2.5 expansion tank overflow

[Iko Iko]

I have a 95 2.5 Milly. It has taken to occasionally spewing coolant out the overflow tube upon shutdown. It had done this a couple of times during the summer on hot days. Now it is happening much more frequently and in the dead of winter. When I top it up I lift the RF corner of the car and fill through the cylinder head mounted filler. The water shows no sign of oil contamination and I haven't noted any evidence of exhaust fumes in the overflow tank. Does this ring a bell with anyone?

[Iko Iko]

Just discovered water on the garage floor directly under water pump which was replaced with timing belt, tensioner etc. less than three years ago. Am wondering if perhaps the shop did not properly torque the bolts in. It appears to only be leaking once the engine has cooled off.

[Kutcht1]

Hmmmmm, sounds like you need to get under there and check that leak out. And by water hope you do mean coolant. Does the car overheat or the temp needle go above half way? There are two caps in the system, one is the top radiator tube fill cap (Fill here)OEM has no spring, the other is on the overflow bottle with the 18 lb. spring I believe. Could also be a sticky thermostat. When was last time it was changed. Myself and others will need additional info after you do some checking.
TomK

[Srperalta926]

Had the same exact problem changed my thermostat and never happened again plus it's the cheapest route to try first

[Iko Iko]

It is coolant. Not loosing enough to cause overheating. Gonna crawl under, remove the splash shield and scope it out further tomorrow. Still thinking water pump. Either got a defective one or improper installation. We'll see...

[bigb]

water pump has a pressure release valve. it could be leaking from there.

I would suggest doing what was mentioned above and pull the Tstat. you need to look inside the system to see if it looks crudded up. better to change a clogged radiator now than to wait until you need a new head gasket

[Iko Iko]

The thermostat isn't presenting any symptoms that, to me, would indicate it is not functioning properly. The temp. needle gets to the half mark in the same amount of time (no lag from being stuck open) and it stays right there. I did my annual flush in August. I bought the car in 2007. It has an after-market radiator in it. I have never seen any kind of contamination or funky looking coolant when doing the flushes. This car has been well looked after. Right now it is still dripping from beneath the right front splash shield. Srperalta, did you have any overheating? Bigb, the relief valve info IS a ray of hope...., but I wonder if it would leak the amount that it is currently losing. Looks to be about a quarter of a pint. Still a slow drip after eight hours since shut-off. And thank you all for your time.

[Kutcht1]

With your new info it has to be the water pump. If it is not leaking from above (hose and fill cap), the water pump is the only other area where it could come out on that side I think. I would still change the T-stat for insurance and see if it persists. Is the lower coolant hose hot after warm up? If so that tells you the T-stat is opening.
TomK

[keninn]

i have never done any work on a 2.5, but i recently did the pump on our black 2.3. looking at epc, the metal inlet on the 2.5 that has the radiator cap on it is the feed for each cylinder head. the 2.3 has a similar type crossover pipe, but no radiator cap. one thing i did notice, is that the crossover pipe, because of the o rings, and i replaced them, needed to be retorqued. what happened is that i had overheat, and while it was an air bubble, i actually pulled the water pump to see if it was bad. so when i went back in, the bolts holding the crossover pipe were just about finger tight. when i redid the pump, after torqueing the first time, i waited several minutes, and then retorqued, and sure nuff, the bolts had loosened up again. i think the o rings deform, and the pipe then loosens. if this is happening with the crossover on the 2.5, then those orings have broken the seal, or they were reused, and have failed. they do NOT come with the water pump, and they are NOT in the head gasket set, so they have to be bought separately. this means ordering them, and waiting a few more days, something a shop really dont like to do. i am betting they reused the o rings. which means going back in and doing everything all over again.
you should rent a cooling system tester. then pump your system, and you will see where it is leaking from

[Iko Iko]

Warmed it up to op. temp and the lower hose heated right up. Does anyone know if the 2.5 has the o-ring set up that keninn was referring to?