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Not so good find on my 502 MPI

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Not so good find on my 502 MPI

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Old 03-13-2019, 05:37 PM
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Default Not so good find on my 502 MPI

We pulled the port engine out of the boat the other night so we could r-n-r the transmission. The job wasnít too bad, but I recommend doing when you do not have the flu! As the hoist was dragging it up, I saw something not so good on the even side of the block. It looks like the head was leaking from the mating surface, or that it may have even cracked above the mating surface (head). Thereís lots of rust to the point where good-sized flakes came off of the block, about the thickness of a quarter,

Iím going to snatch the top-end off and hope the block is okay. I have a line on a set of fresh 088 heads. Iím hoping the deck is good.

Anyone seen it this bad? Nothing froze on this motor, and it was running well until it ran wasted the trans seal (I did have some popping through the intake late season, but I think it was electrical).

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Old 03-13-2019, 05:48 PM
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Old 03-13-2019, 06:47 PM
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I have seen plenty of them corroded there but it is usually from water leaking and sitting there, not from a crack. See what the head gasket looks like when you pull the head.
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Old 03-13-2019, 08:46 PM
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There would be no way for water to sit there. The motor has CMIís on it, and nothing is leaking that I can tell. Itís possible that the old exhaust leaked prior to them being put in this boat. Just speculation.

It would seem to me that maybe the head gasket was leaking/seeping, and the end result is what weíre seeing. It looks like water was coming from there and dripping down the knock sensor and dipstick tune.

Hoping the deck surface is serviceable.
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Old 03-13-2019, 10:05 PM
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Tom just have to ask the one crack middle at like 2 oclock roundish shape kind of looks like possible freeze damage or is peeling rust -- hard to tell in the pic ?

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Old 03-13-2019, 10:16 PM
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I donít think the pictures really show the detail versus seeing it with the naked eye. At first glance it looked like freeze damage to me, but after removing some of the rust, it was all solid. I think what youíre seeing is the paint bubbles up with rust underneath.

Iíve never seen any leaks, and the motor builds 25 psi of pressure at cruise, 35 psi at wot. Iíd think there would be evidence of a leak.

Good eye though BUP. Hoping itís not freeze damage! If so, I guess Iím breaking out the check book.
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Old 03-13-2019, 10:19 PM
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Just reread BUP. Thereís no crack there. I stopped pulling pieces away at that spot. The whole area was bubbled up. The match to that area came off as a solid rust flake/chunk. Solid in that crevice.
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Old 03-13-2019, 10:43 PM
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some serious corrosion. I only see that (real bad block corrosion) on plow trucks around here. By your location you are in salt huh ?
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Old 03-14-2019, 06:42 AM
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Does not look good, did a pair of engines few years back, ended up replacing 1 block and all 4 heads as they were eaten up beyond what I considered usable...
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Old 03-14-2019, 06:46 AM
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Iím in Virginia Beach and run in brackish for the most part, though last year I ran in more ocean water because of where I was keeping her. The boat came from the Chesapeake Bay just south of Annapolis so brackish up that way.

Iíve only had the boat a couple of years; this looks like itís been happening for a while. I frequently washdown the motor, and I spray it with anticorrosives.
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