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Crusader 454XL running HOT at cruising, not at idle. Help!

Hello
I have (2) crusaders 454XL generation VI, they are raw water cooled. The port engine is fine, but the starboard engine overheats at high RPMs. I have been chasing the cause of this overheating for about a month now and I am running out of ideas. I need help.
I have done the following:
1- replaced manifolds and risers.
2- Replaced U-cooler
3- replaced both raw water pump and engine circulating pump.
4- replace engine water pump hose.
5- replaced 1 1/4 intake water hose and cleaned and rebuild the Perko water stainer.

I removed the thermostat and the same thing happens, it overheats at a load. I replaced the thermostat back in the engine.

I noticed that I have a pressure relief valve inside the thermostat housing and I was wondering if anybody had any information on it. Should I remove it? Do I need it. It seems to restrict the water flow at low RPMs I don't know what other purpose it may have.

Other than that, I hate to think that I may have a bad head gasket or a cracked block. Other than the overheating the engine seems to be running smooth.
If anybody has any ideas, I would appreciate it.
 
I had that problem and it was an air leak before the raw water pump.

Jeff

PS: A compression test on the motor would be a good idea.
 
I hope you changed the exhaust ELBOWS when doing the manifolds and risers....did you get the proper gaskets installed correctly?

Leave the pressure relief assembly in the housing...it keeps the cooling system working at lower rpms.

I'd second Jeff's suggestion but would prefer a leakdown test instead...
 
Thanks for the input.
I replaced the hose before the raw water pump and all the gaskets on the intake strainer.
I ll double check anyways and post results
 
Thanks makomark
I did replace the elbows when I replaced the manifolds, I actually don't have risers, just elbows.
and put all new gaskets.
The elbows are the ones that get very hot, you can actually put your hand in the manifold at idle and they are cool, and I check the engine block at idle with an IR thermostat and its also cool. but the elbows get very very hot. Can't put your hand on them.
Then when you run the boat with a load at around 2500 RPM. everything gets hot and very fast.
I am going to do a leak down test this weekend. I am afraid I won't like the results.
I ll post what I find.
Thanks for your help.
 
OK
I did a leak down test on the engine and there is no leak in any of the cylinders.
I flushed the engine with a water and acid solution, and although a lot of crud came out, the same situation remains.
I noticed that the port side of the engine block overheats at the exhaust elbow, and the starboard side does not. Also the water flow through the left side is noticeably less than the right side. The manifold are new, elbows are new, so are both water pumps (raw and circulation) and the oil cooler. I have rebuild the intake strainer and put new gaskets and also replaced the raw water intake hose.
Can the left side of the engine water jacket be clogged up. Anyway I can know for sure? If it is, is there any way to unclog it without taking the heads off?
Also, Is it necessary to have a pressure relief valve in the thermostat housing. Thats the only part I haven't changed.
I am out of ideas and need help. Any suggestions out there?
 
As stated before, you want to keep the pressure relief valves in the outlet housing....but you also need to make sure they are working.

Typically, when the elbows get hot, it's due to them being clogged - since you changed them, they aren't likely to be an issue. so that only leaves raw water flow and at higher rpms as the title says "...not at idle". based on everything that's been done, it only leaves the thru-hull and the seacock. I'd suggest the best course of action would be to measure to raw water pump's output. if its adequate, install a clear hose between it and the oil cooler to see if its output is solid or aerated, the former being the preferred state.
 
Wire reinforced hoses, like your 1 1/4" stuff, have been know to delaminate on the inside. You mentioned you replaced the one that feeds the RW pump. There may be others in your system to inspect.
You replaced the RW pump with new? Wow, you have done a bunch of work on this issue. I'm about out of ideas. You could inspect the RW pump output with clear hose to checks for air bubbles. You could measure the RW pump output pressure to see if its restricted on the input side (low pressure) or restricted on the output side (resulting in high pressure).
 
..."Wire reinforced hoses, like your 1 1/4" stuff, have been know to delaminate on the inside."

Forgot about the possibility of a collapsing hose before the raw water pump. Had that happen with my old '59 Pontiac Bonneville--drove me nuts!

Jeff
 
After working on this problem on many different boats including my own, I found that there is a larger heat exchanger available that takes care of this problem. If you exhaust all avenues with no results, start looking for the bigger exchanger.

Also, remove the sea strainer, it's not needed and is a restriction. Make sure your seacock is a full port ball valve.
 
Thanks for the input,
The engine is raw water cooled so there is no heat exchanger. I replaced all the hoses including the water pump. I did noticed that a piece of the spring inside the hose is missing, I have the feeling it may have been sucked into the engine and is clogging the water jacket in the block.
At this point, thats the only thing I can think might be causing this.
The engine is hotter on one side than the other which suggest a clogged water jacket.
 
yes
its not gone completely but its missing about a 2 inch piece.
I replaced the hose with a new one already.

I am almost sure it could be one of 2 things. A clogged water jacket on the right side of the engine, or somehow the pressure relief valve in the thermostat housing is defective.
The elbow on the right side heats up at least 20 degrees more than the one on the left, and thats at idle. They are both new, with new gaskets and new manifolds.
Can anyone explain the proper function of the pressure relief valve?
 
Well...the gauge shows 160 degrees at idle, which is normal. but with an IR gauge the temperature at the right elbow reaches 200 degrees.
Actually the block does not overheat at idle, manifolds can be hand touched with no problem, and the left side elbow does not overheat either, you can put your hand on it with no problem, but the right side elbow is the one that gets super hot, you can't put your hand on it. This is at idle, once I take the boat out and the RPMs hit 2500 to 3000 the whole engine overheats to 200 plus, and it does it very quickly.

I took the new elbow off, inspected it, and re installed it with a new gasket, thats 2nd time after I have replaced the old ones with these new ones. It was fine.

I disconnected the hoses from the thermostat housing to the right and left manifolds and run the engine, I can notice a lot less water flowing to the right side than the left. The water that goes to the right side which is the one that heats up, has a very weak flow.
Thats why I was asking about the thermostat housing's pressure relief valve.

Also, I don't know if this makes a difference, but when I come back to the boat in the morning and disconnect the hoses from the right and left manifolds, the right manifold(one that gets hot) is empty, no water. The other one drains water out when you disconnect the hose.
 
the poppet valves restrict the water flow at low engine rpm....that ensures the water jacket is full and the liquid in it collects heat as its designed to....with the restricted flow to one side, it indicates the valve isn't opening on that side enough or is 'frozen' and not moving at all.
 
ok...I've never touched that setup....that said, there still needs to be a restriction on a raw water cooled engine....

the water that does make it thru the valve will take the path of least resistance.

Another item to check would be the exhaust hose on the hot side...they don't last long with low water flow...
 
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