Hvithaien

I replaced by expansion tank about a month ago with a brand new one from 928srus.
I have had no leaks other than noticing a bit of coolant residue on the lip forming the joint between the upper and lower half of the expansion tank.
Thinking it was a leaking tank cap and not having any other problem, I left it alone, planing to buy a new cap later.
Today I had the car in for the bi-annual vehicle inspection (MoT) and they showed me a pool of coolant my car had left on hte shop floor during the half an hour it was in.
I drove home and experienced no other leaks, but could see a bit of coolant residue on tank joint, inside fender wall under tank and a bit on top of the right hand side cam tower.
Anyone experienced a failure on a brand new expansion tank?

Hvithaien

Bilal928S4

I think there was a thread where Greg mentioned that all new tanks have that little leak at that joint.

FLYVMO

Yes my previous new reservoir started leaking after a few thousand miles...in that same joint. It is now replaced with another new one in my GT. The "old" one has the plastic warping upwards in that seam.

The replacement reservoir seems to be "glued" more thoroughly at the joints, but only time and pressure will tell for sure if it is any better.

Cheers!
Carl

ROG100

If it is faulty we will replace it - first one I have heard of that leaks.

Hvithaien

That's super Roger!
I will investigate a bit further to be absolutly sure, and contact you when I know more about the cause.

69gaugeman

Also, make sure that the pressure cap is working correctly. And the viscous fan is proper as well. Either (or both) will cause a problem with coolant leaking out. One because it allows for a lower pressure before releasing and the other allows it to get hot.

jwillman

without a good cap the reservoir won't seal and without pressure the coolant will boil and push its way past the cap. It then pours out the overflow tube onto the ground under the car but not all the time so it throws you off.

Hvithaien

Found it! :-)
In the end I discovered I had two leaks from my expansion tank. One tiny leak from one of the small hoses on top.
This leaked onto the lip that forms the joint between the top and bottom halfs.
The coolant collection there made me think that it was the only leak and that it was coming from the joint.
After some further investigation it became clear that the major leak was coming from the hose connection at the bottom of the expansion tank.
Oh joy! I had to take it back out again to fix it!
A new hose clamp and a few hours later it is back on the street again! :-)

Mrmerlin

FWIW when fitting the coolant tank,
you would fix the lower hose to the tank,
and orient the clamp so it can be retightened,
after the tank is installed,
from the bottom of the car.
Remove the tank with the lower hose attached to it.

SMTCapeCod

FWIW I was able to re-attach the lower hose under the tank full tight at the tank, and then thread the hose back to the vicinity of the hard line as the tank is snaked in. I placed the clamp on the hard tube by the 'y', and then manuevered the hose to the front of the tube with a pair of screwdrivers. THen with a bunch of squirming and poor language, eventually got the hose seated up on the tube. Moved clamp down and tightened. I look up from underneath, but didn't like the prospects given the rear A/C tubes, coolant tubes, etc.