Upper Radiator hose collapse

[71Corolla]

1987 Camry LE, 3SFE, 410,000 km. The upper rad hose collapses flat after the car has cooled down for a spell. Happens consistently, the car runs fine otherwise, does not overheat. One thing to note, the head gasket is maybe suspect because I do get a small amount of oil in the coolant over a period of time. Basically between coolant flushes (about 36,000 km or every 3 years) I do see some oil floating to the top, not a lot but it is there. The coolant level also does drop over time, about an inch down on the reservoir about every 10,000 km.

Now before I declare it a bad head gasket I want to exhaust all other possibilities. I really really do not want to pull the head, the car has all original gaskets except for a few minor ones. I've replaced the thermostat, upper rad hose, rad cap, and made sure the tube to the overflow tank is not clogged. I even tried pulling the overflow tube out of the tank and just let it sit free, but the rad hose still goes flat. When I open the cap, the vacuum is relieved and the hose goes back to normal. The coolant level is about what you'd expect, a tiny bit below full because it could not draw anything in from the overflow.

So, I'm stumped. How can the system hold a vacuum, but is not able to suck in coolant from the overflow? It will hold a vacuum indefinitely, which would seem to indicate the system is more or less sound. Or is this just a quirk of a bad head gasket? Now I did not buy a Toyota rad cap, but a "Made in Japan" unit. It looks almost identical to the Denso original. Seems hard to believe that both the Denso and the replacement units are bad.

So am I just wasting my time and delaying the inevitable head gasket job, or something else is wrong?

[Doctor J]

It may sound silly, but does the vacuum valve on the NEW radiator cap works properly?
Does that oil visible in the radiator look like dirty milk, or it is looking similar to kerosene spilled on the water ("rainbow stains")??
When I had BHG on my Supra, the exhaust gases forced coolant out, and the upper hose was stone hard even on the cold car.

[71Corolla]

It's similar to seeing oil floating on water, the coolant looks mostly red (I use Toyota red) after 2-3 years. It has some cloudy look to it actually, but not that bad. The car is 23 years old so I don't expect the coolant to stay perfectly clean, there is bound to be crud that gets released into the coolant. BTW, the car had Prestone for about 10 years, that stuff is crap it caused all kinds of build up, don't ever use that garbage.

I can't be 100% sure the new rad cap is good, but it seems highly unlikely that it is. I will have to bite the bullet and buy a new one from a dealer, I hate doing that and getting raped on price. BTW, how do I test the vacuum valve on the rad cap? It sure doesn't seem like it works, I can't see how the rad hose could be sucked in like that if the valve releases properly.

[Doctor J]

Remove the cap and try to pull that vacuum valve open (move it out about 2 mm); if it requires effort at the beginning, it may be stuck

[71Corolla]

Both the original cap and the replacement look and feel exactly the same to me. I'll grab a new one from Toyota just in case.

[71Corolla]

I put in a new upper rad hose and rad cap, it cured my problem. Both parts are from Toyota. My coolant level in the overflow tank changes slightly, about 1/2" between hot and cold, but the coolant level is stable overall, which surprises me I was sure I had a leak.

So it looks like the combination of a weak upper hose and a non Toyota cap caused the overflow system to not work correctly.

[Doctor J]

On the car I diagnosed the same problem the vacuum valve was obviously stuck so that was easy.

[sub0]

Originally Posted by Doctor J

On the car I diagnosed the same problem the vacuum valve was obviously stuck so that was easy.

I have the same problem with my 1994 Camry V6. I change the Cap and upper host 6 weeks ago and look fine. Yesterday the upper host suck flat again. The car running fine, no over heated. Where is the vacuum value location. I would like to check it out too.

Thanks !

[white90dx]

Originally Posted by sub0

I have the same problem with my 1994 Camry V6. I change the Cap and upper host 6 weeks ago and look fine. Yesterday the upper host suck flat again. The car running fine, no over heated. Where is the vacuum value location. I would like to check it out too.

Thanks !

The valve they are talking about is part of the radiator cap. If you remove the cap (when the motor is cool!), you should be able to see how the cap 'holds' pressure from the radiator with a strong spring and large valve/seal, but if there is 'sucking' from the radiator, there is a smaller valve that opens easily.

-Charlie

[sub0]

Originally Posted by white90dx

The valve they are talking about is part of the radiator cap. If you remove the cap (when the motor is cool!), you should be able to see how the cap 'holds' pressure from the radiator with a strong spring and large valve/seal, but if there is 'sucking' from the radiator, there is a smaller valve that opens easily.

-Charlie

Thanks ! I just flush the rad and I will see what happen tomorrow kind of late now.
I also purchase another rad. cap just in case I need it.

BTW, after I frush the rad. Without the cap on I pull water into the rad to top it up with the car running after a while there is a lot of hot water push out from the rad. while the car is running hot. Is that normal like that.

I don't usually do like this. I usually with the engine off fill it up and with cap on. let the car run for a while and after it cool down. I open the rad. cap again and top up if need

Thanks !

[white90dx]

Once the thermostat opens, there could be water pushed out of the radiator if the cap is off.

It is normal to refill the radiator with the engine on, but you should just give it a couple rev's to get bubbles out, fill it and put the cap on before hot water starts coming out of the upper radiator hose. Leave a little extra coolant/water in the overflow tank and the rest should take care of itself after a few warm-up/cool-down cycles.

-Charlie

[sub0]

Originally Posted by white90dx

Once the thermostat opens, there could be water pushed out of the radiator if the cap is off.

It is normal to refill the radiator with the engine on, but you should just give it a couple rev's to get bubbles out, fill it and put the cap on before hot water starts coming out of the upper radiator hose. Leave a little extra coolant/water in the overflow tank and the rest should take care of itself after a few warm-up/cool-down cycles.

-Charlie

I ran my car a little more last night. This morning the overflow tank was empty and the Rad. is full. I refill the overflow back to full line. After work I am going to run the car a little more. The upper host should not collapse when the pressure build it should flow the water back to the overflow tank and if it collapse again after all cool down process. I will change the Rad. Cap and see.

Thanks !

[Doctor J]

Not sure if it applies to 94 but 2.5 V-6 used to have the air bleed screw near the top hose outlet

[sub0]

After I frush the Rad. and look like is all o.k now.


Thansk to All of you !