Hello bitogers! I have a 2004 Toyota Sienna with 192k miles that is overheating. It started about a week and a half ago. As soon as it overheated I was lucky enough for it to be right next to the shop so I took it straight there (heater on high the whole way and all that jazz) Kept a close eye on it and just made it to the shop. Needless to say I had fingers crossed it was just the thermostat since that's a cheap fix. Lo and behold the thermostat was replaced and problem solved for a week (and 200 miles). Go to crank up the van this morning all was well so I thought. It was overheating again in the driveway here so I let it cool off and took it straight back to the shop (around a mile away if that). Now when it overheated both times there was steam coming out of the puke tank. I checked the antifreeze levels the first overheat and they were just fine. Even pulled the coolant cap off. It's a radiator cap but its not directly on the radiator. It's on a metal pipe at the top of the engine. Anywho my question is why the heck would the car drive perfectly for a week or so and then konk out with the same issue? Is it possible the new thermostat could be bad?
2004 Toyota Sienna overheating
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Bad advice on using no thermostat. Never do that. These cars have excellent cooling systems. I had the same engine and the bleeding of air can take awhile. You said you checked coolant the first time, but steam is coming out the second? Coolant is low it sounds like. The thermostat has an air hole and it should be mounted on top. The small screw on the metal radiator cap housing can be used to bleed off air too. After doing the thermostat and coolant hoses I remember I had to keep adding coolant for some time as air was let out. If the purge tank is kept up higher, as air is released the level goes down and add more until it stays at the mark. The purge tank has to have coolant in it or air is sucked back in.
Originally Posted By: goodtimes
These cars have excellent cooling systems. I had the same engine and the bleeding of air can take awhile.
Your second sentence precludes the first one. No cooling system worth a hoot 'takes a while' to purge air
If the fill neck isn't the highest spot in the system and the system isn't designed so as to never trap air by just filling, then it's not even close to 'excellent'. Not saying that's OPs problem, however.
These cars have excellent cooling systems. I had the same engine and the bleeding of air can take awhile.
Your second sentence precludes the first one. No cooling system worth a hoot 'takes a while' to purge air
Originally Posted By: goodtimes
Bad advice on using no thermostat. Never do that. These cars have excellent cooling systems. I had the same engine and the bleeding of air can take awhile. You said you checked coolant the first time, but steam is coming out the second? Coolant is low it sounds like. The thermostat has an air hole and it should be mounted on top. The small screw on the metal radiator cap housing can be used to bleed off air too. After doing the thermostat and coolant hoses I remember I had to keep adding coolant for some time as air was let out. If the purge tank is kept up higher, as air is released the level goes down and add more until it stays at the mark. The purge tank has to have coolant in it or air is sucked back in.
I wasn't suggesting to run it with no thermostat for the next 100k miles. Just for a trip or two to see what it does. That will not hurt anything. The question is if you can remove the thermostat and put everything back together properly.
Bad advice on using no thermostat. Never do that. These cars have excellent cooling systems. I had the same engine and the bleeding of air can take awhile. You said you checked coolant the first time, but steam is coming out the second? Coolant is low it sounds like. The thermostat has an air hole and it should be mounted on top. The small screw on the metal radiator cap housing can be used to bleed off air too. After doing the thermostat and coolant hoses I remember I had to keep adding coolant for some time as air was let out. If the purge tank is kept up higher, as air is released the level goes down and add more until it stays at the mark. The purge tank has to have coolant in it or air is sucked back in.
I wasn't suggesting to run it with no thermostat for the next 100k miles. Just for a trip or two to see what it does. That will not hurt anything. The question is if you can remove the thermostat and put everything back together properly.
I just spoke with the mechanic and they said they pulled the new thermostat and they still had the old one on hand. They gutted the old thermostat so it's just the assembly and no springs and such. He said he didn't see any leaks and wants me to drive the van with no thermostat for a week or two to see if that fixes the issue. If so then he's going to warranty out the new thermostat and go with a dealer part instead of aftermarket. Said it wouldn't be the first bad new thermostat he's seen from his supplier so fingers flippin crossed still for the cheap fix
What were your temperatures during the time it was ok? Bet it was cooler. From your recent post it could be the thermostat....if it's not:
Seen this numerous times on numerous forums; all winter the vehicles are ok, since when it's cold you don't need much cooling power. Then when it warms up in spring, cooling problems show up.
