Van overheats on idle
July 5, 2018 9:37 AM Subscribe
Our 2007 Honda Odyssey van overheats on idle ONLY. Can you pinpoint the cause?
Admittedly, I don't know a ton about cars, but I do know some. Our 2007 Honda Odyssey van overheats only while idlling - the gauge stays put exactly where it should so long as the van is moving.
My father in law wants to go straight to replacing the water pump, but everything I've read on the internet indicates a bunch of other options (fan, thermostat, etc.). The fan does seem to be operating normally, and the coolant isn't low.
Mechanics of Mefi, what is your opinion on this?
Admittedly, I don't know a ton about cars, but I do know some. Our 2007 Honda Odyssey van overheats only while idlling - the gauge stays put exactly where it should so long as the van is moving.
My father in law wants to go straight to replacing the water pump, but everything I've read on the internet indicates a bunch of other options (fan, thermostat, etc.). The fan does seem to be operating normally, and the coolant isn't low.
Mechanics of Mefi, what is your opinion on this?
Response by poster: it might pay to do the timing belt(s) since you're right there.
We actually had the timing belt done two (ish) years ago. For reasons I don't know about, the water pump was not done at that time.
I actually think its the fan. But its hard to get them to listen to my opinion.
posted by anastasiav at 10:06 AM on July 5, 2018
We actually had the timing belt done two (ish) years ago. For reasons I don't know about, the water pump was not done at that time.
I actually think its the fan. But its hard to get them to listen to my opinion.
posted by anastasiav at 10:06 AM on July 5, 2018
My first guess was the fan, too, but you say that the fan seems to be working—does the AC condenser have a separate fan than the radiator? Just want to make sure that indeed it's the radiator's fan that you've seen turn on and not the fan for the AC. If you've been running the AC during your investigations, just turn it off and test again.
If the radiator fan is turning on and the coolant level is good and you've bled any air out of the coolant system (google how to "burp" your coolant system), then I'd say the thermostat is the big culprit, or less likely the coolant temp sensor.
posted by cyclopticgaze at 10:08 AM on July 5, 2018 [2 favorites]
If the radiator fan is turning on and the coolant level is good and you've bled any air out of the coolant system (google how to "burp" your coolant system), then I'd say the thermostat is the big culprit, or less likely the coolant temp sensor.
posted by cyclopticgaze at 10:08 AM on July 5, 2018 [2 favorites]
If your f-i-l doing the work? Is the part not over 100? It's the orignal? Replace the water pump. Is f-i-l just making a recommendation? Thanks, we'll check it out.
posted by theora55 at 10:48 AM on July 5, 2018
posted by theora55 at 10:48 AM on July 5, 2018
I had a much older Honda than yours, but about the same age as counted from its model year, that overheated not on idle, but when I came to a stop or slowed way down after an uninterrupted stretch of driving, so that it felt initially like it was overheating on idle.
And the culprit turned out to be a weakened spring on the radiator cap, and disappeared completely when I bought a new one.
The explanation was that as the coolant heated up and developed higher pressure from reduced airflow past the radiator, reduced circulation through the radiator because the water pump RPMs went down, and reduced oil circulation, the system was designed to open up a bit at the radiator cap and let coolant out into a reservoir from which it would be taken up again later, but the weakened spring allowed coolant to escape completely, and after a few cycles of that which didn't produce obvious problems, the radiator would really blow.
posted by jamjam at 12:19 PM on July 5, 2018 [2 favorites]
And the culprit turned out to be a weakened spring on the radiator cap, and disappeared completely when I bought a new one.
The explanation was that as the coolant heated up and developed higher pressure from reduced airflow past the radiator, reduced circulation through the radiator because the water pump RPMs went down, and reduced oil circulation, the system was designed to open up a bit at the radiator cap and let coolant out into a reservoir from which it would be taken up again later, but the weakened spring allowed coolant to escape completely, and after a few cycles of that which didn't produce obvious problems, the radiator would really blow.
posted by jamjam at 12:19 PM on July 5, 2018 [2 favorites]
I have a 2007 Nissan, and had the issue where my engine began to overheat on idle and while driving through stop-and-go traffic, even on reasonably cool days (obviously it wasn’t an issue when it was 20 degrees out). The issue turned out to be a combination of my radiator, thermostat and AC condenser, all of which were replaced. In my particular scenario, it was not the radiator cap causing the issue, but the grill, which is of a piece with the radiator.
In any case the radiator is a good place to start.
posted by Autumnheart at 4:00 PM on July 5, 2018
In any case the radiator is a good place to start.
posted by Autumnheart at 4:00 PM on July 5, 2018
Try some sort of relay switch (thermostat relay? I'm not sure of the right terminology. This is ringing a bell to an issue a friend had with theirs.
posted by annieb at 7:11 PM on July 5, 2018
posted by annieb at 7:11 PM on July 5, 2018
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If you say it's working well, then it's down to the water pump. You could replace the thermostat - it's simple and should be changed routinely anyway.
But, I'd bet its the water pump if you are certain about the fan.
I dunno about honda motors, but it might pay to do the timing belt(s) since you're right there.
posted by Pogo_Fuzzybutt at 9:56 AM on July 5, 2018 [3 favorites]