coolaant leaking from seal on expansion bottle lid

[jambla]

got home and went inside for a little bit, came back out and saw what looked to be about two cups of coolant on the driveway under the left front part of the engine compartment. open the hood and I see a slight drip coming from somewhere near the bleed valve and the expansion bottle. turn the car on and let idle to see if she overheats, but everything is staying cool. i back to get over a clean spot of driveway and the leak stops! so that evening and the next day I drive and everything is staying cool and good (its 101 in Oklahoma City, so I know the coolant is flowing). Took to local shop and they want to replace the expansion bottle and reseal eveything. Anyone had a similar experience? 1992 525i, 134k. great shape, no problems at all.

[Classic320i]

Your local shop may be correct! if your coolant system has orginal hoses being 16+yrs old the shop dont want to take a chance patch fixing one area and develop a problem else where. but resealing everything ? they need to be more detail on specific area.

[darkhorse737]

...maybe just too much coolant in the reservoir... you go over the recommended level (when engine cold, about a third to a half of the reservoir) and it will overflow when engine reaches operating temps or runs on extra-load(i.e. a/c on...).

it's a basic science thing. water/coolant expands when heated ;-)