Last week I finally tracked down the source of my coolant leak to be at the thermostat housing. This evening was my first change to tackle the job on my 95 Outback. Put the OE gasket around the OE thermostat and slid it back in, no problem. Noticed while filling the coolant that I still had the same leak at the housing where it meets the water pump. What the hell did I do wrong? Is the thermostat supposed to support itself inside of the water pump underbelly as in holding itself before I put the housing on? Is my plastic housing warped? I gave it a good visual inspection and did not see a problem with the housing. Open for suggestions.

 

Thanks.

I have had a few that did that and they were all the plastic variety. If you can't find an aluminum one I can ship one. Usually the T-Stat stays up in there long enough to put the housing and the bolts in but not always.

I've encountered the same thing on a few EJ's.

I just slap some sealant on them, its worked so far.

Good thinking. Will put some RTV on it tonight at the seam.

I flat file them before install but i bet if you look closer you will find ether the wp leaking or the wp to block gasket leaking

just spray glue a sheet of 800 grit sandpaper to a pane of glass and lap it flat, then reintall. That's what I do.

Well, after putting a metric ton of RTV on this thing, I am now leaking from the radiator house where it meets the housing. I shouldn't have to use all this damn goo to make it not leak. Either I did not install the thermostat gasket right or this housing is crap. I wrapped it around the thermostat like the old one was.

 

After the first use of RTV I started getting coolant leaking out of the bolt holes, more rtv on them and that seemed to fix the problem but I still have the coolant coming past the clamp.

I would replace the hose, clamps, thermostat housing, and thermostat gasket with new one's from the dealer. Those parts are all relatively cheap and dealer quality/price just can't be beat on hoses.

 

I really, really dislike almost all forms of RTV and rarely use the stuff at all. There are cases where I have no choice - mostly on American vehicles where there is a large gap to fill like the intake manifolds on GM V6/V8 engines. I keep a tube of copper RTV around for exhaust gaskets since I tend to see a lot of leaks on aftermarket exhaust systems that fit poorly to the pieces left of the stock system. I find that RTV is messy, look terrible and unprofessional, and is OFTEN over applied. If you have to seriously goop it on then something isn't right with how the pieces are fitting together or it's an American car

 

Mostly I use Anaerobic flange sealant or in the case of threads I use either loctite blue (stick form I find to be most convenient), or loctite 545 hydraulic thread sealant. I know these products are harder to find and more expensive for the DIY crowd but their use will make the difference between a crappy looking goop job and a professional "clean" appearance that will last. Permatex Anaerobic, Loctite 545, and Loctite blue "glue stick" are three items that should be in every tool box and can be procured from Amazon for very reasonable. "My local store doesn't have it" isn't the answer since if you plan to work on your own cars these items should be bought ahead of time just like wrenches and sockets.

 

[/RTV rant of the day]

 

GD

Well, the gasket is new. I do plan to replace the hose and clamps, not thrilled about using cut to fit crap.

 

Is there a thermostat diy somewhere so I can find out if I did something wrong or not?

Pretty hard to do something wrong - unless you pinched the gasket but I've never seen that happen.... I've seen poorly fitting plastic housings and cheap Chinese water pumps that had badly machined housings....

 

Cut to fit hoses are total crap. The dealer hoses are between $15 and $20 each typically and fit really well. Just no good reason to not use them IMO.

 

Though if this is on the STi I would get some silicone hoses....

 

GD

I have an OEM thermo housing ill sell for half dealer price

Just went through this today... I took the tstat cover off to change out a tstat. I was greeted by a huge mass of red rtv. It turns out the years on the plastic housing were bent down a bit. After cleaning it up and putting the cover back on, the edges were contacting the water pump with a big gap in the middle still. I threw it out and used one from my parts pile, and it doesn't leak. I don't know why the last person couldn't have done that... GD, I agree completely, I can't stand messe people make with RTV.

 

I do use the stuff occasionally, but never really need much more than a very thin coat for it to work fine.

I glue them in with avinioc form agasket and only use the meatal wp gasket and subaru thermo oring have had many aftermarket thermostat gaskets leak. Done six water pumps thiss week no leaks yet the ones with aluminum thermostat housings leak less but still need the subaru oring

After cleaning it up and putting the cover back on, the edges were contacting the water pump with a big gap in the middle still

 

this sounds like it was caused by ''over torquing''.

Yea, probably. Some idiot worked on this thing last.