Mercruiser 470 Leaking coolant...why??

[CaptainHook]

I have a 1979 MErcruiser 470, just finished spring commissioning today on this one. Fired right up and ran as it should.

Close inspection found coolant leaking from a weep hole?? On the water pump housing.

This hole is near the mid/upper left front of the water pump housing looking straight at the motor.

What is this telling me, need a new pump? Seals? Worse?

 

[Bt Doctur]

Re: Mercruiser 470 Leaking coolant...why??

The camshaft seals and/or the camshaft end is grooved, the manual is located in the Adults Only section.

 

[Barnacle_Bill]

Re: Mercruiser 470 Leaking coolant...why??

Seal in the pump going bad. The water pump will need to be replaced.

 

[Rocky_Road]

Re: Mercruiser 470 Leaking coolant...why??

I have a 1979 MErcruiser 470, just finished spring commissioning today on this one. Fired right up and ran as it should.

Close inspection found coolant leaking from a weep hole?? On the water pump housing.

This hole is near the mid/upper left front of the water pump housing looking straight at the motor.

What is this telling me, need a new pump? Seals? Worse?

The water pump is driven by the camshaft, and it is very common for the camshaft seal to wear a groove and to leak. The fix is to install sleeves on the camshaft, and replace the seal. Some mechanics know how to double up on the seals (after sleeving the camshaft) for a little added insurance.

Happy boating!

 

[CaptainHook]

Re: Mercruiser 470 Leaking coolant...why??

Soooooo....this is gonna be an expensive on huh??????

 

[Rocky_Road]

Re: Mercruiser 470 Leaking coolant...why??

Soooooo....this is gonna be an expensive on huh??????

Not always.

Read this tutorial on how to fix: http://www.sterndrives.com/470information/470coolantleakrepair.html

 

[Bt Doctur]

Re: Mercruiser 470 Leaking coolant...why??

How much can 2 seals cost? It is a DIY project, about an 7 on the PITA scale.
A lot to remove for access but is easily done

 

[gettin'even]

Re: Mercruiser 470 Leaking coolant...why??

The seals are cheap enough, but the sleeves are a little pricey...about $40 a piece (you will probably need two). The labor may be intensive if you dont have enough room in front of the engine to pull the front "pulley". In that case, the engine has to be removed. Ask me how I know.....lol.

 

[CaptainHook]

Re: Mercruiser 470 Leaking coolant...why??

Wow....reading that tutorial......sounds like a big pain!! Guess I gotta do it though.

 

[BrandonS]

Re: Mercruiser 470 Leaking coolant...why??

I just finished doing mine.
Difficulty: 6
Time: 2-8 hours (depending on how clean your motor is, how easy the gaskets come off and aptitude with a balancer puller)

It really isn't that bad of a job. The hardest part was cleaning the gasket material off of the covers. I took tons of pictures, and plan on doing a writeup on the job (not to knock the other one referenced, but it needs some pics). I did not use the sleeves (redi-sleeve) and am hoping for the best. There were some grooves, but the shaft polished up nicely. I did not have a balancer installer, but was lucky enough to have a solid piece of oak...and an alternator installation kit, and yes, if you hit the balancer with something the magnets will come off.

Brandon

 

[guyaverage]

Re: Mercruiser 470 Leaking coolant...why??

I did not have a balancer installer, but was lucky enough to have a solid piece of oak.........if you hit the balancer with something the magnets will come off.

No balancer installer needed. Just go to Home Depot/Lowes wherever, and get a bolt with the same threads as the balancer bolt, but about an inch or two longer. Use that bolt (with a few washers as necessary, to prevent the bolt from bottoming out as you tighten it) to push the balancer on until the regular bolt can be used. Heating the inside bore of the balancer with a heat gun before installing it on the crankshaft will also help if its being stubborn. I had one install almost completely on as is, and another that required some serious German heat (gudenhot) before it would go on even an inch.

 

[stonyloam]

Re: Mercruiser 470 Leaking coolant...why??

Couple more things, replace the crankshaft seal while you're at it and if you bugger up the pan gasket, get an exacto knife and some gasket material and cut out your own, rather than buying a (very) expensive replacement. It's not so bad but is major (7) PITA. Good luck.

 

[Jim's 470]

Re: Mercruiser 470 Leaking coolant...why??

