I wanted to know do the level in the plastic coolant over flow bottle stay the same or does it fluctuate. I it fluctuates what factors make it fluctuate. Some times I see the level go down. Is it normal for level to go up and down. Why.
Frank
By
Bull6791, May 19, 2014
I wanted to know do the level in the plastic coolant over flow bottle stay the same or does it fluctuate. I it fluctuates what factors make it fluctuate. Some times I see the level go down. Is it normal for level to go up and down. Why.
Frank
It can and does fluctuate - that is perfectly normal. I've seen ones run from MIN to MAX, during the course of operation - some cover less of a range, just fluctuating a small amount. Most owners note that leverls are lower when the engine is cold, rises up in levels as the engine gets to operating temperatures. Just make sure that it doesn't run dry and you should be good to go.
Fish
My mechanic said they do not fill coolant in the plastic bottle up to full line. They fill it to middle of bottle. He said they fill it to middle of bottle because it fluctuates a lot.
I do not know if he is right.
When you do a coolant flush where should you fill coolant to. Middle or full line of plastic bottle.
Frank
You mechanic is giving you a pretty safe level. Like your mechanic - I'm hesistant to fill the reservoir completely up to the full mark - as there is a good chance that it will blow coolant out the overflow at full operating temperatures. That spilled coolant isn't going to hurt the car, but poses a potential danger to animals and the local water table.
But on cars that I know have hard to purge air bubbles, like my old BMW, the old Matrix and my 8th gen - I will fill the bottle to the max line. I just have to watch for spilled coolant, as sometimes coolant will blow out if too full (big air bubble). I haven't measured how much I needed on the newer cars - on the new Matrix - I just added as it got lower, never checked to see how low it could go. Didn't touch the Rav4 yet.
Also filling up the middle makes it easier to see the level in recovery tank. Generally, once the engine gets up to temperature - note the level of coolant in the reservoir. In a properly working cooling system, this should be right at the "full" line. After the car has shutdown and cooled overnight - you could see the levels drop to the "min" mark. That's OK - just make sure it doesn't drop below that. As long as you check the levels when the engine is hot and cold - middle should be fine.
Fish
So it is normal for plastic bottle to fluctuate. So not a good way to tell if you have a leek. So how would you tell if radiator is leak and hoses.
Franj
The resevoir should eventually empty if the cooling system has a leak.
I recently flushed my system & refilled the resevoir to the hot mark when cold to make sure the system was full. The coolant now settles to the halfway point when cold & rises to the hot mark when the engine reaches operating temperature.
^^^ Exactly. You'll know when you have a leak - as the level will continue to fall in the overflow reservoir. Just check the levels right after a cold soak (car off overnight) and note if the level seems to drop over a period of time. As long as the coolant is not leaking internally, ie. bad headgasket, you also have the telltale drips of coolant and crusty residue that is left from evaporate coolant. Might also pickup on a overly sweet odor - which usually indicates a leak.
It is normal to fluctuate and the reason is because the fluid expands when it heats up. The reason there is a reservoir is for a place for the expanded heated coolant to go (radiator has no extra space) when the fluid cools then it gets "sucked" back into the radiator. That is why the level changes. As mentioned if you see the level drop and disapear then you have a leak.
Just to ask a question: between 20k and 30k miles ago I suspected a coolant leek. So I filled my coolant in bottle to full line. The level keep going down. I asked mechanic to check for a leak. He found radiator leaking where metal and plastic meet. The end caps were leaking.
Question: to find that kind of leak does it have to be pressure tested.
How did he find leak.
I needed a new radiator. He replaced it.
He said their was no hole in radiator.
Frank.
The end caps were leaking.
Question: to find that kind of leak does it have to be pressure tested.
Yes, if the leak is small enough, the water may evaporate before a drip is detectable & a pressure tester will be needed.
Cracked seam - that sucks.
Unfortunately, some cars have endcaps that leak more often than others - lots of manufacturers are going to a plastic cap on aluminum cored radiators, so this is not specific to the Corolla or Toyota. Lightweight and pretty cheap to manufacturer - problem is, once you get a crack to form around that sealed/crimped area - you're screwed. They make tools to uncrimp/recrimp those areas - but lots of radiator shops will opt to just replace the radiator - as the cost of the aftermarket replacements are cheaper than the labor to fix the seam on the radiator.
Those usually leak so slowly, you have to pressure test them / tank test them to see if they are actually leaking.
