mercruiser 470 loosing a/f

[jabfd]

hi guys iam posting a new post because the other one was getting to long . any way iam losing a/f i changed my exhuast manifold and before i put it on it held 15 psi on the test bench . also I pressure tested the engine it held 15 psi for over an hour until i took the pressure test off . my oil still looks ok for now only took the boat out for two trips total 40 miles
dont know what it could be when itested the engine it was cold would that make a diffence ? thanks for everbodys help God bless

 

[dn010]

Re: mercruiser 470 loosing a/f

Are you finding fluid in your bilge or is it that you take the pressure cap off the reservoir and there is none in there after you top it off?

On my 470, the cast/pressurized reservoir always seems bone dry when cold, but when it starts heating up it will fill up - plus my overfill reservoir never drains so I never bother with it and it's never overheated...

 

[hall832]

Re: mercruiser 470 loosing a/f

Just to catch up, closed cooling system? Do you know where it its going. Have you checked your heat exchange?

 

[jabfd]

Re: mercruiser 470 loosing a/f

Are you finding fluid in your bilge or is it that you take the pressure cap off the reservoir and there is none in there after you top it off?

On my 470, the cast/pressurized reservoir always seems bone dry when cold, but when it starts heating up it will fill up - plus my overfill reservoir never drains so I never bother with it and it's never overheated...

no a/f in bilge just low when i take the cap off .

 

[jabfd]

Re: mercruiser 470 loosing a/f

no i dont know where its going oil still looks fine at this point . before i had a bad exhaust manifold so it was going into my oil but now with the new /used one i have no idea .The weep hole is clear and dry alsoso not cam seals . i never checked heat exchanger

 

[stonyloam]

Re: mercruiser 470 loosing a/f

If the hose going to the expansion tank or the cap is not sealed well it will push antifreeze into the tank when hot, but will not suck it back into the reservoir because of the air leak.

 

[hall832]

Re: mercruiser 470 loosing a/f

check your heat exchanger, you may have to open it up and check the inside visually.