Who is right and who is wrong about testing radiator leak?

[Learning]

Hi lovely fellows,

I was at a mechanic shop because I detected some coolant leak from my 91 318i and so a mechanic of the shop took a coolant tank pressure tester, screwed it on top of the radiator's reservoir and began to test pressure and we saw some coolant coming out from the seal of the tank where the plastic reservoir meets the metal part of the radiator. Suddenly, the boss of the mechanic saw what was being carried out and he told the mechanic to not doing the pressure test as it would damage the radiator or some parts of it. The mechanic replied agitatedly to his boss how he was supposed to find out where the leak was without pressure testing. Their argument continued.

1. Who do you guys think was right or wrong? The mechanic or his boss?

2. Am I supposed to replace the radiator with a brand new one? The mechanic told me the coolant leak from the seal couldn't be fixed and I must get a brand new radiator. My radiator (after market, not original) is about 7 years old. Is this average life of it?

Thanks in advance for your answers, fellows.

[Dj Buttchug]

any coolant system can easily handle 15psi which is more than enough to pinpoint leaks.

7 years for a radiator is decent, however they will last longer provided you take care of the coolant system and change the coolant.

[Massimo]

That is the correct procedure. You don't have to replace the radiator you can just repalce the expansion tank. But they will not last as long as a radiator replacment.

[gearheadE30]

I'd just go with a replacement radiator. And possibly a different shop.

15 psi should be no problem.

[Learning]

I forgot to mention that although the seal is leaking and the coolant level in the plastic reservoir tank is low near the bottom, my car is not overheating. Thanks goodness, but why is it not overheating? Can someone explain?

[junkiekommando]

I forgot to mention that although the seal is leaking and the coolant level in the plastic reservoir tank is low near the bottom, my car is not overheating. Thanks goodness, but why is it not overheating? Can someone explain?

My tank leaks too but the car doesnt overheat either ..

[davem]

leaks dont cause overheating, losing enough coolant will though.

[bmwman91]

The expansion tank coolant level isn't representative of the whole system's level. There is a pressure-relief back-feed system to it: basically, you can pour coolant into the tank & that will go right to the rest of the system, but the rest of the system only feeds coolant back into the tank when the pressure exceeds some level (hence the name "expansion tank"). So the expansion tank could look dry, and the rest of the system could be nearly full. I hope that makes sense. There is a cooling system diagram for the M42 out there...it looks way too complicated, but shows all of this.

Unless the actual radiator has a leak, don't replace it. Most likely, all you need is probably a new lower O-ring (part 3). MAYBE the bleed screw is leaking, which is also a cheap & easy fix (part 9). Personally, I would just replace all of the little (parts 2, 3, 4, 7, 8, 9) and get another 100,000 miles from it.

http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=17_0502&hg=17&fg=05

[Exodus_2pt0]

Go to a different shop....

I would not work at a shop where the "boss" came back and told me how to do my job.

If the tech needs someone to hold his hand, then something is wrong too. The fact that they argued about this in front of you just makes them look worse.

That being said, most cooling systems operate under about 1 bar (15 psi.) The tech was right. Attach the pressure tester and pump that bitch up to 15 psi, then look for leaks. Done

[Learning]

Now I know that the expansion tank could be replaced, however, the mechanic didn't tell me that, and instead he told me to replace the whole cooling system and that the leak couldn't be fixed :o

I noticed that the leak was coming out from a vertical line where the expansion tank met the radiator tank (somewhere near the middle). And so what part was it that was leaking? By looking at the M42 cooling system diagram submitted by BMWman91 above through this link http://www.realoem.com/bmw/showparts...02&hg=17&fg=05 my feeling is that the plastic reservoir tank is cracked and that's why the leak, but I could be totally wrong as I don't know much about cooling system.

[SpecM]

indeed, any radiator or part of the cooling system that would be damaged by a 15psi was failing anyway. thats how the test works... it makes the weakest parts of the system show themselves