first outing w/ 1994 evinrude 25hp-?'s- update

[miketheknife]

Purchased a E25RER with an 11x9 prop about 2 weeks ago.
Cleaned carb.
new impeller.
new plugs.
sync and link.
compression 118# on both cylinders.
Ran motor in a barrel, started on second pull, smooth idle.
Took it to a local water reservoir for a test run. Had a 12-15 mph wind with a chop. Started and eased out of the n/w zone and ran at about 1800rpm till motor warmed. Boat planed at about 2250rpm and 15mph GPS. 2850 was 19.5mph. At about 3000rpm,the motor started cutting out and the shaft jumped out of the water. I cut the throttle back immediately and the motor idled a little rough for a few second and then smoothed out. I was in 60+ft of water and almost positive I didn't hit anything. Max GPS speed showed 21.9mph.
I tried again slowly. At 2940 rpm, felt some vibration, so I backed off the throttle. As long as I stayed at 20mph or less, everything was great.
This is only the second outboard I have owned. Could it be the wrong prop?
All input will be greatly appreciated,
Mike

 

[Pappy]

since you felt a vibration that apparently was not felt before please check the condition of the propeller, Check the prop for a slipped hub. and check the prop shaft for straightness.
If you are using this engine with a control box make sure you are adjusted properly and do not run again until it is adjusted properly. The shift adjustment is critical to clutch dog life. You may have experienced a clutch dog slipping due to this.

 

[DaleH]

Not sure what hull you ran it on, but I checked a motor of that year and HP on 2 basic Lund skiffs, using the Turning Point Propeller prop calculator ... for a load of 2 people, 6-gallons fuel and 50-pounds of extra gear and I got propellers higher in pitch.

 

[miketheknife]

Pappy, I marked the prop before I took I out and it didn't move. This a tiller motor and it was still in gear after the event. I will check the Prop shaft. I will also check the shift adjustment.
DaleH, the boat is a 1968 Rich Line Guides Choice 15'-8" 235# with 6gal gas, 2 tm batteries, 2 people and about 200# additional weight.
I have done a bit of reading on 25hp since I got this one and the prop seemed a bit lightly pitched.
Mike

 

[Pappy]

On the wires coming out of the pack to the coils is there a tan lead there as well?
If so you may be limiting to around the 2500RPM area. Sure it is pumping and cooling?
The fact that it slowed so quickly as to force the shaft out of the water concerns me followed by
your comment that it idled poorly at first then straightened out.
Do yourself a favor and check compression again for peace of mind.

A couple of months ago I had a brand new OEM impeller in my new to me 1957 Johnson 35hp and the first time out it spun the hub in the impeller and
toasted the powerhead to the point I have to rebuild it. I verified it was pumping before I hit the throttle and 300 yards later......poof.

 

[miketheknife]

Pappy, there was water coming out of the the tell tale on the lower engine cover before and after the event. Can the thermostat cause over heating? I will check for the tan wire on the power pack tomorrow. Also will recheck the compression.
I ordered a 10.5x11 prop today to replace the 11x9. Could not find that the 11x9 was recommended for the 25.
Thanks for your input.
Mike

 

[ADIBOO]

I think the thermostat allows water to enter the engine water jackets. So if the thermostat is stuck closed, the impeller will still be flowing water up the case, but none will actually flow through the engine.

 

[Pappy]

I think the thermostat allows water to enter the engine water jackets. So if the thermostat is stuck closed, the impeller will still be flowing water up the case, but none will actually flow through the engine.

And you would be incorrect on that statement.

 

[miketheknife]

Pappy, there was a tan wire from the power pack. It connected to a temperature switch in the cylinder head cover. The service manual says to disconnect the bullet connector and remove the switch. Unfortunately the switch will not clear the head cover and I broke the wire. Switch on my order list.
Here is a pic of this mornings barrel test.


The flow from the exhaust relief was warm and a good flow from the overboard hose. The motor was running at 1200rpm.
Compression check was good this time also.
Since I have to remove the cylinder head cover, I am going to replace the thermostat also.
What else can I do to verify water flow through the head or check for any blockage?
Thanks for your time,
Mike

 

[miketheknife]

Been doing more research. My power pack is a CDI 113-4767.According to the installation guide "will not accelerate beyond 2500RPM and shakes violently." Causes- high temp, bad temp switch, or bad power pack. Amen on the shakes violently part.
Mike

 

[DaleH]

I had a diode blow out on a V6 I had so the 'SLOW' was enabled, where the shaking is an intentional mis-timing ensbled by the powerpack so you WON'T want to run it fast.

 

[Pappy]

With the tan lead connected the engine limits to around 2500?
Verify that is it by shutting off the engine, temporarily disconnecting the tan lead, starting and seeing if the engine runs past 2500.
You will have to do a stop and re-start to verify.
That engine should run at it's warmest at and just above idle. The thermostat will bring the engine up to around 135f or so. If you do not have a digital pyrometer handy then you should be able to hold the palm of your hand on the top of the cylinder head for around 5 seconds give or take.
Beyond idle the thermostat begins to be by-passed and the engine will normally run around 100f or so....depending on water temp, etc.

 

[CMOS]

I think the thermostat allows water to enter the engine water jackets. So if the thermostat is stuck closed, the impeller will still be flowing water up the case, but none will actually flow through the engine.

And you would be incorrect on that statement.

Pappy - don't want to hijack the OP's thread but can you expand on your statement?


CMOS

 

[Pappy]

Sure!

Water flows from the water pump up the water tube to the adapter.
From there the water enters the exhaust cover, through passages in the exhaust cover to cool the exhaust and immediately activates the overboard indicator.
Water then enters the block from the exhaust cover, flows around the cylinders from bottom port up and over to bottom stbd side.
From the bottom stbd side of the block water enters the bottom of the cylinder head and flows up and around the cyl. head.
From the top of the cylinder head water enters the thermostat cavity where, at a low speed water temp is regulated by the thermostat.
Water then flows down the cylinder head cover from the thermostat cover and exits the powerhead.
Part of the hot water also recirculates from the cyl. head cover back through the exhaust cover to minimize thermal shock in that area before it travels back into the block and exits.

 

[miketheknife]

Installed a new thermostat and temperature switch. Took the boat for a run today and it was still limiting at about 2600RPM with and without the temperature switch lead attached.
Ordered a new power pack. Hope this solves the problem.
Will let yall know the outcome.
Mike

 

[miketheknife]

Finally got back to the lake today. Power pack fixed the problem. Motor ran great. 24.6mph at 5220 WOT.
Thanks for all the help.
Mike

 

[Pappy]

Good deal. If it makes you feel any better I just replaced a pack on a 24' Whaler with twin 200s this week as well for the same issue. As soon as the port engine hit 4500 or above it would go into SLOW with no audible warning. Switched temp switches with the other engine and the issue remained. Temp was just over 105f.