July 20, 201510 yr Its been a topic discussed about a thousand times but I really can't seem to find anything on what happens mechanically to the engine when heads crack between the to valves will it cause the engine to overheat lose compression water in the oil oil in the water can anyone explain what actually happens
July 20, 201510 yr My theory is the crossover pipe lets too much heat get to passenger head. Since I've owned three turbos. I imagine a custom pipe that has separate pipes for each head, then re-groups at turbo. As for a NA EA82, use a quality 2 core radiator and mind the gauge.
July 21, 201510 yr It does nothing you would ever notice I imagine. It's not near any water jackets (the cracks) as far as I know, so no coolant leaks. I'm sure on the super intense scale it causes some type of compression turbulence though.
July 21, 201510 yr I've found most of the heads I've been running have the crack. Doesn't do anything noticeable. I did have one that developed a crack that got progressively worse, until it would drip 16 oz of water while sitting for several hours. The water leaked into the exhaust port.
July 21, 201510 yr I've found most of the heads I've been running have the crack. Doesn't do anything noticeable. I did have one that developed a crack that got progressively worse, until it would drip 16 oz of water while sitting for several hours. The water leaked into the exhaust port.
July 22, 201510 yr Author Ya thanks guys I thought that not to much happens to the engine mechanically
July 22, 201510 yr A severe crack can cause the valves to no longer be fully seated. I always thought that the plugs showed coolant getting into the exhaust chamber from the crack, but it could have been the intake manifold gasket leaking, as well.
July 23, 201510 yr Author So I take it no one has ever developed a car that fluctuates a lot in engine temperature due to the crack between the valves
July 23, 201510 yr If you are constantly loosing coolant, steady bubbles in the radiator with the cap off, that has always been blown headgasket in my experience. The bubble rate will get higher and higher the more you continue running it. You could cheat a few weeks or even months, but it's inevitable. Once you run over normal temp with low coolant, it's just a matter of time.
July 24, 201510 yr Author the only reason why I'm asking is I traded a set of ea 82 single port heads for an 87 gl 3 door coupe with no engine in it. but it has a dual range 4 wheel drive transmission init. The person i did the trade with mechanic and i argued about it for like over an hour had no idea about the crack in the heads being so common that the heads that they had would have been okay 2 reuse. thankfully since I drove over 3 hours just one way to get to the car thay went ahead with the trade anyway so that is why I started this thread just so they could follow it and here everyone's comment so again thanks for all your input if anyone else has anything else to say please do so I'd appreciate it
July 24, 201510 yr The small crack between the valves is very common in EA82 heads. There was a Subaru bulletin about it years ago.
July 24, 201510 yr So I take it no one has ever developed a car that fluctuates a lot in engine temperature due to the crack between the valves No. It's like this: If you take a chisel and put a small nick that doesn't interfere with anything on top of the engine block. does it hurt anything? No. It's marked and has a "crack" but it's benign, it doesn't interfere with anything mechnically. Pound the chisel away for hours until the block cracks through to something important - then will you have issues? Of course. Typical EA82/ER27 cracks are like the first example - they're surface aberrations that lead nowhere. They can always be pressure tested to see if the cracks are benign or not. In turbo engines and severely abused/overheated engines the cracks can enlarge and spread into the coolant and combustion chamber leading to coolant coming out the exhaust ports. But the average engine won't see that.
July 24, 201510 yr Author No. It's like this: If you take a chisel and put a small nick that doesn't interfere with anything on top of the engine block. does it hurt anything? No. It's marked and has a "crack" but it's benign, it doesn't interfere with anything mechnically. Pound the chisel away for hours until the block cracks through to something important - then will you have issues? Of course. Typical EA82/ER27 cracks are like the first example - they're surface aberrations that lead nowhere. They can always be pressure tested to see if the cracks are benign or not. In turbo engines and severely abused/overheated engines the cracks can enlarge and spread into the coolant and combustion chamber leading to coolant coming out the exhaust ports. But the average engine won't see that. Thank you for your input it is muchly appreciated all you guys help me prove my point to the one I was arguing with over this stupid little crack we all know it's no problem to run it but try to get a stubborn old mechanic that knows nothing about Subarus to believe that
July 28, 201510 yr Author ...show him this: Subaru EA82 Head Crack Bulletin 02-88-93.pdf Thank you all I am shere he got the point
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