JoeMX82

I recently picked up my 951 and like most the expansion tank is so yellow you are not able to see the coolant level through the tank. Since the PO drove the car to meet me I did not check the level until I got the car home and it cooled off (next morning it was). Well it was full the top, like you would a radiator and I noticed that the expansion tank has some bulges to it and a few cracks. I have ordered a replacement tank (new) so that I can fill the level appropriately and do not plan to drive anymore until I fix, but my question is would this have caused other damages? If the expansion tank bubbled and cracked I am a bit worry if anything else happened to the cooling system. I do not seem to have any leaks but wondering if anybody has run into this mistake before? Is the expansion tank typically the component that would fail / burst before the radiator, etc.?

odonnell

Replace the cap as well, the system is pressurized and designed to vent at a certain pressure. There's also a hose coming off the side of the expansion tank as an overflow, this should reject excess coolant as the car warms up. Make sure it's not clogged or something.

wildcat077

No worries, those expansion tanks are pretty solid and you would have an overflow hose like Mike mentioned, my car is an 83 and i can barely see through the plastic on mine ... eventually it will get replaced with a brand new shiny white one !
I pressurize mine to 15 psi with a Stant coolant system pressurizer every time i do some engine work and have to remove the head and it really expands visually, it worried me at first but it survives every time !

Cheers
Phil

mrgreenjeans

Not necessarily does this mean anything other than the car was driven often in a hotter climate and has suffered the effects of many cyclings between heating and cooling temps. Some cars with lower mileage don't even show any issues of this. I have several with their original tanks and they appear as new with only slight discoloring due to coolant and age. They are all straight, without bulging or cracking, and exhibit only normal patina of a car showing between 20,000 and 80,000 miles of careful and well maintained ownership.

I do not think I would worry about something like this too greatly since replacement of the tank is now high on your priority list, unless you show signs of other higher mileage or owner abusive maint. on the car. Track days also greatly accelerate the heat cycling of these models plus the fact that 951s produce an enormously prodigious amount of heat underhood due to the positioning of the turbo and other packaging requirements of the 951 specie.

One of the reasons one often times sees the hood suffering paint stressing on turbos and premature aging of rubber componentry and other plastic bits compared to an N/A of the same age and mileage.

Where has this vehicle been used and what is the mileage ?

And a word on the replacement radiator cap. Don't cheese out and use anything less than what came on the car as new: A BEHR cap made of stainless steel with the proper pressure rating for your particular series (1 or 2) and model. In your case a 951. I bring this up because there ARE differences in quality and pressure ratings and many overheating issues have been solved simply by just using the correct pressure cap. Many of the a/m items are crap when applied to the usage on our particular Porsches.

Especially avoid any and all usage of any branded item with URO markings. Total and complete garbage.

JoeMX82

Thanks to all for the responses.


The car is an 86 951 with 73K on her. Car is actually in fantastic shape as bought from the original owner who lived in southern California and most everything is like new on the car. He was an older gentlemen who paid to have anything done on the car (had all receipts back to first oil change) and he was not knowledgeable about particulars on the car. This is why I think he did not notice the coolant being way over-full. I think what happened is that the coolant was so full it expanded under heat, before venting through the overflow tube which is clear, and thus bubbled the tank and cracked it. Question - what is the pressure of the stock cap? I think everything is working fine on the car and running temp is good, I just wanted to see if I needed to replace anything outside of the expansion tank. I think the cap should be fine if it is not leaking, is that correct?

pfarah7

I just purchased a shiny new tank so the original unit (still in decent shape) will go to whomever wants it.

Tiger03447

Dear pfarah: If you want to check the cap out, go to AutoZone for their pressure checker. You can use it at the counter..there are several adapters that may fit the cap. If you use it at the counter, it would be free..perhaps they would help as well. It's a free rental tool if you want to take it home..just pay a deposit...