Posted by DD [209.253.157.5] on Tuesday, November 24, 2015 at 09:58:08 :
I am getting overheating in my new engine.
Here is whats happening:
Starts up from cold.. gradually warms up. Hits 180 degrees, then beyond a bit and stays there a few seconds to a minute....then (I think) the thermonstat opens.. temp drops to about 160? or there abouts.. stays there, then slowly climbs again. stops about 180 again.. for about 30 seconds, then slowly goes right up to a point where it boils over.. weird.
I have repeated this process three times now...in a row
Its like the engine reaches temp, the thermostat opens, then closes, then lets it overheat.
Now some background.
1. the engine is a fresh rebuild..its a 54 (or so) Plymouth 218...being a fresh rebuild, I KNOW its tight, and thats does add additional heat in the form of friction when they are this fresh.
2. I never did clean the radiator by a professional shop, as it seems pretty decent with NO sludge coming thru with a flush wit hthe garden hose... however that said, I decided to use an off the shelf radiator flush...just to be sure it was as clean as I thought......I decided to do this now... when the engine does overheat and boil over, a bit of rusty, dirty water is coming out..when it boils over... so, the flush is doing its job.. but the radiator does have SOME rust apparently.
3. I have a brand new water pump installed. Engine clean as its a fresh rebuild.. thermostate new...
4. I have no antifreeze/coolant in the water. just fresh water for now till I get the flush complete.
5. using a digital laser thermometer pointer, I get even reading across the block, bottom ,top.. well, nothing out of line indicating a blockage in the casting anywhere. in other words, all areas of the block are heating pretty unifomly.
NOW... for what I am t[i][u]hinking [/u][/i]might be the culprit. and this is where I need your thoughts:
the water pump bypass section of tube to the thermostat housing.. its missing.
ya see, the engines I have been working with have been car engines.. the thermostat housing I felt worked best had the water by pass tube welded/brazed up.. I didnt think much of it, until now. perhaps its a VITAL component in keeping the engine from overheating?
I didnt think so, and not ALL dodge engines have this in place? I have seen where the bypass tube section is omitted, and the hose run from this spot to a heater in the cab... and back to a plug in the rear of the head, near the firewall
Perhaps this helps in the water circulation? You need the bypass in place IF your not using a heater and the curculation it provides from the front of the block (water pump) to the rear of the plock (Head)?
Anyway, thats my next step: removing from one of my junk engines a different thermostat housing that has the bypass outlet (or is this inlet) in place.
and adding the water bypass tube over to the water pump... see if this works for me.
Its entirely possible this is the cause, I just am no expert here.
anyone have comment to the importance of this water bypass tube and the role it plays in proper cooling of an engine?
I assume its there for a good reason. :oops: :oops:
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