benc. Posted June 23, 2009 Share Posted June 23, 2009 My trusty 98 OBW 2.5 started overheating on my way back to salt lake from jackson hole last night. The car was fully loaded with gear and 5 people going 80 mph. It just all of the sudden overheats 3 hour into the trip. I have replaced within the last 1.5 years: Water pump (aftermarket), thermostat (aftermarket), and HG The coolant is clear of oil, and the dip stick does not look milky, so I don't think its the HG. The cooling fans are also operating normally After the car overheats, I can let it cool down so I can top off the radiator, then drive the car with the temperature being at the normal spot for about 2-3 miles going 45mph, and then it will all of the sudden shoot up and overheat. Any thoughts? I am suspecting its the water pump or the thermostat, but how do I tell one from the other? Any help would be greatly appreciated!! Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted June 23, 2009 Share Posted June 23, 2009 after the overheat, do you have to top off the coolant and if so how much. Once topped off, until the next overheat, do you then have to add more coolant again after overheat. Any green puddles that taste yummy on the ground where you park the car? When the HG were replaced last year, who did them, Subaru, or a shop and did they install the newly designed OEM subaru HG? It is the thermostat and maybe more. First thing to due is toss the aftermarket Thermostat and put in a OEM from Subaru. thats issues number one. My opinion is it is the HeadGasket, again. Quote Link to comment Share on other sites More sharing options...
Suzam Posted June 23, 2009 Share Posted June 23, 2009 How many miles on the engine itself and on the HGs? How old is the coolant? It may need changing or a burp. If you can, feel the lower radiator hose if it overheats again, if it's cooler could be a clogged radiator or bad thermostat. Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted June 23, 2009 Share Posted June 23, 2009 How many miles on the engine itself and on the HGs?How old is the coolant? It may need changing or a burp. If you can, feel the lower radiator hose if it overheats again, if it's cooler could be a clogged radiator or bad thermostat. any aftermarket thermostat is "bad" get a real one in there. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 24, 2009 Share Posted June 24, 2009 So you're definitely loosing fluid? Wouldn't be a big surprise if it's head gaskets again, but don't overlook simple things. If it's leaking fluid, look under the car and around the engine for obvious leaks. Aftermarket thermostats are really weak indeed. Make sure it's operating properly or replace it. Make sure the radiator cap is in good condition and the radiator as well. Quote Link to comment Share on other sites More sharing options...
benc. Posted June 25, 2009 Author Share Posted June 25, 2009 Thanks for all the replys so far!! I checked the radiator level after the overheating and I only have to add in very little water, and it might be because the coolant is flowing out of the overflow bucket when it over heats. It didn't seem like the thermostat to me, because I can drive the car for a 2-3 miles and the needle for the temperature gage would stay at the correct spot for awhile before the temperature shoots up to over heating. If it was the thermostat not opening, I shouldn't get the leveling off of the temperature at all, correct? I checked for leaks and looked in the coolant and oil stick, so I don't think(hope) its the HG, but I will drain the oil to be sure. Thanks again for all the help! Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted June 25, 2009 Share Posted June 25, 2009 You have the classic description of a bad head gasket. It is very typical on the 98 model. Engine temperature will be normal for a while, then suddenly "spike" to hot in a hurry. Suggest you do a search on this forum and read the archieves on head gaskets as to what many others have posted about this problem. On the 98, the head gasket goes bad, dumps exhaust gas into the cooling system, which causes the engine to over heat. So, in this situation, you won't find the oil milky with water. Suggest don't driving when motor is hot, or you will need to replace the motor. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 25, 2009 Share Posted June 25, 2009 I checked for leaksthese motors don't leak externally when the head gaskets fail. and oil stick, so I don't think(hope) its the HG, but I will drain the oil to be sure.these motors don't fail that way. i can tell you with 100% certainty that you won't find any coolant in the oil so don't worry about it. waste of a good oil change, go ahead and change it after you fix the head gaskets. you probably have a bad headgasket, quite common on these engines. in this motor that means you'll pass all the conventional head gasket tests - no leaks, no oil/coolant mixing, and often in the early stages they don't even fail the "combustion in the coolant" tests. all of your symptoms are pointing to headgasket. Quote Link to comment Share on other sites More sharing options...
davebugs Posted June 25, 2009 Share Posted June 25, 2009 I've been resisting the urge to post. But I'd make a serious bet that it's the HG's again. What brand HG's were installed? By someone knowledgable about Subaru's? Were heads checked and/or resurfaced? Quote Link to comment Share on other sites More sharing options...
benc. Posted June 25, 2009 Author Share Posted June 25, 2009 I've been resisting the urge to post. But I'd make a serious bet that it's the HG's again. What brand HG's were installed? By someone knowledgable about Subaru's? Were heads checked and/or resurfaced? When I installed the HG it was a preventative measure, about ~30000 miles ago, the engine has 190000 right now. Done by myself, definitely not an expert but an average mechanic. But the heads were machined The HG was an off brand from e-bay, one of those where you pay $75 and get a box full of gaskets and o-rings. If I am going through the process of elimination of my problems, how do I know if the thermostat or the water pump is bad once I take them off? You guys are great! Really appreciate the help! Quote Link to comment Share on other sites More sharing options...
davebugs Posted June 25, 2009 Share Posted June 25, 2009 WP's usually leak - I haven't had a Subaru one fail any other way - and I don't consider the gasket leaking a "real" failure. T-stat - some folks boil them. These are both cheap and easy items to replace but that may not help in your diagnosis. Knowing the source of you HG's I'd say you found the problem. When you do it again I strongly suggest using Subaru crank and cam seals while you're in there. Assuming that you use Subaru HG's. Also new oil Pump Oring, check the screws, reseal pump(ultra grey no gasket). I myself can't understand why folks do all this work and use cheap parts in a very critical, internal place. I use aftermarket WP's Intake and exhaust gaskets, belts, etc. But always Suby HG's and seals (crank, cam, and WP). It'll be much easier the second time. Quote Link to comment Share on other sites More sharing options...
vincentmoy Posted June 26, 2009 Share Posted June 26, 2009 WP's usually leak - I haven't had a Subaru one fail any other way - and I don't consider the gasket leaking a "real" failure. T-stat - some folks boil them. These are both cheap and easy items to replace but that may not help in your diagnosis. Knowing the source of you HG's I'd say you found the problem. When you do it again I strongly suggest using Subaru crank and cam seals while you're in there. Assuming that you use Subaru HG's. Also new oil Pump Oring, check the screws, reseal pump(ultra grey no gasket). I myself can't understand why folks do all this work and use cheap parts in a very critical, internal place. I use aftermarket WP's Intake and exhaust gaskets, belts, etc. But always Suby HG's and seals (crank, cam, and WP). It'll be much easier the second time. No offense, but he just said he got some off-brand gasket on ebay for some $75:) I'm guessing the gasket is leaking again, or, hopefully, just the T-stat Quote Link to comment Share on other sites More sharing options...
davebugs Posted June 26, 2009 Share Posted June 26, 2009 Yea - look in the middle of my post that you quoted: "Knowing the source of you HG's I'd say you found the problem." Quote Link to comment Share on other sites More sharing options...
vincentmoy Posted June 27, 2009 Share Posted June 27, 2009 Yea - look in the middle of my post that you quoted: "Knowing the source of you HG's I'd say you found the problem." Wow... I must have totally overlook that:-\ Sorry bout that! Quote Link to comment Share on other sites More sharing options...
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