228 Mercruiser Manifold/Risor Questions

[jjoker023]

I have a 1978 raw water cooled 228 mercruiser 305 v8 overheating i have replaced thermostat, water pump, and impeller. I believe my problem is a plugged manifold or risor what is the best way to clean my manifolds? do i have to completly remove from block? Also the alternator bolts to the manifold via a bracket how do i remove that bracket I took the bolts out of the bottom but it won't release do I use brute strength or?? How can i pressure test before reinstalling? also where can i find a diagram of the cooling hose routing I want to make sure it is all back together correctly all hoses removed from tstat housing and risors ect. please help.. Thank you to everyone in advance
Ryan

 

[HT32BSX115]

Re: 228 Mercruiser Manifold/Risor Questions

I believe my problem is a plugged manifold or risor what is the best way to clean my manifolds? do i have to completly remove from block?

Howdy,

If your risers and manifolds are clogged (with rust) they must be replaced.

Cheers,

Rick

 

[jjoker023]

Re: 228 Mercruiser Manifold/Risor Questions

I got it pulled off and it looks like on the risor it has the water ports around the outside one of them is plugged the others open? is that enough to cause overheating? can i clean them?

 

[HT32BSX115]

Re: 228 Mercruiser Manifold/Risor Questions

water ports around the outside one of them is plugged the others open?

If they're plugged with rust, they must be replaced.....you can't safely clean them. (I would replace both.)

If the manifolds are similarly plugged, replace it all as a kit.

Is this a salt water boat?

 

[MFSMH]

Re: 228 Mercruiser Manifold/Risor Questions

If they're plugged with rust, they must be replaced.....you can't safely clean them. (I would replace both.)

If the manifolds are similarly plugged, replace it all as a kit.

Is this a salt water boat?

Yes you can safely clean the risers by fully submerging them in muratic acid overnight. Be carfull when doing this, you don't want this stuff in your eye! Its going to look like some crazy science project, bubbling and boiling, but by the next day there shouldn't be any sign of rust on the risers. Also try not to breathe this in either, not very healthy. You can get muratic acid at Home Depot or other home center. Rinse really good with water hose

 

[cooter2506]

Re: 228 Mercruiser Manifold/Risor Questions

Ceaning them in the acid will remove the rust but more than likely leave them pitted on the gasket surfaces. Replace the risers and manifolds. Just my opinion. Its better than replacing engine when the gasket surface isnt sealing and you are putting water where it shouldnt be.