MrMethane

So last week I start up my car and am shocked to see the low coolant light on. I just bought the car in January but I figure since its a leftover 04 its probably never been filled. I get out and check the coolant level and sure enough is way below the L. So I fill it up right to the F line.

Yesterday I'm out washing my car when I realize I should probably check the coolant level to make sure its not low again in case I have a leak. I take a look and the level is way above the F mark now. Its about halfway between the F and the top of the tank. Should I siphon some of this out, is this something that could cause some damage?

Also why did the level rise so much its really weird that it was really low and I added a little water bringing it exactly to the full line, now its really high. Maybe the change in outside temperature? It was in the 50s when the light came on and I filled it and yesterday was close to 90 when I checked it again. But it was a pretty dramatic increase in fluid level.

I have also recently noticed a ticking sound when warming up and now I'm wondering if this could be related to the coolant level being too high.

Any thoughts?

Raz0rama

well the coolant tank doesn't tell you how much is actually in your radiator - just how much is in the reserve tank. When you say you added water, did you add just water? I usually do a 50/50 mix of coolant and water. I've had several cars in which the reservoir levels fluctuated, haven't noticed in the 8 but my dad, who's been a mechanic for about 25 years, told me as long as the level doesn't get too low, not to worry. For your own peace of mind, if I were you I'd keep an eye on it and make sure that it doesn't fill up more or go down drastically again, but I sincerely doubt the level in the reserve tank being high will cause serious damage. The level in the actual system is more critical, as it gets cycled under pressure to remove heat from the engine, and no one wants an overheated engine.

Go48

The level of the coolant in the reservoir will vary depending on the temperature of the engine/coolant. When it's hot, the level will be higher, and when cold the level will be lower. Perhaps you filled it when the engine/coolant was cold and then checked it when hot, in which case the level would be higher than when you added coolant. If it's a little over the full mark when it's hot, no big deal.

houstonredrider

Fill it up as much as you want. The reservoir is also called expansion vase. When hot, the coolant it will expand. If there is too much it will overflow through the cap. No big deal. Low=bad, fill it.

When replacing the coolant the shop will put a funell full of coolant on top of your reservoir and run the engine.

Just check those fluctuations. If it gets low often, go to the shop.

MrMethane

Great thanks guys, I'll keep an eye on it.

KostasNK

When should I check the level and add coolant?
When the engine is cold or hot after a long drive?
When it is cold the level is 8cm lower than the F mark, when it is hot the level is higher than the F mark.
What should I do?

Go48

Your owners manual is your friend. Here's what it says:

"The coolant should be at full in the radiator and between the F and L marks on the coolant reservoir when the engine is cool."

As long as the level is around the F mark when warm you will be fine. A little over, a little under is not a problem.

Don't worry, be happy.

RX8rider

Is it just me or is it really difficult to read the coolant level?! It seems hard to see when the coolant is between the L and F, should there be a dipstick in there to make it easier to gauge the level?

dgrx8

i noticed the same thing the other day... i just hit 15k & wanted to check all the fluids along w/ swapping out all my oil for redline & royal purple oils. went to check the coolant & could barely gauge it...

GT-rex

OK, I'm not the only one that feels blind. By the time I could finally read/guage the level, it was a bit over the F line. I guess it's hard to read in anything other than direct sunlight (I was in my parking garage, but on a very sunny day with decent ambient sunlight)...even using a flashlight didn't help. Fortunately, I think it's not enough to really consider trying to siphon any out.

My bigger concern is that my vehicle is barely about to hit 19K and the coolant is already an issue...seems a bit extreme, but after going through threads it doesn't sound totally uncommon with the 8? I haven't noticed any leaks, but I'm now tempted to look more carefully.

Nubo

The cap acts as a pressure relief valve, so any overfilling will take car of itself. However, there are at least a couple of negative consequences to having coolant exit via the overflow tube.

1 - you may smell coolant. Since this might happen days weeks or months after you overfill, the coolant smell will (or should) make you investigate and worry if there's really a leak. A waste of time you could have avoided.

2 - The coolant overflow hose is aimed directly at the connectors for the wiring harness that passes torque sensor readings to the power steering controller. Users have reported problems, and I had some as well. I can't say definitively whether coolant overflow had anything to do with it but after I repaired the harness I also re-routed the overflow so that it wasn't threatening the connectors anymore. (Got the repair info from MazdaManiac's post on his steering problems).

FYI, the difficulty in reading the level is because the tank is a pressure vessel and not just a resevoir. So, the plastic is fairly thick. A very bright flashlight does the trick.

wisconsinben

I've found that shinning the flashlight through the other side of the reservoir will give you a nice back lit effect. The coolant will not let the light pass through easily, so it will appear darker than the plastic reservoir.