Water Temp Fluctuations

[bowtie]

OK, I have a nother newbie I/O question. I just recently purchased an 87 Ambassadore with a 5.7 and Alpha SS drive. The impeller was replaced
about 1 1/2- 2 years ago, but the owner passed away just over a year ago so it has seen minimal use. I have had this boat out a dozen times or so since I purchased it and it always runs around 160 deg when cruising or 180 deg when cruising aggressively, but then always drops back down rapidly after slowing down. Well this weekend I was pulling my daughter on a tube, we were taking it real easy since this was her first time behind this boat and on a new tube. I kept checking the temp and oil pressure and everything was good (temp running 160). Well once she decided she had had enough and I backed off the throttle the temp immediately started to soar and climbed up over 200 deg. As soon as I came to a stop I idled the motor up in neutral and the temp started to slowly come back down and I eventually shut the motor off as it reached back down to 200 deg. After loading up the tube and a short swim, I fired the boat up and it was still indicating about 200 deg but as soon as I started moving it came back down to the usual 160 deg. My question is, what could have happened or is that normal when pulling a tube. I pulled the tube several days earlier and did not notice this drastic temp rise, but I gues I could have just missed it.

[bowtie]

OK, I have a nother newbie I/O question. I just recently purchased an 87 Ambassadore with a 5.7 and Alpha SS drive. The impeller was replaced
about 1 1/2- 2 years ago, but the owner passed away just over a year ago so it has seen minimal use. I have had this boat out a dozen times or so since I purchased it and it always runs around 160 deg when cruising or 180 deg when cruising aggressively, but then always drops back down rapidly after slowing down. Well this weekend I was pulling my daughter on a tube, we were taking it real easy since this was her first time behind this boat and on a new tube. I kept checking the temp and oil pressure and everything was good (temp running 160). Well once she decided she had had enough and I backed off the throttle the temp immediately started to soar and climbed up over 200 deg. As soon as I came to a stop I idled the motor up in neutral and the temp started to slowly come back down and I eventually shut the motor off as it reached back down to 200 deg. After loading up the tube and a short swim, I fired the boat up and it was still indicating about 200 deg but as soon as I started moving it came back down to the usual 160 deg. My question is, what could have happened or is that normal when pulling a tube. I pulled the tube several days earlier and did not notice this drastic temp rise, but I gues I could have just missed it.

[JW]

Pulling a tube slowly you probably were barely on plane? The motor was working REAL hard and was OK as long as there was lots of water pressure. As soon as you slowed down and lost the water pressure, the motor lost it's cooling it needed after that hard pull. So the temp rise.
If it was mine, I'd probably pull the lower and replace the water pump impellor and inspect the pump housing. If the pump housing looks scored, I'd replace all that too.

[bowtie]

Thanks for the suggestion... I was planning on doing that this winter anyway. The guy that actually brokered the deal on the boat also owned the marine service co that did all the work on this boat for the last 8 years or so. He claims that the previous owner "maintained this boat with an open checkbook" and that anytime he suspected a problem he would go over board to get it fixed. For example, he had the lower unit serviced every year, and every year he had the impeller, and housing (whole assembly) replaced. The only reason it has been two years now since it was done was because he got real sick before he passed away last year.