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Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by Joint Custody, Nov 20, 2020.
Just wondering if this is normal both engines upper hoses are collapsed when boat not running.
Does the system not have a coolant reservoir/over flow tank? Possibly bad caps.
mine does collapse which I've read is common however not sure if I've seen it by that much.
Judging by the looks of that hose, I'd agree with Mitch, but both pressure caps at the same time having the vacuum valve stick is a little weird. Sometimes an old soft hose will slightly collapse when the engine cools if there is a little air in the system, like right after I am messing around with the cooling system, cap off, draining and filling etc, as the air works it's way out, no more problem, but that one is really sucked in. When the engine cools, the contracting volume of coolant in the engine draws coolant from the overflow bottle, if the valve is stuck or clogged, it can't and it causes the vacuum that collapses the hose. Tap on the pressure cap with a screw driver handle or ? and see if the hose comes back. I'd replace the caps and if the hoses are old and just don't feel like there is much support in the walls as it should have, new hoses too. That hose looks old
Is that not the reason some hoses come with a spring?
I haven’t seen anti collapse springs in years. Used to be the theory was that bottom rad hoses had springs in them to prevent collapse under high rpm situations when a partially clogged rad might restrict coolant flow and the water pump was trying to suck it out of the rad faster than it could be returned. So yes, that is the purpose of the spring, but different situation.
Recently bought a OEM Merc water pump hose and it had the spring.
My port side collapses about half that much, starboard side is fine.
1 bad cap?
mine too. I know my cap has a worn gasket. I need a new cap. I’m going to replace the hose, too.
Very normal with the 6CTA due to the design of the overflow. The tank is so far away and below the coolant reservoir, and has such a small hose, that the pressure needed to pull coolant back up is pretty high. Unless it is brand new and very stiff, the larger hose collapsing is an easier pressure relief. My mechanic pointed that our and suggested moving the overflow otherwise it's largely ineffective.
My port engine does that. I put new radiator cap and new hose on, it still does that.
Anyone have a link for the radiator cap? Going to Amazon yields a gazillion and I’m not interested in process of elimination.
Also reach out to them with your issue when buying this. They'll get you sorted.
Best in the biz. Good luck
Mine do that also mechanic said it is common. Cap had no effect 9n mine.
Thanks all. I will look into the caps. Good to see it is a common issue.
If it was common I would have the problem...I am never special
The correct cap, besides the right pressure, has a small 1/2" or so sized washer like stem with an o-ring between it and the cap. It has a small spring that holds it tight. When the system is pressurized that is held in place by the pressure, but when the engine cools down it allows coolant to return to the system from the overflow bottle by the vacuum created by the coolant shrinking in size when it's cooled.
If the hose gets soft, as mentioned above, it will collapse and not bring as much coolant back into the system. A collapsed hose is NOT normal, it may be a bad hose design and needs the spring to allow the coolant back into the system. Whether it came from the factory that way or not, I would find a spring to place in the hose.
"A collapsed hose in NOT normal"
My 6CTA's did that on my 460 the entire time that I had the boat. I replaced caps, hoses and it stayed the same. After a couple years I didn't give it any further thought, the boat ran great and never had an issues.