1993 25hp 2 stroke cooling issue

[Jason2tpa]

Hello. My name is Jason and I am at wits end. I have a 1993 25 hp Yamaha 2 stroke. I recently purchased this engine on craigslist knowing it needed some TLC, though NOT knowing what is needed to safely operate. I am mechanically inclined, however, this problem has me clueness. Here's the low down:

After cranking entine I noticed no water coming out of tell tale. I dropped gearcase to inspect water pump. It looks good. New impeller. I even took the water pump (impeller, housing, gaskets, etc) to west marine and they said it looked good. Here are the steps I've taken to fix/diagnose:
*inspect water intake on gear case....good
*clean out tell tale....good
*clean out rubber tube connecting crank case to tell tale...good
*pumped water up through the water tube (mid section)...good
*pumped water down through thermastat out of tell tale and water tube...good
(By the way, intial inspection of thermstat revealed lots of corrosion. Previous owner said engine had sat in his yard for 4-6 months).
*flushed Salt-X down thermastat housing followed by a power flush with garden hose. This solution (blue color) was seen coming out of tell tale, water hose, and exhaust.
*lowered gearcase (again) to make sure impellar turned correctly with drive shaft...good

A mechanic i met thinks I need to remove crank case head (cover) to clean water veins that surround head. I agree this needs to be done since the thermastat is so corroded (i also replaced thermastat and gasket). I noticed that in order to remove crank case cover it looks like the apron to the lower cowling has to be removed to access the 2 bottom crank case bolts. Seems like a big job. Also, I've run engine for no more than 1 minute. I was taught at a young age that if the engine isn't pissing, shut down immediately. However, I recently read that it's necessary to run engine for 5 minutes in order to bring engine to operating temperature BEFORE going through process of opening powerhead. This is counterintuitive to me. Is this safe!!

Any suggestions are welcomed. Thank you in advance.

[TownsendsFJR1300]

Most importantly, are you getting any overheat alarms going off??

The tell tale very often gets clogged up with critters, debris, etc.

Poking some weed eater line thru the line and/or following the line making sure its clear would be the first thing I would do... Compressed air/ water would help open the line if its clogged.

Was the engine run in salt water and never flushed??? That would lead to clogged water passages and an overheat alarm... And no, you don't have to warm up the engine to remove the head bolts. It may help breaking them loose(if frozen).

Most engines, you can get a wrench to the head bolts W/O removing the apron.

Can you reach the lower head bolt(s) with a wrench/ socket, etc??

[Jason2tpa]

Thanks for the quick response. As I indicated in my post, I've cleared water passages from the entire cooling system (tell tell, water tube, etc) EXCEPT the powerhead.

No alarm because the temp sensor isn't connected yet. It wasn't when I bought the engine. But its on my list of things to do.

Yes it was run in salt water, but I have no idea if it was flushed regularly.

I didnt ask if it's necessary to warm up engine in order to remove head bolts. I asked if its ok to run engine for up to 5min, thus bringing up to operating temp, without water coming out of tell tale.

Yes I can reach the head bolts, but in order to remove the bolts the apron must be lowered. The bolts are like 3-4inches long and there isn't 3-4 inches of clearance between head and apron.

[99yam40]

before much else drop lower unit again and rig up water hose to hook up to water pipe headed up to power head, turn on water and see if it gets water flowing out the tell tail and exhaust like the water pump should.

Blow compressed air into tell tail while water is still flowing to try to move things around inside the block to see if that will open up some passages

Before trying to pull head and exhaust cover I would check this thread out, about using Rydlyme
http://www.yamahaoutboardparts.com/f...g-th19434.html

If this does not fix it I would think pulling the power head will be necessary to do a good job of taking apart. cleaning, and putting back together

[TownsendsFJR1300]

Thanks for the quick response. As I indicated in my post, I've cleared water passages from the entire cooling system (tell tell, water tube, etc) EXCEPT the powerhead.

No alarm because the temp sensor isn't connected yet. It wasn't when I bought the engine. But its on my list of things to do.

Yes it was run in salt water, but I have no idea if it was flushed regularly.

I didnt ask if it's necessary to warm up engine in order to remove head bolts. I asked if its ok to run engine for up to 5min, thus bringing up to operating temp, without water coming out of tell tale.

