412matt Posted October 19, 2020 Share Posted October 19, 2020 (edited) So I have an 09 2.5 legacy and it has been losing coolant for about a month. The first time I noticed that it was a bit low so I topped it off and it was fine for about a week. Then I topped it off again a week later. Then it got to the point where I had to top it off every couple of days and I noticed a leak behind the oil pan near the crossmember. Now I have to top it off pretty much every time before I drive it. You can see coolant leaking out of the back of the drivers side head. I’m about to pressure test the cooling system after my car cools down to make sure I don’t have a leak somewhere else but my question is if I added some subaru coolant conditioner would it maybe slow down or maybe even stop the leak? I have had no other issues with the car. It never overheated, it doesn’t blow any white smoke, there is no bubbling in the overflow, and there’s no coolant in the oil. Thanks in advance for the responses. Edited October 19, 2020 by 412matt Link to comment Share on other sites More sharing options...
mwiener2 Posted October 19, 2020 Share Posted October 19, 2020 No chemical additive will fix your issue. It will simply make a mess of your cooling system. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
Pleides Posted October 20, 2020 Share Posted October 20, 2020 (edited) Unfortunately, the only real solution is fixing the head gasket. You can remove your thermostat and not have it meter your coolant flow (to prevent overheating), but I'd probably get ready to drop the car off at the dealership for a trade. Edited October 20, 2020 by Pleides Link to comment Share on other sites More sharing options...
apexi Posted October 20, 2020 Share Posted October 20, 2020 I'd triple check that the leak is coming from there, anything is possible but reading about external coolant leaks from a head gasket doesn't seem to be common here from what I've seen here. Subaru coolant conditioner supposedly is relabeled Holts Radweld, honestly in your shoes I'd try that first. I know the purists would disagree with trying that, but headgaskets cost thousands, and subaru recommended coolant conditioner for years, so how bad could trying 1 bottle really be? Link to comment Share on other sites More sharing options...
mwiener2 Posted October 20, 2020 Share Posted October 20, 2020 The conditioner was meant to be a fix to a chemical issue that caused the headgasket to deteriorate. It was not meant to fix leaks, it will not fix leaks. It will fill your cooling system with a sludge that is very difficult to remove and will reduce cooling capacity. Subaru has not recommended the use of the conditioner for any of its vehicles in almost 10 years. A significant coolant leak like the OP described is most likely an actual leak, and not a headgasket issue. My Mods List (Updated 8/22/17) 2005 Outback FMT Running on Electrons Link to comment Share on other sites More sharing options...
dgoodhue Posted October 20, 2020 Share Posted October 20, 2020 I had a leak at that point on my EJ255 GT, it was from coolant crossover that runs under the intake manifold. I had left one bolt untight when I had the motor redid the head gaskets. Look at the intake for coolant pooling in the back of the motor. Link to comment Share on other sites More sharing options...
412matt Posted October 21, 2020 Author Share Posted October 21, 2020 Yup definitely the head gaskets. Pressure tested it today and you can see the coolant drip from the back of the heads on the bottom. When I do the gaskets I plan on using copper gasket spray. Anybody have anything bad to say about the stuff? Also on head gasket jobs i’ve done in the past we just cleaned off the mating surfaces the best we could with brake cleaner and a rag and put the heads back on. Is there a better way to do this without getting the heads machined? I’m afraid to nick the block or the surface of the head if I use a razor blade to clean it off. Link to comment Share on other sites More sharing options...
anarchyx34 Posted October 24, 2020 Share Posted October 24, 2020 Well ideally you should have the heads machined but tbh when I was a subaru tech we rarely ever did unless the car overheated. You can check it with a straightedge and feeler gauges if you need some reassurance. The service manual explains how. Don't use the copper spray. Use STI gaskets, Felpros or Six Star MLS gaskets. As far as cleaning the surface, use a die grinder with 3M blue pads. You can use a high speed drill if you don't have a die grinder. You need this kind of attachment https://www.mscdirect.com/product/details/68135656?fromRR=Y and these pads https://www.mscdirect.com/product/details/00222877 Get plenty of pads as they clog easily but aren't abrasive enough to cause any damage. You should be able to get them at most auto parts stores. Getting everything very clean is important. Honestly the head gasket job isn't too bad on these. Oh and plan on pulling the motor if you didn't already know. You can do it in-car but it just makes it a lot more difficult. Link to comment Share on other sites More sharing options...
