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For those of you who have been battling overheating woes like I have, there is a timely article that appears in "The Boat Doctor" Q+A section on page 36 of the September 2008 issue of Boating Magazine. The owner is experiencing the same maddening problem that I and a few others have had where the engine temps are ok at idle but gradually rise from idle and get downright hot from about 3200rpms to WOT. I am seeing 225* and climbing @ WOT before I back out of the throttle. I replaced the 140* thermostat. The old one looked fine. The impeller was also fine but was replaced just to be sure and I am still having the same issues. My boat mechanic can't do anything because while running on the trailer out of the water, the overheating does not occur. In the article, Boating Magazine suggests that air is entering at the top of the drive's water pump and getting in the water line, which is causing the overheating problems. They say the the SEI outdrives come with a "single-lipped sealed" pump that should be replaced with a Mercruiser "double-lipped" version that will do a better job of keeping things sealed up and keeping air out. Just thought I would pass this on to anyone that is having the same overheating issues that I am having. I am going to give this a shot. Hopefully it will solve the problem, since I have tried everything else.
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After reading the article, it would appear that The Boat Doctor is referring to the seal on the top of the water pump. The OE part number should be 26-816575A 2
I am pretty sure if you purchase that part from Mercruiser, it will be the same as we are using. I bought some Water Pump Housing kits from a Mercruiser Dealer just recently and that seal looks the same as what we have always used.
Possibly Mercuiser had an earlier design in the 90's and that is what The Boat Doctor is referring to? I will try to contact them and find out.
Tech Support -
Thanks for looking into this...
Would you agree with "The Boat Doctor" though, that air is probably somehow getting into the water line and causing the overheating problem? I bought this boat used with the SEI drive on it already and had no problems with overheating for the first 20 or so hours of me owning it. I have no idea how old the SEI outdrive is or how many hours are even on it. I am guessing that it is 3+ years old since I have owned it for almost a year. Next time I have the outdrive halves separated, I will get the serial numbers and find out. Now the overheating problem happens every time I run the boat. Idle to about 2600 rpms the temp is ok. 2600-3200rpms, it slowly goes to about 190*. From 3200rpms on up temp keeps going up and at WOT it hits 225* before I back off. One I get back to around 2500 rpms, temp falls almost like a rock back down to normal. New Mercruiser 140* thermostat, new Mercruiser outdrive impeller. Boat is raw water cooled and only used in fresh water and is in excellent mechanical condition.
Boat goes back in the shop on Monday. My mechanic is going to check and see if air is somehow getting in to water line in the area of the outdrive impeller. Any other ideas so I can put this behind me??? If this doesn't work, I don't know what to do... It seems like there are only a few of us who are having this issue.Last edited by '93 2655 Ciera; 08-15-2008, 04:02 PM.Comment
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I am taking the boat to the mechanic at 12:00pm EST/9:00am PST, so please post specifically what you think I should have the mechanic check out to resolve this overheating problem. While he has the halves apart, I am going to have him write down the upper and lower serial numbers so I can see if I still have a warranty left. We still have a month or so left of boating season up here in Seattle, so I am hoping to get this issue resolved once and for all and enjoy some trouble-free boating.
Thanks!Comment
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The mechanic needs to check that the water pump wear plates and gaskets are sealed with perfect seal and that the slinger is in good shape and installed correctly. It does sound as though air is entering somewhere.
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Thanks... I will update everyone as to what was found.Originally posted by Tech Support View PostComment
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having same issue
I started out the season ok but noticed that the last few times out my temp was hotter than normal. runniing in my back yard with the water muffs on the leg I do not have the issue. Of course not running at full throttle but did not need to run at full throttle on the lake before it heated up.
I rigged up a system where I could cool the engine and run the leg water pump on 2 seperate water feeds, so I could see what type of water flow was coming from the leg pump. At an idle the water flow from the leg seemed low, beter than a trickel but not alot of volume. I reved the engine up to about 2000-2500rpm and the water flow picked up quite a bit. I had a bail bucket that I started to fill up. This was a 1lbs coffee can (common household type often used in boats) It took about 15-20 secconds to fill this can up. I was also able to easily stop the flow with my finger over the end of the hose. I did not notice any air bubble in the flow but not sure if I realy would expect to. Does anyone know what the flow should be coming out of these pumps? Should there be a certain amount of presure coming from them as well.
I was just coming to the site to look at ordering a pump kit for my leg when I noticed this thread. My intent is not to hijack it, I thought my problem might be the same.
I will be honest the engine was fired up and ran for about 30-60 seconds without water flowing through the leg (the water pump was probably dry as it sat over night and probably drained). From what I have read there is a huge potential for water pump failure if they are ever ran without water in them for even the shortest period of time. Will look for more info on this thread prior to ordering my water pump kitComment
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Running without water for 30 to 60 seconds will certainly ruin the impeller. I'm not sure of the water flow volume at 2000 RPM . I would replace the impeller, this should solve the problem.
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