hairline crack in coolant reservoir

jenksy0198 · March 14

HI all, having previously reported on the hairline crack in the oil filter plastic cup holder that resulted in massive and sudden oil loss albeit at low speed with a cold engine which thankfully didn't result in a lost engine, I have again experienced the same issue but this time in the coolant reservoir.

Looks like the same kind of plastic material but I could not testify to that, however I knew I was losing coolant slowly and on closer inspection the garage has determined a hairline crack in the plastic reservoir vessel. The car is 19 years old this year but you don't expect such structures to fail in my case with with two, oil filter holder and now the coolant reservoir it does look like the these plastic parts are suffering under pressure cycles for sure. Does any one else have any similar experience, as I cannot see any other contributor to such failures, no sunlight exposure, no impacts, just pressure cycles?

Looking forward to the experience share.

Paul

Greydog · March 15

Quote

Morning Paul

Unfortunately BMW as did many other manufacturers started fitting plastic parts not just externally but also internally and with many heat cycles they become brittle as they age

I have seen the the Header tank on a friends Mercedes his was just under the cap around the neck so only showed when the engine was really hot.

When I rebuilt the 4.6 (plastic chain guides Failed) I found several coolant "O" rings in the coolant system were starting to weep. BMW wanted to sell complete hose assemblies but many of the parts I sourced were from the USA (Dinan) new Cams,Throttle body gasket sets amonst them were a set of Viton Coolant system "O" rings worth checking those as well.

Good Find

Dave

X5smw · March 15

My x5 blew through the expansion/ filler leaving me stranded. Have a look through the forum. I had to get the car recovered home.

jenksy0198 · March 18

Got to keep writing about this stuff, especially the plastic parts as they do degrade with pressure and temp cycles as I am discovering. Should probably be replaced each 60K miles Im thinking, just to be safe. The plastic oil filter holder lifeing was alerted to me by a canadian BMW specialist garage who I called in on when there to ask about the part. They were very informative and knowledgeable. Mind you the air temp swings there really do cause issues.

I mean one day I was clocking 85 on the motorway and all was good and the next day I started the car and dropped the whole oil load on the drive. So so lucky on that one.