[sontakke]

All of you are talking as if changing the thermostat on the van is as simple as changing the engine air filter. I am under impression that it is at least as difficult as *first time* changing the cabin air filter aka lot more painful.

 

[0dyfamily]

Cabin air filter change (first time) is a little easier to do than a thermostat change, but not by much.

Thermostat change: first, almost too obvious to mention, but I'm going to....you should drain some coolant from the block and radiator, not all of it. The thermostat is almost at the "high point" in the cooling system. As far as I can tell, the highest point in the cooling system is the radiator filler neck.

Some coolant will still spill out when you remove the thermostat housing. The old thermostat may be "stuck" due to the rubber gasket, for lack of better words, bonding to the block.

Replace, reinstall thermostat housing, refill with coolant, "burp" the system as mentioned elsewhere in the forum.

________________________________________________________________________________________________

Last night I immersed an OEM 78-deg C thermostat and a Motorad 302-180 (82-deg C) thermostat into a pot of water, set a stainless K thermocouple probe into the water, and turned on the heat. As the temperature rose (at a rate of less than 0.1 degrees Fahrenheit per second), The OEM thermostat started to creep open at just over 176-deg F. The Motorad did the same at just over 184-deg F.

At 192-deg F, the OEM thermostat appeared fully open, the Motorad just a shade less. Above that temperature, both appeared fully open.

Only about an 8-degree F difference in opening temperatures, which doesn't seem like a lot, but from personal experience I can say it sure makes a difference in winter time.

OF

 

[Buffalo4]

Did the Motorad look like it opened as 'much' as the OEM? Mine sure didn't, and I tried two OEMs and two Motorads. Course, at my elevation, water boils quite a bit lower than 212F. I can't even get to 198F.
I still believe my problem is with the cheap replacement radiator I bought off ebay. They,the radiators, should all have flow ratings, etc. on them!
If my hwy speed temps didn't get so high, I would definitely have kept that Motorad in my Ody. Temps in the mtns of Colorado get damn cold.
Buffalo4
PS: Yes, changing the thermostat is a PITA, overall, compared to the PITA cabin air fliter in my '03.

 

[0dyfamily]

That Motorad sure did look like it opened just as much as the OEM.

I'm thinking your radiator might be the culprit.

The name brands I look for are Denso, Koyo or Behr.

For thaxman, if it ain't a thermostat on its last legs, maybe it's the radiator as well (clogged). I just hope it's not a pinhole leak in just one of several coolant hoses in the engine bay.

OF

 

[thaxman]

For thaxman, if it ain't a thermostat on its last legs, maybe it's the radiator as well (clogged). I just hope it's not a pinhole leak in just one of several coolant hoses in the engine bay.

OF

240 miles, 3 straight hours. I highly doubt there was a leak in the system or I wouldn't have made it the whole way, esp since the temps creeped up within the first 30 miles. Low-flow in the radiator, well, that is a valid concern.

 

[0dyfamily]

Thankfully, it's not a leak, then. If you keep up on coolant servicing, Honda-Acura hoses last a long time. They really do stand up well to exterior environmental conditions. The big enemy to coolant rubber compound longevity for radiator & heater hoses is electrolytic attack from worn-out coolant (coolant that can no longer maintain a proper pH).

OF

 

[ccervenka]

Just a quick 'Thank You!' to everyone on this thread. As the forum slowly degrades with many of our original thought-leaders moving on, it's refreshing to have a thought-provoking thread as this one going with some of our best veterans contributing!

 

[thaxman]

Did the tstat/fluid swap last weekend. Took the van out for a 90-mi/90-min drive where I went uphill 2000' over 30 mi, to get to a spot where I could run uphill 500' for 3 mi 5% grade all at high freeway speeds in the mid-90s Fahrenheit. With the new OEM tstat I was getting 206F-213F on the long uphill grade, but I was also going pretty fast b/c I was "pushing" it. On the way back, the temps were more in line with what I would have expected: 197-206F but it was mostly a downward grade overall. The hill climb I attempted at 80 but some vehicles interfered so some of the climb was done at 70-75 and I got up over 220F, which seems a bit high. I was running AC the whole time but at some point there and back I shut it all off and saw no differences in water temps. Still seems a bit higher than I want. How to "burp" the system?

