Strange Coolant Leak...

[JaseYpk]

Yeah, so i've got a coolant leak, that only happens sometimes, and in varying quantities. VERY CONFUSED.

i first noticed it a week ago when my reservoir was near enough empty, so i topped it up. and then a few days ago it dropped by about 1cm, so i topped it up.
and then again today i saw the fluid on the floor in a small puddle, (probs only 1cm of the reservoir again). cant work out where the leak is til i get it on ramps, but looks near the bottom of the rad.

Either way, why would it only leak sometimes? could it be to do with the amount of coolant inside the reservoir?
I've got an aftermarket Japspeed rad (50mm) and as a result i fill the standard reservoir a bit over the standard markings. Is this ok?

I'l update when i get under the car and find the source.
Cheers

 

[craig8585]

It's because of your aftermarket rad. The expansion tank is not big enough to cope with the larger capacity of aftermarket rads so it will overflow when hot. My tank us nearly empty when cold but if I top it up it all comes out when hot.

 

[LuPix_S15]

Yes the same with me my expansion tank is almost empty all the time lol...


As long as you don't park up and see coolant dripping everytime you check or... there's an obvious puddle after everytime you drive off then no probs

 

[craig8585]

If the radiator is full when you take the cap off it is fine

 

[andeep]

What Bar radiator cap are you running?

 

[craig8585]

That shouldnt make a difference though. Just increases the boiling point very slightly but on a stock setup you shouldn't even get close to it.

 

[andeep]

I thought it would? With a higher rated rad cap, it will only open at higher temperatures which means that the rad can't divert coolant into the expansion tank.

 

[craig8585]

Yeah but it will still open and the same process will happen, just at a slightly higher pressure. I can see where your coming from and there may be a very small difference in the amount of flow but the rad is the cause of it emptying the tank. I've got a 1.3 bar cap and my tank still looks empty when cold. The first time I noticed it I thought there was a coolant leak too!

 

[andeep]

Ah I get you. I was always under the impression that the rad will never get hot enough to reach a 1.3bar pressure, therefore the rad cap will not open and the flow could never be diverted to the expansion bottle.

 

[craig8585]

Oh no, it will reach operating pressure really quickly The 1.3 bar cap raises the boiling point of the water slightly (as the boiling point of water increases with pressure) and that is the reason for them. TBH it seems like a bit of a gimic as the boiling point is around 112C at the standard 0.9 bar IIRC and that is more than your ever likely to experience with a decent cooling system.

 

[LuPix_S15]

lol Craig I'd love to agree but... I hit 115 to 120 deg after 3rd to 4th outing on Nurburgring. Was a mental hot day though so that didn't help!! :wack:


But then again 13 mile laps on one of the world's most demanding tracks plus ambient temps of over 25 deg that day it came as no surprise my coolant was getting HOT HOT

 

[Auss15]

Also check your water pump,SR's are notorious for water pump failure.

 

[JaseYpk]

well thats been an intersting read! cheers for the replies, didnt realise the cap maintained the flow to the expansion tank! (mines 1.3) I thought it was just to stop it sloshing out the top! haha. Every day is a school day

Are there any aftermarket expansion tanks available? So that i dont need to keep filling up!
Cheers

 

[craig8585]

No, I couldn't find any. Would have to be a custom one but you'll be fine with the standard one. Don't bother topping it up because it will just spill out the overflow each time you use it. As long as the rad itself is full then your fine.

James - 120C is just too hot. You must have been on the brink of boiling your fluid. Did you have your twin fans installed then? If so you need ducting to divert air through the rad, or something similar.

 

[Dan H]

Also check your water pump,SR's are notorious for water pump failure.

I'll second that.
I had a leak on my old 180sx that turned out to be from the water pump. The seal must have been going, and it was dripping from the little hole on the bottom of the pump.

 

[Auss15]

Are there any aftermarket expansion tanks available? So that i dont need to keep filling up!
Cheers

Yes there are,Greddy make a very nice breather tank ( a mate has one fitted) that will help with higher expansion

 

[LuPix_S15]

No, I couldn't find any. Would have to be a custom one but you'll be fine with the standard one. Don't bother topping it up because it will just spill out the overflow each time you use it. As long as the rad itself is full then your fine.

James - 120C is just too hot. You must have been on the brink of boiling your fluid. Did you have your twin fans installed then? If so you need ducting to divert air through the rad, or something similar.

Actually Craig come to think of it must have been the oil temp getting to 120 deg :wack: I was just thinking back in June on Der Nuerburgring I didn't have the water temp sensor fitted doh?! Ah just forget what I said... I'm having yet another blonde moment lol

 

[craig8585]

Haha, I thought itvsounded a big high! 120 for the oil is fine I think. I wouldnt want my water to go above 95 really. Cooling can be an issue on these cars when the natural path of the air is all but cut off by a huge intercooler! I've just spent anither load of money on a more powerful twin fan setup with a more accurate and advanced fan controller which should mean my temps stay within a 5C range under all conditions.

 

[LuPix_S15]

Cool nice one Yeah I really want to rip out the aircon system as a) it's heavy and b) the damn radiator is sandwiched right between the cooler core and water rad core!!! grrrr

 

[JaseYpk]

Yes there are,Greddy make a very nice breather tank ( a mate has one fitted) that will help with higher expansion

ooh looks nice that one! looks like its only got a small capacity though? i'l have to do some research. Is your mates fitted to an S15 is it?

It says you need a sensor adapter for it? i take it the radiator overflow connects to the bottom, then the next one up to your expansion tank? and a sensor to another and the top one on the cap goes to fresh air? no? :s