Crusader 454 Cooling

[Will Fish]

It's been quite sometime since I posted on here. I just picked up a new to me boat with twin Crusader 454 350hp motors. It has a closed FWC system and raw water only sees the Raw water pump, U-Coolers, Heat Exchanger, Risers and Elbows.

It seems my manifolds are running really hot, which are antifreeze cooled. Manifolds read up to 235 at the dock at a fast idle. The temp gauge reads between 160-175, which was confirmed at the thermostat housing via IR gun. I've changed the thermostat (160deg) and heat exchanger (was leaking coolant thru the exhaust. I also changed (2) collapsed/leaking hoses 1-from manifold to heat exchanger, and 1-from manifold to thermostat. I also burped out all the air from the system.

IR temp of the manifolds are now 195-210 at a fast idle at the dock. I have no idea if this is normal or not. I've never actually checked the temp of a manifold, especially on a closed cooling system.

My raw water system operates as it should. Strainers were cleaned, water pumps had major rebuild and new impellors installed, U-Coolers are new. Risers and elbows were replaced last year from previous owner. The IR temp on the elbows are <90 so they are staying nice and cool.

Is 190-210 normal at a fast idle for a closed cooled manifold? IR temps were taken all over the manifold, front, aft, side, bottom at ports and they were all around the same temp.

 

[alldodge]

190 and above is not normal even with closed cooling

Have you taken the end caps off the exchanger to see if there is any corrision?

 

[Will Fish]

Heat exchanger is brand new. I had 235+ before I changed the exchanger and burped out the air

 

[alldodge]

What does the thermostat housing measure?

 

[alldodge]

Would say, if thermostat housing reads close to 160, then you might be ok. If housing is also hot, then look at the circulating water pump on the front of the motor

 

[Will Fish]

Heat exchanger is brand new. I had 235+ before I changed the exchanger and burped out the air

Engine, thermostat housing, and dash gauge all coincide with 160-170.

 

[alldodge]

I think your good

Water pump is moving enough water to keep motor cool

 

[Will Fish]

anyone ever used barnacle buster on their freshwater side? I’m thinking since heat exchanger is new I can bypass the heat exchanger and circulate with a bilge pump and a 15gallon bucket

 

[alldodge]

Hey @Scott Danforth what say you
The issue with BB is its hard on the seals. Might start a leak in the circulating water pump

 

[Will Fish]

Fair enough. That was my concern these motors are original or at least assumed original with 1900/2000 on the hour meters. They run good with 135 compression on my port and 130 on starboard.
My plan is to get this season out of them and yank them and rebuild over the winter. At which point, everything will be replaced new.

 

[Scott Danforth]

2000 hours means there is 1500-2000 hours of life left.

At 350hp, BBCs should last about 6-7000 hours as that is not stressed.

Barnacle buster is just muriatic acid and water. Agreed, not that good on shafts or the seal springs. Oxalic acid would be milder

Is the HX factory OEM, or aftermarket? OEM would be Sen-dure or Champ depending on vintage. Being 350hp, if they are blue, most likely sendure

Have you rodded out the raw water side?

Is the oil/ps cooler plugged? That is usually where the restriction is as that is the first serious strainer in the system

IIRC, the PCM/Crusaders use Jabsco pumps, have you serviced the impeller? Sea strainers? Have you checked for

If you have AF in the manifolds, you have a full system. I believe factory t-stat was 170-172

Got a pic of the plumbing?

 

[alldodge]

This should be for front mounted HX

 

[Will Fish]

This should be for front mounted HX

 

[Will Fish]

HX is aft mounted and is new after market from https://lencoheatexchangers.com/

Factory thermostats are 160deg and I just replaced it.

U-cooler is also new from Lenco.

Thru hull and sea strainer clean and clear.
The water pump is a Sherwood E85. Just “major” rebuild kit including new impeller.

i did not rod out the raw water side, as the exhaust at the elbow is less than 90deg.

Hours are low for BBC but they are 32 years old. I know I can certainly get more out of these motors but the plan for now is to rebuild them next offseason

 

[alldodge]

Had a 50/50 chance on front to rear mount HX, oh well
With both motors doing the same, then I'm thinking its normal
The motor temp is correct, mans higher. The circulating water pump is the only thing that can make a difference in heat, and if it wasn't working right the motor would have an issue

Hey @tpenfield how's the temps on your mans?

 

[tpenfield]

Here are some temperatures of my engine up to operating temperature, running at idle.




The water coming out of the exhaust manifolds, heading to the H.E. is normally about 155-160˚ F. If that is helpful. I am getting about a 30˚ F rise in coolant temperature at idle within the exhaust manifolds. Also getting about the same (30˚F) rise in coolant temp running through the engine block. Overall a 60-70˚F temp rise of the coolant running through the system at idle.

It might be best to get an IR temp reader (gun) and map out the temperatures that you are seeing in your system. It could help isolate where the temperature is dramatically rising.

 

[Will Fish]

Wouldn’t operating temp be 160-170, which is what you should have off the thermostat housing?

I will write my numbers down next time I got down to the boat. I’m definitely much hotter than any of your numbers. I will say the block and thermostat housing maintain operating temps of 160/170

 

[Scott Danforth]

Measure water flow from the raw water pump

 

[Will Fish]

Raw Water flow is good. Everything on the raw water side is <85/90deg. And that’s really just at the elbow. Raw water pump U cooler we’re <70. Heats up a bit in the heat exchanger as it should, and riser and elbows are 80-90