Merc 470 having some MAJOR issues...

[Banditz]

Hey guys!! sorry been awhile since i posted up. Lost internet connection for awhile, almost had to sell the boat but now it looks like she's gonna stay mine!

Now, for my issue. Last year you guys had me running GREAT! Now...not so much! LOL Over the winter I took care to winterize her..or so i thought. I added stabil, ran antifreeze through all the lines. And changed the oil in the outdrive as well as engine. Upon breaking her out this year I noticed right away I had made a mistake. The heat exchanger had come apart due to freezing water. Well, got that fixed and no more issues there!
Now, took her out after adding good fuel, changed out the fuel filter, changed the oil again for shyts n giggles, checked the trim fluid level changed it, changed the lower unit fluid again. You name it. Oh, and changed the plugs too....

took her to the lake she started right up idleing nice and smooth! Went out slowly for about two miles or so letting the oil get around the engine and let her build back up or loosen up whatever you wanna call it. Now..after all that I finally opened her up slowly. She got up on plane and in less time than it takes to think about it i was at full throttle, trimmed out, and cruising along at about 51mph. I know, had the gps with me. Well, went up and around the lake around and around all the time keeping an eye out on temp..oil pressure, you know the normal stuff. Decided to go under a bridge to head UPSTREAM to by one of my old stomping grounds. Figuered in the river anything bad happen I can always float back down ya know. Well, went to slow down adn she stalled. Slowly at first then she just died outright.

Finally after I thought she was flooded I realized that if i held the top butterfly open on the 2bl carb that she started right up! No problem at all! figured ok...well she sat for a long time so lets get some fuel running through her and see how she does. Opened her back up to about 40 or so. Had the cover off since I had been working on the engine to get her running again anyway and figured I MAY have to do it again so i didnt wanna have to remove everything again. Well, after about five minutes or so i decided to slow and see how she responded. She did NOT die now..i was happy!! So i went to go again and boom! She started sounding like she had a huge air leak!! Like a whistle almost. Before I knew it she stopped making the noise BUT she started sounding like she had a rod knocking!! I stopped asap to see if something had maybe fell into the engine...nothing. She stopped making ANY noise when I stopped the boat and just idled smooth as could be. Guessing the carb issue is gone now. But worried about the motor..

Anyway figured well she's not making any noise now..hopefully she wont again. So i began to give her some gas and the nosie was gone! I was happy again..lol. But not for long. i putted around at about 20mph for at least 20 minutes. Not a sound to be heard but a perfectly running 470! Then it happened...I decided to give her some gas and see what happened. brought it up to 30 mph and she slowly started the knocking again. I about cried! Everytime I slowed down she would stop making the noise. She was at about 170degrees if that, she has ALWAYS ran cold... The voltage was fine, the fuel was definatly getting to her, and I changed everything and did all the routine stuff before I took her out!
What the heck is going on! She will drive all day long at 20 or so mph without a single knock...but you bring it up to 30 or so and she starts it again. A friend of mine says that with these engines being known to go through head gaskets that he would change that and see what happens. But to me that sounds like a long shot if I ever heard one! I have a guy who has 2 470's one just rebuilt by him for $900. Figuring I may HAVE to just accpet my losses and buy the new engine and swap her in. Kinda figured it would be worth going to a larger motor..but don't wanna do something thats not safe ya know. Way to many threads on people doing unsafe crap and getting shafted for it.

The boat is a 1987 19ft glastron. Figure its been long enough you guys MUST have forgotten that. lol...thanks for any info or advise you can give!! Will

 

[Banditz]

Re: Merc 470 having some MAJOR issues...

Sorry I KNOW...LONG post. But i wanted to give as much info as i could so you guys could give the best answer YOU could. hopefully yall know something I dont!

 

[Eric 3.7LX Alpha 1]

Re: Merc 470 having some MAJOR issues...

Hey guys!! sorry been awhile since i posted up. Lost internet connection for awhile, almost had to sell the boat but now it looks like she's gonna stay mine!

glad to see your able to keep her.

