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09-11-2020, 12:51 PM | #1 |
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Carbon filled pistons, white tipped spark plugs, and white on valves
So im tearing my ej257 down and this just astounds me. What is causing all this? They are manley pistons, i suspected bad HGs (which explains the white on the valves and spark plugs) but why is there so much carbon on the piston face? It looks like a mix of coolant and oil but i cant be certain... any thoughts?
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09-11-2020, 12:53 PM | #2 | |
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https://drive.google.com/folderview?...4cAFUvl1qIO9mW |
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09-11-2020, 01:53 PM | #3 |
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09-11-2020, 02:01 PM | #4 |
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white on valves and spark plugs just means a relatively lean burn, maybe even a perfect one depending what you really mean by "white"
nothing to do with coolant and every piston has a carbon coating once it's run, so again, depends what you really mean and how much pics don't work so nobody knows |
09-11-2020, 02:40 PM | #5 | |
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https://ibb.co/Y8svbyS https://ibb.co/N2Lz0Fr https://ibb.co/f1txMMC https://ibb.co/j40NfwF |
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09-11-2020, 02:42 PM | #6 |
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09-11-2020, 02:52 PM | #7 |
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wow that is a lot of crap on those pistons
personally I don't think the exhaust valves and plugs look so bad, the difference however between them and the rest of the chamber is what seems odd to me. The rest of the cylinder looks like a crappy rich poor mixed burn, but the exhaust and plug look like a very stoich or borderline lean high egt situation. Was it running poorly or what? |
09-11-2020, 03:06 PM | #8 | |
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I guess the difference could be a blowby issue but the boiling coolant is what made me think it was a HG issue So i bought a cracked ringland block and planned a new short block build. Took this one out of the car and started trearing it down and was suprised at how much crap it had in the cylinders. Im planning on moving the heads off this tore down engine to the new shortblock so is it necessary for the heads to be disassembled and cleaned or should i just use a degreaser and clean the carbon from the chamber the best i can? |
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09-11-2020, 03:17 PM | #9 |
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it looks like alot of carbon building up, di you run it very hard?
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09-11-2020, 03:38 PM | #10 |
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Not too hard i would say, its a rotated 3582r daily driver, i did one track day with it where oil temps saw 240+ degrees but before and after that never saw above 220, do oil changes every 3k miles etc, the basic maintenance stuff
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09-11-2020, 03:43 PM | #11 |
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maybe its just carbon buildup,cuase everything else looks okay but your plugs look a little clean, did you run e85 or gas in it?
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09-11-2020, 03:47 PM | #12 |
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09-12-2020, 12:42 AM | #13 |
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09-12-2020, 07:05 AM | #14 |
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09-12-2020, 09:00 AM | #15 |
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09-12-2020, 01:36 PM | #16 |
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that would be more of a question for your machinist,Its too hard ot tell from pics, if you are worried, get a straight edge on it and get a flashlight behind the straight edge and see if there is any light coming through... I know this isnt very sceintific or exact, but it will help put your mind at ease
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09-12-2020, 01:38 PM | #17 | |
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I would rebuild the heads especially change the seals and the other wear items just for good measure personailly Last edited by subaru_gc8; 09-12-2020 at 01:50 PM. |
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09-12-2020, 07:49 PM | #18 |
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Nothing looks out of sorts - the plug may be wrong heat range or a lean mixture. All that carbon crap is normal. From the looks of those pistons I am guessing that engine is fairly new.
Funny thing - a head gasket coolant to combustion leak will actually steam the carbon off the head and pistons as a tell-tale of where the leak is. Looking at the pictures at the resolution posted I don't see signs of a leak for that head. Doesn't mean it doesn't, I'd need to inspect the gasket and look much closer at those mating surfaces for a proper diag. What were the results of your carbon dioxide test? If your bubbles were from the combustion chamber there would have been CO2. Check heads for warpage after cleaning. |
09-12-2020, 09:55 PM | #19 | |
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Im considering not getting the heads decked (for simplicity sake) and cleaning it up a bit and using a technique used by a few on here with success but ultimately making sure the heads are flat and not warped |
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09-13-2020, 09:25 AM | #20 | |
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A small amount of bubbling when first started in the upper res is not that big a deal. given the look of the pics if you had a head gasket leak it probably be more likely to manifest after the engine warmed up and was put under load. As far as petroleum smell that is odd - if you had a head gasket leak and could smell it in the coolant (that would be a large noticeable leak with overheating, explosive overflow) it would smell more like exhaust. CO2 test is when you draw air from the cooling system through a test fluid immediately after opening the pressure cap. The fluid will change color in the presence of CO2 which indicates combustion gas in the cooling system. NOT resurfacing the heads or measuring for flatness is the worst thing to do if you tore it down for a suspected leak - the whole point of tearing it down is to find the cause. The majority of times the head surface isn't flat and that is the cause - especially with MLS gaskets. You are allowed up to 0.05 mm (0.002") warpage, any more and you need to resurface. of the 300-400 suby engines I've repaired head gaskets on I've only seen 6 that didn't require resurfacing, and they were just within limits. Here is a single stage tester and a two stage. I prefer the two stage in case you get a little coolant in the first stage. Mine is an old German made that I bought in 1986 working for VW. One of the most useful pieces of test gear I have besides my volt/ohm meter. |
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09-13-2020, 06:43 PM | #21 | |
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Quote:
I will look at the flatness of the heads and see, it wasn't so much a smell of gas or oil but exhaust so there was definitely CO2 in the coolant. |
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09-14-2020, 09:51 AM | #22 |
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IMO that looks way more carbon build up for a 60k eng then there should be. Its caked on there and flaking off. Kinda does look like burn on sugar from coolant.
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09-14-2020, 11:22 AM | #23 | |
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Quote:
Bought a straight edge and will be checking for warpage this weekend, if all fairs well going to out the heads on the new shortblock and get it back in the car. If they are warped they will be decked and then put back together |
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09-14-2020, 12:41 PM | #24 |
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09-14-2020, 01:43 PM | #25 |
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Ya that's the weird thing. It almost looks like the heads and SB are from two different blocks
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