Merc 470 Exhaust Valve?

[alexr254]

I just finished rebuilding a couple 1989 merc 470's.

I got both running great, but started having major issues with one. Apparently something went wrong with my rebuild and water is getting into the oil causing a milkshake...

So i checked the cam seals first, and checked if the weephole is clogged. Nope its not clogged and i did put on speedi sleeves just incase. Nothing coming through the weephole. So i decided to check the head gasket.. Maybe i put ii on bad. So i went ahead and removed the head and put in a new gasket just incase. Since then i havent tested, but hope this resolves the problem.

I also have issues with water getting into the cylinders, i am finding the spark plugs wet. The motor is on a stand, not in the boat, and is not connected to an outdrive atm. So we are running raw water from the garden hose. We left the water running even while the engine was off, i suppose this caused water to overflow from the exhaust manifold into whichever cylinders are open at the time it shuts down. Although no one confirmed this, its logical to me.

Are there some sort of flaps or anything i am missing for the exhaust manifold? All i have is a gasket...

Am i missing something here?

 

[stonyloam]

Re: Merc 470 Exhaust Valve?

If it were the head gasket you would have antifreeze in the oil (assuming it is filled with antifreeze). The only way that I can see that water from the raw water side of the exchanger could get into the cylinders is if it splashed or sprayed back into the exhaust manifold from the seawater exit in the exhaust elbow, which could happen with the engine off. I don't think the shutters could block enough water to fill the elbow, but maybe? How much water do you have in the oil?

 

[EddiePetty]

Re: Merc 470 Exhaust Valve?

...or you could have an ill-fitting/improperly installed gasket/blank at the transition from reservior/riser flange.
Additionally, when the out drive is installed and you are operating on muffs, the impeller pump stops/greatly restricts the flow of cooling water when the engine is not turning. Without the drive, cooling water flow is un-restricted and thus prone to back-fill the exhaust when the engine is not running.

 

[EddiePetty]

Re: Merc 470 Exhaust Valve?

"......The motor is on a stand, not in the boat, and is not connected to an outdrive atm. So we are running raw water from the garden hose......"

Got another thought brewing.

Are you running the cooling water to the heat exchanger or directly to the engine?

 

[stonyloam]

Re: Merc 470 Exhaust Valve?

I agree with Eddie, I think your basic problem is running the water while the engine is not running. There is no way the water can back up the exhaust when running. I would say put her back together and give it a try, being very careful to shut off the water before you turn off the engine. Running the engine for a short time with no water flowing into the seawater side of the exchanger should not hurt a thing.

 

[alexr254]

Re: Merc 470 Exhaust Valve?

If it were the head gasket you would have antifreeze in the oil (assuming it is filled with antifreeze). The only way that I can see that water from the raw water side of the exchanger could get into the cylinders is if it splashed or sprayed back into the exhaust manifold from the seawater exit in the exhaust elbow, which could happen with the engine off. I don't think the shutters could block enough water to fill the elbow, but maybe? How much water do you have in the oil?

I wish i knew which shutters your reffering to.

We didnt fill the engine up with AF yet, its running with water in the closed cooling system, until i am sure there are no leaks. AF isnt cheap enough for me to use for testing. Also when we lift the engines into the boat i will again change all fluids to the proper ones.

The raw water from the garden hose is going into the heat exchanger.

Additionally, when the out drive is installed and you are operating on muffs, the impeller pump stops/greatly restricts the flow of cooling water when the engine is not turning. Without the drive, cooling water flow is un-restricted and thus prone to back-fill the exhaust when the engine is not running.

This is exactly what i am thinking. This explains the plugs getting wet, but not the water getting in the oil.
And there was ALOT of water in the oil. It looked almost like white-out...
I put the other engine together in the exact same way and i dont have this issue with that one, which is what pointed me in the diretion of the head gasket, i may have simply installed it bad the first time. Now i will need to wait until next weekend to test, in the meantime maybe i can find some other possibilities.. Just incase the head gasket change does nothing to help.

