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Cooling System

77K views 990 replies 33 participants last post by  bmoneyg 
#1 ·
Hey all, if anyone read my 5 page saga on cooling, sorry for the long read! Anyway, I have a new tstat and coolant and it's working fine. Thermostat is now opening at 105 every single time, even after running for 30min.. all is well, however if I sit in traffic for an extra ordinary long time, like let it idle for 15 min, it will start to climb to 107, but will drop back to 105 when moving, and then drop back down to 102/103.. then driving and stop and go it will run to 105, back to 102/103 and so on, so I know the tstat is opening correctly, but it seems something is not working 100% if it's getting a little too hot idling for a long time, keep in mind this is after driving for 30-40min and then idling for about 15min.. good thing is it's not going to 108 like before.. I know my aux pump is going out, I read other reports on here of others having the same noise mine is making and replacing it resolved it, so I bought one from the dealer and will redrain and replace, but that should have nothing to do with idling..

Also when I drain the coolant and start my car after refilling the water pump makes a really bad loud noise for about 30sec until it evidently gets water inside. I noticed it did that this morning after sitting over night.. I am wondering if my pump could be going, it's got 50k on it, but I don't want to replace stuff thats not bad, and I am wondering if there is something else or another reason that would happen..

Any ideas would be great, thanks!
 
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#771 ·
Lower hose has nothing to do with tstat opening only fan turning on, temp at wp is what determines the tstat opening.
 
#772 ·
Therefor if you gut the old tstat and put a tstat in lower hose, you would essentially be replacing the tstat on our wp
 
#774 ·
I have a question? Why did I get a check engine light on when I cut just one coil of the stact? I don't think 750 is different from 745??? Did any body cut a coil and installed it in there car??? If I gut my stact I think I'll get a check engine light???
 
#775 · (Edited)
Ok here is update:
My valley pan was leaking all over, that's why I was loosing pressure and tstat wasn't working at all!

Didn't install a new one yet, but I think it was the main root of a problem. Need sec air hose it was broken too;(

If you never replaced valley pan and the car is 5-7 old. Replace it ASAP!
 
#778 ·
Idk maybe im confused and if you gut the old tstat and put a custom one right after the tstat, it somehow wont open? I dont get how that would make the water colder on the side of the tstat that is connected to the wp?
 
#779 · (Edited)
Ok ok the flow comes out of the water pump in the top hose that's why its hot,100c plus.The flow returns out of the bottom of the radiator back to the pump.The stock tstat opens at 105c letting hot coolant flow in top hose to radiator.The stock tstat sits in the flow of hot coolant inside the water pump.An INLINE tstat would need to allow or stop the HOT flow not the cold returning from the radiator flow.A tstat in bottom hose might not reach enough hot coolant as the stock housing would still need to be installed.Inline in the top hose would always see the hottest coolant and open at your favorite temp letting flow go to the rad. But the heater aux pump would need to be dealt with as it coolant source would be cut off when my inline tstat was closed.Shoo wee.

Sent from my M975 using Bimmer App
 
#780 ·
Okay now i am understanding more or less what you are getting at. I know nothing about this cooling circuit or what goes where to where. All i have done is replace hoses and havent ever looked at how the loops are.
Me personally i would rather wait for the custom tstat to arrive.
 
#782 ·
The top hose expels the hot water.. even when the thermostat isn't working and the lower hose is cold the top hose is hot, it's got water going thru it and into the radiator.. I don't see why this inline thermostat can't solve our issue, but I would put it on the lower hose right where the stock one was, or close to it.. I don't see how it can help on the upper hose, it will be open constantly once the car warms up.
 
#783 ·
Inline tstat might only work in lower hose, installing it in upper hose will change small with big circuits.
Anyhow I did valley pan and pipe job, but unfortunately I still have leak from rear plate!!! Looks like everything leaks on this engine.
Now it's better, but still I can feel that there isn't enough pressure to open tstat completely when idling...
 
