470 water in number 4

2fishy4u

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Aug 3, 2015
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Hello all, its me again with another famous 470 problem. If your reading this and thinking of a boat with a 470. Dont, Seriously stay away.

With that said, the next problem and one that may just make me sink the boat. I replaced my port with a reman last year. I have 130 hours on it. Comming back in from the last trip, 100 feet from dock the port stalled out and would not start. Sounded flooded. Pulled each plug. 1, 2, 3 all good. Number 4 wet...... I crank it over with number 4 out. Out comes sea water..... So I got sea water pooring into cylinder 4. I pull the carb and there is a 1/4 inch of water in the intake manifold......
So since its sea water I assume it cannot be the headgasket. Coolant is clean. Oil is showing trace of water obviously. So how many ways could sea water end up in number 4?
 

Bt Doctur

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Aug 29, 2004
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just 1, hole in the riser, everything else has A/F in it
 
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HT32BSX115

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Dec 8, 2005
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Hello all, its me again with another famous 470 problem. If your reading this and thinking of a boat with a 470. Dont, Seriously stay away.



Huh?:faint2: You said you have a boat with a 470.......How could I NOT think of a 470?

just 1, hole in the riser, everything else has A/F in it
I can add one I suppose........ severely leaking riser (blocking) gasket.
 

stonyloam

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Mar 13, 2009
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Yeah either a bad exhaust elbow casting (corroded hole from water jacket into the exhaust) or gasket. Pull the elbow and take a look. the only other thing could be missing exhaust shutter and water backed up into the exhaust.
 
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2fishy4u

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So, as with everything that has happened with these craptastic engines. It turned out the riser rusted a hole inside that blew its way right up and into the exhaust filling all the cylinders with sea water. Yeah its a freaking nightmare. Only 130 hours on that engine. And to top it off, the idiot at the parts store gave me a reverse rotation starter saying it was standard rotation and after installing on the other engine, when it fired cranking backwards it broke the timing chain. So after 24 hours on a new engine its screwed too.

In the words. as someone who has experienced everything with these engines, and spent over 30k making this boat new. I still have 2 screwed engines. Stay away from these things regardless of how cheap the boat is.
 

stonyloam

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I know it can be frustrating, but ANY marine engine can have a riser rust out and it was human error that got you the wrong starter. Had my old 470 out yesterday and it ran fantastic. Hang in there and when you get her running right it will be worth it, well maybe not but at least you will feel better. Good luck!
 

HT32BSX115

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So, as with everything that has happened with these craptastic engines. It turned out the riser rusted a hole inside that blew its way right up and into the exhaust filling all the cylinders with sea water.
Well, to be honest........as much as I would stay completely away from the entire family of 470 engines, This problem was not because it was a 470! It's a closed cooling riser failure.

And your starter "problem" had nothing to do with the engine either............

I would however, suggest you stay inside when there's lightning in the area!!!
 

2fishy4u

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Thanks for all the help guys. It was indeed a hole in the riser. Spent 2 weeks rebuilding the motor. Finally finished last weekend. Everything started up great, So went to start up the starboard, and the starter is bad. Grrr no problem, run to the marine store and ask for a starter for a mercruiser 3.7 470. He asks me standard or reverse. I say its standard rotation. I get back to boat and install the starter, its cranking fast!!! But it does not fire, I pause for a minute, then try again, BAM metal on metal slam and engine will not turn at all. I get out the remote starter switch to see what is going on. I notice the starter is trying to turn the engine backwards! So I take it back to the parts store, and tell him he gave me a reverse rotation starter. He says no, its standard. Counterclockwise..... I then have to prove to him that he is wrong and its clockwise rotation (when looking from the front). So he then gives me the right one. I intsall it but of course it acts like its seized.
I get someone to come and see what happened he said timing chain broke. I was curious this last weekend So I pull all the plugs, hit the starter and water blasts out of every cylinder..........
So, here is the theory and I would like your guys opinion. I think the reverse rotation starter spun the drive and impeller backwards, thus creating a suction in the exhaust that sucked water up and over the riser into the cylinders. All 4 was completly full of water, but no water anywhere else. oil was clean as no leak down had occured yet. The riser and manifold are 6 months old and in perfect condition. The engine has................ 24 hours..........I litterly just finished break in when the other engine happened coming back in.
HT32BX115 I am definitely avoiding any storms at this point. I have had many of the standard 470 issues, and many more of the WHY ME issues that just should not have happened unless your luck has run dry, and my luck ran dry the minute I bought this boat. Seriously, every time something goes wrong, its worst case. I started doing all my own work thinking that it was just poor mechanics in the area, but no. Its a combination of very bad luck, and some very efficient boat gremlins that just dont give up.
 
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HT32BSX115

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I think the reverse rotation starter spun the drive and impeller backwards, thus creating a suction in the exhaust that sucked water up and over the riser into the cylinders.
Hey, don't feel bad! I just pulled my(closed cooled) port exhaust manifold and riser and found antifreeze in one of the cyls of my 454! completely full of 50/50 AF/water) AND it was in there for quite some time! I was pretty lucky though, very little in the oil and the cyl wasn't frozen. In fact,I don't think it hurt it at all! (50/50 AF prevents corrosion!, especially if it's completely full!

I had a riser gasket leak on that side. and it's been that way for a couple of years at least. At first, I thought it was a cracked manifold but it held 15 PSI for hours.
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Your problem was NOT likely due to turning your impeller backwards.

Any engine is a positive displacement air pump. If you turned the engine backwards, it would pump (air) backwards. If you "dip the exhaust pipe in the water (which , it IS) Turning backwards on an exhaust cycle with an intake valve closed and exhaust valve open would draw water into the exhaust.!! Once you have any amount of water in the combustion chamber, it would hydrolock.

Where are you with this right now?

Did you replace the starter (with the correct starter) pull the plugs, purge the engine and restart it?
 
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2fishy4u

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I pulled the head and cleaned out the cylinders. drained and changed the oil. I am almost done with reassembly, but I am not going to try to start it until I know for sure how the water got in there. Because it ran perfect before the starter, and it was cranking over fast in reverse for a minute. The water got in there while I was cranking it causing the hydro lock. But I am not a mechanic by trade, I just became one because of all the issues I cant keep up financially......
 

stonyloam

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Well let's see..... If it was turning backwards the exhaust valve would be open and the intake valve would be closed when the piston was going down instead of up, sure seems like that would suck (literally) and fill the cylinder with water. It also could have forced water up into the intake and carb, something to check if you have not already. You sure seem to be a Murphy's law magnet. Good luck.
 
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