Hey guys,
Long time no see. On Saturday I was running errands in my old 06 Toyota Sienna daily driver. While waiting in line at the local Dunkin Donuts I happened to glance at the gauges(not sure what made me look) and noticed the temp gauge higher than normal. While waiting a long time because the line was long, the gauge climbed even higher. Around the time I was getting my food it had crept to the full red mark. I was on the phone to my wife asking her if she could pick me up as I thought for sure I was going to have to shut it down. I decided to push it a bit, and see if it cooled off once moving. Got out on the road while still on the phone with my wife, and the gauge goes right back to normal in like a half mile. Rest of the trip home was uneventful, but only about 2 miles.
Sunday I decide to try to trouble shoot the problem. I took the van for a ride, and it got up to normal operating temp. Bring it home, and let it sit in the driveway idling while I shuffle around some cars(including a new project, more on that later) , checking on the gauge every now and then. Pop the hood and check on the operation of the fans. Both working, but on slow speed. Turn on A/C which isn't working as I think it need a recharge. Both fans come on faster, and at one point go full speed for a little while. Eventually the temp gauge starts rising again. Doesn't appear to be the fans which I though it might have been. I take it for another ride around the block, and the temp goes back to normal. Get home, and shut it down.
Wait a couple of hours and open the small cap that is on the engine. Find no visible coolant in the neck. Squeeze the hoses, and hear coolant splooshing around. Check over flow tank/ reservoir. and it is empty. Go to my local FLAPS and get some Toyota style red coolant. Added a little over a half gallon into the system, and tank. Run the engine, and get some bubbles out of the system. Cap it off, and take it for a ride. Temps normal. Bring it home, and let it idle. No rise in the temp. The lose of coolant tells me I have a leak, or it's going somewhere. No oil in the coolant, no coolant in the oil. I park in the same spot in my driveway all the time, and no puddles what so ever. Doesn't appear to be smoking. Thoughts? FYI, 06 Sienna LE 3.3 litre V6, 210k, owned sine Jan 07, timing belt and water pump changed twice, last around 2018 and 50K miles ago I think. No leaks that I can see. I do have a cooling system pressure tester, but no adapters for the small cap that is on the engine.
Thanks,
Chris
TGMF
HalfDork
5/16/22 3:12 p.m.
My thoughts......
-You may not have a leak, rather you lost coolant when it got so hot it boiled over.
-Insufficient coolant flow. This could be either water pump related, or a faulty thermostat. I'd attempt to verify flow issue by cranking on the cabin heat. does it stay hot during extended idle, or does it cool down some then get hot again when reving the engine?
- if the above doesn't pan out you could be facing a failing head gasket. uncommon, for this engine, but not totally unheard of either.
TGMF said:
My thoughts......
-You may not have a leak, rather you lost coolant when it got so hot it boiled over.
-Insufficient coolant flow. This could be either water pump related, or a faulty thermostat. I'd attempt to verify flow issue by cranking on the cabin heat. does it stay hot during extended idle, or does it cool down some then get hot again when reving the engine?
- if the above doesn't pan out you could be facing a failing head gasket. uncommon, for this engine, but not totally unheard of either.
Now that you mention this I remember one time over the winter the heat was very low at idle, but fine with engine revs, or driving. I didn't give it a lot of thought at the time as it was stupid cold, and thought it was just because of that. What does that tell you? Water pump, or thermostat? FYI it's on the original radiator, but again I don't have any visible leaks. I didn't see steam or a puddle under the car when it got hot in the drive through line. I even looked back at the area I was in line, and didn't see anything.
If it's still behaving the same after topping off the coolant and making sure there's no air in the system, I'd blame the water pump. If the pump impeller is coming apart it may still be able to move enough coolant at higher RPM but not at idle.
Also, if the system wasn't full but there was still coolant in the overflow tank, replace the pressure cap.
The auto parts stores will "rent for free" a pressure tester if you want the one with the correct size caps.
I prefer O'Reillys for rentals. Here, they seem to offer more stuff
TGMF
HalfDork
5/16/22 3:50 p.m.
In reply to Mazdax605 :
consider that the heat in the cabin is supplied by coolant flowing through the heater core, which is just a tiny radiator. The heater core is not restricted by the thermostat as the thermostat is not part of the heater circuit. Any time the engine is running with the heat on, coolant is supposed to be flowing from the engine to the core back to the engine.
Now, if you have a low coolant flow condition, the incoming air going across the heater core will absorb all the heat from the coolant inside the heater core, and will not be able to maintain the requested vent temp. This presents to you, as a temperature drop at the interior vents. If giving the engine some revs (spinning the pump faster) brings the vent temp back up, you know that there is insufficient coolant flow inside the heater core, and therefor very likely the entire cooling system. If the cooling system doesn't have enough flow to keep the cabin heat hot, there's no hope it will be able to keep the engine cool at idle, it simply isn't circulating coolant fast enough.
This could be from either low coolant (air in system) or a failing pump.....not much else.
Also, for leaks.....does your van have rear heat? if so, there are lines under the vehicle, as well as a rear heater core. All could leak and cause a low coolant condition, so don't just look under the engine area.
TGMF said:
In reply to Mazdax605 :
consider that the heat in the cabin is supplied by coolant flowing through the heater core, which is just a tiny radiator. The heater core is not restricted by the thermostat as the thermostat is not part of the heater circuit. Any time the engine is running with the heat on, coolant is supposed to be flowing from the engine to the core back to the engine.
Now, if you have a low coolant flow condition, the incoming air going across the heater core will absorb all the heat from the coolant inside the heater core, and will not be able to maintain the requested vent temp. This presents to you, as a temperature drop at the interior vents. If giving the engine some revs (spinning the pump faster) brings the vent temp back up, you know that there is insufficient coolant flow inside the heater core, and therefor very likely the entire cooling system. If the cooling system doesn't have enough flow to keep the cabin heat hot, there's no hope it will be able to keep the engine cool at idle, it simply isn't circulating coolant fast enough.
This could be from either low coolant (air in system) or a failing pump.....not much else.
Also, for leaks.....does your van have rear heat? if so, there are lines under the vehicle, as well as a rear heater core. All could leak and cause a low coolant condition, so don't just look under the engine area.
I'm certain I have no puddles under the car, front or rear. It doesn't even leak oil after 200k. I'm thinking it might be lack of flow due to low coolant level, but what I don't know is where it went. I think I'm going to rent the proper pressure tester so I can check that out. Would it hurt to do a block test of the cooling system to check for combustion gasses in the cooling system? I would like this car to last me a few more years. As much as I'd like to replace it, I do love it, and it has been paid for now 10 year going.
Toyota coolant is wonderful because it leaves a stain of pink crystals where it leaks.
Water pump leaks are common.
When overheated, the blocks warp. It does not sound like you overheated it, just got it into the red.
Be sure to check the coolant pipes to the rear heat as well. Salt loves to wreck these.
https://www.siennachat.com/threads/coolant-leak-rear-lines.58571/
