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YOUR RESEARCHCoolant Tank - Thermal Protection?
Leading reported evidence
Check japanese cars also self ventilate their pressurized radiator
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Last time I checked the Japanese cars also self ventilate their pressurized radiator, but NOT their reservoir.
Leading evidence: 'Check japanese cars also self ventilate their pressurized radiator' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'issue is related' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check japanese cars also self ventilate their pressurized radiator' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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In those applications a recovery style tank may be used instead.
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Suspected cause · Original poster
I suspect the issue is related to multiple heat soaks the tank experiences from year to year, primarily from the external heat of the engine.
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Suspected cause · Original poster
I suspect the issue is related to multiple heat soaks the tank experiences from year to year, primarily from the external heat of the engine.
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With all the issues that appear to exist with the 996 coolant expansion tanks cracking and leaking, has anyone tried some sort of thermal protector? I suspect the issue is related to multiple heat soaks the tank experiences from year to year, primarily from the external heat of the engine. What about applying some type of Urethane coating rated to 250F+? This might protect against the thermal heat, but might also act as an adhesive keeping the plastic tank intact. The link here is a spray application, which may not be useful on an installed tank, but I am looking for a brush-on version that might work.
If installing a new tank in the future, I think I would apply several coats of this product before installing in my p-car.
Any thoughts?
https://www.walmart.com/ip/CRC-Ureth...Clear/23912440
Cracking expansion tanks is an age old problem. IMHO, spraying an external coating will do very little to decrease your chances of a future crack. Why? The quick answer - it's plastic! ... it will deteriorate over time. Most cracks begin internally and push outward and weaken the polymers that "hold" the plastic together. Polymer degradation is the result of heat/cold cycles, chemical affects, and high pressure. Over time, as the thermal plastic hardens with age, cracks will begin to form. The result are leaks.
If engineers knew that external heat intrusion was the primary culprit, I'm pretty sure you'd see heat shields around the tanks. I've never really examined the cracks closely on some of my old tanks, but what you wanna bet the cracks usually happen around the exit port on the tanks? Just a wild guess.
No, the coating wont prevent the bottle from cracking. Not like Japanese cars, which the plastic tanks are not pressurized, the German ones are. BMW are the worst. Their E46 tanks are guaranteed to crack in a few years and left you stranded. German over-engineering doesn't in this case.
It's not over engineering but limitations of the engineering because of the shape of the car. Those tanks are pressurized because the highest point of the cooling system is the tank and to self ventilate the system, the tank needs to be under pressure. Otherwise you'll end up with air pockets in the system.
The design of the coolant reservoir is because of the shape of the car ? That's a good one. Also, the tank is pressurized to self ventilate ? That's another good one. Look at some Japanese cars' coolant recovery system, they don;t need to pressurize the bottle and they never ever crack. Its all in the design and very under-engineered by BMW, Mercedes and Porsche in this case.
The highest elevation point in the cooling system in these cars is the overflow tank and therefore it needs to be pressurized to self ventilate. Have a look at it when you open the hood of these cars. There is always a reason whey things are designed. Slapping an "over engineered" comment is just shortsightedness . I don't like it how they do it either but I understand the reason.
Remember, don't bet what you're not willing to part ways with.
Here's what I documented when I changed my tank. I thought for sure the leak was going to be at a seam or stress riser. Nope. Right in the freakin middle. My thought is that since this unit is pressurized, the tank failed via creep in the flattest section.
Eeeek, that's a serious crack man! Your car doing drugs these day? lol That crack is above the exit port, right? Am I close? ... like in horse shoes and hand grenades? hahahaha
Are we talking about the pressurized bottle crack or are we talking about something else as you mentioned about the ventilation point. What does that have to do with the crack on the bottle? So what you are saying is the ventilation at the highest point has to do with the crack ? Last time I checked the Japanese cars also self ventilate their pressurized radiator, but NOT their reservoir.
If you want the cooling system to self ventilate the air pockets than, the highest point of the system needs to be pressurized. Since the highest point in these cases are the overflow tank, they need to be also pressurized. Most Japanese cars have the radiator at the highest point and therefore, have a radiator cap on them as opposed to the overflow tank. I hope this clears things up as I don't know how else to explain it any simpler.
Henry, you can't compare a reservoir tank to an expansion tank. Two totally different things with different design considerations and uses.
http://blog.cantonracingproducts.com...on_vs_recovery
Regardless of the pros and cons of reservoir or expansion tank, the fact is the Porsche tanks are under pressure and are known to crack. This are the same with BMWs also and they are notorious to get you stranded when they burst....and it happens way too often because the bottle is plastic and when it ages we all know the weakness of such design. A simple design change to whatever the Japanese system uses will solve that problem altogether. The radiators are under pressure, but not their overflow tanks and they rarely seldom crack. That is what I was trying to point out, but the other party insist on the venting of the pressure at the highest point which has nothing to do with this thread at all.
The article clearly explains why the 996 requires an expansion tank and not a recovery tank like you proposed.
"In many modern cars the radiator is mounted lower than the engine. Since the radiator is lower than the engine a pressure relief and fill point that is higher than the engine is needed. This is accomplished with an expansion tank. When the radiator is high enough to act as a fill point and pressure relief an expansion tank is not necessarily required. In those applications a recovery style tank may be used instead. "
You realize that it
isn't
a simple design change though, right? You would need to raise the top of the radiator above the engine and add a radiator cap. Not only is the car now going to look terrible, you'd need to remove the front bumper to add coolant.
If you can't understand this, I don't know what to tell you.
Perhaps, but this is not a unique Porsche problem. BMWs are prone to bursting their coolant bottles under pressure and their radiators are located conventionally, not like the 911s with plumbing routed all the way to the back. If it is necessary to have an expansion tank, at least use metal instead of plastic. As it is now, for such a critical function as engine cooling, if it is busted out there you are stranded. But then you will have those vouching for Porsche's engineering aptitude to say "it is better that their expansion tank blows instead of their radiator while under extreme pressure. My point here is, it is a half-*** under engineered system and those that side with Porsche's engineering aptitude will always vouch for them regardless.
I have some sympathy for your comment but I don't think anyone is saying Porsche coolant system design in the best in the world. Rather, people are just trying to point out there's a reason for this specific design choice. It's just another engineering problem full of compromise.
If cost and weight were no objects, I'm sure they will put a metal coolant tank, which will never crack. I have complained a lot of times about their IMSB, oil pressure sensor, window regulator, etc myself. Regarding that tank, just replace it every 4~5yrs it's not so bad.
This is a source reference. Confirm exact model applicability in the original material.
