F_Throttle

I just got back from a track day and at the end of the 4th session I opened my hood and found coolant everywhere.. I had to put in 3/4 gallon in it to get it to the full marker in the reservoir. I thought it was just a lose cap or hose fitting, so I nursed it 100 miles home. I later found out from a mechanic that the radiator is leaking.

I kept an eye at the temperature all sessions: oil was 2 markers away from the top and the water temp stayed the same.

1. With that much coolant gone, why didn't a low coolant light go on? Is there even one?
2. As long as the temps were reading OK, was there any potential damage to the engine? Top speeds were 110, and was mostly in 3rd gear (although close to redline in sections).

Thanks!

lobuxracer

iTrader: (2)

If this happened to me, I would do a leakdown test immediately. Indicated temperature depends on the sensor being wet. If it isn't, you could see either low or high temperatures on the gauge that don't correlate to the actual engine temperature at all. The sensor is designed to isolate coolant measurement and not gain heat from the surrounding metal.

There is no sensor for coolant level. I've never seen any manufacturer even attempt this.

Your best indication everything is OK is the oil temps. If you only went 2 bars below top, you're probably just fine - I saw the same indication when I was at CMP doing 20 minute sessions in 102F heat. Your oil may or may not be OK - this is why I run oils with high thermal breakdown temperatures (Mobil1, and now Renewable Lubricants), but that indication is pretty solid and means despite everything it's not likely you cooked your engine. All that said, I'd still get a leakdown test to be sure.

F_Throttle

Thanks Lobu! Just who I wanted to hear from. This is the first I've heard of a leakdown test, so thanks for the recommendation.

p.s. 102 on a track day, is a stay at home for me.. what a trooper.

illwillem

Do you know how much smoothing is done in the gauge logic? I know many OEMs program in a bit of a lag time and averaging on the sensor sweeps to keep the gauge from fluctuating to much and having customers bring their cars in for their 'problem'. I agree with the above, as long as it was solid for the whole session youre likely fine, what you want to look for is big immediate spikes, thats typically indicative of the sensor reading steam (steam vapor reads is much hotter than water) meaning your sensor is no longer submerged.

In a past few of my racecars i've wired a pretty simple dummy water pressure light out of a 5psi pressure switch. Essentially under 5psi the sensor grounds a circuit and a cabin mounted LED comes on. Remember, an 'up to temp' water system builds pressure of around 7-10PSI so having this light does two things: If under 5PSI the light is on telling me "Don't be revving all crazy till it warms up". Once warmed up and on track, if the light come back on it tells me, "you've lost pressure in the system". That could mean a cut hose, a blown radiator cap or potentially help me quickly diagnose a head gasket issue. These are especially useful on mid-engine cars with LOTS of hose length for things to go wrong- ask me how I know.

Glad you made it home on its own legs, any track day where thats the case is a good one