Mercruiser 454 tear-down - pulled the heads off - rusty exhaust ports

[04fxdwgi]

Re: Mercruiser 454 tear-down - pulled the heads off - rusty exhaust ports

Just an update on this thread, since it has been a while. . . I'll post some pictures as well. . .

Problems/Issues found:

Rusty/pitted valve seats on #4 exhaust and #5 exhaust. I had a machine shop install new valve seats and grind the valves. The other valves were good so just some manual grinding to freshen them up.

I found substantial amounts of iron sediment in the water jackets on the engine block. I popped out the core plugs (aka freeze plugs) and removed all the sediment with a power washer, etc. The machine shop said that the areas in between the cylinders were running hot, based on looking at the heads. Probably the sediment had something to do with that.

Bottom end of the engine checked out good, little/no wear, so I left it alone.

The timing chain looked a little sloppy, plus the cam sprocket was the kind with nylon teeth. so, I replaced it with a Melling high performance set.

I'm still waiting for the marine head gasket kit (on back order) so I can re-assemble the heads. Meanwhile, I am taking care of lots of rusty parts with Naval Jelly and POR-15 engine enamel.

I'll post some pics later on . . .

OK, here are some pics . . .

View attachment 122349View attachment 122350View attachment 122351View attachment 122352View attachment 122353
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Good job, exactly what I would have done. The new timing gears will give you a little piece of mind, being redone with steel gars instead of the plastic. Will make a little more noise, but you won't notice it. IMHO. New freeze plugs, gaskets and she'll be like a new motor. Taking it out was 80% of the job and the refresh was peanuts compared to doing it again.

Now wait for the next boating season and enjoy........ BTW, I'm origionally from the South Shore, myself.

 

[vi]

Re: Mercruiser 454 tear-down - pulled the heads off - rusty exhaust ports

Hi Ted, nice work, looks like your on the downhill side! Did alot of material come out with the power washer and how did you leak test the heads? Great boat website too!

 

[tpenfield]

Re: Mercruiser 454 tear-down - pulled the heads off - rusty exhaust ports

Hi Ted, nice work, looks like your on the downhill side! Did alot of material come out with the power washer and how did you leak test the heads? Great boat website too!

Yes, a whole lot of iron sediment came out of the engine block with the power washer. I did not really have any way of measuring it, but I would say that the water jackets were about 1/3 -to- 1/2 full of the stuff. I initially tried to get some of it with just a screw driver, but it really needed to be blasted and flushed out. The cylinder heads had relatively little, as the iron would tend to settle at the bottom of the water passages.

I used a 'leak test' gauge (OTC #5609 I think) for the leak testing and I ran 60 psi. My web site has a picture of the gauge in one of the 'rebuild' pages. Keep in mind that the compression test looked OK with only +/- 5% difference between the cylinders. Going forward, I think that I will always do a leak test in addition to a compression test.