With a new thermostat that leaves the water pump, the radiator, or both. Have a look inside your radiator while the vehicle is running. Look for scale inside, and then when the thermostat opens, look for flow. If it's scaled inside, then at 14 years it's time to replace. If it doesn't flow, same for the water pump.
Seen this numerous times on numerous forums; all winter the vehicles are ok, since when it's cold you don't need much cooling power. Then when it warms up in spring, cooling problems show up.
With a new thermostat that leaves the water pump, the radiator, or both. Have a look inside your radiator while the vehicle is running. Look for scale inside, and then when the thermostat opens, look for flow. If it's scaled inside, then at 14 years it's time to replace. If it doesn't flow, same for the water pump.
Hey JLTD the times I drove it were around 2pm - 3pm during the week. It was around 75-85 degrees outside each time. Drove for around an hour each day and used the ac cooling. Total of 25 miles each day but it's all back country roads so no stop lights, signs, etc. This morning I was in regular small town traffic and it was fine until right when I got home. The temps were fine all last week and such too! So it's definitely weird. I'm really hoping it's not a bad waterpump. That's a pricey part and is powered by the timing belt. Not comfortable with timing belts so that's definitely a mechanic deal.
Does the radiator fan work? Overheating when sitting still idling is often because the fan did not start when it should.
Test for head gasket leak by starting the engine cold with the cap off and revving it. If bubbles or coolant blow out it's likely a blown head gasket. (This test works better when you have a thermostat that is not "gutted", because with a closed thermostat there should be no action at all in the radiator lines until the engine warms up and the thermostat opens. There is no reason to ever run without thermostat anyway.)
Also when the engine is hot, check if the heater works.
Don't keep driving while overheated.
Test for head gasket leak by starting the engine cold with the cap off and revving it. If bubbles or coolant blow out it's likely a blown head gasket. (This test works better when you have a thermostat that is not "gutted", because with a closed thermostat there should be no action at all in the radiator lines until the engine warms up and the thermostat opens. There is no reason to ever run without thermostat anyway.)
Also when the engine is hot, check if the heater works.
Don't keep driving while overheated.
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Yep radiator fan works. The mechanic said everything looked good with the thermostat out. They also stated there seemed to be some moisture under the thermostat so I'm thinking the thermostat didn't get a good seal. Anywho they said drive it without a thermostat for a week or two, bring it back by so they can check the levels and such, and if all looks good they'll order an OEM thermostat from the dealer and put that in.
You have something that is allowing air to get in.Your old coolant was full of air bubbles,when they changed the thermostat they poured in new coolant.You drove it and put air back into it.Air pockets will block coolant flow,making the temp sender read "HOT".The new air/pressure pushed coolant into the overflow tank and its obviously hot so it will steam.The garage doesn't have a hotplate they can warm to 195 and test that old thermostat?
The lack of thermostat won't help temperature control, it's a band aid at best
Get a Toyota thermostat and o-ring, and put it in
Then correctly bleed the system with a spill free funnel, I'll bet it starts coughing out air and sucking down coolant
While your doing this, you can monitor heater output and cooling fan cycling
Get a Toyota thermostat and o-ring, and put it in
Then correctly bleed the system with a spill free funnel, I'll bet it starts coughing out air and sucking down coolant
While your doing this, you can monitor heater output and cooling fan cycling
Sounds like it is intermittent so thermostat IMO.
Originally Posted By: michaelluscher
The lack of thermostat won't help temperature control, it's a band aid at best
Get a Toyota thermostat and o-ring, and put it in
Then correctly bleed the system with a spill free funnel, I'll bet it starts coughing out air and sucking down coolant
While your doing this, you can monitor heater output and cooling fan cycling
The cooling systems on 3.3L V/6 Siennas do not trap air so they don't need to be bled. The 3.3L is also not known to have head gasket problems unless it has been badly overheated.
