So now I’m wondering if I should replace that top part of the radiator, where the cap goes on to. Would it be safe enough just to unbolt it from what it’s bolted to? It looks easy enough, but I’m concerned that it might be somehow attached to something I shouldnt mess with. Like a timing belt. Or part of the engine. Should I just take it off? Would be easy to clean then. And also replace if necessary. It’s pretty rusty inside.
A headgasket leak will continually blow combustion gasses into the engine’s water jacket and that will force the coolant into the reservoir, then when whatever coolant is left in the engine contacts as it cools it’ll draw air in through the headgasket leak rather than pulling coolant from the reservoir. Air will be much easier to draw in than the coolant.
A headgasket leak will reduce the coolant in the engine also by drawing it into the cylinder on the intake stroke, vaporizing it, and pushing it out the exhaust with the combustion gasses. This will further reduce the coolant in the engine.
In any engine 4-cylinder an above, when the engine is shut down there will always remain one cylinder on the intake stroke, with the intake valve open. Let’s assume for the sake of illustration that you have a four cylinder. If the headgasket breech involves cylinders #1 and #2, the odds of one of these having the intake valve open when the engine is shut down is 50%. The cooling system as it cools and contracts will simply draw air in through whichever intake valve is open.
The other thing about air is that it can be compressed by pressure. Once most of the coolant has been blown out and sucked out due to the headgasket breech, and the air in the cooling system pressurized to 16psi with combustion gasses, when the engine cools the contents of the cooling system, being mainly air, will simply contract as they cool until the pressure drops to ambient. The air having been compressed whereas coolant would not have been (coolant doesn’t compress well), it isn’t going to draw anything as it cools. The pressure will simply drop.
In short, your problem is not a clogged tube to the reservoir, it’s the breech in the headgasket. Until you get that fixed, your symptoms are going to continue.
Instead of trying a magic leak plug additive, which is more likely to clog your radiator tubes than plug your headgasket, have you considered replacing the headgasket?
Thank you for that in depth answer. Yes, I have considered replacing head gasket, but it’s going to cost min $2,500 for my 2000 model V6 camry conquest . Car is worth around $3000. (was worth. now not so much.)
I like that you said all that about the air being pulled from the crack, not pulling from the reservoir. The thing I’d still like to know is, if the hole to the reservoir is blocked with rust, then even if there was no crack in the head gasket, there is a malfunction with my overflow and there is pressure in the engine, which I would assume is not good. Correct?
So I am worried that when I fix this with seal-up, that the excess pressure in the engine will still cause problems. Which is what I want to avoid because I know it’s already fragile due to a patch-up job, not a proper gasket replacement.
So I am wondering if I can take the top part of the radiator, where the cap goes, and either replace or try to unblock the hole to the reservoir. I want to make the coolant overflow work so the I can pressure off an already weakened system.
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Sort of correct. You wouldn’t have the “rust” in the hole in the reservoir if you didn’t have the combustion gasses contaminating the coolant.
Nope. You’d need the skills and equipment of a radiator shop to do this.
The cooling system absolutely needs to be pressurized without regard to the function of the overflow. It raises the boiling point of the coolant in the engine above the engine’s normal operating temperature. Without the ability to hold pressure, the system will just repeatedly boil and the engine overheat.
Note that the engine will overheat with a blown headgasket anyway. The engine is blowing extremely hot combustion gasses directly into the coolant, adding high heat to it faster than a cooling system is able to dissipate it.
Bottom line: you’re trying to fix the manifestations of the problem without fixing the problem. That never works.
Sorry.
Your Camry is much different than the Trooper in the beginning of this thread, the cooling system cap is on the water outlet attached to the engine. The water outlet can easily be replaced however if the engine/head gaskets have been damaged due to this cooling system malfunction and overheating it is too late. Are you certain the engine has a blown head gasket?
Is this what your engine looks like?:
http://s787.photobucket.com/user/akalian_01/media/engine.jpg.html
You would not be able to blow back through the overflow tube unless the coolant pressure cap is off.
I don’t see the 90 degree elbow you spoke of…could you post a picture?
Ok, thanks for that.
I have put seal-up in it and hope that can temporarily do something positive to the head gasket.
In my car, the coolant reservoir, and the cap of the radiator, might be on a different part to other cars. I called the wreckers to see if they had this part.
They do. I will go to check it out tomorrow. He called it the thermostat housing. However, and i mentioned it to him too, the thermostat on my car is on the lower radiator hose. Which i’ve replaced this week so i know it’s definitely not up the top there. Here is a pic. My finger is pointing to the area of the overflow valve inside the housing that seems blocked, hence the coolant not going into the overflow.
