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470 mercruiser

s_thomas

New member
"I just joined tonight hoping

"I just joined tonight hoping to get some good ideas about an engine? noise. I bought a 1984 Imperial boat this summer with a 470r. Afer a couple of short trips around our local lake, I took the boat to a dealer to have a reverse cable replaced. After 6 weeks they finally finished. When I went to pick up the boat, the mechanis said that it had a loud noise in the engine. After a very heated disscusion, he told me that he doubted that I had ever had it running. I brought it home and the noise seems to be at crank shaft speed rather than a rod or main bearing noise. My question is, could something been put back together wrong in the lower unit? Thanks very much for any ideas. Steve."
 
"If they worked on the cables.

"If they worked on the cables... Not sure how you could end up with a rod knock or anything like that. Would love to know more.,.,

DH"
 
What does the oil look like?

What does the oil look like? Does it feel gritty? What filter is on it? Fram? Oil weight should be at least straight 30W or 25W40 wt.
 
"I had the engine running with

"I had the engine running with muffs the day I took it to have the cable changed, so I know it didn't have any issues with a noise. I haven't had it running to pull each plug wire to try to isolate a rod bearing noise,but I'm having a hard time believing somethong went wrong with the engine at this dealer. The oil looks and feels fine. Steve."
 
"Dealer "scare tactic"

"Dealer "scare tactic" works on many people. Old engines make a variety of noises. He may be just trying to drum up business from you. "Never give a sucker an even break." W.C. Fields
snow.gif
"
 
"Guy, thanks for taking the ti

"Guy, thanks for taking the time to offer suggestions. I have quite a bit of automotive repair experinence, but like a lot of other people, pretty new to boats. I understand "scare tactic" , but I'm pretty sure this isn't the case. The noise I have now certainly wasn't present before the reverse cable was changed. As I stated earlier, I had the boat out on our lake with no noise. I wasn't able to always shift into reverse,so that is why I took the boat to this dealer. Would it be possible the drive shaft wasn't installed correctly? Thats the only thing I can think of outside of the engine that turns at crank shaft speed. I have run the engine long enough to hear the noise, but have not done any trouble shooting to try to isolate the location of the noise for fear of causing major damage. I know about pulling spark plug wires one at a time to chechk for rod bearing noise, but as I said Ihaven't done that yet. I was hoping to get some ideas on things to check, that did not involve running the engine. Again thanks for your imput. Steve."
 
What does the noise sound like

What does the noise sound like. Does it remain steady or oscillate with the engine's RPM's?

You can remove the OD and run the engine using a water hose adaptor to the inlet. Troubleshoot the noise like you would an auto engine. Keep the RPMs low. If the noise leaves; that would put the source in the OD or the engine coupler which could be worn from a misaligned OD to engine.

Take a look at the engine mount bases to see if they are solid. The U-joints may be worn out; they should have lubed them and the gimbal bearing.
 
The noise is steady. I've

The noise is steady. I've had the engine started a couple of times and just ran it at idle. I haven't pulled each plug wire while the engine is running to try check and see if it is a rod bearing. I wouldn't say the noise is a knocking sound like a rod or main bearing. The noise starts just as soon as the engine starts running. I feel that the noise is at the same speed as the crankshaft speed. That's why I wondered if the drive shaft might be the scorce of the noise. I'll probably start with pulling the out drive off and go from there. Steve.
 
"[b]"That's why I wond

""That's why I wondered if the drive shaft might be the scorce of the noise."

Ayuh,...

The outdrive turns with the crankshaft, all the way to the propshaft,...

It's only 8 nuts,... Pull it,+ See..."
 
"If the problem would be u-joi

"If the problem would be u-joints or a gimble bearing, could this be from improper re-assembly? Steve."
 
"Steve,...

Diagnose the Pro


"Steve,...

Diagnose the Problem 1st,....

We're here to Help you,...
Not to assign Blame....

Until you Find the Problem,...
This is Nothing but a Guessing Game....

Which,.. Btw,... Get's Old Quickly...
Unless there's Answers coming back...."
 
"My thought was, that if they

"My thought was, that if they made a mistake putting the unit back together, they would be willing to correct the problem at their expense"
 
"Steve, pull the oil filter, c

"Steve, pull the oil filter, cut it open and check the filter media for rod or main bearing material. It's not hard to do,just don't use a saw ,because that will leave metal in the cut filter. I use a filter cutter ,but if you don't have access to one you can use a SHARP metal handled gasket scraper to slice the end off at the threaded end,right below the lip. This will tell you right NOW if the noise you are hearing is bearing related or not. keep us posted as to what you find TURBOMAN"
 
"MistaHays & turbo-man, th

"MistaHays & turbo-man, thanks for the thoughts. I do have a filter cutter in my shop.I'm also going to pull an oil sample and send to my
Cat. dealer. Hopefully, after doing these two things, this will tell me if the problem is in the engine. Thanks again. Steve."
 
"John Moore, you kiss your mot

"John Moore, you kiss your mother with that mouth?
I have a 470 and it runs like a top.
You have 2 posts and at best they are both troll posts. Not needed here.

Steven if you had the boat around the lake twice and no paculiar sounds then take it to a shop and now it has paculair sounds, it sounds like the shop has done something or not done something correctly. If all they touched was the outdrive then you might work backward from there isolating where the noise is coming from. If you can, remove the outdrive and start there. If you can prove it was from the shop they may make things right. Hard to tell."
 
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