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Subaru 2.5 Best Coolant Temp?
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Spey Caster
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PostPosted: Sun Nov 12, 2017 4:41 pm    Post subject: Subaru 2.5 Best Coolant Temp? Reply with quote

Hope I am on the right thread.

I am trying to find out what coolant temp range would be considered normal for my Westy Subaru Conversion. I understand the thermostat opening temps, but wonder where the normal operating range would be for around 3,000 RPM on the flat. Mild temperatures.

Thanks
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dobryan
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PostPosted: Sun Nov 12, 2017 5:38 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

In my experience I’d
say in the 180-192 range measured
at the coolant manifold.

Mine have always run in the low
180’s but I know others
than run
up to the low 190’s
with no issues.

Lowest I
see is
175ish in the dead
of winter.
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Spey Caster
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PostPosted: Sun Nov 12, 2017 6:28 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

Hello Dobryan

I was thinking of putting a temp gauge in. Running the sensor off the top rad hose. Would this make sense?

I don't really trust what I am seeing on instrument temp gauge.
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owokie
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PostPosted: Sun Nov 12, 2017 8:14 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

I'm almost always at 181.4 with the RMW kit. 183 if I have the heater on. Hottest ever 203 going up Wolf Creek on a hot day.
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wesitarz
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PostPosted: Mon Nov 13, 2017 12:34 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

Spey Caster wrote:
Hello Dobryan
I was thinking of putting a temp gauge in. Running the sensor off the top rad hose. Would this make sense?
I don't really trust what I am seeing on instrument temp gauge.


I put an inline sender (VDO) just off the engine.The temp rises a little later than the temp shown on my stock VW gauge (sender in the manifold).It seems to run at just over 180 degrees on the gauge. It came in handy showing a rising temp in stop and go traffic (not showing on the stock gauge),which I finally diagnosed as a faulty blue pressure cap. I got the inline fitting cheap on Amazon.
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dobryan
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PostPosted: Mon Nov 13, 2017 5:41 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

On my 2002 EJ25 conversion I am using a scangauge off of the OBD2 port on the ECU. It is reading the Subaru temp sensor that reports to the ECU. I have a VW temp sender on the manifold that runs the stock dash gauge.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

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Jake de Villiers
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PostPosted: Mon Nov 13, 2017 11:04 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

I have 75,000 year round miles on my 2000 2.5 conversion and the stock temp gauge reports the Subie engine temp just fine. The modern thermostat and coolant flow keep the temp remarkably constant in all conditions.
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Franklinstower
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PostPosted: Mon Nov 13, 2017 11:41 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

on my high compression franken motor, I have recently noticed the temps around low 190's and maxing at 203-205 going up the passes. This is reading the ECU temp using the B-10 software.

I know my cylinder temps are probably hotter due to the compression (last check about 215 psi in all cylinders) But even then I still think its getting too hot. I am about to start diagnosing why the temps are climbing so high. I use the Vanaru coolant system (not Tom Shiels bypass system) My rad is only 7 years old and I have never added any of the coolant conditioners, so I doubt it is a clogged radiator.....I am going to pick up the HF laser non contact thermometer and shot various hoses to see what it is reading compared to the temp gauge.

Any suggestions?

Paul
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dobryan
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PostPosted: Mon Nov 13, 2017 12:07 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

Summer of 2015 I had a thermostat slowly fail by not opening all the way (dealer thermostat). I noticed it because the temps were running about 10 degrees higher up slight long inclines (190 vs 180) then they used to be and were getting hot quicker up big inclines.

I pulled the thermostat and tested it and it was only opening about 50%. Replaced it with a new thermostat from the dealer, checked in hot water first, and all is normal.

This only applies if you were running lower temps and now are seeing higher ones....
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https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794
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Syncro Jael
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PostPosted: Tue Nov 14, 2017 8:39 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

dobryan wrote:
Summer of 2015 I had a thermostat slowly fail by not opening all the way (dealer thermostat). I noticed it because the temps were running about 10 degrees higher up slight long inclines (190 vs 180) then they used to be and were getting hot quicker up big inclines.

I pulled the thermostat and tested it and it was only opening about 50%. Replaced it with a new thermostat from the dealer, checked in hot water first, and all is normal.

This only applies if you were running lower temps and now are seeing higher ones....


Ever since I have owned the van it always seemed to run hotter than everyone else says theirs does. I installed an aftermarket gauge and put the sensor in the in the thermostat to radiator hose. This let me "see" the thermostat working as it opened and closed. So I replaced the radiator a few years ago. That seemed to help a couple degrees. A little over two years ago I had a rebuilt engine installed. Added the RMW tank. But it still seemed to run hotter than I thought it should. I combed the fins in the condenser and that made a big difference. But in the summer it would always kick the AC off when out on the highway. So I added a manual switch to run the fan and turn it on early. This year I replaced the condenser, new stainless tubes going forward, and it did not make a big difference. The cooling system would always run in the upper 180° to 200° depending on the load. It also ran hotter at highway speeds with RAM air?

So this last weekend I was coming back from Moab. 60° ambient temps and on the freeway at 70mph I noticed both temp gauges above normal. The stock gauge was above the LED, which is over 200°, and the gauge in the thermostat line was in the 190° range. My oil temp was climbing too. So I put both heaters at full and it cooled down, but was still running hot. I stopped and the overflow was overflowing. I tapped on the thermostat housing a few times, let the system cool for a while. Then proceeded on. It ran its normal temps again until I went down a long canyon, everything cooled off as it always has, then it started to heat up again. I then knew the thermostat was stuck shut. Both heaters on full and I made it the last 30 miles home.

