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Old 06-07-2017, 02:29 PM   #1
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Default Rocker cover gunk

Hey guys few weeks ago I posted about gunk in both rocker covers on my mercruiser 4.2L v6 (190) vortec well I've finally got home from work to starting working on it so far I have started up engine to run it to normal temp 175 then emptied oil out all came out clean oil with no contamination in the sump and then cleaned the rocker covers the best I could then added 4 litre of engine flush ran it on idle for 15 mins check oil stick and was crystal clear let engine sit for 30 mins then ran it again for 15 mins and was still Crystal clear but when running on idle on the breathers on the rocker covers was if steam was coming out so I'm getting water in somewhere I'm thinking either 3 things cracked blocked or inlet manifold gasket or the risers are letting water in to the pistons and pushing water up through valves anyone experienced this
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Old 06-07-2017, 10:35 PM   #2
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And you say you saw no water coming out in the oil?! That's looking pretty bad. I'd pull the heads and have them rebuilt. Putting them back on gives you new head, intake, and manifold gaskets. Only other thing is the block and that's probably lowest on list of likelihood.
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Old 06-07-2017, 10:53 PM   #3
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Yae no mixing in the sump only gunk in the rocker covers so my next move is testing the risers making sure they aren't leaking if they aren't then move onto inlet manifold gasket and check that and check for cracks underneath there if not then move onto the heads just can't see 2 heads goin at same time as I have gunk in both rocker covers
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Old 06-08-2017, 01:14 AM   #4
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I'm just going to say good luck, the oil passages in the head are connected to the block passages and all drain into the pan.

IMO you are planning to spend a fair amount of money on a hope, I would just bite the bullet and replace the engine. You have been talking about this for over a month now and the season is passing you bye.
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Old 06-08-2017, 06:43 AM   #5
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I have a mercruiser specialist coming over this weekend to have a look see what his thoughts are, engine blocks over here aren't like states there much more expensive for new block they sell for £4000 plus and that just block no inlet manilfold or carb or exhaust risers or water pump just block only
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Old 06-08-2017, 11:22 AM   #6
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Quote:
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I have a mercruiser specialist coming over this weekend to have a look see what his thoughts are, engine blocks over here aren't like states there much more expensive for new block they sell for £4000 plus and that just block no inlet manilfold or carb or exhaust risers or water pump just block only
I understand about the cost as you posted it in your previous thread. You description is a long block; block, heads and all internals. A short block is the same less the heads.

I doubt the mercruiser guy will be able to tell much with out a complete disassembly and magufluxing the casting to look for cracks in the block and heads.
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Old 06-08-2017, 11:41 AM   #7
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Yae your right, but I'll see what his thoughts are before spending £££ on new block
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Old 07-04-2017, 11:33 PM   #8
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How did you make out Marty?
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Old 07-06-2017, 10:15 PM   #9
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Done compression test on all cylinders and results where cylinder 1 was 155 cylinder 2 was 157 cylinder 3 was 155 cylinder 4 was 65 cylinder 5 was 150 cylinder 6 was 170 so took off exhaust and noticed water in manifold then started taking inlet manifold off and the gaskets where fine and no signs of cracked block then taken off both heads and the head gaskets where fine but exhaust port on cylinder 4 was corroded and inlet valve and exhaust valve where corroded as well so wasnt seating properly and causing the low compression and letting water in causing the gunk in the rockers
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Old 07-06-2017, 10:29 PM   #10
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The valves are bad because of burning water, I.e. Tuplid valves burnt seats. This happens due to bad exhaust that allowed water intrusion. The engines back pressure sucks water in through the exhaust valve durning the final degrees of the exhaust stroke. Compressing water forces it past the piston rings and into the crankcase where it mixes with oil.
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Old 07-07-2017, 05:16 AM   #11
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There was no mixing of oil in the sump was only in the rocker cover and was clean as well under the inlet manifold
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Old 07-07-2017, 11:37 AM   #12
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Quote:
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There was no mixing of oil in the sump was only in the rocker cover and was clean as well under the inlet manifold
I strongly disagree, you won't know unless you pull the engine and remove the pan. How did the lifter valley look when you removed the intake?
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Old 07-07-2017, 12:03 PM   #13
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That was all clean as well only place there was gunk was under the rocker cover
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Old 07-07-2017, 12:45 PM   #14
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Quote:
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That was all clean as well only place there was gunk was under the rocker cover
I find that hard to understand as in the first picture you posted the gunk is drippping into the holes where the pushrods go into the lifter valley. Your boat your decisions.
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Old 07-07-2017, 01:06 PM   #15
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I don't see how you would isolate water to only the valve cover. In previous posts you mentioned the dipstick tube being 'clear' (free of water in the oil). However oil doesn't circulate through the dipstick tube.

I would assume if you have water in the valve covers, you have water circulating through the system.
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Old 07-12-2017, 10:26 AM   #16
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there was no gunk circulating not even under the manifold where the push rods go down to i was surprised myself
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