Sorry for the confusion. Sometimes too much information is not a good thing.
The first guys probably determined the leak is very small / slow and it will take a few days for enough dye to show up so they can find it. My comment about not waiting too long is more appropriate for a larger leak. Given too much time, the leaked-out dye will spread all over making it impossible to trace it back to the source.
Imagine if you had water in your basement. If it was a real tiny leak that only happened after a heavy rain, you might not see the leaking water unless it rained for a few days. That would be the same as driving your car for a few days. My recommendation referred more to a larger leak. If you found a foot of water in your basement after every rainstorm, you wouldn't wait until the next day to look for the leak; you would head down there as soon as the rain started.
I hope that part makes sense. I would go with the mechanic's recommendation because they can actually see how big the leak is. They probably know it will take a while for the dye to show up.
As for the dealer, things always get lost in translation between the mechanics, service advisors, and you. Mechanics talk in technical terms the service advisors often don't understand. Service advisors try to interpret that into something both of you understand. They are good at translating your complaint or request to the mechanic, but they are terrible at diagnostics. That's why they sometimes will say they never heard of your problem before when really, it's one the mechanics see over and over. No deliberate disception was intended, but that's the impression customers are often left with. Just remember that mechanics have good car skills and poor people skills. Service advisors have good people skills and very little car skills.
As for the pressure test, the service advisor you spoke with has confidence in his mechanics that they can find the leak. In some cases there are places where they repeatedly find leaks on almost every car so they know right where to look. That's one of the advantages of going to the dealer. Because they are so familiar with your model, they often find the problem faster than the independent mechanics who have to be experts on many more brands and models. Had you spoken directly with the mechanic, he would likely have expressed a little less confidence in his ability to find the leak quickly. There's always the chance it will allude him.
99 percent of the time pressurized coolant will push out through the leak and should be fairly easy to see. It doesn't matter if the system is pressurized with a hand pump / tester or if it's due to the coolant expanding as the engine warms up. There's always that one percent of the time where pressure on a rubber seal could cause it to be forced to expand and seal better, or warmed up engine parts could expand and temporarily block a leak. That's what I was referring to about pressure causing a leak to seal. It doesn't happen often, but often enough that most mechanics will test for a leak a second time when the engine cools down if they don't find it when the engine is hot.
Another example is in order. I have a tire on my sad van that will go flat if it is only pumped up half way. It leaks when it has low pressure. If it is pumped up all the way, it doesn't leak. The higher pressure makes the tire seal to the wheel better and there is no leak.
As far as " things not adding up", you're actually getting the same service, just approached in different ways by different mechanics, and explained in different ways by different people. From what you've shared so far, I don't think anyone is trying to mislead you. Too much information from too many sources is similar to getting different advice from different doctors for the same ailment. Both treatment plans might work but could involve different tests.
Saturday, March 20th, 2010 AT 10:48 PM