wopfe

A month ago i came to the conclusion that mine was leaking fluid (my engine is out right now), first i was in denial, but the missing peaces of paint right underneath where a good pointer. MrMerlin convinced me and i went for a new tank, hoses, cap and even a level sender. Total about 500 euro's from a european partdealer. I must say: i think it is the right decision now my engine is out. I sleep really good knowing this wont have to be removed in about 39 years.

Here a link to my post: https://rennlist.com/forums/928-foru...ngine-bay.html

FredR

Good to know I am not the only one smart enough and/or lazy enough to figure than one out!

Carl Fausett

I should clarify. The challenge with replacing this part is not due to whether you are installing the plastic one from Porsche or our aluminum replacement.

The difficulty is caused by the fact that the reservoir was installed on the car before they hung the fender. This is what covers up that 3rd mounting bolt and makes coolant reservoir replacements sort of a bear. Fortunately, the coolant reservoir rests on mounts and the M6 fasteners just hold it down so it doesn't slide around. This makes it holding it in place with just the two fasteners you can get at just fine.

wopfe

Agree with Carl. Even without an engine in the car 2 out 3 is the best you can do.

dr bob

Hmmm. I placed the rear bolt with a magnetic tool, finished with a 1/4"-drive socket with a universal and extensions. It's not impossible. Might be tougher if you have big hands, but with the right tools it's just another procedure. Also, attack/attach the hose from underneath.

FredR

Bolting a piece of plastic to the chassis with no isolastic mount makes me wonder just how good an idea that really is. We know that exposure of plastic to UV radiation makes a mess of plastic but there's not much sunshine in that corner of the garden. It is commonly perceived that heat eventually does for the plastic and maybe that is the case but I often wonder if the degradation of the tank might be caused by the vibration energy being passed through the chassis long term ultimately causing micro cracks that in turn allow coolant to discolour the plastic into that yucky almost opaque brownish colour it eventually turns into.

Slip the tank in there, just let it sit there possibly on thin rubber sheet under the support arms and just leave it there given the poor thing cannot go anywhere once the hoses are connected. Maybe not the thing for the purists but...?

The Forgotten On

Plastic in the engine bay is mostly degraded by ozone generated from the ignition system as far as I know.

FredR

Blake,

The story regarding ozone degradation is something of an urban myth. To my knowledge it does not directly degrade anything plastic. Ozone is a strong oxidising agent and if something is going to oxidise then ozone speeds up that process. Modern plastics have various additives in them and nowadays damage to plastic exposed to UV in say dash panels has been greatly reduced because of technological advances.

The expansion tank is not going to be damaged by UV because it is shielded from it, whether the heat causes damage or the coolant it is exposed to internally I do not really know but common sense should tell us that an engineer does not expose something to agents that will degrade said material unless of course there is no other option which in this case there is as Carl has demonstrated. What I can say is that our aged expansion tanks do not seem to crumble in their natural habitat but they do degrade and at some point may [will?] lose integrity. Mine is still functioning but cosmetically it looks awful.

Thus my logic querying what is degradation mechanism is actually taking place.

Koenig-Specials 928

Carl Fausett

We considered a sight glass in our reservoir, and then dropped the idea as it created a number of failure points.
That clear PVC tubing shown in your picture is generally meant for the food industry and will not endure pressure well. I feared bursts and leaks that it could cause.
So I looked at building in a glass or rigid plastic sight glass, and costs jumped a great deal, plus we still had all those failure points.

Given that the car is equipped with a low-fluid-level sensor already, I felt that the sight-glass created more problems than the very small benefit it might provide.

Koenig-Specials 928

I hang out with a few friends with motorcycles.
This sightglass setup is frequently used on their gas tanks with more or less 0 psi(g) pressure