Bent prop shaft and no water flow... related? (solved)

[fakirone]

So, the good news is the powerhead on my 1995 Mercury 25 hp 2 stroke is back together and running GREAT! Once all the exhaust and cylinder cover gaskets were replaced, along with carb, reed, and base gaskets, as well as new bolts all torqued to specs instead on half finger tight and half breaking off, the compression came up to 130 and 125 respectively (hand cranked, throttle closed). She fires right up and purrs like a kitten. Runs WAY better than it did before and that's without the new plugs I bought.
BUT, there is no water coming out the pee hole. I put the muffs on and ran it for maybe a minute, I doubt as long as two, but nothing. How long until the thermostat is supposed to open and I see flow? Am I missing something?

Right before the thing stopped working (still think that the actual failure was because of a couple melted electrical connections) I smacked a log pretty good and bent the hell out of my prop. When I was looking at it yesterday I notice that the prop shaft was bent a bit too, maybe an eighth off or so, could this somehow be related? I already have a new impeller that I was planning on putting in, but this seems like it's something else. I was told that the impeller was replaced last year. Could smacking the log have somehow cause the loss of water flow, which caused the overheating, etc, etc?

I would love a little guidance.

Also, how difficult is replacing the prop shaft, I was looking at the manual and it seems pretty technical. I have never been in a lower unit before, but I am pretty handy, can I do it myself?

 

[turbotodd]

The bent prop shaft probably isn't going to cause lack of cooling water flow. That said, when you've got the foot off for servicing of the pump/impeller, I'd have a good close look at the splines. Look for twisting, specifically. It's pretty tough to twist a splined shaft, but it does happen sometimes. Prop shafts included.

Last Merc 25 I was into, seems like it would pee a real weak stream at first but as the t-stat opened, it would be hot and heavy. Then once the powerhead cooled and the t-stat closed, back to cold and weak. Repeat over and over until I ran the thing across the lake full throttle for a while and then it stayed hot and heavy.

Perhaps the impeller is showing signs of failing?

I hate that system. No/very little pee water (tell tale) with a closed t-stat. Have to sit at the ramp until the thing heats enough to tell you that the pump works. Seems like there outta be a way to 'fix' it to work like most all other motors?

 

[fakirone]

turbotodd » 03 Jul 2014, 00:41[/url]"]The bent prop shaft probably isn't going to cause lack of cooling water flow. That said, when you've got the foot off for servicing of the pump/impeller, I'd have a good close look at the splines. Look for twisting, specifically. It's pretty tough to twist a splined shaft, but it does happen sometimes. Prop shafts included.

Last Merc 25 I was into, seems like it would pee a real weak stream at first but as the t-stat opened, it would be hot and heavy. Then once the powerhead cooled and the t-stat closed, back to cold and weak. Repeat over and over until I ran the thing across the lake full throttle for a while and then it stayed hot and heavy.

Perhaps the impeller is showing signs of failing?

I hate that system. No/very little pee water (tell tale) with a closed t-stat. Have to sit at the ramp until the thing heats enough to tell you that the pump works. Seems like there outta be a way to 'fix' it to work like most all other motors?

I was thinking the drive shaft, but it still seems intact, prop engages and all. I have never pulled the lower unit before, but I guess that's my next step then. Hope I don't F stuff up!

 

[fakirone]

Is there anything that I need to know or need besides the impeller?

 

[jethro]

I have the same exact motor and I believe there is no t-stat. It should be peeing water immediately.

The impeller kit is what you need along with a tube of Merc 2-4-C lubericant. It will come with the gaskets you need, the impeller and a new key for the impeller shaft as well as the driveshaft seal. Buy the genuine Merc impeller kit and it will come with the tool that you need to install the driveshaft seal.

 

[lovedr79]

its a pretty easy job to do. I destroyed my propshaft a few years ago on a rock. tip: check to see if tohatsu has that model of motor. it saved me a ton of money when I had to replace the bearings and gear in my lower unit. I got screwed by mercury on my propshaft for about $250, after the fact I found out that tohatsu makes the mercury outboards I discovered the propshaft was about half the cost of what merc wanted. the gears were about half the cost when I ordered them.

