Author Topic: Thermostat or something else? (Read 2443 times)

Stehle · « **on:** February 10, 2016, 09:04:24 am »

As of yesterday my water temp gauge has been acting up. Car struggles to get to operating temperature. It will jump up to operating temperature if I Rev it, but quickly drops back down to 1/3. Most of the time (yesterday and today) the gauge needle reads between 1/3 and 1/2. The latter being operating temperature, of course.

Thinking of replacing my rad cap and seeing if that changes anything. Otherwise, thinking it may be my thermostat that is sticking open.

Not sure if it could be anything else. It's not going above operating temperature so I'm ruling out air pocket or HG.

It was slightly odd this morning. Got up to operating temperature and stayed there for 5 minutes while I was driving 100,then started to drop back down as I drove between 60 and 80km.

Also, should note, I checked the coolant level in the radiator this morning before driving and it seemed fine.

LilDrunkenSmurf · « **Reply #1 on:** February 10, 2016, 09:18:20 am »

Yeah, I'm going to say it's not the rad cap. If it was the cap, it would constantly be bleeding pressure, and you'd be closer to overheating. Sounds like the thermostat is stuck open.

Stehle · « **Reply #2 on:** February 10, 2016, 10:14:50 am »

That is my understanding as well, but a part of me really hopes its a simple $10, 5-minute fix and will probably try the rad cap first, anyway.

Sigh, I feel the thermostat is definitely something I should do myself, but never done it before.

LilDrunkenSmurf · « **Reply #3 on:** February 10, 2016, 10:39:48 am »

I mean... Kind of. I don't know specifically for the Legacy, but you'll lift the car up, disconnect the lower rad hose, drain the system, unbolt the T-stat housing from the block, likely 2x10mm or 2x12mm bolts, pop it out, pop the new one in, put it back together, and fill r up.

Personally, I'd be too lazy and would take it to balance auto or something and get it done.

Stehle · « **Reply #4 on:** February 10, 2016, 10:51:32 am »

You sound like you know what you're doing. Does the prospect of a beer make you any less lazy?

LilDrunkenSmurf · « **Reply #5 on:** February 10, 2016, 11:02:34 am »

Quote from: Stehle on February 10, 2016, 10:51:32 am

You sound like you know what you're doing. Does the prospect of a beer make you any less lazy?

Tell you what, I'll get to you right after my wedding planning and moving houses. Does sometime mid-July work for you?

RockThePylon · « **Reply #6 on:** February 10, 2016, 12:10:41 pm »

Just one beer? Come on man.

I gotta be half-lit by the time the job is done for it to be worth my while.

farva · « **Reply #7 on:** February 10, 2016, 12:54:29 pm »

Hell you don't even need to pull the rad hose just loosen the bolts and let it drop that way. It's maybe a 10-15 minute job most of the time spent letting the coolant drain and refill.

RockThePylon · « **Reply #8 on:** February 10, 2016, 01:22:36 pm »

Make sure you have a big container to catch the coolant. It's splashy.

Claw · « **Reply #9 on:** February 10, 2016, 03:47:29 pm »

How far away from a timing belt replacement are you? Could look at doing that while you're down there chugging coolant.

Stehle · « **Reply #10 on:** February 10, 2016, 10:31:37 pm »

Pretty far. I just had it done like 20,000km ago. Subaru dealer swayed me away from touching waterpump... "they're one thing that almost never fails.. If it ain't broke don't fix it"

In hind sight should have at least done thermostat.

Sounds like it's a party at my place, though. I'll supply the 60.

I reckon I can drive with this for a week or two until I pick up parts? Only thing that may suffer is fuel economy? Or should I avoid driving until the thermostat is replaced.

RockThePylon · « **Reply #11 on:** February 10, 2016, 11:34:06 pm »

If it was me, I'd block off most of the rad with coroplast and wait until summer.

Make the block off easy enough to remove at the side of the road if things get too roasty, but with winter(ish) temperatures, it should be fine with 75% of it blocked off.

farva · « **Reply #12 on:** February 11, 2016, 06:53:07 am »

Quote from: Stehle on February 10, 2016, 10:31:37 pm

Pretty far. I just had it done like 20,000km ago. Subaru dealer swayed me away from touching waterpump... "they're one thing that almost never fails.. If it ain't broke don't fix it"

In hind sight should have at least done thermostat.

Sounds like it's a party at my place, though. I'll supply the 60.

I reckon I can drive with this for a week or two until I pick up parts? Only thing that may suffer is fuel economy? Or should I avoid driving until the thermostat is replaced.

It is extremely rare for Subaru water pumps to fail. If they do fail they normally go on newer cars due to manufacturing defects. My leggy had 378k on the factory water pump with no issues.

