Hard Impeller over heating

[Iprof]

Last spring I had an oil leak the o ring between the upper and lower 1/2 of my out drive needed to be replaced. This is no big deal and only takes about a 1/2 an hour. While the lower unit was off I had them change the impeller, I had owned the boat for one season but I was not sure when the impeller was last changed. They had one in stock and put that one in and the other they ordered and put it on a week later. About 2 weeks after I was in the water I started to have a problem with over heating at idle. If I increased the rpm's to 1000 it cooled down. We pulled the main line at the oil cooler and no chunks from an old impeller and the oil cooler is clear. I changed the thermostat same problem then the circulating pump same problem. I go through the summer like this no problem I just have to make sure I keep the rpms up. Today we pull the drive look at the water pump and the housing is fine, I was hoping for a cracked housing to solve this problem. When we pull the water pump the impeller is in one piece but is very hard, a lot harder than the new one that I have. The fellow that owns the marina is my best friend and my mechanic, he suspects that the impeller was old inventory and the veins set in the position they are in now. He thought it funny that an impeller would get that hard that fast but it is the only thing that could cause this problem. I should add that I boat in fresh water and the boat has always been in fresh water. Here are a few pictures to show you how the impeller is set.

a

Taken 5 minutes after removed.

Taken 1 1/2 hours after sitting in a hot sun. The impeller is to hard and even though it looks good, not worn at all it needs to be replaced. Knock another thing off my boat todo list now if I could just get that cupboard open.

Ken

 

[Sundancer]

Old inventory or did he put the OLD impellar back in? Seems like something isn't quite right. I hope the new impellar fixes your problems!

Which cupboard are you having trouble opening? Is it on of the rolling tambor doors?

 

[Summer Fun II]

Hey Ken, Post this on the other less popular site. :grin:
I'll bet MR Know It All Rick will tell you to change over to a VP drive. So you won't have that problem. :smt043 .

 

[Iprof]

Old inventory or did he put the OLD impellar back in? Seems like something isn't quite right. I hope the new impellar fixes your problems!

Which cupboard are you having trouble opening? Is it on of the rolling tambor doors?

No it was a new one last spring at this time but he could tell by the inventory number it was old. If we had 2 of them we would have know right away. The new one that we put in today was soft the other was hard very hard.
The cupboard is the one just before you go down into cabin, the long one. I do have to replace the two tambor doors in the aft cabin. I had a water leak in the rail mount last summer and the tambor doors got we. I had to destroy them to get in and dry the cabinet out on the starboard side. I fixed the leak the same day I found it. It's amazing when you go away for 6 weeks on the boat and only spend 3 days at a marina all the little things you find wrong on the boat. I will know the first day the boat hits the water on the overheating issue. I figure it has to be the impeller there is nothing left to change and when we turned it in the housing the blades on the impeller would not open when it went past the large opening for the water pickup.

Wayne we should leave that Verbose jerk behind to work on his 30 year old engines.

I should tell you that my slip fee per year is $0.00 and all my repairs cost me $0.00 so it is not like I am getting ripped off on my repairs. :grin: The benefit of having a best friend that owns a marina.

Ken

 

[bigcathunter]

It may not be the impeller, I had the same problem and it ended up being the springs that hold the check balls closed were weak in the t-stat housing. I took them out pulled on them out a little longer and that cured my problem. It was a fix I came acrossed after pulling my hair out after changing the impeller and t-stat. You may want to give it a try if the impeller isn't the issue.

 

[Iprof]

It may not be the impeller, I had the same problem and it ended up being the springs that hold the check balls closed were weak in the t-stat housing. I took them out pulled on them out a little longer and that cured my problem. It was a fix I came acrossed after pulling my hair out after changing the impeller and t-stat. You may want to give it a try if the impeller isn't the issue.

Thank you for reminding me of that. I did check the springs and the adjustment, even switched them to the other engine, same problem. Being old and lazy I did check the easy things first but I would bet that there are things that others might think of that might help someone else that comes across the same problem.
If anyone else has any suggestion I would like to hear them, I wanted to share this problem, bet I am not the first or the last to have this happen.

Ken

 

[Ka1oxd]

My last bot was an issue with some idiot put the thermostat in upside down. Had the impellar replaced, the exhaust manifolds, and internal water pump. Nobody check the thermostat. I do not use that mechanic any more, back to doing it myself.

 

[DaNinja]

My last bot was an issue with some idiot put the thermostat in upside down. Had the impellar replaced, the exhaust manifolds, and internal water pump. Nobody check the thermostat. I do not use that mechanic any more, back to doing it myself.

I've replaced my thermostats before. Upside down? How is that even possible?

And to the OP, that's a seriously messed up impeller.

And in reference to the quote above...can an impeller be installed backwards?

 

[Ka1oxd]

This was an older style where the thermostat was in an extended block that attached to where a normal thermostat would go on the engine. This standoff was just two big pieces of metal bored out and the thermostat could go in either way with a couple of house nipples on it. The thermostat was upside down when I pulled it off.

When I first got that boat, I did not have any overheating problems. I brought it to a new mechanic because my other one retired to pressure test the outdrive and replace the impellar. He charged me for the new impellar and never put it in. This new mechanic did lots of things that really upset a lot of boaters in the area. He is now out of business.