Hello Everyone,

 

I have a 2002 Impreza TS MT with 137k on it.  Head Gaskets were last done about 60k ago.  The water pump, radiator hose, thermostat, and all associated gaskets were replaced at that time.  The water pump never sealed very well and has a slow drop from the gasket, not the weep hole.

I recently replaced the radiator cap (maybe 10k ago).  The car has never overheated and the temperature gauge sits right about where it should when warm, maybe ever so slightly biased towards cold.

I turned the heat on the other day and it was barely warm.  I picked up a bottle of coolant and poured about 1/3 of the bottle straight into the radiator with it uphill from the heater core.  The heat came back, I figured it was just low from the slow perpetual leak I never got around to fixing.

The car does not burn excessive oil (maybe 1/2 qt low at time of oil change.  There is no indication that the car is burning coolant, but it is hard to tell when driving.  I do not smell anything sweet in the exhaust, but that's not a surefire diagnosis.

A couple days later, heat is gone again.  I add a little bit more coolant but it doesn't help.  I drive the car a little later and the heat is fine.

I have noticed the radiator hose is quite hard to the touch when the car is hot.  If I release the pressure on the radiator cap, the overflow reservoir  bubbles.

Is this all caused by the leak letting air in?  Bad water pump? Bad thermostat?  Dreaded head gaskets?

 

Cheers,

Andrew

Sounds like you still might have some air in the system which could account for the recent cold/hot heater output but where did all that initial antifreeze go if you had to add 1/3 of a gallon and then top it off again a few day later? Keep driving and burping it and make sure the overflow hose is not sucking air instead of coolant each time the car cools off at night. Is the coolant level in the overflow bottle staying the same, rising or falling? The radiator hoses should become hard when hot as it is under pressure but if it was too much pressure, the cap would vent it to the overflow bottle. If you are able to keep adding fluid every few days at a regulars rate and can't see it visually leaking anywhere then you might have a HG issue but don't jump to quickly to that conclusion. I've had coolant leaks that were small enough to not drip on the ground but puddle and evaporate.

It sounds strange the the overflow only bubbles as you start releasing the cap.  Did you get the right cap that allows excess pressure to overflow into the bottle, but also lets water suck back into the radiator after the engine gets cold?  For subaru OEM caps, the ones with the tabs are for the overflow bottle, they have a one way valve for back flow.  The fully circular ones are pressure release only, no back flow.  Aftermarket ones you have to check carefully.

 

I ended up pulling the water pump it was leaking pretty bad.  I went to install the new pump and it turns out two of the bolt holes were stripped so now I am working on getting those repaired but no one seems to stock any repair products.

I've also read the gasket must be OEM, metal type - not paper WP gasket.

 

others will correct me if I'm wrong

1 hour ago, 1 Lucky Texan said:

I've also read the gasket must be OEM, metal type - not paper WP gasket.

others will correct me if I'm wrong

Not correcting, just offering a data point.  That seems awfully fussy to me.  I've never had to replace a water pump in an EJ22 or 25, but it needs to be pulled in the course of removing the timing cover on the H6 3.0 .  I just used whatever gasket was in the kit; I don't think either was metal, just fiber, and I always give those a coat of gasket goo (it's the only place I use that stuff routinely).  The first of those two engines now has at least 5000 fresh km on it with no leaks.  Much of that was in hot weather, and this morning we woke up to -30, so it's safe to say that it's getting stressed.

7 hours ago, nvu said:

It sounds strange the the overflow only bubbles as you start releasing the cap.  Did you get the right cap that allows excess pressure to overflow into the bottle, but also lets water suck back into the radiator after the engine gets cold?  For subaru OEM caps, the ones with the tabs are for the overflow bottle, they have a one way valve for back flow.  The fully circular ones are pressure release only, no back flow.  Aftermarket ones you have to check carefully.

 

I have one of the caps with a lever on top to release pressure.  I'll get an OEM style one just in case.

5 hours ago, 1 Lucky Texan said:

I've also read the gasket must be OEM, metal type - not paper WP gasket.

 

others will correct me if I'm wrong

The old gasket was paper, it was also an auto parts store water pump.  The new pump is Subaru and a metal gasket.

 

The new pump is in, I had to re-tap 4 of 6 holes and install heli-coils.  They kept stripping out as I torqued them to 9 ft-lbs.  I don't understand why they stripped but they did.  For the record, I'm using Snap-On's aircraft grade torque wrenches so I know I wasn't over torquing.

Edited November 9, 20223 yr by Daskuppler

36 minutes ago, Daskuppler said:

The new pump is in, I had to re-tap 4 of 6 holes.  They kept stripping out as I torqued them to 9 ft-lbs.  I don't understand why they stripped but they did. 

