Chrysler 318 Ran too Hot removed distribution tubes--runs too cool

Facts:

Motor was running hot. Rebuilt engine 2015. Sherwood dual pocket pump. (pump diagram shows tubes in manifold). Water input is upper front of manifold. Original manifolds had tubes. This week replaced manifolds with Barr CM1-6672-A manifolds. Diagram for Barr states with upper front water input do not use tubes. Osco "tech tips" states water should input at bottom manifold at lowest point to fill and eliminate air and exit using Water Distribution tubes.

Issue: First left tubes in. With tubes ran very hot. Over 200 degrees. Removed Water Distribution tubes (per Barr instructions)and now am running barely above 100 degrees. Note: Impellers good. Thermostat good. Any thoughts? Thanks

where are you getting your temperature measurements from?

Block core temp is under 100? or manifolds are under 100?

use infrared temp probe and map hot or cool spots?

The 100 degree temp was from the sending unit which is Located in the intake manifold just ahead of thermostat housing. Thanks for reply.

I have the same issue but I have Osco Manifolds. Did the conversion too by installing the copper tubes. Chrysler S/B states you should install the the tubes into the upper back hole of the exhaust manifold and plumb the cooling water so it enters the manifold at the aft lower end. I too removed my water input from the front and my LM318 runs really hot. I hope someone out there can help with this. Curious to know why this is happening. Usually Service Bulletins are dead on.

My intake has always been upper and forward on manifold. Ran well for 20+ years. Not sure why original manifold with water distribution tubes worked well and the new Barr run hot with and cool without

Here's a link when this was discussed awhile back.....

http://www.marineengine.com/boat-fo...ution-tubes&highlight=chrysler+manifold+tubes

Jack