Overheating issue on crusader

[1rider]

I pulled the heat exchanger (wasn't fun getting it out) inspected and cleaned it. It really was in great shape and only found a little build up where the zincs are situated by the honeycomb.

Reinstalled everything with a new thermostat, filled up the system and still have an over heating problem. I did learn a couple things however...

1) I left the cap off the degas bottle to monitor the water level, which I added to twice until it stopped dropping. Ran until the overheat warning, about 212 degrees or so and shut it off. On this system the degas bottle is part of the circulation loop in the cooling system (suppose to help avoid air trapping) so because I had the cap off I was able to check the temp of the water...it was cold, not even warm!

2) the heat exchanger was completely cold as well as was the water coming out the exhaust.

3) once it reaches temp to activate the thermostat I noticed that the water started overflowing out of the degas bottle leading me to think that pathway is blocked?

So right now I think my problem is one of a couple things; either I have some debris creating blockage, or something is wrong with the fresh water pump. ( although it is belt driven)

I would like to try removing all the hoses I haven't already and trying to use water pressure from a hose to clear or ensure there is nothing blocked. Is this a bad idea?

Any other thoughts on my next direction?

Here is a waterflow diagram-

And the engine-

 

[El Mar]

Does it over heat at idle or just when running on plane??

Any chance the thermostat is installed backward or the wrong one??

 

[1rider]

Does it over heat at idle or just when running on plane??

Any chance the thermostat is installed backward or the wrong one??

It is on the hard (dying to get it splashed!). I have only run it at idle. Thermostat is new and installed correctly.

 

[artodea]

Get yourself an infrared thermometer and follow where the coolant should be flowing while idling - you should see where it's blocked where there is a thermal gradient.

Home depot has one for 30 bucks

Good luck

 

[djmarchand]

It sounds like an air bubble in the coolant side. By only running at idle you are not creating enough hydrodynamic pressure to force it out.

Start it up from cold and run it at about 2,500 rpm until the thermostat opens then run if for a few more minutes. Keep the cap off and replace coolant as the level drops.

David

 

[Sailorgp]

might even try running the engine with the thermostat removed. just to see if it still overheats

 

[captainlarry84]

The motor looks nice & fresh so I am ruling out risers and a blockage. It sounds to me that you maybe air bound and the fresh water is not moving. You need to make sure that all air is out of the fresh water system. Fine all the bleed cocks and open them along with the cap removed and motor running to purge all air out of the system. Antifreeze must be added slowly and carefully so no air is trapped. Remember you fresh water pump only circulates water and does not pump water so any air will stop the movement.

 

[1rider]

I hope to get this fixed tomorrow afternoon. I can't imagine trying to run it at 1800 rpm let alone 2500 rpm while on land. As it is at 670 rpm idle the raw water pump empties a 5 gallon bucket in a little over a minute. Can you really do this?

There really are no bleed offs according to the manual. The degas bottle is suppose to allow trapped air out of the system.

With the system full of water I tried running the engine with the return hose off of the water circulating pump to see if it was moving anything and nothing happened. However I suppose that could be because of air?

I should also explain that the engine ran perfectly when put away for the winter. This spring I drained the closed system cooling and filled it with new coolant as it was time and after that the overheating began.

 

[Dfrenzy]

Are you sure its not clogged at your tranny cooler. Take the intake hose off at the fresh waterpump and back flush it. Is your impeller good?

 

[captainlarry84]

I hope to get this fixed tomorrow afternoon. I can't imagine trying to run it at 1800 rpm let alone 2500 rpm while on land. As it is at 670 rpm idle the raw water pump empties a 5 gallon bucket in a little over a minute. Can you really do this?

There really are no bleed offs according to the manual. The degas bottle is suppose to allow trapped air out of the system.

With the system full of water I tried running the engine with the return hose off of the water circulating pump to see if it was moving anything and nothing happened. However I suppose that could be because of air?

I should also explain that the engine ran perfectly when put away for the winter. This spring I drained the closed system cooling and filled it with new coolant as it was time and after that the overheating began.

Go to where man last touched:

This spring I drained the closed system cooling and filled it with new coolant as it was time and after that the overheating began.

It sounds like you filled her to fast with coolant and trap the air for sure. You may have to drain her again & next refill the system very slowly making sure that the motor takes the full manufactures recommended amount.