Well, went to slow down adn she stalled. Slowly at first then she just died outright.

How fast did you slow down when this happened? Was it a gradual thing or did you drop the throttle from WOT to slow? Sometimes when you slow down too quickly seawater can get back into the cylinder from lack of shutters in the exhaust.

It's possible a push rod might be slightly bent from it from the engine trying to compress water, which doesn't compress. Maybe the sound is a rocker you hear. Of coarse this is just a possibility and a guess on my part. You could do a compression test on the engine, and pull the valve cover off and have a look if anythings not right.

 

[badbowtie]

Re: Merc 470 having some MAJOR issues...

I would pull the dipstick first and see what it says color and level since you have already ran it. Since the riser froze and cracked I would be worried when it melted were did all the water go down in the motor. Also like eric said I would check the compression

 

[stonyloam]

Re: Merc 470 having some MAJOR issues...

Hope figure this out and that it is not a serious problem. One thing, on your winterization, you do not have to use antifreeze, just pull the aft plug on the exchanger and let it drain. Pull the hose on the PS cooler to make sure it drains (if it is empty, you should not ever have to do it again), then put it back together and you are done. I do it right on the ramp when we pull the boat for the winter. Good luck

 

[Banditz]

Re: Merc 470 having some MAJOR issues...

Ok guys thank you for all the replys.


I will pull the plugs asap and check them. I know better than to just "slam on the brakes" so to speak. I have heard way to many storeis from you guys on here talking about water going in the rear. The problem actually started when I was still running at a good pace. Thats WHY i slowed down to begin with. The heat exchanger is what froze up. Not the riser. I am thinking they are two different things at least! LOL Sorry..not the best with tech names of things. I ran the engine on my hose for about 30 seconds in my driveway before I realized the heat exchanger was not working. the water was pouring OUT of the exchanger into the bottom of the boat. All over the place to be honest with you. LOL Drained all the water out, let the engine cool down, then did the repair. Once done, no more leak.

Now..the only issue I have with what you guys are saying is that the engine lost NO power..not once. Even when It was knocking she still had teh same amount of go power..I would have thought only being fourbanger that a dead or distressed cylinder would definatly show a loss of power. Or am i wrong in thinking that? I will know soon enough. Gonna pull the plugs this afternoon when I get home.
Now, one last thing..if it is teh issue, and the water was getting in....is the motor pretty much a goner? If so i need to get that other one soon..I don't want the guy to sell it on me and me be left with a bad engine and no replacement.

 

[solar7647]

Re: Merc 470 having some MAJOR issues...

Can you get us some sound, maybe a quick vid it would help a ton. If we can hear how the sound is timed to the engine we could narrow it down to valve train or if something is just loose. A puckered up flap can make alot of noise not to mention other things.

 

[nola mike]

Re: Merc 470 having some MAJOR issues...

i'd still be worried about the riser; if you didn't drain the exchanger, you still had water in there, could have cracked it = water leaking back into engine.

 

[stonyloam]

Re: Merc 470 having some MAJOR issues...

i'd still be worried about the riser; if you didn't drain the exchanger, you still had water in there, could have cracked it = water leaking back into engine.

I don't think that there is any seawater in the riser. The exhaust manifold is cooled by antifreeze, and the seawater from the exchanger is simply dumped into the exhaust through a hose fitting (cooling the shutters), and could not accumulate in there to cause a freeze crack.

 

[Banditz]

Re: Merc 470 having some MAJOR issues...

So you guys really think that having that water drain back in would cause the knocking then? Would i be able to fix that or would the engine still be gone? i was unable to get to her today..too dang busy with my boy...gotta love kids. Mine is the best "toy" i have!

 

[stonyloam]

Re: Merc 470 having some MAJOR issues...

The plugs should tell you a lot. If there is water getting in there the tips will be "steam cleaned" white, while the normal plug insulator tips will be tan. Your problem started while you were running, so it seems unlikely that water intrusion is the problem. Are you sure it is an engine knock, as a long shot, there is a casting plug at the back of the head that can rust out, and dump the #4 cyl exhaust out. Gets pretty loud and can sound like a knock. If you hold your hand back there you can feel it coming out.

