kcvpr

Apparently my radiator likes to shoot coolant out of the coolant overflow port on my isis radiator. I just replaced the radiator cap, and im doing the thermostat tomorrow.

Any Ideas? I have read that it could be the head gasket? hope thats not the case

Mikester

There is supposed to be a line from the radiator port to the coolant overflow reservoir for that very reason.

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jr_ss

My guess is you have a blown head gasket pressurizing your coolant system... Do a leak down or hydrocarbon test.

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AsleepAltima

ive seen stuck open t-stats do the same thing.

Paparazzi

OR this!! Is there a line??

Chrischeezer

so coolant is overflowing out of the... coolant overflow port on the radiator...

is that what your saying?

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jr_ss

Under load...

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AsleepAltima

you didnt say whether or not you have a line going to the coolant reservoir...

cotbu

Most likely cause from description is:
weak radiator cap
blown head gasket

lol stuck open thermostat

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AsleepAltima

I don't see what's funny about a stuck open thermostat - I've seen just about every crazy thing happen in the last 24 years since I started wrenching.

Mikester

Thermo stuck open = coolant continuously flows

Thermo stuck closed and/or no hose connected to overflow reservoir = OP's problem.

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AsleepAltima

Purty goddamn sure I'm not making shit up.

hOngsterr

its possible that you didnt bleed your system
correctly so thats why its like that.

I've witness so many coolant issues, people changed everything, but in the end its really just the bleeding process.

OR your headgasket might be blown.

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cotbu

What's funny is, that answer for this problem!
It was not an attack on you. If, you would like me to explain why it's funny? It would require a diagram and probably some paint editing, but that could get complicated.

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AsleepAltima

dude, ive been a tech since 93 and been wrenching since i was 15. i didnt say it was the answer, i said ive seen it. ive seen lots of crazy stuff that makes no sense. i wasnt taking it as an attack though, im just saying, crazier shit happens and i did ask if he has a line attached to it.

cotbu

so if the line to the reservoir was not there coolant should just shoot out? That would mean the coolant should shoot out if the line was there, but fill the reservoir or leak all over the ground. That's still not an answer to this problem. The op didn't state whether he was at operating temp, or when it starts to shoot out, but if you know how a radiator cap works then you know it's not what you suggested.

If the op has the proper radiator cap that fit's his radiator, it is supposed to open under pressure.

If the op say's it's fixed when he replaces the thermostat? He/she lied.
HowStuffWorks "How does a radiator cap work?"

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kcvpr

I have only noticed the problem when the car is at or near operating temp. I do not know if it also does this when cold. there is no coolant overflow line on the radiator, because as far as i know it should not be shooting coolant out of the overflow port unless it is overheating. According to the temp gauge the car has never overheated either.

the radiator in question is an sr specific radiator from isis racing, the original cap that came new with the radiator did the same thing along with a new cap that was made for nissan's that i purchased yesterday.

cotbu

Could you post a video, I'm thinking it's just bleeding off excessive pressure with a little coolant being spit out. If it's pumping out or following the rpm it maybe more serious.

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kcvpr

yeah, ill try to do that as some point tonight. If I had to guess though, its not happening untill i start to build boost.

Darren

the coolant in the system expands and contracts with different temps... the coolant overflow is not just for overheating, it's for expansion and contraction.

Just put a hose on the thing and call it a day.....

kcvpr

Here's a link to the video when it clears YouTube. Sr20 coolant problem - YouTube

It was just barely warmed up in the vid. From being parked for 8.5 hrs

I can re-upload the video if needed when I get some wifi for better quality.

jdsr20det

+1

Sent from my DROID RAZR using Tapatalk 2

cotbu

First of all, you at least realize that you have a problem.

I would do a combustion gas test and or a leak down test.
I would not yet get a higher pressure radiator cap unless you pass one of those test.
Why, you may be masking the real problem and end up blowing the coolant hoses under the intake or worse.

I would also quit driving until it's fixed, right now with no reservoir you are allowing air into the system, your radiator cap is not holding pressure, and you are loosing coolant.
The coolant system is not efficient and if you were to overheat i don't think you'll be able to cool it down, before damage occurs.

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jr_ss

Pull your rad cap while your car is idling. Obviously, you need to pull it before it gets hot and visually check for air bubbles coming out. If you see air bubbles, you have an issue with your head gasket. As stated earlier today by me, do a hydrocarbon test if you see bubbles.

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Kingtal0n

Nothing like a hot debate about hot fluids.

Many radiator caps are set to open around 15psi. Why not open at 1psi instead? Or 25psi? The whole point of having pressure in the coolant system is mainly to increase the boiling point of the fluids- thereby keeping it in a liquid form and not gaseous, which would potentially create hot spots. Imagine if a bubble of gaseous vapor forms around the combustion chamber? No more water can reach that spot and it turns into a "hot spot" capable of causing preignition.

