Mercruiser 470 Coolant Loss and Milkshake Oil

Benny67

Chief Petty Officer
Joined
Apr 21, 2015
Messages
571
I agree. I don't know if it was totally empty, but the coolant drained signficantly, and when I pulled the drain plug into the bilge, the first 4-6 seconds was Mountain Dew, followed by chocolate milk shake.
Reading this makes me draw the conclusion that you're doing something wrong.
This issue sounds almost 100% certain it's the front Cam seals/speedi sleeve replacement are the culprit.

I'd stop screwing around and check that. If is not the issue you might as well do it anyway because it's gonna need it sooner or later.
 

emmurphy50

Seaman Apprentice
Joined
Jul 29, 2014
Messages
40
He keeps saying almost empty, kinda empty, probably mostly empty. Op, test it actually empty.
I started tearing apart the elbow and manifold... :(. I'm a Chemical Engineer and my thoughts were if it were freely gravity draining into the pan somewhere at atmospheric pressure that pressurizing it would only make it go more so, and it didn't.
 
Joined
Mar 27, 2010
Messages
3,008
I'm pretty sure if it was from the elbow/exhaust manifold, it would leak into the engine through the exhaust valve in the head, which would cause you to have coolant sitting on top of the pistons rather than in the pan, unless your valve seal was shot, then it could get into the lifter valley and drain down that way.
 

Benny67

Chief Petty Officer
Joined
Apr 21, 2015
Messages
571
I started tearing apart the elbow and manifold... :(. I'm a Chemical Engineer and my thoughts were if it were freely gravity draining into the pan somewhere at atmospheric pressure that pressurizing it would only make it go more so, and it didn't.
I'm an EE. My brother in law is a chemical Engineer for Shaw industries and I wouldn't let him work on my boat based on a degree from a school.

These guys here have everyday knowledge on these specific models. Some or none of them may or may not have an Engineering degree but I do and I come here regularly to read and ask questions. This form and it's people deliver sound advice time and time again.

Advice, it's 99.9% the Cam seals.
 

emmurphy50

Seaman Apprentice
Joined
Jul 29, 2014
Messages
40
I'm an EE. My brother in law is a chemical Engineer for Shaw industries and I wouldn't let him work on my boat based on a degree from a school.

These guys here have everyday knowledge on these specific models. Some or none of them may or may not have an Engineering degree but I do and I come here regularly to read and ask questions. This form and it's people deliver sound advice time and time again.

Advice, it's 99.9% the Cam seals.
I don't disagree. I just don't want to tear into the cam seal project without an evidence of weeping and two pieces of bizarre information: 1) It passed a pressure test, 2) it drains while not under pressure into the oil, and at times rapidly. I'll let you know what I find, and I wasn't trying to be smarter than anyone else, just explain my logic and where I was coming from.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,265
you have a 470

that means you will change head gaskets often (iron head on an open deck aluminum block guarantees failure)
you will need to change cam seals and do a speedi sleeve (soft cam snout guarantees failure)
 

ddrieck

Senior Chief Petty Officer
Joined
Jul 12, 2007
Messages
666
I apologize if I have highjacked this post....
With all the talk of it more than likely being the cam snout have a groove worn in it I just checked my 170 to see if there is coolant coming out the weep hole. Yup, sure is... so I ordered the new seals and gaskets right before posting this reply.
Anyone know exactly what speedi sleeve the OP and I would need to fix the grooved cam snout??
 

jhamblett

Seaman
Joined
Mar 18, 2021
Messages
53
I apologize if I have highjacked this post....
With all the talk of it more than likely being the cam snout have a groove worn in it I just checked my 170 to see if there is coolant coming out the weep hole. Yup, sure is... so I ordered the new seals and gaskets right before posting this reply.
Anyone know exactly what speedi sleeve the OP and I would need to fix the grooved cam snout??
99087
 
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