If this is your daily driver, and you don't have proper service records, then it will be wise to do a full cooling system overhaul. If not now, then within the next 3 months.
Last edited by alang1990; 11-02-2018 at 05:35 PM.
Member
Some people just love to run their mouth and over complicate everything just to hear themselves speak. Eventually they are banned, again.
It's dripping some coolant. Find the leak(a dollar says it's the water pump) and fix it. Inspect the rest and carry on. Avoid Chinese pumps or you'll be doing it again soon.
Last edited by ross1; 11-03-2018 at 04:31 PM.
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Member
OK I finally got a chance to get the car in the air and check it out. Now it won't leak! Everything seems fine. WTF???
Member
It may only be leaking when its hot and under pressure. Try using a pressure tester on the expansion tank.
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Advance auto parts has a coolant pressure tester on their loan a tool program.
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I ran the car for almost an hour and nothing came out. Pressure testing might help but I'm fairly sue in my running it the pressure came up.
I'm lost
Maybe. Although you're a little south of me I imagine it's still pretty cold there. "Almost" an hour, from a cold cold car, at idle (I'm assuming), might not build up enough heat/pressure. Heck after coolant work I need to let the car idle around 30 minutes before I can even start bleeding. Coolant just sits in the expansion tank until then.
Member
I was thinking the same thing. I actually ran the RPM's up to 2500 and held it for a while. The temp gauge did drop and then go back up to normal. Still no leak. I think I'll change the loser hose and clean & flush the system. Then add new antifreeze. Since I have on summer tires the car sits in the garage for now.
Member
Another round of tests similar to the first round. Coolant level was down a bit but not too bad. Filled it up and tried to run it to see if it would leak. I have no leaks. I had a bit of a problem getting it up to operating temperature. I had to run it oround 2500 rpm for a while and then shut it down. I went back out and got it to operating temp again. This time after I shut it off I was able to remove the cap from the expansion tank without any problems. I know you should never do that as hot antifreeze should come out. I didn't get even a hiss of any pressure trying to escape. Is it possible the cap went bad and all I need to do is replace that?
Member
If the system is not holding pressure you have effectively lowered the boiling point of your coolant. Is there any evidence of the cap venting coolant?
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[QUOTE=jmo69;30152287]If the system is not holding pressure you have effectively lowered the boiling point of your coolant. Is there any evidence of the cap venting coolant?/QUOTE]
I have found no leaks anywhere. Is the cap testable? I'm at my wits end right now with this. The only thing I did was add water to the system as I figured I would be draining it all back out to replace the coolant.
I'm lost
If you're not getting to operating temp, that's your t-stat. But based on my experience that's not likely the source of your leak.
Fortunately I've found coolant leaks relatively easy to find as it leaves white crud when it dries. Have never really needed to run it/pressure check it.
Again I would still recommend doing t-stat, WP, expansion tank and cap, and maybe radiator. You don't know the history and the entire coolant system has a reputation as being a weak point of the car. Expansion tank can crack with little to no warning. Radiator end tanks can fail. WP is prone to leaking and/or bearing failure and/or impeller grenading. The only thing you know for certain so far is your t-stat is likely stuck open, but fixing that likely won't fix your leak. To me these things just scream that the system is due for a refresh.
Member
OK I finally got time and parts to fix. looking at thermostat, fan clutch (checked and it's bad), cap bleed screw and new BMW antifreeze.
Drained the system and the expansion tank won't drain. What gives? Car is raised in the air and I would think it would drain once I pulled the drain plug on the radiator. What an I missing?
I'm lost
Drain from the block drain plug too
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