overheating crusader

[labrador]

Have a 40 aft cabin with 454 crusaders. Stb engine overheats when above2500 rpm. Have checked coolant, cleaned strainers, replaced impeller. No luck! Risers are 4 yrs old however before I change them could the problem in the tstat? What else am I missing?
Skip

 

[krush]

let's start with simple. Pull the hoses off the oil coolers etc and back flush them. Sometimes crap gets thru strainers and clogs them up.

 

[the kuz]

Are you pumping water out the exhaust the same as the port side?

 

[labrador]

Seem to be pumping the same at idle, can't tell when running

 

[Bob Bradley]

Belt good and tight?

 

[Maynard Rupp]

I have a pair of Crusaders in a 36C. I also have lots of experience with these engines. If yo, or anyone else ever had a failure of one of those miserable sea water pumps, this could be the culprit. Anytime you change an impeller becsause it has lost one or more lobes, you MUST find those rubber lobes. Usually they get trapped in an oil cooler, or under the thermostat. Be confident that you have none of those downstream of the pump. If that doesn't cure the problem, change the thermostat. If you have coolant hoses to the hot water heater, that will usually make that engine run a little cooler.

 

[67hat34c]

heat exchanger and oil cooler should be acid washed to remove scale that can cause poor heat transfer.

I am a big fan of going through whole cooling system and replacing parts and cleaning up other parts. And as always there could be more than one problem concurrently. Start from the outside of the through hull and go through the whole system to where it discharges from the Risers.

By the way I acid washed ours last time by using Genesis system. took off exhaust hose and put it in bucket for the return and hooked up a bilge pump and plumbed it to the oil cooler then to heat exchanger then to each riser

 

[labrador]

Maynard, I have the old impeller and it is not missing any of the lobes. Actually looks good enough to keep on the boat as a spare. The risers on both engines were changed at the same time when I bought the boat as the stb engine was running hotter then. When changed problem went away. Can I get a thermostat from the auto parts store or do I have to go direct to crusader. Sorry about being so dumb but the only engines I worked on as a kid were Briggs and Stratton on my go cart.

 

[Maynard Rupp]

Maynard, I have the old impeller and it is not missing any of the lobes. Actually looks good enough to keep on the boat as a spare. The risers on both engines were changed at the same time when I bought the boat as the stb engine was running hotter then. When changed problem went away. Can I get a thermostat from the auto parts store or do I have to go direct to crusader. Sorry about being so dumb but the only engines I worked on as a kid were Briggs and Stratton on my go cart.

You can get the thermostat at any Marine store. I think West Marine has them. Because you are not the first owner, it is very possible that someone has lost an impeller. The thermostat is cheap and easy though, do that first.

 

[Boatsb]

NAPA and any respectable autoparts store can get you the thermostat at half the usual Worst Morons price. Why pay more for their inferior service?

 

[Beckytek]

Skip, Check the wire connection going to the heat sensor. My engine was showing the same overheat for a while also. The wire connection was loose and the guage reading was faulty. The sensor is right in front of the thermostat housing. It's easy to get to. Ron