Best New 4-stroke engine (150 hp)

[Jason2tpa]

having gauges that will tell you if an overheat or low oil alarm is setting comes in handy.
you need to test the alarms and see if they set the alarm and indicate as they should when they come in
guessing is not the way to go

I believe the OP does have gauges...or at least I've taken that he does from his words in bold below:

I think overheat or low oil will give an alarm at the helm and, although the alarm checks out ok, there is no alarm when this occurs.

[99yam40]

I believe the OP does have gauges...or at least I've taken that he does from his words in bold below:

But has he tried setting the alarms to activate to see if they show up?

[Psalm 99]

I agree that the problem is most probably temperature related. Once the engine gets up to operating temperature (or over), the CDI steps in and places the engine in 'limp mode'. When I got the engine with 325 hrs on it, I installed new thermostats as a simple precaution. Once the carbs were clean and the fuel system re-done, engine ran well until this problem surfaced. Makes a lot of sense that the engine must be driven to get up to the temperature where the problem occurs. I have removed and tested per manual the three thermal sensors which connect to the CDI. Additionally, I removed and checked per manual the two thermostats. I visually inspected the passages around the stats for salt buildup and the passages I could see were pretty clean. Sure seems like the alarm system should sound when this occurs. I've simply checked that the buzzer at the helm works. Not sure how to 'set the alarms to activate to see if they show up'. Guessing I should hit each of the three temperature sensors in place with my heat gun. I can do this with a remote temperature sensor gun to record the temperature while I leave each sensor in place in the block. Do I need to be running the engine on muffs while I do this or simply turning the ignition switch on be sufficient. New day and not quite ready to give up. Sure appreciate all the help. This is something pretty small and maybe I'm going in the right direction.

[Jason2tpa]

The engine side thermosensor wire has 2 pig tails that plug into the sensors 2 pig tails. If you were to unplug the sensor from the engine side wire, then plug together the engine side thermosensor pig tails and start engine, the high temp alarm should immediately trigger. Check both sensors.

[99yam40]

short one or both temp switches with key on or with it running to see if gauges see it and sound the alarm.
drain the motor oil tank with key on to see if gauges see it and alarm shows.

if they do as they should, then you know it cannot be those when running if the gauges do not show anything

testing for good spark on all plugs and timing is in spec when the problem shows up should give indication of possible CDI problems or inputs to the CDI problems.
the problem has to be happening to find it

[99yam40]

The engine side thermosensor wire has 2 pig tails that plug into the sensors 2 pig tails. If you were to unplug the sensor from the engine side wire, then plug together the engine side thermosensor pig tails and start engine, the high temp alarm should immediately trigger. Check both sensors.

you are saying sensor when you should be saying switches
sensors use resistance , switches are open or closed

[Psalm 99]

With the ignition key on but the engine off, I shorted to two thermal sensors installed on either cylinder head and immediately got a buzz at the helm for each unit. Then I lifted the riser out of the on-board small oil tank and also got a buzz. However, there is a third small device which I also assumed to be a thermal sensor. Its threaded into the right cylinder block and connects directly to the CDI unit with two blk/yellow wires. I disconnected the wires at the CDI unit and shorted the fitting but got no response from the helm. Always assumed this was a thermal sensor but I could be wrong. I feel we're going in the right direction and will appreciate any comments

[TownsendsFJR1300]

I don't know what year your engine is but I assume it's used in SALT water (as you looked for corrosion).

It's not un-common for the head and cylinder cooling passages to clog up (usually badly when it goes into limp mode) with cooked on SALT..

You can flush every time after use, but normal usage, run out to spot, turn off a hot engine, salt cooks to the hot block(just a little).

Multiply that several runs a day, times everyday you go out, times the YEARS the engines been in salt water, it DOES ADD UP.

Last engine we "de-salted" was my neighbors 200 2 stroke Yammy, The lower cylinders were SO CLOGGED UP, I don't know how it ran that long.
(It would go into safe mode if run over 4300 RPMs. Cleaned, it revved to full throttle, no more shut downs).

You should have some anodes in the heads. Pulling at least lower one and inspect, may very well show you some serious clogging.

I'd probably yank at least one head as it's probably due for cleaning anyway.


Should you throw in the towel, my F150 will push my Angler 20'4" CC to 45 MPH...
Performance (except more weight) is very similar to my old V6 Evinrude but with THREE times the mileage (easily)..
It took some time to get used to not screwing with the choke. Just turn the key (like your car)..

[99yam40]

With the ignition key on but the engine off, I shorted to two thermal sensors installed on either cylinder head and immediately got a buzz at the helm for each unit. Then I lifted the riser out of the on-board small oil tank and also got a buzz. However, there is a third small device which I also assumed to be a thermal sensor. Its threaded into the right cylinder block and connects directly to the CDI unit with two blk/yellow wires. I disconnected the wires at the CDI unit and shorted the fitting but got no response from the helm. Always assumed this was a thermal sensor but I could be wrong. I feel we're going in the right direction and will appreciate any comments

You may have screwed up pulling the oil unit up and out.
there is a foam seal that has to be in there , and any sludge in there could have gotten in.
as I said drain the tank, not sure where you got the idea to pull the unit.

also did the gauges show something when the alarms sounded?

