I have a problem with my car after installing the Mugen Cooling mods. The coolant level in the reserve tank keeps dropping below Max. I've had the cooling mods for almost 2 weeks and had to refill it 3 times already.

1st time I had to refill (morning after the install):
Coolant level was a little above Max and dropped down to 1/4 above Min. Filled it a little above Max again

2nd time I had to refill (a couple days after the install):
Coolant level dropped down 1/4 below Max. Filled it a little above Max again

3rd time (A week after the install):
Coolant level dropped down 1/4 below Max. Filled it a little above Max again

Almost on my 2nd week and it's already a little below Max. I followed the instruction provided on this site (installed the fan switch first, removed the t-stat housing and took the OEM one out, removed the OEM t-stat gasket and put that on the Mugen t-stat, made sure the nipple thing on the Mugen t-stat was pointed @ 12 o clock and everything was tightened but not over tightened). I made sure I got all the air out by leaving the radiator cap off and started the car and I also squeezed the 2 radiator hoses.

I looked for signs of leaks around the T-stat housing and under my car near the radiator drain plug is. Can't find any? Any ideas what the problem could be?

 

Its not a reserve tank, its an overflow tank. As the coolant expands, the excess will get dumped into the tank, and as it cools, it draws the coolant back into the system.

When were you checking the system for coolant? Was the car warm?

The coolant in the reserve tank will fluctuate a little. As long as there is enough in the radiator, you should be fine.

 

As you have mentioned there are no leaks, or anything then you have nothing to worry about..

 

Opps, yes the overflow tank.

Hmm I've checked it when the car is both hot (right after driving it) and in the morning before I leave for work. Level seems to be about the same. I don't notice any fluctuation (cold/warm/hot) in the coolant level. I will check in the morning, I just checked an hour ago after coming home and the coolant level is slightly under Max.

 

You should always check the coolant level when your car is cold.

 

Make sure to bleed the system when you do any cooling system service, you can just add coolant/antifreeze into the radiator when its cold and think its full because the thermostat isnt open so it wont transfer the liquid into the engine... Make sure to bleed/burp the system for any locked air... Also make sure you dont have a leak and most importantly that the fan works...

 

Fan works and I'm almost sure I don't have any leaks. I looked around the t-stat housing and looked under the radiator.....no signs of leaks. If coolant leaked out and dried up by the heat, it should have a white/greenish color. That's what I was looking for around those areas.

Also if there's air in system, you would think the coolant level would just fluctuate then? Howcome I have to keep refilling it because it never goes back to the level I filled it upto? I will try to bleed out more air though.

I will try to re-bleed the cooling system again. So while the engine is cold, take the radiator cap off, turn the car on and let the fans come on twice, also squeeze the 2 radiator hoses......anything else I need to do to get air out of the system (if there is any).

 

That should be it.

 

When it's cold, pull your radiator cap. Fluid level should be right at the top. If you see air, you may have a cap that isn't sealing fully. If sealed fully, when the fluid in the radiator contracts, it should draw in fluid from the overflow and not suck any air.

 

Hmm is there a test I can do to see if my radiator cap is fully sealing? Anyone else have problems with their Mugen radiator cap? Also does the radiator draw enough fluid from the overflow to be actually notice-able if I watch it?

 

i know that when i had i got a new radiator the dealer told me to keep an eye on the coolant as it cycled. it took a couple days of adding to it for it to finally fill up without taking all th ereserve into the system.

 

^ It has almost been 2 weeks now since the install. Although the first couple days I had to put a lot more into the overflow tank.

 

As I read through your original post again, I realized that I didn't catch everything.

You may not have a problem. Do NOT fill the overflow tank to more than MAX. If it drops to below MAX, just drive it and monitor the level. If it's stable and does not go below MIN, you're probably fine.

I did the Mugen mod but only installed the thermostat and fan switch. Eventhough I have the Mugen cap, I elected not to use it as I did not want to add increased pressure to the system. Increasing the pressure increases the boiling point of the fluid but my thought was that it should not be an issue. I should not be boiling over the system with the stock cap. If I do, I've got other problems that I should deal with.

 

LOL good, you scared me for a sec. So what do you think it is then? Just air still left in the system?

 

if you have air in the system your dumbie temperature gauge on your dash cluster would go past the half way point.

 

^ The temp gauge inside my car is below 1/4 when I drive on the highway and below 1/2 when I drive around the city. So I think it's working fine.

 

I don't see any problem, the only thing weird is you have different temps reading while mine always consistent with both city/highway driving at just above 1/4 mark.

 

Mind you I'm still NA. Your car is prolly producing more heat than mine.