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I am really trying to understand the pressure system here. What you said makes total sense. So I can’t understand how, if the coolant can normally flow through this little overflow, into what looks like a pretty flimsy little hose, and a pretty flimsy plastic overflow container, with a plastic lid on it, wouldn’t this mean that there is essentially a way for the pressure to escape pretty easily? That is, if it wasn’t blocked with rust like it is currently.
With respect, sheri, I wish you hadn’t tacked your question onto someone else’s thread. I don’t know who I’m answering anymore, and the OP seems to be getting pushed aside.
The answer is that the radiator cap, whether it’s on the radiator or a separate passage, is a pressure valve AND a check valve. It allows pressure beyond its rating, typically 15-16psi, to pass from the engine, and free flow off fluid in the other direction. I can’t tell from the existing photo, where that tube goes, but I suspect it’s the bypass that allows some coolant to flow internal to the pressure side of the system even with the thermostat closed. In short, coolant can circulate even when the engine is cold, it just doesn’t go out to the radiator.
But now that there are two different questions comingled, I don’t know which questions were yours without going back and sorting everything out. I’m getting all confused.
With a cold engine, remove the pressure cap. You should be able to see the entrance of the tube to the overflow reservoir. Try to push a wire from the inside-out.
it’s blocked with rust. that’s my point. Which is why i’d like to replace it, but am not sure if that is an easy job. It looks like the part is bolted on and wouldn’t be too hard. But i’d love some advice on that.
Sorry about that. I’m new to forums. That tube goes to a plastic overflow tank. But it’s blocked with rust. So i was thinking i should replace that metal part the cap attaches to to get a free flowing valve to the coolant. I’m worried that the pressure building up because the overflow is blocked, is going to put more pressure on the engine.
Thanks Nevada, I thought we were talking about the radiator itself. That diagram helps.
The water outlet (below the cooling system cap) is not difficult to replace, takes less than an hour for an experienced tech.
It is # 15 in the diagram;
Yes. The 90 degree angle is inside the water outlet: entry being coolant valve, exit being down the water outlet. It doesnt just go directly into the side of the water outlet. So it’s blocked easily.
Thanks for that. Would you think there’s any special tools needed? I’m not that experienced, but It looks to me like I could unbolt it, and unattach a few cords. As long as there’s no mysterious danger or fragile thing underneath there I should be worried about.
I managed to change the thermostat, which was pretty hard to get to, so would you think I could do this part? The only thing stopping me from having a proper mechanic doing it is money.
Nevada I am quite certain that it’s a head gasket issue as the mechanic that looked at it briefly did a test with a blue dye that turned green as he kept it on the radiator outlet.
I will get a second opinion when my mechanic friend is here in a week. Could could the blue dye turning green possibly mean anything else?
I am hoping that with some kind of seal-up chemical welder I can fix the problem for as long as I can. The car is pretty old and I am quite attached to it because it’s been in the family since it was new, and I feel like it’s a trustworthy car.
It’s tempting to save to pay the $3000 to fix the engine. But the car is worth around $3000 and the interior parts are beginning to fall apart. I am fixing those too, but with all the rust in the engine, and the general wear and tear I wonder if I need to learn to let it go.
The most difficult part will be disconnecting and reconnecting the bypass hose under the manifold, #17 in the diagram. If you don’t have spring clamp pliers and a hose tool to perform this it will be very frustrating. Look between the water outlet and intake manifold to see the hose and clamp. It is easy to reach with the manifold removed but that is a lot of work.
I would try to carefully clean out the reservoir hose fitting with a small drill bit.
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That is a very good idea. I can stick wire into the part where it turns 90deg inside the outlet. But using a drill might be enough to get something out so I can clear the rest.
I had a look. Those clamps were all over the radiator too. They’re so difficult to work with! Extremely frustrating. I took them off and replaced them the screw on ones. Do you think I could replace that one on the bypass hose with a screw clamp?
I’ve had good luck unblocking small clogged tubes w/a handheld vacuum pump gadget sometimes.
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That sounds good. But in this case I would imagine tha tth pressure from the hot coolant coming into the overflow container should unblock any minor blockage. Which it’s not doing currently, so i think it might be a bit rusted and blocked quite tight.
It seems a stretch to think that the cap relief port is plugged with rust so tightly that it can’t be cleaned using a drill bit in your fingers. I suggest that you take the cap and rubber hose off and begin with a 1/16" bit and work your way up to a 1/4" before doing any dismantling. And keep in mind that the blockage may be the result of a block sealer that has been added to patch up a blown head gasket.
And filling the overflow will not fill a radiator that is low. The overflow bottle will catch the coolant that expands with heat and then as the engine cools and the coolant contracts vacuum pulls the expelled coolant back in. The radiator must be topped off when cool and the cap functioning for the overflow to work as designed.