As I said before there are switches and they are different than sensors

If the gauges showed the oil and temp alarm, and they have not been showing up when the RPM drops then you can rule those out for what is happening.
check to make sure all plugs are sparking when the problem is there and see if timing is changed

[Psalm 99]

I pulled the oil riser per manual about 6 months ago to check the resistance at the marked points in the riser. Did it again on my own volition as it seemed simple. I checked for sludge in the oil tank last year and it was pretty clean (drained a cup from the bottom catchment).. It started to rain pretty heavy so I didn't check the gauge at the helm for a blinking lights, just got the buzzer. Will do a better job when the sun comes out. The third temperature sensor is for the engine jacket water and I'm not sure if the CDI unit will go into limp mode should this get too high.
Boat is a 20.5' CC Hydra Sport Lightning. 150 hp is plenty for this boat although the extra 60-70 lb in the stern will not be welcome. Already use trim tabs as the boat is heavy in the stern right now. Been holding on to some 'Salt Away' which I never got around to using. Will something like this be sufficient to clean the engine water passages? I've changed the lower water pump impeller twice and the tell-tail flows strongly. The wash down water at the docks around here are pretty heavy in minerals and the local mechanic has even said it better not to use the water to flush the engine. I'm on rainwater catchment here and periodically flush the engine with rainwater which is fairly acidic. This engine was produced in 2004 and installed in 2005.

[99yam40]

seems like you have proved that over heat and low oil level is not what is causing your problem.

Did the manual say anything about making sure the foam seal/filter gets back into position if pulling unit with the tank full of oil?

may want to drain the tank and make sure, and not do that again unless you drain the tank 1st

[TownsendsFJR1300]

Been holding on to some 'Salt Away' which I never got around to using. Will something like this be sufficient to clean the engine water passages? I've changed the lower water pump impeller twice and the tell-tail flows strongly. The wash down water at the docks around here are pretty heavy in minerals and the local mechanic has even said it better not to use the water to flush the engine. I'm on rainwater catchment here and periodically flush the engine with rainwater which is fairly acidic. This engine was produced in 2004 and installed in 2005.

Salt Away won't clear out those passages should they be clogged.

Many times, pulling the heads and removing HARDENED salt is the only way to remove it.

You can replace the WP assembly, have plenty of tell tale flow BUT that water is NOT FLOWING adequately around the cylinder jackets / head as their literally clogged shut.

The 200 HP engine we did was easily 90% clogged, (he would flush occasionally) and his engine was much older than yours.

Checking an anode and peeking into the HOT part of the engine (the cylinder near the head where ignition would be the hottest) should give you an idea of any debris inside before pulling heads (if actually needed).

BTW, some folks have had good results W/O pulling heads doing a Rydlem Flush (SP?). Do a search, there's several threads on it. (If the passage is fully clogged, Rydlem won't get thru)


*An interesting read: http://www.yamahaoutboardparts.com/f...ppet-valve-pcv

[Jason2tpa]

Salt Away won't clear out those passages should they be clogged.

Many times, pulling the heads and removing HARDENED salt is the only way to remove it.

You can replace the WP assembly, have plenty of tell tale flow BUT that water is NOT FLOWING adequately around the cylinder jackets / head as their literally clogged shut.
[/B]

Scott points out in bold above an all to common unknown fact by the average outboard motor operator. If water is exiting the T/T then the WP is functioning and the engine is being provided with cool water....wrong. Water exiting the T/T implies ONLY that the WP is functioning.

Scott also makes another key point that is commonly mistaken...Salt X or likewise product will unclog corroded water passages...wrong. These products are used for the prevention of salt build up. Once corrosion has impaired the cooling system from doing its job, the use of such products is moot.

[zenoahphobic]

Yes.
The pisser only shows the pump output. Which is really only useful in gauging the change in the water pumps efficiency, but corrosion and salt obstruction further up may very well improve the pressure on that stream! So a possible false indication possible.
It seems to me that it has less reliability than the conventional Buzzer and limp mode slowdown.
Although I may get critism for this, my current tell tale doesn't, and I am not too worried.
Why? because that tell tale has a greater restriction than the other passages and has a propensity to get blocked with fine sand and whatever. And my boat on a float in the water, makes it risky to reach out to the outer edge of the motor to stick a fine wire up it to clear it.

[Psalm 99]

Did a little study on Salt Away and the suggestion to remove the cylinder head(s) and visually inspect the water passages was right on. Also, the engine jacket water temperature sensor does not appear to sound the buzzer at the helm when shorted similar to the two cylinder head sensors. I'm assuming that the engine jacket water sensor is also capable of placing the engine in 'limp' mode. Removed the right (starboard) cylinder head and, unfortunately, there was very little build-up. All passages were at least 95% clear and the small amount of build-up was mostly removed with a wire brush. Also, I removed the engine jacket water senor and tested per manual. Tested right up to spec.

One thing was puzzling: Thought I'd run the Salt-Away thru the system as I had the stuff right there. Engine started right up on muffs but the helm's tach didn't record accurately at first (recorded 800 rpm when engine was going about 1800). This lasted for only about 10 seconds then everything worked went back to normal. About the only thing electrical item which I haven't looked at are the wiring harnesses. Could any wire which affects the tach also affect place the engine in 'limp' mode?