#784 ·
See thats what i was saying if tstat opens into lower hose why would we put a tstat on the upper hose? Lol
Either way im anxious for the tstat :thumbup:
 
#786 ·
Iirc hesaid a mech did it for him bc he didnt want to get sick again ;)
 
#788 ·
The lower hose never gets hot enough to even open the stock tsat.Its the water leaving the tsat that opens it.Thats why its going to the radiator and its HOT.The tsat is 105c it let this temp coolant go to the rad except for the engine warm up bypass.The bottom is the COLD return how could it open a 105c tsat!?
 
#789 ·
On another note Ive been curious about better under hood temps altogether.Ive had a lot of hotrods and this is a fight in summer at car shows.Before you say anything Ive also has 5 BMWs over the years. Anyhow I had a new windshield put in and didnt put cowl cover back in as it was damaged in the process.Now driving for a few a days without it I have noticeably cooler all around temps.Still get to 105 at idle but takes longer and cruise is down to 101.Im might look into some nice real venting.Hate to cut hood but maybe could do something else besides venting body.
 
#790 ·
Maybe we should pressure test our engines.. if there is a leak in the valley pan or a leak in the back plate, it would have to show.. I can open my cap in the morning and still have pressure, so if I do have a leak, it's got to be a small one, not that it matters I guess.. but if I am going to drop the tranny I will probably buy a low mile one to replace it or at the very least replace the torque converter..
 
#791 · (Edited)
Well there is another thing I was talking about 20pages ago:
You test it on cold engine, right???
So..... You got the point;)
It might show smth, but 105 vs 10C is a huge difference, that's why you see your pressure ok in the morning.

I think rear plate is super important bc it pumps coolant into the heads!
And if it has same exact crappy profile gasket as valley pan, so why wouldn't it fail??
 
#793 ·
Hello community im having an problem with inpa i flash the new firmware of the trans fine but the engine mod i cant see some kind of error. As i need to see lower hose temp, my car temp is up there 103, 105, 107 etc in dash i install new aga coolant pipe new stat all new coolant hoses new bmw coolant etc (my second water pump make a humming noise come and go non stop but if shut heater off it stop making noise) trying to make this car what it was ex owner did not take care of it did not care for it. Its up too me to bring it back sharp. Thanks for all the help guys
 
#794 · (Edited)
If you have 107 after aga pipe installed, then it's your rear plate cover.... Very common problem. Once you fix all the leaks and restore factory pressure your car will run much nicer even with 105 tstat!
Damn I don't want to drop the tranny but it seems like the only option. 95c Tstat will save our souls;$

Taken from 5 series forum:
@ 93000 miles both valve covers and both upper timing covers
@ 96000 lower oil pan gasket, water pump, radiator and valley pan (coolant leak)

Now at 103000 and the car is "under construction" again:
- upper oil pan gasket
- oil gasket behind the alternator bracket
- coolant leak behind the transmission (end cover 11147504376) ? very painful project
http://realoem.com/bmw/showparts.do?...51&hg=11&fg=10
 
#795 · (Edited)
So... Thinking that you're lucky after 100k miles and 9-10yrs is just not smart, right?:)
This is where we lose that coolant pressure. Lower tstat will not help here much..... But for future safety -yes. Think about it: if you fix coolant pipe with vp, more pressure will destroy half dead rear cover, this is what happened to me;(
Some nice pics:
 

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#796 ·
That is exactly what I have been saying for weeks now.. :( My cooling pipe is okay, but I am probably going to buy the AGA pipe and swap it anyway.. what pipe did you use again? As for dropping the trans.. is that a really hard job?

When my car is started from completely cold and I drive it right away it would surge RPM's between a couple hundred RPM's for the first minute or so when it was at a low RPM.. well changing fluid made a big difference, but at 500RPM I can hear the TC, but at 700RPM it goes away.. also I notice my shifts are a little on the soft side.. sometimes can be rock hard, so I know the clutches have to be okay.. do you think I should replace TC while I'm at it? They're like $1,200 or something I think..
 