 

[Banditz]

Re: Merc 470 having some MAJOR issues...

Nah...its a knock for sure. just wasnt sure if it was a engine knock..or something else. Sounds to me like aengine knock as it slows and speeds up with the engine speed.


If it helps at all, i drove her around for at least 30 minutes with it running perfectly fine at or around 20mph in big circles. As long as i did not bring teh rpm's up to high she did not knock. I was able to floor it to get up on plane like normal, and then just pull her way back to stop from hitting that knocking stage. but below that she was great...And when floored, no issues...all of it was just as the rpms got up there that i had issues. I was hoping you guys would say nah man, your :whatever: is what was knocking not the engine..lol. Dangit!

 

[Banditz]

Re: Merc 470 having some MAJOR issues...

If that was not clear this should be..

At idle up to about 3k...she has NO knock at all. After I hit 3k or so she starts and gets worse till i pull back for fear of something going through teh block!

 

[stonyloam]

Re: Merc 470 having some MAJOR issues...

If that was not clear this should be..

At idle up to about 3k...she has NO knock at all. After I hit 3k or so she starts and gets worse till i pull back for fear of something going through teh block!

Doesn't sound good. I do remember reading about some wrist pin problems with the 470, but can't find it now. This is interesting reading though: http://www.remanufactured.com/Engine_Noise_Diagnosis_101.htm especially pulling the plug wires to isolate the knock. Good luck.

 

[solar7647]

Re: Merc 470 having some MAJOR issues...

If that was not clear this should be..

At idle up to about 3k...she has NO knock at all. After I hit 3k or so she starts and gets worse till i pull back for fear of something going through teh block!

I really think a video with some sound will help solve this. Every thing I have read being suggest would cause a constant knock not just at high rpm. It really sounds like it may be something that isn't a engine killer, but it's hard to be sure since we can't hear it.

 

[nola mike]

Re: Merc 470 having some MAJOR issues...

I don't think that there is any seawater in the riser. The exhaust manifold is cooled by antifreeze, and the seawater from the exchanger is simply dumped into the exhaust through a hose fitting (cooling the shutters), and could not accumulate in there to cause a freeze crack.

Are you sure? Water definitely flows through the riser. I think that as long as the exchanger isn't drained, the riser still could have water in it; when you drain the exchanger the water backflows out. I mean, SWC engines crack risers/manis when not winterized. Also, no one's addressed that this knock might be gimble bearing/u-joints. Seems that if this was major engine damage, it would be getting a lot worse with as hard as the OP's been driving it.

 

[stonyloam]

Re: Merc 470 having some MAJOR issues...

Are you sure? Water definitely flows through the riser.

Well I think so LOL. The manifold is close cooled by antifreeze, and the seawater is dumped into the exhaust just above the exhaust elbow, way downstream and simply exits with the exhaust gasses. Look at the fourth photo here on e-bay to see what I am talking about: http://cgi.ebay.com/ebaymotors/3-7-...3788986QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear I think the 470 problem is when either the riser corrodes or the gasket fails and dumps antifreeze into the exhaust ports of the head. If the exchanger is not drained the hose to the exhaust may still be full, but there is no seawater in the riser itself to freeze. IMHO

 

[solar7647]

Re: Merc 470 having some MAJOR issues...

The water is dumped directly into the exhaust, it dosnt flow or keep in the riser any place that it could freeze and crack it, that is unless he used water instead of anti freeze in the engine. The flow diagram:

The point about the drive is a very good one.

 

[dubs283]

Re: Merc 470 having some MAJOR issues...

you need to do a compression check

i have had bad head gaskets that sound very much like a rod knock at higher rpms

definitely pull the drive and check out your transom assy components and the drive itself

 

[nola mike]

Re: Merc 470 having some MAJOR issues...

@ Terry/Solar: Yeah, you're both right. I forgot where the hose was on the riser; looks like any water will end up either out the exhaust or in the hose to the exchanger.