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Engine operating temp

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"I have twin 1996 Crusader 454

"I have twin 1996 Crusader 454, TBI, 350hp engines. At crusing speed, my temp gauges register about 165 degrees. Engines run fine, but I'm wondering if this is the correct temp. If I changed the thermostats to a higher temp, would I get better fuel efficiency?"
 
"Don't go any higher with

"Don't go any higher with raw water cooling! If you have FWC, you can go to about 190 F, possibly a bit more.

A laser-pointed temperature gun (40 bucks at Harbor Freight) would tell you if the gages are accurate (and a bunch of other good info. I never leave the skip without mine.)

Jeff"
 
1988 454 crusaders with sea wa

1988 454 crusaders with sea water cooling and closed (anti freeze)system. Both engines running about 160 degrees idle but about 190 - 200 when cruising. Looked at thermo but previous owner must have removed it. Mechanic is going to look at them and check real temps with scope but says that the engine shouldn't oprate at more than 170. impellers are good. Any thoughts?
 
"Too hot. That "no t-stat

"Too hot. That "no t-stat" business would bother me. I suspect there's crud in the heat exchangers, or strainers, that's causing this. Be really careful you don't blow a motor.

Jeff"
 
strainers and hoses are clear.

strainers and hoses are clear. Boat hasn't really been cruising in last two years. Does heat exchanger "crud" build up more sitting still? I have heard that you need to take them to a radiator place and soak them in some kind of acid but another told me to "blow them out". what is a good temp while cruising and what size thermo would you use?
 
Most exchangers have removable

Most exchangers have removable ends so you can clean the bundle out.

Jeff
PS: Be sure to replace the'zinc' rod at the same time.
 
"I have twin 1988 454's an

"I have twin 1988 454's and the port eng. run @ 190 to 200 at cruis rpms but cools to 165-170 at idle. The sbd eng. runs at 170 at cruise. Both raw water pomps & impellers have been replaced & hoses and strainers in good contition.The systems are closed cooling on the engines & raw water on the exhaust. The port heat exchanger was boiled out 5 or 6 years ago (previous owner says it always ran about 180 after that). This change to higher temp. has only happened in the last month, but remained after changing the raw water pumps. Any ideas?"
 
"I had a problem with my engin

"I had a problem with my engine running too hot. I had the heat exchanger serviced at a radiator shop, cleaned the strainers, replaced the impeller and still had problems. Turns out the oil coolers also needed to be serviced at the rad shop. They were 90% blocked. Unfortunately, you can't get into these guys to clean them. The rad shop has to remove the ends to clean them. Check your zincs every couple of months. I was surprised how fast they go sometimes and not others."
 
"Make sure on raw water cooled

"Make sure on raw water cooled motors, you check your manual. Crusader directs stats to be 140-142 deg. Very important in salt water, less of a prob in fresh."
 
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