7.4 increased operating temp

[995jim]

Hi, I have a 23' wellcraft with a 454 and was operating the boat at approx. 3800 rpm for a few minutes on a nice smooth stretch of lake erie and noticed the temp gauge up 5 + deg from where it normally reads (150) causing the secondary temp sender to emit a signal to the temp light so I backed off to 3300-3500 rpm and gauge dropped back to normal. The impeller was replaced approx. 2+ yrs ago with Im guessing at best 20 hrs of use on it. Im wondering how many items can be a factor to cause this increase in the temp. The engine is all original never touched and is 1990 vintage. The water pump on the block has never been replaced either. A new stat was just installed before use as well. Any input would be great .
thanks jim

 

[Scott Danforth]

check the impeller

 

[GA_Boater]

Maybe after 28 years some of the hoses are deteriorating.

 

[alldodge]

Im wondering how many items can be a factor to cause this increase in the temp.

Can be several, and include the ones previously mentioned, defective impeller, bravoits, corrosion, gauge going bad, temp gauge sender

 

[tpenfield]

A new thermostat may have slightly different characteristics. The oil coolers could need some backflushing. Impeller, as mentioned.

 

[Bondo]

The engine is all original never touched and is 1990 vintage

Ayuh,..... The raw water impeller is always the 1st place to look in any over-heat situation,.....

The odds of the circulatin' water pump bein' the cause is very, Very slim,.....

 

[995jim]

impellor checked out ok (replaced while apart) ,new temp sensor at time of symptom . Will a circulation pump fail like an automotive with a weep hole? I guess the oil cooler is the next check, the hoses don't seem to be choking at any point. How much oil will drain if I pull the oil cooler ? My stat housing has the bypass plastic check balls which appear in normal condition but can those affect any operating temp? thanks jim

 

[alldodge]

They do have weep holes, and there will not be much oil loss when pulled. You should be able to back flush and look at it without removing the lines

 

[995jim]

One other reoccurring issue is that after cruising and pulling the trittle back to an idle the gauge jumps up mabe 20 degrees then slowly returns to 150 as if something has to catch up.
Any other ideas? what are bravoits? as mentioned in a previous reply. I'm considering replacing the circ pump if someonr thinks this symptom may be from a circ pump,
thanks jim

 

[alldodge]

Bravoits is where the intake hose fitting starts to swell closed. It mostly happens in salt water but can have issue in fresh. To check fo it, the intake hose ftting is removed and see if you see some similar to this

 

[995jim]

is this at the lower unit I take ?

 

[tpenfield]

is this at the lower unit I take ?

transom assembly . . .