 

[fakirone]

jethro » 03 Jul 2014, 09:34[/url]"]I have the same exact motor and I believe there is no t-stat. It should be peeing water immediately.

The impeller kit is what you need along with a tube of Merc 2-4-C lubericant. It will come with the gaskets you need, the impeller and a new key for the impeller shaft as well as the driveshaft seal. Buy the genuine Merc impeller kit and it will come with the tool that you need to install the driveshaft seal.

It definitely have a thermostat, I replaced it when I replace the cylinder cover gaskets.

 

[fakirone]

lovedr79 » 03 Jul 2014, 09:47[/url]"]its a pretty easy job to do. I destroyed my propshaft a few years ago on a rock. tip: check to see if tohatsu has that model of motor. it saved me a ton of money when I had to replace the bearings and gear in my lower unit. I got screwed by mercury on my propshaft for about $250, after the fact I found out that tohatsu makes the mercury outboards I discovered the propshaft was about half the cost of what merc wanted. the gears were about half the cost when I ordered them.

How would I check to see if there's a Tohatsu version?

 

[stevesecotec02]

Your 1995 2 stroke is not a tohatsu. Tohatsu only makes the 4 strokes 30hp and under for merc. Your merc is the same motor as my 1994 mariner 25hp and the impellar change is easy. Hardest part for me is getting the dang shift linkage hooked back up .

 

[lovedr79]

Sorry about that. Shift linkage can be a bear.

 

[fakirone]

Well, here you go with another example of DON'T TAKE THEIR WORD FOR IT! The previous owner told me that he had replaced the impeller not too long before I bought the boat/motor, I was planning on replacing the impeller myself anyways, but wasn't able to get to it before Father's Day. The family wanted on the river so we went. I had run the boat once previously and it was peeing fine so I didn't expect any issues.
Anyways, obviously the PO misrepresented the truth about the impeller change, because I certainly found the reason that I had no flow.

The impeller is completely disintegrated.

So, good news, the power head is running tops and I have found the problem with the water flow. Now I just need to pull the prop shaft and see if I can straighten it out. I honestly don't think it's bad enough to worry about, but considering all of the work I have done at the point I figure I might as well reseal the gear case and sort that last little issue out.

I do have one other question though, I noticed a little bit of corrosion around the drive shaft seal because the water pump face plate gasket was shot. Do you guys think that this is anything serious to worry about, or am I good to replace the seals and get this thing back together and on the water?

 

[JMichael]

A couple of years ago I acquired an 8 horse Merc with a bent prop shaft. It also had water in the oil when I drained the lower unit. According to my dial indicator, the shaft was 8° out from straight. The manual says that 6° is the limit before replacing. After pricing new and used replacement shafts, I knew it was more than I was willing to invest in the little motor. I decided to try and straighten it myself. I was able to straighten it out enough to get it back to within 1° of straight. I reinstalled the shaft and figured I'd replace the seals if my repair job worked OK. As it turned out, the bent shaft must have been distorting the seal enough that it was causing it to leak, because it never leaked again and the motor ran great after the repair. I know the motor and shaft you are dealing with are larger, but if you have the equipment, I'd say there's a good chance you can straighten it and get it back to within tolerance limits.

 

[fakirone]

JMichael » 07 Jul 2014, 12:25[/url]"]A couple of years ago I acquired an 8 horse Merc with a bent prop shaft. It also had water in the oil when I drained the lower unit. According to my dial indicator, the shaft was 8° out from straight. The manual says that 6° is the limit before replacing. After pricing new and used replacement shafts, I knew it was more than I was willing to invest in the little motor. I decided to try and straighten it myself. I was able to straighten it out enough to get it back to within 1° of straight. I reinstalled the shaft and figured I'd replace the seals if my repair job worked OK. As it turned out, the bent shaft must have been distorting the seal enough that it was causing it to leak, because it never leaked again and the motor ran great after the repair. I know the motor and shaft you are dealing with are larger, but if you have the equipment, I'd say there's a good chance you can straighten it and get it back to within tolerance limits.