Stehle · « **Reply #13 on:** February 20, 2016, 07:41:18 pm »

Thanks to the help of RedndWhite, changed my thermostat today.
However, didn't seem to fix that problem. Also, to note, the old thermostat didn't appear 'stuck open' either...

When driving, the car warms up as normal. However, randomly while driving the temperature gauge swings in the yellow range pictured below.
It will move from perfectly warm down to the bottom of the yellow range within seconds. Sometimes it stays there (if I'm driving on deerfoot), other times, it returns back to operating temperature

If I give it more gas it tends to move up a little (a given).

I guess its not a big deal (at least the car isn't over heating)... but I would like to figure out what the heck started this randomly.

In the above pic, the car was driven for 40 minutes before it was parked and I took the picture. As you can see... not ideal temperature.

Stehle · « **Reply #14 on:** February 21, 2016, 03:00:36 pm »

So I attempted to burp the coolant for about an hour today.
Took the car for a short cruise and same symptoms persist.

Plugged in my AP and decided to check the coolant temperature that way.
On idle it fluctuates 175 - 180F.
Going 110 on it fluctuates between 160-165F.
The total range was 147 - 185F, depending on if I had my foot off the gas completely or not.
The 147 - 155F ranges were very short lived spikes.

It seems that 'normal' coolant temperature should be about 190F.

The gauge fluctuated during this entire time as normal. Spent most of its time at the bottom of the yellow range pictured above.

RockThePylon · « **Reply #15 on:** February 21, 2016, 09:40:04 pm »

What thermostat did you use as a replacement?

The temperatures will swing quite a bit. But, usually, it won't drop lower than your thermostat's rated opening temperature (except I've seen it drop lower when it was -35, crusing on the highway).

I'm wondering if you found yourself a 160F thermostat (Generally, a stock thermostat starts opening around 180F).

Cruising coolant temps of 160-165F is consistent with a low-temp thermostat.

Stehle · « **Reply #16 on:** February 21, 2016, 10:08:58 pm »

I used Subaru OEM. I don't recall what it was rated for but Redndwhite may recall. (I believe it may have been rated for 78C?)

To note, I checked my AP logs from a couple of pulls I did February 2015 and I was lucky enough to log coolant temps. They were almost identical to now. 145 F to 190F. Generally sitting around 170F.

Can anyone else with an accessport confirm their temps in this weather?

From all the Google scouring I did I'm starting to think it's the coolant sensor. I have new OEM kicking around so will try to swap that out. According to repair manual it's behind the alternator.

RockThePylon · « **Reply #17 on:** February 21, 2016, 10:45:53 pm »

If you already have a new sensor, give it a shot. They're easy to replace.

Loosen tensioner, remove belt, remove pivot bolt, shift alternator aside.

Remember that the sensor has tapered threads, so don't over-torque that mofo.

Stehle · « **Reply #18 on:** February 23, 2016, 06:36:36 am »

Update on this.

The video in this thread (on the first page) is exactly what happens. I read specifically what MortySnerd said.. I went and wiggled the main harness + every other wire I could find to see if it would cause the gauge to fluctuate. It did not....

However, I did not drive the car since then, until today... The temperature gauge was rock solid on optimal temperature. I plugged in the AP and it reported a range of 182F to 190F.

Coincidence? I'm not sure... but I don't believe it's a mechanical issue at this point.

jellynuts · « **Reply #19 on:** February 23, 2016, 09:14:09 am »

Good job on troubleshooting all that through! A little anti-climactic, but a win is a win.

Midnightsky · « **Reply #20 on:** February 23, 2016, 12:07:02 pm »

Its funny, my EJ20G swap is doing the same damn thing. We unplugged a rad fan fuse and slipped some cardboard between the rad/condenser. It somewhat tries to slip below optimal temps from time to time but it does not drop as much. We were able to make it go flat cold while driving on stoney trail before we pulled a fuse and added cardboard. We also changed the thermostat and its an oem 78C stat so were also still trying to find this gremlin. Suggestions have been the koyo rad is just too big, but the previous motor never went cold like this. So far what we have been able to determine is that both rad fans like to run constantly, thus pulled the fuses for one of them. We poked all the connections too and nothing.

Stehle · « **Reply #21 on:** February 23, 2016, 08:38:24 pm »

I can say with 90% confidence it's a wiring issue somewhere. I wish I had been able to isolate it more (down to the wire or specific harness) but if it happens again I'll start by wiggling the ecu harness and see if that changes anything.

While I agree this was an anticlimactic ending, I'm glad as heck I didn't take it to a mechanic. Would have probably replaced the whole coolant system by now and it'd still be an issue.