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Off Road SHO 10-02-2012 03:07 PM

Which way does thermostat go?
Okay so I originally put my new thermostat with the spring up; unfortunately, the engine was upside down on an engine stand at the time. Found out right away and reversed it.

Drove fine for a while and now the needle is shooting all the way to the top of the gauge AND I lose all heat out of the heater and I'm losing coolant but can see where. Did a pressure test on the cooling system and it held 16 lbs for hours on end.

Called Brokenindark and he suggested to pressurize it to 18-20 psi. Did that and found a pinhole leak in one of the heater hoses up by the firewall. Removed the offending inch of hose and now it holds 18 psi no problem.

New radiator cap. Pulled the thermostat out and I did have it in according to the Subaru Manual, with the spring on the engine side. Took it in the house and brought it to a boil with a thermometer in the pan. It's a 170 and by 175 degrees it is starting to open and by 200 is fully open, about a 1/4" gap all around.

Thermostat has only one writing on one of its support posts and it says "MOTORAD". If I take this to mean Motor side and Radiator side, it is backwards; that is, the coil spring is on the radiator side.

What's my next step guys? Leakdown test? Hydocarbon test?


twisty 10-02-2012 03:21 PM

have you tested it all together with the hose fixed and thermostat replaced? those pinholes can be annoying for sure, it could have been your issue.

jamal 10-02-2012 03:22 PM

spring side in the water pump, bleed hole up.

Sounds like air in the system. A funnel that fits into the radiator where the cap goes is very helpful for bleeding, as is parking on a slight incline.

Off Road SHO 10-02-2012 03:43 PM

re-filled it after I fixed the pinhole and it did the same thing.

Spring side was towards the water pump side and the plate with the bleed hole sits horizontal so there is no "up or down". The jiggle valve was working though because it let the water dribble out of the engine.

I guess I'll see if I can find some way to pressurize each cylinder; not much room in there.


silentguy 10-02-2012 04:46 PM

Bleed for air as suggested.

You can also unscrew the Air Bleeder screw on the left side of the rad, when looking at it from front of car.
Keep rad cap off, and fill while it is at operating temp.
Be careful of hot antifreeze though.

johnegg 10-02-2012 05:28 PM

1. if the t-stat is not a subaru t-stat, this will cause problems.

2. burp the system. fill it SLOWLY with the vent plug out. i'm not going to re-write all of ther instructions or how to. i've written it several times. you can find it in a search.

the slower you fill it the less likely you will trap air.

did you replace the head gaskets?
what brand of head gaskets did you use?

found it.


Originally Posted by johnegg (Post 3658508)
the last 2 times i have filled an empty cooling system on an ej25 engine, i have used a very unusual method and have had NO problems and have not had to burp.

i put the gallon of coolant on top of the engine, either the passenger strut tower or the air box near the firewall. i then use a small diameter tube (~5/16 inch, inside diameter) to siphon the coolant out of the jug and into the rad. (it helps if the tube is clear so you can see the coolant as it gets close to your mouth.) after the jug is empty, i then start over with a half jug (2 qts.).

this is a very slow process because of the size of the hose, but more so due to the very small difference in height. the system fills very slowly and has time to back fill the engine thru the top rad hose. i make sure the rad cap is at least level with or usually higher than the rest of the rad. having the vent cap open helps too.

the first time i did it i tried to burp it but i ended up wit h less coolant in the system than when the siphon had finished. so this last time i just let the siphon do its thing and then put the cap on. no problems.

it works great, but it is really, really, slow. so i do it while i'm finishing up the last little bits of whatever i'm working on.

this is so slow that if you did it and then watched it you would give up and start pouring long before it got done. but it is a great time to open a beer and admire your work.

i doubt this is a good technique for a car that needs to be burped, but it works great for filling empty systems.



Originally Posted by johnegg (Post 3934328)
the small vent cap is the trick to filling correctly. coolant WILL NOT flow into the upper rad hose / engine block unless you have the vent plug removed. and even then you have to fill it SLOWLY.

once you have slowly added as much as it will take with the vent plug open, close that, fill to the top of the rad and start the engine. when the t-stat opens the coolant will burp out of the rad and the level will drop. (in most cases it will drop, but if you filled it slow enough the system MAY be full.) top it off and put on the cap.

(my solution to filling slowly is to siphon the coolant out of the jug and into the rad. i use a 1/4''- 3/8'' clear tube about 10 feet long that i bought years ago and i use it for all of my siphoning needs. it fills the rad so slowly you get bored. but you can rotate tires or change the oil while you wait. once it is full, mine will not burp. it is full.)

on a side note:
if you used a non-subaru t-stat you are going to have trouble. they do not work and it will over heat. i know some of you do not want to believe this but it is true. i was one of them for a long time.

there are several parts on these engines that MUST be subaru. and hopefully you do not damage anything learning that.