Yes I can reach the head bolts, but in order to remove the bolts the apron must be lowered. The bolts are like 3-4inches long and there isn't 3-4 inches of clearance between head and apron.

You don't need 3-4" of clearance for the bolts...

Just enough that once the head is loose from the block, (Bolts are probably 1" out, maybe?) you can pull the head (with the bolts sitting loose in the head)..

[Jason2tpa]

Thanks all for the responses. Ive pushed water up water tube in housing through tell tale and exhaust. Its flowing good. I havr not tried compressed air so I'll try that.
I definitely have to connect the temp sensor wiring to the CDI (it wasnt connected when i bought engine). Though the original connection was severed. However, the pink & black wires are coming out of temp sensor. And the pink black from CDI too. I just have to splice in a connection. Are familiar with the gauge wire I should use to splice?

[plumbob3261]

Thanks I will have a look at the week end it has got a 1.1/2ltr oil tank on the engine.

[99yam40]

Thanks all for the responses. Ive pushed water up water tube in housing through tell tale and exhaust. Its flowing good. I havr not tried compressed air so I'll try that.

If water flows through the system and out the TT and exhaust with the water hose connected,there is no need to try compressed air.
but no flow using the pump itself then the there is a problem with the pump not pumping properly.
Sucking air or exhaust, leaking water out before it hits motor block, or something else

[Jason2tpa]

Hey guys here's an update. I hooked up the temp sensor and used a continuity tester to make sure sensor was receiving/sending signal. All good. So i felt comfortable dropping boat in water to run the engine hoping it would piss, at the very least. No go. Temp alarm light up after running engine in idle for approximately 2 min. I did notice exhaust expelling from tell tale. Under normal circumstances with water coming out of TT, you wouldn't see the exhaust. Right? Or does seeing exhaust out of TT indicate a head gasket leak?

Either way, Ive confirmed water passage through gear case intake, water tube, and tell tale, up and down, including pumping water down thermastat and watching water come out of TT, water tube and intake. With these free and clear passages, even if the head passages were clogged, water should still be pumping out of TT with a properly functioning water pump. Especially becuase water will take the path of lest resistance, which would be out of TT. So that means one thing...its got to be the water pump or one of its components, even though Ive double checked its function. If it was working, id see water out of TT. So I'm gonna pick up a complete kit today to install.

Your thoughts on my last paragraph?

[TownsendsFJR1300]

As posts #4 #8 and your end in post #9 note, when putting up manually into the powerhead it flows.

Seems you have it narrowed down to the pump itself..

Agreed the WP should be inspected and changed yearly anyway.

That would be the second thing to check after checking for a clog in the pisser itself..

[Jason2tpa]

Agreed. Pisser is clear. After buying engine I inspected pump and components. Impeller looked brand new. Though the housing is beat up...heat warped and then some. Im hoping this is the reason its not pumping. Perhaps its not providing a secure fit to allow the impellar to suck water. We'll see. Keep yall updated. Thanks again for everyone's help.

[TownsendsFJR1300]

Agreed. Pisser is clear. After buying engine I inspected pump and components. Impeller looked brand new. Though the housing is beat up...heat warped and then some. Im hoping this is the reason its not pumping. Perhaps its not providing a secure fit to allow the impellar to suck water. We'll see. Keep yall updated. Thanks again for everyone's help.

This ^^^ HIGHLIGHTED, WILL CAUSE YOUR ISSUE BY ITSELF.

Wish you would have posted that earlier. Would have saved you a bunch of time..

[Jason2tpa]

You know what Townsends, you're right. I brought the complete pump kit, including housing, to my local west marine store to get their opinion. They thought the housing was a bit beat up, but should still work. I took their word for it and reinstalled. But again, I'm hoping this is the problem. If so, then at the very least I've become practically an expert with the cooling system on my engine lol.

[TownsendsFJR1300]

I've read of "good looking housings" causing pumping issues.

I think you have the entire KIT, don't replace just one item, replace ALL the o-rings, retainers, and that housing, ESPECIALLY since its been OVERHEATED.

It doesn't take much to ruin that pump housing. ANY dry start, even 15 SECONDS, will burn it up..

Have at it and post back when its pee'ing!

[LOWRIDER60]

Had a similar problem with my 40evinrude,I pulled the head and the area behind the t stat was caked with that pasty white corrosion crap. You might want to check your compression also to see if the overheating caused any problems .