Unknown history, manifolds and risers?

[hnt]

Hi,

I bought a 1996 Pursuit Denali 2460 with a M/C 5.7LX efi Bravo III with raw water cooling.

The boat was purchased new in Texas and used in salt water in its early life. I bought it through a dealer in St.Louis where is was used on the Mississippi for most of its life. I now keep the boat rack stored in CT (salt water)

I have now idea of the hisory of the manifolds and risers and there is a chance that they might even be original.

I ran the boat all las summer and I had no coolong problems at all.

Should I pull the manifolds and risers and inspect them and if all looks good put and new gaskets and inspect again in a year?

or should I just replace everything because of the unknown?

 

[Don S]

Re: Unknown history, manifolds and risers?

Just pull the risers off and check the gasket surfaces. That is what normally goes bad first. The gasket surface between the exhaust port and the 4 water passages corrode away.

 

[ratherbeboating]

Re: Unknown history, manifolds and risers?

checking is fine and i agree with don s. if you have the money changing the riser isnt a bad idea. generally the riser goes bad first. in most cases you can go through 2 risers to 1 manifold if done in time.

 

[hnt]

Re: Unknown history, manifolds and risers?

Thanks,

Thats really good information.

What about removing the manifolds and trying to clean any junk out of them? Is that worth the effort?

 

[Don S]

Re: Unknown history, manifolds and risers?

checking is fine and i agree with don s. if you have the money changing the riser isnt a bad idea. generally the riser goes bad first. in most cases you can go through 2 risers to 1 manifold if done in time.

Typically (in a raw water cooled engine), if a riser goes bad so does the manifold. Check both carefully.

If they are plugged up and need cleaned out due to rust, they need replaced. It's kind of an early warning system, next warning is the engine needing replaced.

 

[hnt]

Re: Unknown history, manifolds and risers?

Thanks Don

I appreciate your help on this. I will check both the manifolds and the risers carefully and make a determination in early spring as to replace or not. The boat is tucked away in the indoor rack storage building so nothiing will happen for a while.

Cheers

 

[hnt]

Re: Unknown history, manifolds and risers?

Don,

I pulled the risers as you suggested and the mating surfaces on the manifolds and risers looked very good so I cleaned them up well and put it back together with new mercruiser gaskets.

I also replaced the thermostat and the impeller. Everything is working fine.

When should I do this again? Yearly?

Thanks for all your help!

 

[Bondo]

Re: Unknown history, manifolds and risers?

Don,

I pulled the risers as you suggested and the mating surfaces on the manifolds and risers looked very good so I cleaned them up well and put it back together with new mercruiser gaskets.

I also replaced the thermostat and the impeller. Everything is working fine.

When should I do this again? Yearly?

Thanks for all your help!

View attachment 141082View attachment 141083

Ayuh,... Is that pictures of the Cleaned surfaces,..?? They coulda been cleaned alittle cleaner....

The lower portion on the riser looks to be gettin' Thin...

 

[hnt]

Re: Unknown history, manifolds and risers?

Those pictures were before I cleaned them up.

The picture of the riser is a bit deceiving. The thickness of the mating surface is actually very uniform on all four sides