I ran the dial on mine this weekend and I am .051 off, the tolerance according to the manual is .006. So, considering that the shaft is slightly twisted as well, I ordered a new one today, $309, ouch.
Since my impeller disintegrated, over heating my engine, which caused me to break off 6 bolts replacing the exhaust and cylinder cover gaskets, as well as both side reed, carb and powerhead base gaskets, I am now about $600 into this motor. That being said I have 130-125 compression, a new prop shaft, a complete gear case re-seal and impeller and the thing runs fantastic. I guess it could have been worse.

 

[JMichael]

I'm not sure where my brain was when I was typing that response, but for whatever reason I substituted degrees for thousandths, so that should have read .008, .006, and .001. If you're an optimist, you have to look at it and say that you couldn't have replaced that motor for what it cost to repair, so it was a good investment.

 

[fakirone]

JMichael » 08 Jul 2014, 11:06[/url]"]I'm not sure where my brain was when I was typing that response, but for whatever reason I substituted degrees for thousandths, so that should have read .008, .006, and .001. If you're an optimist, you have to look at it and say that you couldn't have replaced that motor for what it cost to repair, so it was a good investment.

I am being an optimist for sure.

 

[fakirone]

Alright, impeller replaced, new seals in the lower unit as well as a new prop shaft. Time to bolt her up, cross my fingers and hope she runs, pees and shifts!

 

[onthewater102]

lesson learned - with used outboards ALWAYS check the impeller before starting...

I horror story with the condition of mine, only in my case the previous owner was apparently drooling on himself stupid because he put an extra paper gasket between the impeller housing and plate (which was shredded and stuffed up the feed tube) didn't have the ring washer/gaskets in the proper locations (actually he only had 1 of the 2), didn't have any of the screw bushings for the impeller housing and had one fin of the impeller bent in the opposite direction of the others - though it was the only one oriented correctly for the rotation of the motor...

Somehow he managed to get the key lined up...and bolted it back together. Didn't manage to reconnect the tiller style shift linkage. I knew I was in for it when I didn't pay for the motor with the boat & trailer and the carburetor and other miscellaneous parts came in a child's sandcastle pale intermixed with parts to his chainsaw.

 

[fakirone]

Starts, pees and shifts! The motor sounds fricking fantastic.
[fingers=crossed] Water test tomorrow. [/fingers]

 

[fakirone]

Got the boat on the water and she ran fantastic, that is besides the 6 gallon tank that I switched to missing the fuel pick up tube and my having to tilt it on it's side to run.
Starts right up, idles great (WAY better), shifts significantly smoother and pees like a race horse. I got 31 miles an hour downstream and 28 up. I don't know what RPM as I do not have a tach, but I am pretty dang happy with the results.

 

[fakirone]

onthewater102 » 16 Jul 2014, 19:16[/url]"]lesson learned - with used outboards ALWAYS check the impeller before starting...

I horror story with the condition of mine, only in my case the previous owner was apparently drooling on himself stupid because he put an extra paper gasket between the impeller housing and plate (which was shredded and stuffed up the feed tube) didn't have the ring washer/gaskets in the proper locations (actually he only had 1 of the 2), didn't have any of the screw bushings for the impeller housing and had one fin of the impeller bent in the opposite direction of the others - though it was the only one oriented correctly for the rotation of the motor...

Somehow he managed to get the key lined up...and bolted it back together. Didn't manage to reconnect the tiller style shift linkage. I knew I was in for it when I didn't pay for the motor with the boat & trailer and the carburetor and other miscellaneous parts came in a child's sandcastle pale intermixed with parts to his chainsaw.

Wow, that is a mess. I was definitely much better off. Honestly, the issues I had are all my fault (besides the prop shaft, I think that was already bent). I knew better than to not change the impeller myself, but I was too excited and used it anyways. You live and you learn.