 

[alexr254]

Re: Merc 470 Exhaust Valve?

If it was the cam seal leak, it would go through the weephole, correct? I did make sure that it is not clogged.
I put on 2 speedi sleeves to cover the entire area of the cam, i put brand new cam seals with locktite... I dont know what else i can do...

As far as i can tell, the raw water cooling does not even come close to any oil. So even if there was backwash, the only effected part would be igniton because the plugs are wet.

There is also a cooling system for the oil (oil filter to under the intake manifold), which i removed while testing for the leak, its not that for sure, since even after i removed it and changed oil.. The oil turned to milk again..

I also made a closed loop in the power steering cooling, to eliminate that as well. Still milk.

hmmmmm
if it makes any difference, there is no oil in the water.

Besides the head gasket i cant think of anything.

Can it be caused by the valves not seating properly? I was in the process of breaking the engine in...

 

[montejw360]

Re: Merc 470 Exhaust Valve?

I put on 2 speedi sleeves to cover the entire area of the cam, i put brand new cam seals with locktite... I dont know what else i can do...

Just to be sure, you installed the cam seals facing the correct direction, right? The open side of both seals should face the water pump impeller, towards the front of the engine away from the timing gear on the end of the cam shaft.

 

[alexr254]

Re: Merc 470 Exhaust Valve?

Just to be sure, you installed the cam seals facing the correct direction, right? The open side of both seals should face the water pump impeller, towards the front of the engine away from the timing gear on the end of the cam shaft.

Yup they are both facing the outside.

Theoretically even if this were the case and i did install it wrong, wouldnt i see liquid coming out the seep-hole?

 

[stonyloam]

Re: Merc 470 Exhaust Valve?

I wish i knew which shutters your reffering to.

I was thinking of the exhaust shutters, but they are still in the boat duhhhh. LOL. If you have no water coming out of the circulating pump weep hole, that is not the problem. The only way that water can get in past the valves would be through the cylinders, past the rings. Not likely to happen in any significant amount. Hate to ask, but did you retorque the head after running it the first time? Did you use the OEM Mercruiser head gasket? The OEM gasket has extra silicone strips to help it seal, maybe worth the extra cost. That is all I can think of, good luck.

 

[alexr254]

Re: Merc 470 Exhaust Valve?

The only head gasket i can find are the sierra ones, which is what i am using. Would you be able to link me an OEM head gasket for sale?
Im taking a ride to westmarine today in Jacksonville, if they have one i will get it.

these are the bolts i am using:
http://www.ebasicpower.com/pc/QSTHB370N/MER37ENG


I did attempt to re-torque. It did nothing since all the bolts were still at 130lbs when i tried it (waste of time imo).

 

[stonyloam]

Re: Merc 470 Exhaust Valve?

Would you be able to link me an OEM head gasket for sale?
Im taking a ride to westmarine today in Jacksonville, if they have one i will get it.

I did attempt to re-torque. It did nothing since all the bolts were still at 130lbs when i tried it (waste of time imo).

Here is one with the part# on e-bay http://www.ebay.com/itm/Mercruiser-..._Accessories_Gear&vxp=mtr&hash=item2eb838bf1c you can see the difference with the strips. There should be a mercruiser dealer between you and Jacksonville that has one.

Here is another link for Mercruiser parts http://www.mercruiserparts.com/Show...bnbr=130&bdesc=CYLINDER+HEAD+AND+ROCKER+COVER

IDK, they put an awful lot of emphasis on retorquing in the manual. PITA but probably the wise thing to do.

 

[montejw360]

Re: Merc 470 Exhaust Valve?

Yup they are both facing the outside.

Theoretically even if this were the case and i did install it wrong, wouldnt i see liquid coming out the seep-hole?

True that, yes you should have water coming out of the weep thingy.

 

[alexr254]

Re: Merc 470 Exhaust Valve?

ok its either a cracked head or block... #@$!@#$%^ <--- me cursing!

I will take the head to the machinist t have it pressure tested... I hope its not the block...

Even if it is i have a spare of both, but still.. so much dam work...