 

[pugsley]

definitely sounds like air, drain it and start over, maybe when refilling, leave the thermostat out, so you can start the motor, and have full circulation immediately (of course put thermostat in after all air is out). another thing, when you start it on the 5 gallon bucket, run a garden hose into the bucket while you are running, it should almost keep up with the motor, allows a little more run time to circulate, and purge air.

 

[1rider]

Go to where man last touched:

This spring I drained the closed system cooling and filled it with new coolant as it was time and after that the overheating began.

It sounds like you filled her to fast with coolant and trap the air for sure. You may have to drain her again & next refill the system very slowly making sure that the motor takes the full manufactures recommended amount.

I agree. I am not sure how to fill the system "slowly" because I get to a point where gravity no longer pulls the fluid down into the system and and the air that occupies the system prior to filling that I am trying to displace prevents the water circulator being effective.

 

[artodea]

I have used a vacuum fill system for one of my cars that is otherwise impossible to purge - it uses compressed air through a venturi to draw a vacuum on the cooling system. Once a vacuum is pulled you draw in the coolant. I use this:

UView 550000

 

[traditions]

I have had good luck getting air out of cooling systems by putting a drill pump on one of the heater hoses,or in your case one of the smaller hoses that goes to one of the manifolds.When hooking up hot tank coils on some boats its hard to get all the air out,and this has worked great,and you don't have any hot coolant going every where trying to crack a hose to let out air.Some times I use a bucket with some coolant in it ,or just get a small length of hose and put the pump in line and run it for a while.

 

[1rider]

AIR, AIR, and more AIR!!! I have some it out, enough to maintain temp at idle but based on the manual I've only got about 2/3 of the coolant mix the engine should hold in it now.

I have had good luck getting air out of cooling systems by putting a drill pump on one of the heater hoses,or in your case one of the smaller hoses that goes to one of the manifolds.When hooking up hot tank coils on some boats its hard to get all the air out,and this has worked great,and you don't have any hot coolant going every where trying to crack a hose to let out air.Some times I use a bucket with some coolant in it ,or just get a small length of hose and put the pump in line and run it for a while.

I may try this, I have not used a drill pump before but will likely pick one up tomorrow as it has proven to be a bear to get this air out.

 

[captainlarry84]

There you go..... always go back to where man has touched.....

 

[Pedlyr]

I usually fill cooling systems with a pump. I install a ball valve on the drain or lowest possible point. Take the cap off and open any petcocks. By pumping the coolant in from the bottom, it vents the air easier. As the air bleeds, coolant should start to come out any petcocks or open plugs.

 

[BillD]

AIR, AIR, and more AIR!!! I have some it out, enough to maintain temp at idle but based on the manual I've only got about 2/3 of the coolant mix the engine should hold in it now.



I may try this, I have not used a drill pump before but will likely pick one up tomorrow as it has proven to be a bear to get this air out.

IMO, don't mess with trying to top off adding coolant until you have the boat in the water.

Take her out with a crew member and "motor around" in gear say 1000-1200 rpm with the cap off and add anti-freeze slowly while the engine warms, thermostat opens and the engine purges air.

This is the best way to refill and purge air out of a motor.

Larry hit your problem on the head ! What did the owner/mechanic do last that changed something ?

 

[LittleGidding]

I have used a vacuum fill system for one of my cars that is otherwise impossible to purge - it uses compressed air through a venturi to draw a vacuum on the cooling system. Once a vacuum is pulled you draw in the coolant. I use this:

UView 550000

Very old thread, I know. But my understanding is that vacuum filling is the preferred way to get coolant back into all the possible chambers in which an air bubble could lock out coolant flow. Prevents hot spots in block or head. My question is, using vacuum, do you need to deal with the thermostat issue in a cold engine, or is that moot using this technique? I need to change out my fresh water coolant soon on Yanmar 315 6LYA

 

[artodea]

Very old thread, I know. But my understanding is that vacuum filling is the preferred way to get coolant back into all the possible chambers in which an air bubble could lock out coolant flow. Prevents hot spots in block or head. My question is, using vacuum, do you need to deal with the thermostat issue in a cold engine, or is that moot using this technique? I need to change out my fresh water coolant soon on Yanmar 315 6LYA

Vacuum filling can be done on a cold engine. The thermostat vent will permit full evacuation and coolant will flow to both sides when filled. It's a little unnerving to see the coolant hoses completely collapse under vacuum but it's all good when filled. Good luck!