Expansion Tanks Empty After Revving?

MrSweet1991 · 06-25-2020, 07:16 AM

Hi All,

So cut a long story short I gave the engine a quick rev to get rid of the smoke that accumulates after leaving it idle for a while and I think I remember hearing like a pop noise and around 10 seconds later I had the coolant yellow symbol appear.

Shut engine off and checked to see coolant everywhere and a big puddle, the AA guy came out and topped it up then pressure tested it and found nothing.

I've just got it up to temp and done about 2800rpm and there's not a drop of coolant coming from anywhere. I don't want to give it a quick rev like I did before because coolant will probably splatter everywhere again, but any ideas what could have happened to drain the expansion that quick but then also go back to some sort of normal operating because where ever it did come from its now holding okay.

I wasn't sure if the expansion cap is a probability as they're rated at 140 and I'm wondering if maybe that released it?

Phil325i · 06-25-2020, 07:29 AM

Worth checking if the radiator vent hose has fractured. It's a bit of a weakness:

Chappers 71 · 06-25-2020, 03:16 PM

The plastic side tanks on the rad are also prone to leaking, I'm currently on my third rad. Both the original & the first replacement both sprung a leak near where the bottom hose connects.
Currently got a Hella in there now, first replacement was a Nissens that failed after only 23,000 miles (three & a half years)

06-25-2020, 07:16 AM	#1
MrSweet1991 Captain 129 Rep 828 Posts Drives: BMW E90 330D M Sport Join Date: Apr 2017 Location: West Midlands iTrader: (0)	Expansion Tanks Empty After Revving? Hi All, So cut a long story short I gave the engine a quick rev to get rid of the smoke that accumulates after leaving it idle for a while and I think I remember hearing like a pop noise and around 10 seconds later I had the coolant yellow symbol appear. Shut engine off and checked to see coolant everywhere and a big puddle, the AA guy came out and topped it up then pressure tested it and found nothing. I've just got it up to temp and done about 2800rpm and there's not a drop of coolant coming from anywhere. I don't want to give it a quick rev like I did before because coolant will probably splatter everywhere again, but any ideas what could have happened to drain the expansion that quick but then also go back to some sort of normal operating because where ever it did come from its now holding okay. I wasn't sure if the expansion cap is a probability as they're rated at 140 and I'm wondering if maybe that released it?
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06-25-2020, 07:29 AM	#2
Phil325i Brigadier General 615 Rep 3,194 Posts Drives: E92 325i MSport Coupe Join Date: Apr 2012 Location: UK South East iTrader: (1) Garage List 2009 BMW 325i Coupe [6.00]	Worth checking if the radiator vent hose has fractured. It's a bit of a weakness: __________________ E92 pre-LCI 325i - Ohlins R&T; H&R spacers; M3 strut brace; Swift thrust sheets; 3 x chassis braces; diff brace; N53 V-brace; 034 subframe inserts; BMS clutch stop; BMS CDV; RE g/box mounts; Delrin shift bushes; Saikoumichi OCC; Cyba scoops; BMW Perf Exhaust; HEL s/steel brake hoses; M3 rear spoiler; Recaro Sportster CSs; M3 white dash LEDs; LED Angels; LED side repeaters; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof/clear front
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06-25-2020, 03:16 PM	#3
Chappers 71 Major General 5480 Rep 5,421 Posts Drives: Beige G31 40ix m sport Join Date: Feb 2016 Location: Kent, The Garden of England iTrader: (0) Garage List 2018 G31 xdrive 40i ... [4.00] 2006 E92 335i SE [9.50]	The plastic side tanks on the rad are also prone to leaking, I'm currently on my third rad. Both the original & the first replacement both sprung a leak near where the bottom hose connects. Currently got a Hella in there now, first replacement was a Nissens that failed after only 23,000 miles (three & a half years) __________________ G31 40ix M Sport E92 335i. E36 328is coupe E39 540i V8 6SP manual E34 3.6 M5. E34 525i sport. VW Jetta Mk2 GTI 16v. 1679cc 1967 resto-cal beetle
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