So we need the pressure if the temperature is going over the atmospheric boiling point of water- about 212*F right?

Lets stop right there and draw a conclusion. If the water temp never hits 212*F, then technically, it never needs to be pressurized, because it will never change state (vaporize). But technically, we are wrong! Because most liquids, including water, have a partial pressure, meaning that water molecules are constantly escaping the surface of the liquid exposed to the pressure keeping it in a liquid state. That is why water evaporates from an open cup despite it being well below 212*F. SOME of the molecules near the surface of the liquid are moving fast enough to escape to gaseous state.

So, there is also a NEED to keep the water contained. That is, to prevent it's escape to the atmosphere. We can contain it in the coolant system if we seal the coolant system up, right? Well, we can try. Even a very tight coolant system is going to lose some water molecules over time.

But now we have an objective: keep the water molecules contained, and keep them in a liquid state by applying additional pressure when necessary to keep it from boiling.

Also, circulate it, such that it may exchange heat with the surrounding. Heat from the engine enters the coolant and raises the temperature. Heat gradually escapes to the atmosphere as the coolant is moving, not directly because it is moving, heat is transfering from not only the radiator but also the hoses and lines and even the engine block itself is losing heat of course. But we are expecting to get alot of heat in the coolant system and we are expecting the radiator to exchange enough of it with the surroundings to keep the engine's coolant temperature at a specific temperature.

WHAT temperature? While this is not part of my originally planned discussion, it makes sense to mention, heat is energy and more heat is more energy. Technically speaking, the more heat we keep around the engine, the better its efficiency will be, as long as the heat does not interfere with it's anticipated chemical reactions and processes. In other words, excessive temperature is bad because it does many horrible things to an engine, such as ruining the oil, causing detonation, excessively expanding metal parts and it can even deform them and cause engine failure.

But some heat is necessary. SO I ask again, what temperature? If you read around, you find that many recommendations will land you between 175-215*F. And choosing what temperature from that range is based on the engine you currently own. For a turbocharged engine (ours) we might anticipate a temperature rise during a full throttle run, perhaps 10-20*F rise in coolant temps on a drawn out 5th gear highway run. So it makes more sense to start low, around 180*F, and let it rise to around 200~

Lets start there. 180*F coolant temp. Yes, water is better than ethylene glycol at absorbing and storing heat without gaining temperature, that is, water's heat capacity (Joules of heat absorbed compared to increase in temperature) is very good, better than actual coolant. So run the most water you can for the best temperature stability. In Florida I run less than 20% coolant. Also, use DISTILLED WATER (or reverse osmosis). Never run tap water in anything you care about unless you need to limp home.

Last, these reasons already mentioned for the problem stated (blown HG, bad radiator cap) I agree with to start here, then branch out from there to more exotic possibilities.

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kcvpr

Well, I'm pretty sure I'm getting air bubbles out of the radiator. Ill have the car idling warmed up and ill make sure the radiator is full. I then rev the engine for a while, it will overflow a bit and while I'm holding the throttle I see bubbles around 1/2 - 1" in diameter come out of the radiator. I assume this means the headgasket it allowing the coolant to pressurize?

jr_ss

Yep, sounds like a headgasket issue. Go buy a hydrocarbon test and verify its a headgasket.

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shift_down

leakdown test this beezy

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Mikester

Dude, I mean absolutely no disrespect to you when I say I laughed my ass off when I saw that vid. you NEED a hose to the overflow reservoir. The reason it shoots out when you give it throttle is the pressure in the system increases when the water pump rotation speed increases... Anything under pressure (whether it be from the pump or heat or both) is going to migrate thru the path of least resistance. In this case, it's out the hole that should be connected to an overflow reservoir.

And then there's what Darren said below:

^^This is the fix. You don't need to do a leak-down test or check the head gasket for this one... The reason there are bubbles is because you are allowing air directly into the system via the very hole water is shooting out of... Every time you rev up, water shoots out... on rev down, air gets sucked in to take the place of the water... After doing it so many times, there is going to be air bubbles all throughout the system. If there were an overflow reservoir like there is supposed to be, only coolant would be able to flow in/out of the hole... keeping the system bubble-free.

It doesn't matter what the pressure rating of your cap is when there is a wide-open hole right under it. The overflow reservoir allows coolant to flow into it when its hot; and back into the radiator when it cools and/or the pressure subsides.

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jr_ss

Correct, however, you should not have air bubbles in the coolant system what so ever. If its idling, and he is seeing air bubbles coming out, there is an issue some where and it's pressurizing the system.

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