That doesn't scan.  You're putting steel bolts into an aluminum hole.  That means that it's the aluminum threads that stripped, and all the tapping in the world isn't going to replace the lost metal.  So I assume you mean you put in helicoils.

1 hour ago, jonathan909 said:

That doesn't scan.  You're putting steel bolts into an aluminum hole.  That means that it's the aluminum threads that stripped, and all the tapping in the world isn't going to replace the lost metal.  So I assume you mean you put in helicoils.

Yeah, meant to say that but forgot to include the heli-coils.  We'll hope for the best.  One of them didn't feel super tight.  They were a pain in the rump roast to do in that area.

5 hours ago, Daskuppler said:

The new pump is in, I had to re-tap 4 of 6 holes and install heli-coils.  They kept stripping out as I torqued them to 9 ft-lbs.  I don't understand why they stripped but they did.  For the record, I'm using Snap-On's aircraft grade torque wrenches so I know I wasn't over torquing.

btw, the coolant crosspipe bolts love to strip too,  I've had bolts strip or snap when trying to loosen.  anywhere there are 10mm bolts in aluminum touching coolant are prone to corrosion and have weakened threads.

a little late on water pump tips, but i've had good results swapping a 10mm bolt for a 10mm stud and nut on the water pump.  it makes installing with the gasket a breeze.  you have to grind down the stud beforehand so it doesn't protrude into the t-belt area, ask me how i know. 

11 hours ago, nvu said:

btw, the coolant crosspipe bolts love to strip too,  I've had bolts strip or snap when trying to loosen.  anywhere there are 10mm bolts in aluminum touching coolant are prone to corrosion and have weakened threads.

a little late on water pump tips, but i've had good results swapping a 10mm bolt for a 10mm stud and nut on the water pump.  it makes installing with the gasket a breeze.  you have to grind down the stud beforehand so it doesn't protrude into the t-belt area, ask me how i know. 

I did think about putting in an 8mm bolt opposed tot he factory M6 but I didn't think it would fit through the hole on the water pump or gasket, maybe I should have gone that way.  I'm really hoping it doesn't leak I only got the one bolt torqued to about 6ft-lbs.  I'm going to pick up a bottle of the Subaru Conditioner today along with a Subaru radiator cap.  If it still leaks, maybe I'll try one of those epoxy/Loctite thread repair injections since this is a pretty low torque application.  I think I can access the one bolt without removing the timing belt.

Edited November 9, 20223 yr by Daskuppler
typo

On 11/9/2022 at 6:08 AM, Daskuppler said:

Lochtite

Isn't that the lake in Scotland with the most distilleries around it?

Edited November 22, 20223 yr by jonathan909

2 hours ago, jonathan909 said:

Isn't that the lake in Scotland with the greatest number of distilleries around it?

haha, my bad on the spelling.  We actually just got back from Scotland. 

23 hours ago, 1 Lucky Texan said:

I've also read the gasket must be OEM, metal type - not paper WP gasket.

 

others will correct me if I'm wrong

Yep, paper gaskets seem to leak.

Stamped metal ones generally do not. Many aftermarket companies have figured this out, and supply a metal gasket, but not all.

 

 

I'm assuming that since the incorrect water pump gasket was used, that the incorrect head gaskets were used as well....so just assume those will fail, and they may leave you stranded (OEM coated gaskets tend to just leak oil, OEM MLS gaskets tend to outlast the vehicle).

 

 

 

It sounds like the water pump is getting air in it and cavatating, that easily could just be from your external leak, or it could be a head gasket.

13 minutes ago, Numbchux said:

Yep, paper gaskets seem to leak.

Stamped metal ones generally do not. Many aftermarket companies have figured this out, and supply a metal gasket, but not all.

 

 

I'm assuming that since the incorrect water pump gasket was used, that the incorrect head gaskets were used as well....so just assume those will fail, and they may leave you stranded (OEM coated gaskets tend to just leak oil, OEM MLS gaskets tend to outlast the vehicle).

 

 

 

It sounds like the water pump is getting air in it and cavatating, that easily could just be from your external leak, or it could be a head gasket.

I used Felpro triple layered gaskets.  It was about 65k ago, I've learned a lot since then and buy very few things from auto parts stores anymore.

The new gasket on the water pump is metal but I'm still struggling to get one of the bolts to torque down completely.  The heli-coil starts to spin at about 6 ft-lbs.  I was thinking a little bit of Loctite on the heli-coil, let it cure, and then thread the bolt in.  This is all assuming it starts to leak again.  My heat ddid partially go out this morning, but I'm hoping that's just remnant air in the system after refilling.  No visible leaks yet.

