I have a R1 with just over 79K miles on it. It is stock, almost completely with the exception of a silicone hose job and Pettit AST (boost gauge too). I drive it on the weekends and leave it in a parking deck during the week. I have been out of town and haven't driven it for about 2 weeks. Before starting it I checked the coolant and oil, they seemed okay. It started right up and I let it idle for about 4 or 5 minutes. Looked underneath it for any fluids while it idled (paranoid...cautious...whatever). Everything checked out. As I pulled out of my parking spot I looked at the concrete again and their it was, the dreaded puddle. I stopped got out of the car and yep... its coolant. I looked under the car again with it idling, don't see anything leaking. I moved the car again, and there is another much smaller puddle of coolant. Under the hood there is no steam, no visible liquid of any kind, and no strange noise. It only seems to leak when the car is in motion. The coolant light never came on, I'd say there was about 1/2 - 3/4 glass of coolant on the concrete. It was dark out, the garage is lit, but not well so I will have to wait until the morning to really look into it. Needless to say, I didn't drive her anywhere. I had her parked on an incline so the passenger's side sits higher then the driver's side (small incline, the ramp of a big parking deck).

In the morning I will start looking for the leak... any ideas would be helpful. The AST was installed about a month ago, I checked the hoses there, they seemed fine.

 

maybe somehow you had too much coolant in the system and it went to the overflow tank mine did that when i started it up once so it sat in that plastic piece until i move the car a little then it was slush back and fall out.

 

Thanks for the response. A part of me really hopes it is only something like that, but when I checked the coolant prior to starting... it was only about half way on the stick...

 

1 reply........ Awesome
(at least I didn't get yelled at)

 

Richard, where is the coolant located on the ground? Under/near the passenger headlight? If so, this is from the coolant overflow tank, the same one who's dipstick you checked. You can see how the "throat" of the bottle goes down and forward, yes? Right at the base of the neck there is a small black grommet which will spit coolant if the overflow tank is overfilled.

The tank will also overflow if/when it gets presurized from the coolant system if the pressure is coming from gas being forced into the coolant system (i.e. blown coolant O-Rings that seal the housings together, a REALLY common failure in these cars). The overflow will also overflow if you fill the tank up to the top when cold (thermal expansion of the coolant into the bottle as it's supposed to do). Lastly, coolant can overflow if you are constantly having to top off the coolant at the engine filler neck. What happens here is a vicous cycle of adding coolant to the engine, having it pushed out into the overflow tank, but not drawn back in upon engine cooldown (as its supposed to do). When it isn't drawn back in, usually due to a leak of some type, the level in the engine goes down, so you add more, but of course it gets pushed one way into the overflow bottle, and after a while, the bottle pees on the floor. This last problem can be caused by a pinhole leak in your system, wherein the leak seals when the engine is warm (heats up, expands, seals the leak), then opens up during cooling, making it impossible to pull coolant back into the engine from the overflow.

Easiest way to diagnose this is a coolant system pressure tester, which any reasonably good NAPA or equivalent should carry (or online tool places as well). You want to make sure your coolant system will hold ~13 psi when cold, preferably with no drop whatsoever (overnight is long enough).

Blown O -rings also act like this, as the coolant seal is compromised internal to the combustion areas. This will often manifest as quite thick white smoke coming from the tailpipe on startup. Don't confuse this with the normal condensation burn off from the exhaust. Look at other cars and how much steam comes from their pipes when they startup around where you are at this time of year. If yours is much more thick, billowy, and lingers, you have problems.

Good luck! Coolant system in this car is probably the worst bit of engineering, with 14 coolant hoses (though the 70 odd vacuum hoses that turn to plastic due to underhood nuclear reactors erstwhile termed pre-cats are a close second. But they only need to be replaced once. Break open the cooling system, and it never seems to go back together for long...).

 

Another, not nearly as disastrous, problem that causes coolant overflow from the O-F tank, is a bad AST cap (leaks around the periphery and thus doesn't draw coolant back into the engine), or a leak in the hose that goes from the AST to the O-F tank (this will cause the same problem). Also, a recent post mentioned an AST cap area that was warped and the cap couldn't seat properly to it.

Check these out before you assume an o-ring failure.

Having said all this, a pressure test is still a good idea, even though it will not diagnose the stuff in my first paragraph.

 

Spurvo, DaveW, thank you for the tips, I will go and get a pressure tester today. The AST is only about a month old and has less than 300 miles on it, but I will look at that and hope its not an O-ring issue. Its hard to say where the coolant is leaking, as I don't see any leak until I move the car, but it looks like it drops coolant for a quick second much further behind the O-F tank and more towards the center. Thanks for the help, its very appreciated!

 

Well, after looking at it a bit more closely, the leak appears to be happening toward the front of the car at the back of the radiator just left of center (when facing engine)... maybe from the radiator or from a coolant line around there. Either way, nothing leaks when the car is first started, but then after it idles for a minute or so, it starts leaking. Then once the car is warm it just stops. I can drive it for awhile and no more leak. I am going to let it cool and then try the whole process again.

 

I have had a simalar problem to you.

Top of the radiator where the metal meets the plastic.

Its the gasket inbetween metal and plastic that degrades and causes it to leak.

when the car is cold the ruber gasket shrinks and causes a leak, when the car warms up the gasket expands and seals the leak.

When you are driving and the pressure is higher you may lose coolent and not notice.

this only applies if its the same leak i had.

Good look.

 

Thanks, and that definately sounds like what could be happening...

 

I could see the coolent slowly creaping along the top of my rad where the join is.

Could see it through the mouth of the car at the front.

Dont forget there is a similar seal at the bottom as well.

 

Dexcool caused leaks in my Mazdasport radiator, at the tube joints. Went back to zerex G05, no more leaks, at all.

 

^^^^ good summaries on overfill tank leaks, and blown o-rings.

as for other common problems that lead to coolant loss.. i know coolant leak from the rh side around the turbo area can be caused by the 2 turbo coolant hoses.

are there other causes in this region? i seem to have leaking from somewhere between the primary and 2ndary turbos, but its not the 2 usual coolant hoses..