I have a bit of real life experience with this problem (and others with my 470). I have had the internal water pump apart 3 times so far. First time was done by a boat mechanic who tried the "use the bolt" method of replacing the crank balancer. He stripped the bolt to the point that it would not come out in the normal fashion...don't try to replace your balancer that way!!

The mechanic replaced the water pump seals (there are 2, one for oil and one for water) but the water leak continued so I took it apart myself. I found the camshaft bearing surfaces rusted and grooved and since I had no ready fix for the grooves I buffed the shaft as best I could and tried to position the seals (be sure to install them in the right direction. always the open side of the seal facing toward the pressure side of oil and water; meaning they are essential "back to back") off the grooves but be careful not to block the weep hole. Take a coat hanger to ream out the weep hole to ensure it is clear of corrosion as this is the only way to keep water out of the oil in the event of water seal leakage...VERY important!!!

When replacing the counterbalance (after repairing the smashed threads) I used a dowel placed inside the face around the bolt to return the balancer to its normal position (use hard wood not metal). Under no circumstance strike the balancer in the area of the magnets as they will surely be damaged or dislodged. You of course risk damage to the crankshaft bearing thrust surfaces in hammering the balancer in but just don't be too brutal. I have not had a problem with that issue but recognize that it is a risk you take to save money on an installer tool.

While my fix did slow the flow of coolant through the weep hole it did not completely eliminate it. My most recent attempt did fully stop the flow. I used the shims (EZsleeves) and did the whole repair again. My camshaft measured .370 inches and I used the next larger sleeve as they did not have one in my exact size. I fixed them to the camshaft with epoxy and they are holding very nicely now. As there are different size shafts, I suggest that you remove the front cover and measure yours before ordering the shims (you do need 2) and you will have to find a retailer who sells them by size as opposed to aplication as the only application charts I have found are for automobiles. I got mine from a very helpful marine shop in Havasu, AZ (whose name I can't immediately recall).

My leak is resolved but I still have a temp problem and it is not circulation, either sea water or internal. It does not seem to be the heat exchanger. It has been quite effective in the past and I have checked/cleaned it to find it in good operating condition. I do note that there is a 2 inch diameter hole in my my external exhaust bellows (between the boat and the outdrive) and I wonder if there may be a damaged anti backup baffle in the external bellows area that may be restricting exhaust flows. Does anyone know if my 1986 Glaston 6 meter with Mercruiser 470 and Alpha I, Gen I outdrive has a baffled exhaust? Also is it possible to replace the bellows while the boat is in the water?

Best of luck to all you 470 owners!!

 

[jerryjerry05]

Re: Mercruiser 470 Leaking coolant...why??

Good news! If it's not leaking into the motor and just leaking out the hole.
You can loosen the cap and it will relieve the pressure.It won't leak as bad and you can use the boat till you fix it.
That's a temporary thing.It needs to be fixed.J

 

[stonyloam]

Re: Mercruiser 470 Leaking coolant...why??

The mechanic replaced the water pump seals (there are 2, one for oil and one for water) but the water leak continued so I took it apart myself. I found the camshaft bearing surfaces rusted and grooved and since I had no ready fix for the grooves I buffed the shaft as best I could and tried to position the seals (be sure to install them in the right direction. always the open side of the seal facing toward the pressure side of oil and water; meaning they are essential "back to back")

That is not correct, BOTH seals are for the coolant, and both seals face (open spring side) away from the block, toward the the pressure (coolant) side. The purpose of the second seal is to stop any coolant that leaks past the first seal from entering the crankcase and forces it out of the weep hole. There is no oil pressure on the rear seal. That can be confusing. Yeah 470's rock, no cracked blocks here!

 

[stonyloam]

Re: Mercruiser 470 Leaking coolant...why??

No balancer installer needed. Just go to Home Depot/Lowes wherever, and get a bolt with the same threads as the balancer bolt, but about an inch or two longer. Use that bolt (with a few washers as necessary, to prevent the bolt from bottoming out as you tighten it) to push the balancer

To essentially duplicate the Mercruiser tool, do above except: Thread a nut all the way up on the bolt, put on a couple of large washers and thread the bolt all the way into the bottom of the hole in the crank. Turn the nut against the washers to push the balancer onto the crank. That way you are not putting any undue stress on the crank threads.