Mercruiser 470 - Another Noise issue

[nwboater45]

I have a 1989 Bluewater with a Mercruiser 470, 3.7L, 165hp engine. It has a strange noise in the front of the engine that I cannot figure out. It seems to be centered around the circulation pump and stator. I have run a steth0scope down the head and everything sounds fine. I have run down along the block and that sounds fine as well. I put it at the front of the engine and I can hear the noise but just can't pin point what it is. It almost sounds like a bearing going bad. Do circulation pumps have bearings that go out? Or any other ideas on what this maybe? I have attached two links for videos I posted on YouTube. The noise doesn't sound like valves tapping or rods knocking but more of a ticking. I have heard other engines on here but haven't run across this noise. Any ideas would help.



Mercruiser 470 3.7L engine noise - YouTube

Mercruiser 470 3.7L Engine Noise - YouTube

Mercruiser 470 3.7L engine noise - YouTube

Mercruiser 470 3.7L Engine Noise - YouTube

 

[Bt Doctur]

Re: Mercruiser 470 - Another Noise issue

If I had to guess I`d say it sounds like the timing chain adjusting shoe,

 

[nwboater45]

Re: Mercruiser 470 - Another Noise issue

Thank Bt.....I am curious to know why you would think it is that. Is it a problem you have run into before? Also is the repair something you have to take the motor out of the boat for?

 

[stonyloam]

Re: Mercruiser 470 - Another Noise issue

Thank Bt.....I am curious to know why you would think it is that. Is it a problem you have run into before? Also is the repair something you have to take the motor out of the boat for?

You do not (as long as you have room to pull the rotor). The procedure to get to it would be similar to replacing the cam seals, which you might as well do if the adjustor is the problem.

 

[nwboater45]

Re: Mercruiser 470 - Another Noise issue

Stony, do you think it is the timing chain shoe? Is it an easy fix or atleast something easy to get a visual check on? I will start pulling out the repair manual to see.

 

[stonyloam]

Re: Mercruiser 470 - Another Noise issue

Stony, do you think it is the timing chain shoe? Is it an easy fix or at least something easy to get a visual check on? I will start pulling out the repair manual to see.

I really don't know. The Dr. is pretty good so it might be. Take an auto stethoscope (or a long screwdriver to the ear) and listen to the front cover area just below the waterpump cover. The fix would be kind of a PITA but not too difficult. You would have to drain the antifreeze, pull the rotor off of the crank, remove the stator, remove the water hose, and the engine water pump cover, then the pump impeller, then the timing chain cover. Here is the procedure for replacing the cam seals, you get to them exactly the same way: Mercruiser 470 coolant leak Looks like you have enough room so you should not have to mess with the motor mount. Unfortunately by the time you can get a visual you are there. Here are the parts you need to take off: http://www.mercruiserparts.com/Show...39469.png&inbr=908&bnbr=170&bdesc=FRONT+COVER Here is where they talk about the tensioner: Boatinfo - Mercruiser Service Manual nr. 8 - 1985-1989 - Mercury Marine 4 Cylinder Engines But as said am not sure that is the problem.

 

[Bt Doctur]

Re: Mercruiser 470 - Another Noise issue

listening to all the videos it sounds more like a constant rattle ,like spring steel dragging across a chain or something.If it was a GM i`d go with fuel pump rod but you dont have one.There no wat to tell for sure unless the front cover is pulled.Could research it using the ford 302 auto motor.pretty sure it uses the same type of tensioner.

 

[wrestling coach]

Re: Mercruiser 470 - Another Noise issue

Take the belt off your power steering pump and see if the noise goes away. Check power steering fluid level.

Dennis

 

[nwboater45]

Re: Mercruiser 470 - Another Noise issue

@ Stony - Thanks for the links. I pulled my manual and also viewed the service manual #8. Your right it does look like a PITA job but must be done. There are no real good images of the tensioner location but the service manual does show what a bad one looks like. I need to check the chain defelection anyways. I use to race cars so I am use to a little wrenching but my race engines had a time belt and not a chain so that is something new.

@BT - thanks. I did put a stethoscope on engine several weeks ago. The noise is loudest on the front cover plate so that is why I though it might be the pump. I looks like the tensioner is right behind that so I think I am going to open her up and see what happens.

@coach - I just might try that and see what happens. My guess is if the noise goes away then it might be the pump and it is stays then the tensioner.

Time to get the hands dirty and I will report back.

 

[nwboater45]

Re: Mercruiser 470 - Another Noise issue

Alright I have done a little more research. There are two special tools for the removal and install of the rotor. I have read some replies by Stony that the puller from Autozone can be use. But what about the intall. I looked on Ebay and nothing. I called 4 different marine service places and none have it and won't loan/rent them out. One guy did say his service guys just use a harmonic balancer intaller to put it on. I can get one of those from Autozone as well. But does anyone know where you can get the actual tool? Or has anyone use a harmonic balancer intall tool to install the rotor. At this point I am thinking of going to an alternator.

 

[nwboater45]

Re: Mercruiser 470 - Another Noise issue

Here is a photo of the tensioner. A few large grooves have developed so it looks like it needs to be replaced. Here is the problem. I have looked all over online and these are now obsolete. So does anyone know what the replacement part is? I am going to put on a new timing chain as well.

 

[stonyloam]

Re: Mercruiser 470 - Another Noise issue

Yeah the autozone puller worked fine for pulling the rotor, but would not work to install it because the rotor was too deep. So I made a spacer out of a short piece of pipe so the installer did work. A socket might work. You can make an installer out of a piece of threaded rod or a long bolt (1/2 inch fine thread) a stack of greased washers and a nut. If you use rod you just have to grind a couple of flats on the end so you can hold it with a wrench. Anyway thread the nut on the bolt as far as it will go.put on a stack of washers or a pipe to take up the space, then thread the bolt all the way into the end of the crank. Then all you have to do is line up the rotor and turn the nut and the washers will push the rotor on. you can add washers or spacers as needed to get the rotor to seat. You do not want to turn the center bolt to pull it on because it could damage the threads, and you do not want to pound on it because that could dislodge the magnets in the rotor. Here is a photo of the Mercruiser tool: Boatinfo - Mercruiser Service Manual nr. 8 - 1985-1989 - Mercury Marine 4 Cylinder Engines. pretty simple nothing more than a spacer that screws in and pushes the rotor on just like the washers would do.

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 470 - Another Noise issue

The Timing Chain tensioner is part number MER75202
Tensioner | Timing Chain | Mercruiser 3.7L 76-89

Looks to be back ordered from them though.

I was able to get the puller/installer tool from Auto Zone and used the installer to press the damper back on. Maybe they have a couple of different styles to choose from.

 

[nwboater45]

Re: Mercruiser 470 - Another Noise issue

Eric, I have been to atleast 30 Mercruiser parts web sites and none have them. They either say No Longer Available, obsolete, unavailable, or out of stock (which I think goes with the 3 previous). So I was wondering if anyone knows what the fix is. I will try and call around to some service techs tomorrow.

Stony, thanks for the tip. I saw your install tool idea on some other posts. Looks like it will work. I am just baffled on this tensioner.

 

[stonyloam]

Re: Mercruiser 470 - Another Noise issue

I am just baffled on this tensioner.

It doesn't look so bad, I would just reuse it.