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Coolant woes help

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Hi guys. 

 

After some pointers if possible. Changed the main stat other week as temps low. Took to a friends garage where looked like original was still in pmace. Swapped for a not genuine stat which seemed to go well. But when up to running temp there seems to be a fine leak somewhere. Niw its not dropping coolant but does need topping up every other day. 

 

So, thinking it was the non genuine stat it was changed again. Turns out again non genuine stat but all seems to fit well but again. Same issue. Small leak. 

 

Could this be fown to the stats not being genuine? Or the O ring in the lower rad pipe. Which cant seem to get one from BMW only full pipe. 

 

Any ideas? Could it just be that it is not a genuine stat? Anyone else come across this issue before. 

 

Thanks so much. 

 

Cheers

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Could be you are just working out an air lock in the system. 

 

Turn heaters up to full heat and blip throttle a few times that should help the coolant fully circulate and drive any air to the expansion tank. Check level again and top up. 

 

There is probably an approved BMW method of doing this in newTIS.

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tried several ways to bleed, does seem to leak more on short journeys, unless its all evaporating when engine hot, ordered a genuine stat so will install that and see where it leads

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Make sure you screw the coolant cap closed until fully locked and then unscrew it so it moves freely and leave it at the middle. Rookie mistake by fully locking it... And then the head gasket needs changing if you do fully lock it.  If you have diagnostic software you can do it manually(more helpful) but if you don't, leave the ignition on with heat to the max and blower to the lowest and auxiliary electric pump will get rid of any air in about ten minutes time(won't work with webasto tho) 

If it still loses coolant the EGR thermostat might be leaking or you damaged some O-rings I'm the process...

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9 minutes ago, Biotoxic said:

Make sure you screw the coolant cap closed until fully locked and then unscrew it so it moves freely and leave it at the middle. Rookie mistake by fully locking it... And then the head gasket needs changing if you do fully lock it. 

 

Where did this come from??

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Try it yourself. Not too sure about F-series, but it's been like that since E36 was released :) Plastic coolant cap have a pressure... Not too sure how it's called exactly but it regulates the pressure at the coolant system. It's not like a ambient pressure, but slightly above. 

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1 minute ago, Biotoxic said:

Try it yourself. Not too sure about F-series, but it's been like that since E36 was released :) Plastic coolant cap have a pressure... Not too sure how it's called exactly but it regulates the pressure at the coolant system. It's not like a ambient pressure, but slightly above. 

 

 

How does this work? My cap is tight and is designed to release pressure over a certain amount 200kpa or something.  Are you topping your coolant from evaporation every so often then? 

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No idea how it works, but I had a E36 and after a service some dude tightened the coolant cap and after a while I had cracked cylinder head and leak at the head gasket. Friend had a 530i and everything seemed fine untill I unscrewed the coolant cap... No coolant at the expansion tank and he complained about no heat coming from the vents... As it turned out he had a cracked head gasket... by fully locking the coolant cap it increases the coolant system pressure and if there is a leak somewhere coolant will slowly leak away..long story short, engine starts to mystically overheat although there is some coolant left at the expansion tank when the cap was unscrewed. Usual problem with 325ish engines.

Regarding your question I topped it up about two years ago when I changed the coolant itself. Haven't had a need to top it up since. If you notice at the E60 expansion tank there are like a wee ridges on  the expansion bottle where the cap is  and it goes down on the one side of it. Designed for a overflow I suppose... See the image Screenshot_20190830-214937.thumb.png.81328a3ec3ecb8e7051aafd82aeefaed.png

Edited by Biotoxic

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The cap on expansion tank has a pressure valve (1,4 bar diesel; 2,0 bar petrol) to relief pressure from the coolant system if needed. The cap itself should be tightened normally. If the cap is left loose it won't hold pressure which makes the coolant boiling point lower than it should be in a pressurised system.

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The cap is designed to vent pressure before anything damage can occur. Both my E46 and E60 were/are tightened fully. I'd suffer coolant loss in the E46 if I didn't.  I notice some guy called Nathan BMW has a youtube video claiming the same thing which I think he's overfilled the system and there's no place for the expansion of coolant.

 

Every forum from the E36 through to the E46 proclaims that your coolant system is made from chocolate and you absolutely must replace every component of the cooling system if you want to have a reliable car. Shirley one of these heat-cycled plastic parts would give before the head gasket. I do notice the caps have an arrow on them, no idea what that's about.  Edit: Cap must click...

 

Shotlight_20171009_121225.jpg

Edited by Deviant

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When i changed my stats i drained the coolant and put the exact amount of new coolant back in. I think it was 5l. I started the car and watched the pump circulate the coolant in the expansion tank for a few minutes to clear any air and then put the cap back on. If the coolant is too low the car will indicate it on the idrive. The cap has always been tightly screwed on from day one. Topping up the coolant should only be done when the coolant is cold. If you are getting leak then it may be that it has been overfilled. Opening the cap when it's boiling is not a good idea as the pressure will cause it to overflow. Did you think you have overfilled it?

