[micali]

I have an 05 sienna and I started having an intermittent OH problem these last few weeks.
We've had record heat in our area these last few months and one day the van OH so I pulled over and added some water. After it cooled down we drove with no issues for a few days. Now rinse and repeat for a few more times. I added antifreeze as well but it still OH.
I've removed as much of the old fluid as possible and replaced it with the Asian brand antifreeze. Whats been happening is even after I did this it's still OH. It seems to go for a couple days with no issues and then it OH. The last time I put it on a hill, engine up, and filled it so the bubbles would work their way out. I thought it fixed the issue but today it did it again. What is happening? Should I buy one of those no spill fiunnels and try that? I'm at a loss for what's going on.

 

[micali]

Also, one time I checked the fluid with the engine running there was some foaming coming from the radiater cap. There was a lot of bubbling as well. I bought this little bottle from wall mart that fixes head gasket leaks and after about 5 mins the foaming and bubbling stopped. There wasn't any water in the oil or oil in the water. I've only put in distilled water as well. The van has 300,000 + miles on it so I'm not going to spend a lot of money on it.

 

[3Wheelerguy]

Posible thermostat to start.I have seen some rad fans fail on the high mileage 2nd gen.

 

[micali]

I thought about the T-stat. Could it be trapped air? This after I put a gallon of water back in.

 

[happycamper]

Pretty sure you have a head gasket issue. Continuous bubbles means exhaust gas is getting from the cylinder to the coolant.

 

[micali]

Well, I will buy one of those no spill funnels and see if the bubbles are continuous or just air after I let it run for a while. Time will tell.

 

[q0987]

@micali,

Combustion Leak Detector

Amazing deals on this Combustion Leak Detector at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

You can use this to confirm whether or not you have a head gasket issue. If not, you can use no spill funnel to proceed the coolant bleeding.

 

[98 SNAKE EATER]

Had a similar problem with my mom's 06 Limited

Turned out to be an intermittent cooling fan issue.

The housing for the fan motor would sometimes lose connection and cause it to overheat (flex it with your hand and it would start/stop)

Replaced the entire fan assembly as it wasn't available separately and it's been fine eversince