CLICK & CLACK’S CAR TALK

DEAR TOM AND RAY:

I have a 2002 Subaru Forrester. Upon my monthly check of fluids, I was shocked to see that there was no cooling fluid in the reservoir. I immediately took it to the shop, where they told me the head gasket was blown, and it would cost $2,000 to fix. After doing some research, I found that Subaru had a service bulletin about this problem and advocated the use of a special Subaru additive for the coolant that could “possibly” stop the leak. So I asked the mechanics to put the additive in my coolant. My mechanics then advised that I should just drive the car until it overheats, and only then fix my head gasket. So I have two questions: (1) Is it truly possible that this “additive” will fix my leak? And (2) if the additive doesn’t fix my leak, should I really wait until my car overheats to fix it? Thanks.

- Catherine

TOM:

It is possible that the additive will fix your leak. For years, Subaru has had problems with its head gaskets “seeping.” They would remain intact (i.e., not torn or broken), but would allow fluid to seep through or around them. And if your head gasket is just seeping, and not actually blown, the additive could work.

TOM:

The fact that you check your levels every month is actually discouraging to us, Catherine. Because that means the coolant reservoir went from full to empty in less than a month. That suggests that the solution may involve your home equity line in addition to the additive. But by all means, try the additive first.

RAY:

But don’t just wait for the engine to overheat. That’s bad advice.

TOM:

Right. Let’s say your head gasket really is broken. You try the additive, it doesn’t work and the car overheats. If it overheats badly enough, you could crack or warp the heads or damage the block. Or you could degrade the oil so badly that you damage the engine’sbearings, which will shorten the life of the engine considerably. So you really don’t want the car to overheat, ever.

RAY:

Instead, now that the additive is in there, check your coolant reservoir every day for a while. See if you can assess whether the level is continuing to drop, and if so, how quickly. If it stops losing coolant, then have your garage do a pressure test and, hopefully, proclaim the problem solved.

TOM:

But if the coolant level continues to drop, you want to find someone to fix it before the car overheats. And I’d suggest that that person be a different mechanic.

RAY:

Right. Your current guys didn’t know about the Subaru additive, and they gave you bad advice about what to do next. Ask friends who own Subarus who they use in your area. Or check out The Mechanics Files at cartalk.com. And let us know how it works out, Catherine.

DEAR TOM AND RAY:

Please help me settle a bet with my father-in-law ... the winner will buy the loser his next battery. My father-in-law claims that even though car batteries may be marked “maintenance-free,” if the battery has vent caps you can pry off, you should do so, and check and - when necessary - refill the electrolyte levels as needed. I say no, that modern car batteries do not require checking electrolyte levels, and that by prying off the vent caps, you actually could cause some harm to a maintenance-free battery. Can you help settle our bet?

- Michael

RAY:

We can, but you’re not going to like the settlement, Michael.

TOM:

Back in the 1970s, battery manufacturers switched over to calcium lead plates, because they seriously reduced outgassing.

RAY:

Outgassing, aside from being a byproduct of eating a beef-cheese-chorizo burrito, is when the fluid inside the battery heats up and “boils off.” It’s similar to what happens when water boils and gives off vapor - eventually, you run out of water.

TOM:

Because calcium lead grids reduced outgassing significantly, and all but eliminated the need to add water to the battery cells, these batteries were called “maintenancefree.”

RAY:

But they don’t eliminate outgassing completely. And if the engine compartment is subject to extremely high temperatures, even a maintenance-free battery can lose fluid.

TOM:

With maintenance-free batteries, outgassing is most likely to happen in areas of the country that get extremely hot in the summer, or where cars are in constant stop-and-go conditions and their engine compartments get up to very high temperatures.

RAY:

Most people will never need to add water to their maintenance-free batteries. In fact, the vast majority of batteries don’t even allow you to check the fluid levels anymore. But if your maintenance-free battery does have removable caps, there certainly is no harm in removing them and adding water if the fluid happens to be low.

TOM:

It’s not a regular maintenance item, like it was 20 or 30 years ago, Michael. But you owe your pop-in-law his next battery. If you’re really lucky, his next battery will be for his flashlight.

Click & Clack (Tom and Ray Magliozzi) dispense advice about cars in Car Talk every Saturday. E-mail Click & Clack by visiting the Car Talk section of

cartalk.com

HomeStyle, Pages 41 on 10/23/2010

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