 

[0dyfamily]

I "burped" our 2002 & 2003 by driving it onto some ramps on our slightly inclined (uphill) driveway, and ran the engine with the radiator cap not installed. Eventually, it got warm enough to open the tstat and push coolant (and air) through the radiator. As it "burped" out the air, the coolant level would drop a little, sometimes requiring me to add a dash of coolant. I even pulled on the throttle assembly to run it at slightly higher revs once in a while to push the coolant through with more authority.

While doing this, the fans were turning on, off, on, off, as expected. Eventually, all of the air in the block and heads migrates to the radiator via the top hose, and there it stays at the top of the radiator. As long as I had just enough coolant to keep the top of the core submerged in coolant, it seemed I was doing this correctly. I shut down, topped off, put on the radiator cap, and topped off the reservoir.

Yesterday was almost 107-deg F, and I drove east on almost level terrain for an hour at 70 mph, A/C on the entire way. ScanGauge said 198-deg F.

thaxman, I believe our Odysseys have two temperature sensors. One feeds the gauge, and the other feeds the PCM (and ergo, the ScanGauge data feed for that parameter I.D.). If the radiator isn't clogged, coolant is flowing, thermostat is doing its job....I'm wondering if it's a bad data feed.

For Buffalo4: I think I may have found an OEM 82-deg C thermostat! Acura p/n 19301-R8A-A00 from the 2013-2015 Acura RDX should be a drop-in replacement for our Odysseys.

Also, I would tend to agree with Buffalo regarding flow. I boiled another pot of water, dropped in my Motorad 302-180 and the Honda OEM tstats yet again, and it does appear that the Honda OEM tstat does have more cross-sectional area to flow coolant than the Motorad offering. I haven't had troubles with the Motorad unit, but for all those who want to purely stick with OEM, we all now have an option.

I may drop by an Acura dealership and see if the guys at the parts counter will "help a bro' out" and let me see one to compare to the Odyssey tstat. If it has identical dimensions, we may have a winner here.

OF

 

[John Clark]

The best way to burp it is to use one of these:

https://www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY

And then follow the procedure in the service manual. It involves full hot and cold cycling of the front and rear systems.

 

[0dyfamily]

John Clark, you are the man who has everything.

I forgot the obvious; turn on the heater to full hot when burping the system.

OF

 

[Buffalo4]

I "burped" our 2002 & 2003 by driving it onto some ramps on our slightly inclined (uphill) driveway, and ran the engine with the radiator cap not installed. Eventually, it got warm enough to open the tstat and push coolant (and air) through the radiator. As it "burped" out the air, the coolant level would drop a little, sometimes requiring me to add a dash of coolant. I even pulled on the throttle assembly to run it at slightly higher revs once in a while to push the coolant through with more authority.

While doing this, the fans were turning on, off, on, off, as expected. Eventually, all of the air in the block and heads migrates to the radiator via the top hose, and there it stays at the top of the radiator. As long as I had just enough coolant to keep the top of the core submerged in coolant, it seemed I was doing this correctly. I shut down, topped off, put on the radiator cap, and topped off the reservoir.

Yesterday was almost 107-deg F, and I drove east on almost level terrain for an hour at 70 mph, A/C on the entire way. ScanGauge said 198-deg F.

thaxman, I believe our Odysseys have two temperature sensors. One feeds the gauge, and the other feeds the PCM (and ergo, the ScanGauge data feed for that parameter I.D.). If the radiator isn't clogged, coolant is flowing, thermostat is doing its job....I'm wondering if it's a bad data feed.

For Buffalo4: I think I may have found an OEM 82-deg C thermostat! Acura p/n 19301-R8A-A00 from the 2013-2015 Acura RDX should be a drop-in replacement for our Odysseys.

Also, I would tend to agree with Buffalo regarding flow. I boiled another pot of water, dropped in my Motorad 302-180 and the Honda OEM tstats yet again, and it does appear that the Honda OEM tstat does have more cross-sectional area to flow coolant than the Motorad offering. I haven't had troubles with the Motorad unit, but for all those who want to purely stick with OEM, we all now have an option.

I may drop by an Acura dealership and see if the guys at the parts counter will "help a bro' out" and let me see one to compare to the Odyssey tstat. If it has identical dimensions, we may have a winner here.

OF

Wow, how did you find that? I will buy one, after further checking, and try it out.
How did you figure out that it would work in the '03 Ody.
I am impressed. :cheers: :ahh:
Buffalo4
PS: I may even try that water wetter stuff since I will have to add some coolant anyways.