#799 ·
Thanks.. the one thing that really made me not want the URO pipe is, well they could be around longer than AGA, but they clearly copied them, it's easy to see.. and they used a rubber seal, where AGA used Viton.. so I believe the AGA pipe will solve the problem for good.. though I have no proof of course..
 
#803 ·
$300 isn't too bad.. I have a lift.. I just don't know what all is involved in dropping it.. I know replacing the guibo wasn't the best, but not hard.. all the panels, and I just let the exhaust and driveshaft hang.. but I know all that will have to come out for the trans drop.. :(
 
#804 ·
Ok guys update on my bimmer.:)) over a WK since the work and no leaks:))) and I put in ROYAL PUPRLE COOLING with the BMW COOLING AND CHECK OUT MY TEMP:))))) this is two hours of driving in NYC. Speedometer Auto part Vehicle Car Gauge
 
#814 · (Edited)
Ok guys update on my bimmer.:)) over a WK since the work and no leaks:))) and I put in ROYAL PUPRLE COOLING with the BMW COOLING AND CHECK OUT MY TEMP:))))) this is two hours of driving in NYC. View attachment 359737
That's nice! What kind of work did you do? Rear cover y/n?
What temps you had before?

When driving tstat opens up early so aux fan kicks in. When idling it won't be controlled by DME, so it should kick in only at 105C and lower hose would be at 65C. To test it when driving isn't that easy if no one checking.
Aux fan kicks in every time lower hose temp is higher than ~ 65C.
I remember when I had no leaks in the city there was 96-98C if 0-5C.
So now you know what's a good temp for e65. So tell everyone with N62 here that I'm not crazy and caused real emergency over something very important!!
 
#820 · (Edited)
I'm always afraid when I'm in SF that an earthquake is going to swallow it while I'm there.. For some reason I thought you were in Asia or something.. but I figured I'd ask.. Part of me is tempted to just drop the car off tomorrow at AGA and drop $1,600 on the install, but I can't spend that kind of money on labor that I could do.. :( I have a feeling my rear seal or valley pan is leaking.. I am sure I'll fix it and the rear plate will go 6mo later.. but I'm keeping my fingers crossed..
Asia??? Hmm do I sound Asian??
Ha ha I'm no darker than you;)
If I were you I would do the rear plate for this money, bc you have no wheep hole leak, may be vp leak.

Keeping fingers crossed wont do anything, and thinking that rear plate for some miraculous reason is still normal after 10yr ??? It's no different from valley pan, same exact design and is prone to failure. M62 has a crossover pipe, which you can replace easy after intake removal. N62 sucks at this point!!!
Did you know they had e65 with straight 6 M54 and M57 in Europe??? Imagine problem free e65!!! V8, V12 is not very popular there and is expensive.
 
#827 ·
Asia??? Hmm do I sound Asian??
Ha ha I'm no darker than you;)
If I were you I would do the rear plate for this money, bc you have no wheep hole leak, may be vp leak.

Keeping fingers crossed wont do anything, and thinking that rear plate for some miraculous reason is still normal after 10yr ??? It's no different from valley pan, same exact design and is prone to failure. M62 has a crossover pipe, which you can replace easy after intake removal. N62 sucks at this point!!!
Did you know they had e65 with straight 6 M54 and M57 in Europe??? Imagine problem free e65!!! V8, V12 is not very popular there and is expensive.
Sorry I can't understand this post, I think your asian accent is coming out in your typing? :)

Anyway, a quick way to test the valley pan/rear plate is pressure test the system, if theyre leaking you will see it right off the bat.
 
#805 ·
Nice... Forgive my ignorance but wth is royal purple cooling? Lol
 
#806 ·
Product Violet Purple Automotive cleaning Fluid


It a cooling additive. I use to use this on my TTsupra. It works pretty good.
 
#807 ·
They said to use only one but I always use two bottles:))
 
#808 ·
Sounds like water wetter but a diff brand? Have you used water wetter to compare ?
 
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