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I’d add my name to the list of people saying do not drive round with the  expansion tank cap open. If anything it will increase the likelihood of blowing the head gasket as the boiling point of the coolant will be lower than the engine expects it to be. This is especially true on the petrols as they are designed to run at >100 degrees C in certain conditions. The pressure in the system keeps the coolant from boiling at these temperatures.

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When i bled originally the coolant was pulled away when ignition and heaters were switched on. Then ran car with cap off till steady stream feeds back in.  Always topped up to highest point where max shows on the yellow inside. 

 

Hoping it is just poor aftermarket parts. Will feed back when OEM fitted. 

 

Cheers guys for the input. But cap is always screwed fully on mine. 

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Sorry but leaving the cap opens the biggest load of crap I have heard. It's a pressurised system with a pressure valve in the cap.

Sent from my SM-G920F using Tapatalk

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3 hours ago, GoNz0 said:

Sorry but leaving the cap opens the biggest load of crap I have heard. It's a pressurised system with a pressure valve in the cap.

Sent from my SM-G920F using Tapatalk
 

 

Precisely. And I took my E36 M50 from 58k miles up to over 190k miles over 13 years  with no head gasket failure. It had the usual radiator replacement and water pumps and a hose or two, that was it for the cooling system. Coolant changes every 2 years like clockwork.

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Agreed, you must run a pressurised coolant (when using water) as the BMW petrols will often run over 100DegC in parts of the engine. If those ali parts are bathed in steam instead of water then hot spots will occurr that will eventually warp the head or damage cylinders.

Edit: Or use a coolant that has a higher boiling point that then doesn't need pressurising or manage the ECU to run a cooler mixture setup.

Any alternative coolant suggestions that are BMW electric water pump friendly?

 

I have had leaks on other (cooler running) motors and as a bodge I ran with the cap lose to prevent coolant water pressurisation from forcing the water out of a leaking system, which works fine until a warm sunny day or you are sat in traffic for a while and the water flashes over to steam to push the water out the expansion tank and boil you over. At which point either fix the leak or if the car is on it's last few months of life, treat the coolant to a good measure of Holts Radweld Plus 250ml sealer and follow the basic instructions... to my surprise, 3 months later and the misses' car is still holding water coolant pressure ;). Previously it was dumping over 1L on the ground after each trip to town in warm weather but couldn't be assed to get dirty locating a leak behind the block on an old dying 2005 Renault Grand Scenic :oops:.

 

 

Edited by DarkHorse

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So. I changed to a genuine stat. All good there. But have noticed while watching as the other half turns car iff there appears to be water leaking from the water pump pulley. Have read about the weep hole. Should i change the water pump now? Noticed it drop fluid onto the belt when the engine is turned off. 

 

Cheers guys

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Yeah my water pump failed unexpectedly on the motorway last year quite a long way from home. Got a low coolant message so stopped in good time without the engine heating up. You don't want that to happen to you.

 

Evans waterless coolant is an option I guess, 

http://www.evanscoolants.co.uk/

 

I don't know anyone who has tried it, but I've always been tempted to use it in the future if I have to replace the radiator and obviously the system is drained then..

Edited by Tuvoc

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It took me about 15 minutes until the water ran clear when I had the hose pipe in the top whilst my water pump was off, you can't drain the block in these cars for some reason.

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1
19 hours ago, Tuvoc said:

Evans waterless coolant is an option I guess, 

http://www.evanscoolants.co.uk/

 

I don't know anyone who has tried it, but I've always been tempted to use it in the future if I have to replace the radiator and obviously the system is drained then..

 

It seems more hassle than it's probably worth. If the warning light comes on and you need to top up or you develop a slight leak away from home, you cant nip into any garage and get a bottle of compatible coolant to get home. 

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Well you could carry a top-up bottle. 

 

I may be wrong but I think in an emergency you can top up with water as they do mix, but far from ideal because then you'd lose the benefit and have to drain down the whole system again and re-fill again with 100% Evans. And it isn't cheap.

 

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8 hours ago, Tuvoc said:

Well you could carry a top-up bottle. 

 

I may be wrong but I think in an emergency you can top up with water as they do mix, but far from ideal because then you'd lose the benefit and have to drain down the whole system again and re-fill again with 100% Evans. And it isn't cheap.

 

Thing is with these blocks you would need to drain with a vacuum coolant exchanger to get the old stuff out.

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As I said earlier m8, the correct way is to use a vacuum coolant filling system that draws a vacuum and technically would remove most of the fluid when you pull a vacuum, the flush solution would remove the rest and again need drawing out before filling with coolant.

 

To me a complete faff considering the G48 lasts 4-5 years anyway.

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