The radiators on 2004 Siennas are known to have problems and Toyota issued a couple of service bulletins on them for cracking/leaking (they tend to crack in an area where leaking is not readily apparent, but the system won't pressurize so you will have overheating problems). Even if it isn't cracked/leaking, since the van is at least 14 years old, IMO the radiator is the likely culprit, it is probably partially plugged/restricted. Install a new radiator, an OEM thermostat, and refill with Toyota 50/50 Super Long Life (pink) Coolant. You should be good to go.
The lack of thermostat won't help temperature control, it's a band aid at best
Get a Toyota thermostat and o-ring, and put it in
Then correctly bleed the system with a spill free funnel, I'll bet it starts coughing out air and sucking down coolant
While your doing this, you can monitor heater output and cooling fan cycling
The cooling systems on 3.3L V/6 Siennas do not trap air so they don't need to be bled. The 3.3L is also not known to have head gasket problems unless it has been badly overheated.
The radiators on 2004 Siennas are known to have problems and Toyota issued a couple of service bulletins on them for cracking/leaking (they tend to crack in an area where leaking is not readily apparent, but the system won't pressurize so you will have overheating problems). Even if it isn't cracked/leaking, since the van is at least 14 years old, IMO the radiator is the likely culprit, it is probably partially plugged/restricted. Install a new radiator, an OEM thermostat, and refill with Toyota 50/50 Super Long Life (pink) Coolant. You should be good to go.
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Took the van out for a drive today and so far so good. Now goodtimes may be on to something here. The puke tank was at the correct mark when I left the house, came back and it was on the low mark. I've had this happen many times right after a coolant change so not TOO worried just yet. I called up the mechanic and asked them if they wanted me to go ahead and top off the coolant in there. They said with the engine hot it should be at the full mark so add some water and keep an eye on it the next few days. Most likely there was more air getting out of the system. Now I did notice the engine ran much cooler today but that was expected with no thermostat. Have a few more days of country road driving this week so going to keep an eye on the puke tank each day to see what happens
Originally Posted By: michaelluscher
The lack of thermostat won't help temperature control, it's a band aid at best
Get a Toyota thermostat and o-ring, and put it in
Then correctly bleed the system with a spill free funnel, I'll bet it starts coughing out air and sucking down coolant
While your doing this, you can monitor heater output and cooling fan cycling
You can't fit a funnel like that on a Sienna without removing the cowl, and you don't need one, anyway.
Make sure to use an OEM thermostat with the plastic housing. Aftermarket plastic housings are often inferior material and are likely to crack prematurely.
The lack of thermostat won't help temperature control, it's a band aid at best
Get a Toyota thermostat and o-ring, and put it in
Then correctly bleed the system with a spill free funnel, I'll bet it starts coughing out air and sucking down coolant
While your doing this, you can monitor heater output and cooling fan cycling
You can't fit a funnel like that on a Sienna without removing the cowl, and you don't need one, anyway.
Make sure to use an OEM thermostat with the plastic housing. Aftermarket plastic housings are often inferior material and are likely to crack prematurely.
Originally Posted By: wag123
michaelluscher said:
Get a new thermostat, complete drain and fill of the cooling system.
The engine block drain which gets you the most of the coolant out is right behind the radiator right next to the neck of the exhaust. Remove the head shield and its easily visible. You drain radiator and this block plug an an entire 8Q comes out. The remaining 2Q is somewhere in the engine block and heaters. $50 for coolant and not sure what the thermostat costs.
One experiment to do if you replace the coolant, when the radiator drain is opened, it should flow really fast and then a small trickle. If it drains and drains you have a partially clogged radiator - aftermarket radiators are far better than stock and bigger and better.
The engine block drain which gets you the most of the coolant out is right behind the radiator right next to the neck of the exhaust. Remove the head shield and its easily visible. You drain radiator and this block plug an an entire 8Q comes out. The remaining 2Q is somewhere in the engine block and heaters. $50 for coolant and not sure what the thermostat costs.
One experiment to do if you replace the coolant, when the radiator drain is opened, it should flow really fast and then a small trickle. If it drains and drains you have a partially clogged radiator - aftermarket radiators are far better than stock and bigger and better.
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