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1961 Chris Craft Roamer overheats

D

dennis

Contributing Member
" Okay I have a stumper. The e

" Okay I have a stumper. The engines are 350cu.in. Chris Crafts with flywheel forward. Twin engine set up in a 1961 Chris Craft Roamer,problem is with engine running hot at 2800rpm and higher. Both engines are new blocks (1yr. old) and are freshwater cooled using Econo heat exchangers.
left engine runs great,temp. normal, right engine overheats and builds up pressure but not from steam. If the engine is ran on a cruise and then sits for 2-3 days it will blow air from the fill cap when removed. This is using the original cooling circuit common on these engines from this era,ie; positive flow pump mounted on the back of the generator (twin vane pump),no thermostat and no engine mounted water pump. There are no blockages in cooling system and impellers are good. Any ideas or original drawings on this engine cooling system ? "
 
"Dennis, can you clarify if ai

"Dennis, can you clarify if air escapes out the fill cap after the engine has been sitting cold for a couple days - without the engine running? Or that air blows out with the engine running? Also, are you sure air is running out (pressure) or running in (suction)? They can sound very similar when removing the cap.

If the system is being pressurized by other than heat, that would seem to point to gasket or manifold problems, permitting combustion pressure to enter the system. Suction in the system when the engine is cold seems normal.

"
 
" Croozertoo, air blows

" Croozertoo, air blows out after sitting for a few days,no suction. Also noticed that if I make up temp. pick up and return lines and place them in a bucket that the pressure does not build and engines heat is normal. I know that there will be no pressure build up this way as it is atmospheric pressure only. If you are familar with this set up the cooling circuit comes in the front of the heads and out the back. "
 
"I'm familiar with the fly

"I'm familiar with the flywheel forward CC's, but just going by general experience with FWC systems. Your comment that caught my eye was "cooling circuit comes in the front of the heads and out the back". Unless the FWC changes the routing (which would be hard to explain considering the block and head are fed from the low end and outlet through the holes in the heads) it sounds like the routing is reversed.

In both the block and exhaust manifolds, gravity dictates that the inlets are low and the outlets are high. Reversing the flow would cause hot spots in the system.

I have a schematic from my 1960 model 283 showing the manifold and block flow. Email me at [email protected] and I'll send it as a .jpg" attachment.

"
 
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