SOMETIMES, not very often, a ''high quality'' replacement part will work, but ''cheap'' aftermarket parts are never a good solution for these ''subaru only'' parts. they end up not working correctly and you not only have to redo the work (twice the labor) you have to buy another, usually more expensive, part. buying parts twice is never cost effective, even if your labor is free.


Originally Posted by johnegg (Post 3987372)
1/ remove vent plug on radiator at top hose.
2/ fill radiator at fill neck / cap SLOWLY. this is key.

(i have written this a couple of times and it works great, for me. but it is so odd and extreme i really don't expect any one to follow it. sit the jug of coolant on the passenger strut tower and use a long tube, about 1/4 inch diameter, to siphon the coolant in the rad. the process is so slow you will get bored, but slow works in this situation. )

3/ when full install the vent plug and rad cap.
4/ start the engine and run it up to full operating temp. then shut it down and wait for it to cool down.
5/ open the rad and top it off. mine usually only takes a couple 3-4 oz.

(most folks run the engine with the rad cap off to burp it. but i have found that when it burps it looses more coolant than it really needs to so i just heat it up and then let it cool before i open it. all you really want to do is circulate the coolant and eliminate any air bubbles. the siphon is so slow it really does not need much burping or topping off. this is different than most other fill and burp process. )

good luck.

Off Road SHO 10-02-2012 08:01 PM

It is not a Subaru Thermostat; a MotoRad brand. It seals fine and I've tested it with a pan of water on the stove.

I did the remove the vent plug deal and filled it ever so slowly. I then let it sit for a while and then topped it off, put back the plug (a royal PITA BTW), put the cap back on, squeezed the upper radiator hose numerous times, removed the cap and topped it off again. I've let it sit for a couple of hours now and the level hasn't gone down any. I will do a few heat cycles up to operating temp and see if I can add some more water after it cools down.

Thanks for the help guys.


monkeyposeur 10-02-2012 09:08 PM

We need a johnegg radiator burping sticky for crying out loud!

johnegg 10-03-2012 07:41 AM

if you fill the rad too fast you trap air in the block. the coolant will not flow down the top rad hose into the block and the air will not bubble up. in some circumstances it will not happen even if / when the t-stat opens.

you may have to drain it down part way to release the air bubble and then refill slowly. the coolant does not flow past the t-stat . it has to flow in from the top slowly enough so the coolant can run down while the air runs up, all in the same pipe. once the coolant blocks the flow of air up you are stuck.

if you think about the position of the coolant crossover pipe on top of the block, the coolant has a long way to go to get to the driver side. which means there is a lot of opportunity for an air lock.

the siphon is so slow there is no chance of an air lock, unless you use a really large hose.

i have a ''fill tube'' device i use for adding ATF and emptying oil drain catch basin. you can use it instead of a funnel. it threads on to either a one gallon coolant, ATF, type jug or a one quart oil bottle. it has a 12 inch tube and a valve built in so you can up end it before you release the flow of liquid. i have not tried this as a coolant filler, but since the tube is so small it could work. just don't squeeze the jug to force the coolant out of the jug and into the rad.

this shows it attached to a measuring jug. i bought it without the jug. not expensive.

but the bottom line is open vent plug and fill slowly.

broknindarkagain 10-04-2012 07:09 AM


Originally Posted by Off Road SHO (Post 4097493)
It is not a Subaru Thermostat; a MotoRad brand.

I thought you picked up the thermostat from the dealer?

Off Road SHO 10-04-2012 09:20 PM

I thought I did also, must have been the 2.2 that's in your GT that I got from Subaru. I don't think it's s thermostat problem though, but I'm hoping like hell it's not something major.


Off Road SHO 10-06-2012 05:52 PM

Wow, this thing keeps taking water, though it's down to 1/4 cup now. There has got to be a better way to fill these suckers up. I'm going to invent something.


broknindarkagain 10-06-2012 07:42 PM

Yeah, they can be retarded.

Off Road SHO 10-14-2012 11:37 AM

I lifted the front end 3 feet higher than the back with my lift and it didn't take more than a half cup of coolant, so I know it's as full as I can get it.

It wont over heat just idling but as soon as you take it down the road, up she goes and doesn't come back down. Needle fluctuates rapidly as I'm driving, between sort of hot and very hot.

I read the temp with my infrared thermometer and get 225 at the intake of the radiator, fresh from the engine. This has got to be a blown head gasket.

I adapted an old compression tester to take air pressure and put it in the cylinder, but don't think I'll be able to spin it into a spark plug hole with its rubber hose and no room between the valve cover and the fender well. We'll see.

I should have never switched out that 2.2.


broknindarkagain 10-14-2012 06:10 PM

How many miles are on the engine since it was installed and it started doing this? I'm curious if the original overheating popped a headgasket.

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