I've seen the paper water pump gaskets blow out - but that's usually if they are not coated in sealant. The paper absorbs the coolant and becomes soft and cooling system pressure is enough to force it out. 

Mostly we use the OEM gaskets because

A : The good quality pumps like Aisin and NPW come with the metal gasket

B : The gaskets come off clean requiring no clean up of old sealant.

C : They always work, they never leak (assuming you don't have stripped mounting bolts - we routinely thread-repair all of them). 

And Fail-Pro is great for old Chevy's. Terrible for imports. 

GD

11 hours ago, GeneralDisorder said:

I've seen the paper water pump gaskets blow out - but that's usually if they are not coated in sealant. The paper absorbs the coolant and becomes soft and cooling system pressure is enough to force it out. 

Mostly we use the OEM gaskets because

A : The good quality pumps like Aisin and NPW come with the metal gasket

B : The gaskets come off clean requiring no clean up of old sealant.

C : They always work, they never leak (assuming you don't have stripped mounting bolts - we routinely thread-repair all of them). 

And Fail-Pro is great for old Chevy's. Terrible for imports. 

GD

Great information, hopefully the HG holds on for a while....

 

What do you use to repair threads?  do you think a little bit of thread locker on the one loose heli-coil will tighten that up enough to torque it down or do I need to remove the whole thing, get a new water pump gasket, insert a new heli-coil (this would be the third one in the hole), and go from there?

I did have a really fubar'ed hole on one block and went with a 12mm stud and 12mm nut.  Retapped it to fit the 12mm stud.  The water pump housing needed drilling slightly larger, but the fix saved an otherwise usable ej25 block. Luckily the hole was in the center of the pump and barely had enough room to fit the 12mm nut.

I'm probably using the wrong terminology, but what I mean was the stud that normally fits in where a 12mm hex head bolt goes.  Really not sure the actual size of the stud was, the nut was 12mm hex head.

Dug through camera, still have pics

Edited November 11, 20223 yr by nvu

If it had a 12mm head on the nut then it was an 8mm stud. 

Thread repairs - there are many. I use https://www.threadtoolsupply.com/ for generic screw thread inserts at my shop. 

If you want the best - here's what the US military supplies on the Forward Repair System ( https://frsn.dk/ )

https://www.jergensinc.com/Threaded-Inserts

GD

Edited November 12, 20223 yr by GeneralDisorder

On 11/12/2022 at 8:08 AM, GeneralDisorder said:

If it had a 12mm head on the nut then it was an 8mm stud. 

Thread repairs - there are many. I use https://www.threadtoolsupply.com/ for generic screw thread inserts at my shop. 

If you want the best - here's what the US military supplies on the Forward Repair System ( https://frsn.dk/ )

https://www.jergensinc.com/Threaded-Inserts

GD

Awesome, thanks!

 

I got it all put back together with a little red thread locker on the one heli-coil I just could not get to torque down all of the way.  Everything torqued down fine.

 

I did notice on startup, there was a pretty loud and high pitched whine from the front of the engine.  It dissipated with time and fluctuated with RPM.

I ended up replacing all of the timing pulleys, tensioner, and belt, could the whine be related to any of the new parts?  I torqued all the new timing parts down to 29 ft-lbs

15 hours ago, Daskuppler said:

I did notice on startup, there was a pretty loud and high pitched whine from the front of the engine.  It dissipated with time and fluctuated with RPM.

I ended up replacing all of the timing pulleys, tensioner, and belt, could the whine be related to any of the new parts?  I torqued all the new timing parts down to 29 ft-lbs

My first guess would be that the timing belt notches were rubbing a tiny bit on something but soon wore down so no noise after that. Noise from a bad bearing would usually get worse, not go away. 

6 hours ago, azdave said:

My first guess would be that the timing belt notches were rubbing a tiny bit on something but soon wore down so no noise after that. Noise from a bad bearing would usually get worse, not go away. 

I'll run with that, thanks!

Heater went out again this evening. Ran for about 5 minutes got to operating temperature and the vent she went from cold to hot instantly. Never went out again during the drive.

I had a smell of coolant in the garage a couple days ago but there were no visible leaks and no coolant on the floor. The heater worked fine every time until this evening when I picked the car up from the tire shop.

Assuming you mean "no coolant on the floor of the garage", how about on the passenger side floor pan i.e. a leaky heater core?

8 hours ago, jonathan909 said:

Assuming you mean "no coolant on the floor of the garage", how about on the passenger side floor pan i.e. a leaky heater core?

Nothing there either. The smell is only outside of the vehicle.