 

[Buffalo4]

Now if only I could find a high-flow Motorad (or another brand) thermostat that would work on my '03 Ody.
Here is a link to that model type: https://youtu.be/OSGLgUq3vtk
They claim almost a 50% increase in flow volume at wide open.
Now, if I can only find one I can use which is rated at 180F or close to that number.
Hotter in the winter for heat, defroster, etc and cooler in the summer when the temps go way up!! :cheers:
Buffalo4
PS: I think the condenser fan goes on at around 210F and the radiator fan at around 199F if the ac is turned off.

 

[Buffalo4]

Ok, now I see that the Acura one can be replaced with the Motorad 302-180 which is the same one I used in my Odyssey, for less than a few thousand miles.
Damn, I would sure like to find a 180F thermostat for my Ody that had better flow than the 302-180.
So, looks like i might just have to try the Accura OEM one, if I can't find a high flow one.
Buffalo4
PS Happy Father's Day to ALL that are Fathers. :ahh: :cheers:

 

[0dyfamily]

Buffalo4, I found it by looking at a Motorad 302-180 compatibility chart that I accidentally found on the web, and perused it until I found the 2013-2015 Acura RDX, which is pretty much in similar fashion as your search.

I was checking the OEM's for Acura and Honda (like the guys at Tama, Inc., who make thermostats for Honda and Nissan, as far as I can tell), and accidentally stumbled upon that Acura part # discovery. It may be forever until I get to the big city and check the Acura parts counter, so I just may bite the bullet and buy one, measure it (or just stand it up next to my OEM Honda Odyssey tstat on my desk), and report back with the results.

...Happy Father's Day to ALL that are Fathers. :ahh: :cheers:

Likewise, to all. :cheers:

OF

 

[thaxman]

Follow up post:

After my test back on Father's Day, which it was OK on, we hit the road yesterday. Full of people, stuff and a rooftop carrier, temps outside were high and water temps were too: back to high 220Fs. You can see in the MAF thread, that I had MAP problems too. Well, the temps were consistently 30F higher than they should be so we decided it had to be that the radiator had reduced capacity. 4 hours later, it was, in fact the radiator. Temps are back to normal. Was even able to climb the Grapevine at speed with the A/C on and at what has to be max weight limit. Never got above the mid 210Fs on the climb.

 

[0dyfamily]

Thanks for checking back. This is a first for me, at least in recent years, as coolant chemistry has improved so much. Every radiator I've replaced in the last 15 years or so was due to damage from road debris.

OF

 

[thaxman]

Because I lost a percentage of cooling, I think I ended up with a clogged core

 

[Buffalo4]

Follow up post:

After my test back on Father's Day, which it was OK on, we hit the road yesterday. Full of people, stuff and a rooftop carrier, temps outside were high and water temps were too: back to high 220Fs. You can see in the MAF thread, that I had MAP problems too. Well, the temps were consistently 30F higher than they should be so we decided it had to be that the radiator had reduced capacity. 4 hours later, it was, in fact the radiator. Temps are back to normal. Was even able to climb the Grapevine at speed with the A/C on and at what has to be max weight limit. Never got above the mid 210Fs on the climb.

What brand was the replacement? Did you also change the thermostat and radiator hoses? Those radiators are a PITA to change, at least on my '03.
I bought a low cost radiator for my '03 on ebay and that was a mistake. Doesn't leak , but it doesn't cool as well either.
I sure wish that had a coolant flow volume value, etc at a fixed pressure listed for the radiators. :cheers:
If I (hopefully not) ever have to change it again, I will buy a Denso,Koyo or another proven high quality radiator. :ahh:
Well, one of the benefits of a new radiator is the new clean ATF cooling tubes in the bottom of the radiator.
Buffalo4

 

[thaxman]

Autozone radiator, OEM tstat, Gates hoses. Temps seem OK. Abt 180F all over Norcal. I was getting up to mid 210Fs up the Grapevine...full load of 6 people, full camping gear, clothes, food - and far too many soda 12 packs to avoid CA aluminum surcharges - like over 100 lbs.
Probably could have done the job in 2-2 1/2 hours if it was daytime and I had a clean garage instead of a pitched driveway AND it wasn't 105F after because it was after dark. Bumper, headlights, brackets, tilt the darn thing forward, etc etc. Sucks, esp the tranny lines