Max Capacity Posted October 24, 2020 Share Posted October 24, 2020 https://subarufanclub.cz/wiki/_media/modely/impreza/sti_technical_service_bulletins.pdf About half way down that is a section on prepping the surface for HG's. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
412matt Posted October 24, 2020 Author Share Posted October 24, 2020 Well ideally you should have the heads machined but tbh when I was a subaru tech we rarely ever did unless the car overheated. You can check it with a straightedge and feeler gauges if you need some reassurance. The service manual explains how. Don't use the copper spray. Use STI gaskets, Felpros or Six Star MLS gaskets. As far as cleaning the surface, use a die grinder with 3M blue pads. You can use a high speed drill if you don't have a die grinder. You need this kind of attachment https://www.mscdirect.com/product/details/68135656?fromRR=Y and these pads https://www.mscdirect.com/product/details/00222877 Get plenty of pads as they clog easily but aren't abrasive enough to cause any damage. You should be able to get them at most auto parts stores. Getting everything very clean is important. Honestly the head gasket job isn't too bad on these. Oh and plan on pulling the motor if you didn't already know. You can do it in-car but it just makes it a lot more difficult. Are the sti gaskets multi layer steel like the six star ones? Link to comment Share on other sites More sharing options...
dgoodhue Posted October 27, 2020 Share Posted October 27, 2020 Are the sti gaskets multi layer steel like the six star ones? Yes Link to comment Share on other sites More sharing options...
awfulwaffle Posted October 27, 2020 Share Posted October 27, 2020 As far as cleaning the surface, use a die grinder with 3M blue pads. You can use a high speed drill if you don't have a die grinder. You need this kind of attachment https://www.mscdirect.com/product/details/68135656?fromRR=Y and these pads https://www.mscdirect.com/product/details/00222877 These any better than the white bristle discs that was recommended in this TSB? http://www.bescaredracing.com/sti/tsb/cylinder_head_gasket.pdf Link to comment Share on other sites More sharing options...
08SpecB_DE Posted October 29, 2020 Share Posted October 29, 2020 These any better than the white bristle discs that was recommended in this TSB? http://www.bescaredracing.com/sti/tsb/cylinder_head_gasket.pdf Much better. I always use the blue discs as well, which are primarily meant for aluminum. The bristle pads fall apart and make a mess too easily imo. Link to comment Share on other sites More sharing options...
412matt Posted October 29, 2020 Author Share Posted October 29, 2020 Does anyone know which year sti or wrx gaskets will work on an 09 2.5i? The dealer said there is two different head gaskets for the same year frame sti. Link to comment Share on other sites More sharing options...
412matt Posted October 29, 2020 Author Share Posted October 29, 2020 Also I called several subaru service and parts departments and they said that you don’t need to replace the water pump because they hardly ever see them fail. should i replace that and should I also replace the thermostat when I do the head gaskets? Link to comment Share on other sites More sharing options...
Pleides Posted October 29, 2020 Share Posted October 29, 2020 Water pump should be done with the timing belt every 105K or 8 years. No need to change it if it has been done recently, although a belt itself isn’t that expensive and it wouldn’t be a bad idea if the engine is coming out of the car anyways. Link to comment Share on other sites More sharing options...
412matt Posted November 20, 2020 Author Share Posted November 20, 2020 Does it make a difference if you use the blue disc on a drill vs just cleaning the surfaces with a gasket scraper? Is one better than the other? Link to comment Share on other sites More sharing options...
Gars05 Posted November 27, 2020 Share Posted November 27, 2020 I recently went with the Six Star gaskets and no copper spray. Used a razor blade, rag, and brake cleaner. Also went with a Six Star thermostat. One thing that worked well for me was to fit the drivers side head gasket over the bolts and on to the head first. I used rubber bands on the ends of the head bolts to hold them in place. Most of the directions I read said to place the gasket over the guide pins on the block which worked well for the passenger side. The drivers side is too tight though even with the engine jacked up. Link to comment Share on other sites More sharing options...
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