Intake manifold issues

[postmortem]

I have an aq225d, 1984 gm305 sbc, which had a leak in the port water jacket of the intake manifold. Water would bubble out of it when running. I replaced the gasket but after a few trips is started doing it again. Also, both sides of the middle water jackets get so hot that the paint disintegrates. Does anyone have any insight on this issue? I believe the surface is irregular and needs to be straightened. Any help is appreciated.

 

[jimmbo]

That's not a water passage, it is the exhaust riser crossover. The area between the two bolts is where a choke bimetal would mount. If it is getting that hot there, there is probably blockage in one of the exhaust pipes, like a back flow preventer is stuck closed forcing more or all the exhaust from one side of the engine thru this passage. Volvo used to have them(backflow valves) years ago. The heat of the more than usual amount of exhaust gases is probably warping the manifold and causing the water to leak at the real water passage and run along the top of the intake/head interface

 

[postmortem]

It's like that on both sides..does this mean both sides are bad? Should in dismantle my exhaust manifolds, is that where the valve would be?

 

[jimmbo]

The valve( #51) would be down stream of the exhaust manifolds. The heat riser is a passage on the bottom of the intake. Exhaust would be free to travel from one side of the engine to the other, enormous back pressure doing so. Its purpose to heat the bottom of the intake manifold beneath the carb.

 

[postmortem]

Another person said that marine intake manifold gaskets have the crossover blocked off and that using auto gaskets would do this, does that sound right?

 

[jimmbo]

Order a set of intake gaskets from Volvo, that would certainly answer that question. Being that marine engines run quite cool, I would think the heated intake was a necessity