Mercruiser OEM Riser Gaskets

[FreeBeeTony]

I have a full FWC'd system and it's about the 5th season, planning on changing them this fall.
Yesterday I noticed the overflow was overflowing. Temp seemed normal.
Last time this happened the block-off gaskets broke through between the manifolds and risers causing raw water to be pumped into the fresh water side.
I think this happened again. I need to pressure check the cooling system.

What is the p/n for the OEM gaskets that do not require a block-off plate?
How long should those new OEM block-off gaskets last?

 

[FreeBeeTony]

Think I am going to pressure test the freshwater side....If it leaks then I will start the engine and see if the "anti-freeze" level rises. If it does I'm going to go after the riser gaskets.

Sound like a plan?

 

[Bondo]

Sound like a plan?

Ayuh,..... Hi Tony,..... Sounds like the best way to figure out what's up,.....

Does yer antifreeze taste salty,..??..??

 

[FreeBeeTony]

I didn't taste it but it looks diluted....

 

[Fun Times]

IWhat is the p/n for the OEM gaskets that do not require a block-off plate?
How long should those new OEM block-off gaskets last?

The time they last seems to very as I've seen the non block offs gaskets leak within 2 years while others have lasted 10+ years both with or without corrosion issues.

The cooling system does produce roughly around 15 psi... So even though they're good quality gaskets, a gasket that's blocking flow under pressure is going to eventually ware out a bit sooner then normal one could imagine.

Item number 11 should be the gaskets you hopefully will need vs a anything else being wrong.
http://www.mercruiserparts.com/Show...=150&bdesc=EXHAUST+MANIFOLD+AND+EXHAUST+ELBOW

Good luck.

 

[Bt Doctur]

Try to locate the SS steel blockoff plates and just use regular gaskets above and below

 

[FreeBeeTony]

I was going to ask about the SS plates.
Think they are a better idea?

 

[rick3452]

When I had an "overflow" problem... My Heat Exchanger failed and mixed the antifreeze with the raw water and pumped it out the overflow..

 

[HT32BSX115]

How long should those new OEM block-off gaskets last?

My block off gaskets have been leak free for about 10 years. I don't run in salt though.

If I pull mine, I'll probably put "plates" on it.