Yesterday I removed the thermostat. Put it in a pan on the stove with a candy thermometer. The thermostat never started to move until it reached about 190° and only fully opened at boiling. I took it out, cooled it, and did it again and again. A couple times it would not open at all even in boiling water.

I purchased a new OEM one from the Subaru dealer. $32 with the gasket. It was different from the one that I pulled out. So I am not sure if the old one is aftermarket and not Subaru.

Burping, bleeding, and all that work. Then a test drive. The cooling system ran at 173°-179° with an ambient of 64°. It did not matter if I was on the freeway doing 70mph or on the back roads putting at 25-50mph.

I believe that the condenser was impeding the airflow with my old engine and that is why it was running hotter than it should.

I now believe that with a new radiator, condenser, and the new engine, it was running hot because of a faulty thermostat from the time the engine was installed. I have read that 190° range was acceptable so I did not worry about it.

I am out for more test drives but my hopes are up I finally found the issue after years of running hotter than what I thought was normal. The thermostats looked very different.

This is what the old one looked like:

Image may have been reduced in size. Click image to view fullscreen.


And the one I purchased from a Subaru dealer:

Image may have been reduced in size. Click image to view fullscreen.

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dobryan
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PostPosted: Tue Nov 14, 2017 9:01 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

Your old thermostat looks aftermarket. The dealer thermostats are noticeably more robust than aftermarket in my experience.
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MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794
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Jake de Villiers
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PostPosted: Tue Nov 14, 2017 8:21 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

dobryan wrote:
Your old thermostat looks aftermarket. The dealer thermostats are noticeably more robust than aftermarket in my experience.

+1 I installed an aftermarket themostat when I first did the Subie swap and it failed pretty quickly. Strictly OEM now.
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artacoma
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PostPosted: Tue Nov 14, 2017 9:31 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

84-89 C all day long
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PostPosted: Wed Nov 15, 2017 10:02 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

When I started this thread I did not have a clue about all the different options and ideas. I am amazed at all the great info.

One thing for sure. I am changing my thermostat to a dealer one. I have no idea what the heck is in there now. Better safe than sorry.
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PostPosted: Thu Nov 16, 2017 11:59 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

Spey Caster wrote:
When I started this thread I did not have a clue about all the different options and ideas. I am amazed at all the great info.

One thing for sure. I am changing my thermostat to a dealer one. I have no idea what the heck is in there now. Better safe than sorry.


FYI - I read Beck Arnley 143-0710 Thermostat are re-packaged OEM t-stats for a lot less than the dealer.
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PostPosted: Thu Nov 16, 2017 6:14 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

Metric Motors in Centerville, Utah, installed a 2003 2.5 in my van, and the coolant temp is about 188 on my scan gauge. I called them because of this thread and they said they use a 195 degree thermostat as per original specs. Still wondering.
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PostPosted: Thu Nov 16, 2017 6:24 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

michaelbteam wrote:
Metric Motors in Centerville, Utah, installed a 2003 2.5 in my van, and the coolant temp is about 188 on my scan gauge. I called them because of this thread and they said they use a 195 degree thermostat as per original specs. Still wondering.


Stock is 78c t start = 172 f.
Should give about a180f water temp
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PostPosted: Fri Nov 17, 2017 8:25 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

temps - normal 180 F - 190 F
on a warm day do not be shocked to see temps of 200F, if you get to 230 its time to stop doing whatever your doing. If your pulling a trailer up a hill at 80mph then its time to pull over and cool it down.

I recently went thru the high temp battle with my Subaru ... what I learned none of is proven science just based on my experience.

1. use only a OEM thermostat ...
2. the cast pump is better !
( there are photos on the internet showing side by side images )
I began having high temps up to 220 on hot days. If I drove until the engine was hot then slowed down to a low RPM my temps would rise quickly if I started driving again the temps would drop. most of the time the fan would not cycle on. What I believe happens, when the Motor is hot ! and then you slow down and lower your RPM's the stamped water pump does not move enough coolant. since changing the pump to a cast high flow pump I have not seen high temps, my temp stays solid at 180. It was immediately Clear the cast pump was more efficient.

again this is just my opinion. I cant say for certain the stamped pump is a problem but I am not the only one who has changed their pump and resolved their high heat problem.
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PostPosted: Sat Nov 18, 2017 12:28 pm    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

FWIW I have never seen temps above 203f. At that point the high speed fan comes on and lowers the temps. In general I get the higher temps climbing up hills at a slow speed (maybe 20-30 mph) due to road conditions, curves, etc. Not much air flow thru the radiator. At highway speeds never had a temp issue when the thermostat was working properly.....
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Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

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https://www.thesamba.com/vw/forum/viewtopic.php?t=746794
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Jake de Villiers
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PostPosted: Sun Nov 19, 2017 11:20 am    Post subject: Re: Subaru 2.5 Best Coolant Temp? Reply with quote

dobryan wrote:
FWIW I have never seen temps above 203f. At that point the high speed fan comes on and lowers the temps. In general I get the higher temps climbing up hills at a slow speed (maybe 20-30 mph) due to road conditions, curves, etc. Not much air flow thru the radiator. At highway speeds never had a temp issue when the thermostat was working properly.....

This mirrors my experience exactly. The Subaru engine and the Vanagon cooling system work very well together.
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