!987 Evinrude 175 HP E175TXCUA Running Issue

[KRH1326]

Hello All,
I have two identical motors. Motor A threw a rod, and was sidelined. Was using motor B, until a head gasket failed. Opened up motor B, to install new head gasket, and found cracked cylinder. Completely stripped blocks A and B down to case halves.

Rebuilt existing motor from case halves A, bearings and crank B. Best pistons and rods from both A and B, all with new rings.

Completely broke down and cleaned carbs.
Verified and tested all ignition components.
Complete powerhead gasket kit.

All assembled, following actual factory ( not seloc or clymers, etc.) manual.

A 30 yr. outboard mechanic acquaintance told me to increase the main jet size by one, for problems common to the cross-flow motors. I told him my budget was already blown, and he then advised me to run a #52 bit, by hand, through the jets, after consulting size charts and part numbers. This bit barely removed any material at all.

Runs in driveway with lower end in a tank/tub with muffs simultaniously. The tub part just catches the water and keeps the lower unit submerged, to help with exhaust sound.

Set up all of the linkages, as per manual, and it starts and runs ( very smokey from the assembly oil and the double oil/gas for break in) and I can slip it into gear briefly. All seems well.

At the dock, I can start it, with high idle, but it stalls out when the throttle lever is returned to nuetral ( single lever top mount binnacle) to engage forward or reverse, every time. Extremely frustrating ride home.

In driveway, with muffs, and lower submerged.... it runs fine... still smokey (see above) and shifts fine...

I checked timing again via #1 and #2 cylinders, and both are on the money. I then hooked the timing light up to each and every spark wire, to make sure that each coil was in fact firing.

Scratched my head, threw my tools across the yard, found and picked them up, grabbed a smoke and fresh cup of coffee, and sat down and thought...

A) Can the higher water level on the motor, at the dock actually in the water, actually make some sort of difference? I ask this because it seems to be the only difference between success in driveway and dockside failure.

B) How can I detect if each cylinder is actually getting fuel/air and really "firing"? Even though I know there is power to spark plug?

C) Can the one size jet increase be the cause?

D) What am I missing?

Any help and input would be GREATLY appreciated. ( Mechanic friend is several states away, or I would ask his help.)
Kenny

 

[Faztbullet]

First dont listen to that mechanic as its a no-no to drill jets as they have to be reamed to size. The drill bit can leave swirls in brass and change flow rate of jet!!! And yes the extra back pressure at lake will effect motor starting and idling, on a hose or tube the idle should be set at around 1100-12-- rpm as when in water it will lower to about 900-1000rpm Check if a cylinder is actually working remove front air cover and use spray bottle with premix in it and sparl into each barrel of carb, if one has no fuel or lean engine will pick up rpm, if its ok it will bogg and lose rpm..

 

[KRH1326]

Thank you Faztbullet. I do still have three more carbs that I can rob original jets out of, if I have to. Will try the spray technique, after work tomorrow.

 

[racerone]

What colour stripe is on the orange wire to each coil ?------Is the top one on each side blue and the bottom green ?

 

[KRH1326]

I would like to think that I have those leads right, but I could easily see that mistake. Will look in the light tomorrow, after work. Thanks Racerone.

 

[KRH1326]

I couldn't wait to go look. Hoping for something so easy, lol. Both are blue up top, green on bottoms...

 

[emdsapmgr]

Agree, don't drill the jets. The high speed jets on that model/year should be .061C mains. Stick with factory jet sizes unless you've done other mods the engine. Set the idle on the engine when on the boat and it's floating normally in the lake. Set it for 650-700 rpm's when in forward gear. You can't set it on the trailer. Each engine/boat combination is different due to the depth each boat floats in the water. (exhaust backpressure differences.) That idle timing can affect idling/shifting. A timing light is good to show spark, but does not indicate if that plug is contributing to running the engine. When the engine is running, pull the spark plug wire off #1 cyl. The engine rpm's should go down somewhat. Replace the plugwire and do each of the others. One at a time. They should all lower the rpm's when each wire is off. If one does not, (even tho it's sparking) that cyl may not be getting enough fuel. It's a similar technique that Fastbullet recommended in his post, #2. Now that you have your new engine running, you should baseline some things so that you can compare for future reference: 1. compression on each cylinder 2. Idle head temps as measured with a laser temp gun. 3. Max Timing degrees. This will be helpful during your years of ownership going forward. Does this engine still have the factory 35 amp alternator? You may get to the point that you need to check the cranking voltage output on the ignition side of the stator. If it's low, it can affect idle firing.

 

[KRH1326]

Thank you emdsapmgr, I will use these checks after work today, as well.

 

[KRH1326]

Ok. A fair night's sleep... And have a plan for after work. 1) Pull the air cover. While there, check each carb drain for fuel. 2) Pull and clean all plugs. Test each one, at it's coil, to ground, for spark. 3) Start up motor, spray each carb bore with pre-mix, for RPM changes. 4) With motor running, pull each plug wire for RPM change. 5) Set timing for 11-1200 RPM, but have gear on hand to check and reset at dock. Am I missing anything?

 

[KRH1326]

Ok guys.... An update. Pulled air cover. Had nice gas in each carb bowl. All plugs fired, at every coil position. Ran motor and sprayed each carb bore. None resulted in higher RPM. They either seemed the same or bogged. Pulled off each plug wire, one at a time. Each resulted in loss of RPM. Now what I failed to mention earlier ( my mistake and apologies) is that I have the timing set down low, approx 7-800 RPM on muffs. Just enough to keep from stalling. This motor IS a 25", and I have a med to low transome. The bolts that hold the lower unit, to the midsection are just about even with the bottom of my hull. This brings me back to my original questions if the back pressure is the only difference between success on muffs and failure in the water. Can the back pressure be so much greater that I am flat out stalling out at the dock? Reading Faztbullet's and Emdsapmgr's reply is setting of all kinds of flags and horns, lol.

 

[emdsapmgr]

Any chance that you have an extra-long engine (25" midsection height) sitting on a boat with a 20" height transom? When the boat is planning, the water streaming from under the transom should flow just under the large anti-ventilation plate just above the prop. If that plate is buried under water when at planning speeds, it will cause way too much drag: you should see tons of water spray, have poor acceleration and low top speed.

 

[KRH1326]

It is a 25". The boat is 21' 1968 Wellcraft CC with that wild bow flair. The transom had been rebuilt before I owned it. I'm not sure where to measure from. I use this boat in very rough, choppy water, that when tide and wind disagree, leaves heavy swells. It happens, but not often that my prop breaks surface. The lower unit bolts are about even with hull bottom, which, off the top of my head, puts that plate one or two inches below that. When either motor was running nice, 175 HP puts that heavy old boat in a nice plane, approx 30 GPS-MPH @ 3000 RPM. Does not seem to have excessive spray in wake. All I need for fishing. If it's not raining after work today, going to go set all timing and linkages, in the water.

 

[emdsapmgr]

You measure the height of the boat transom this way: From the top side of the lip of the boat splashwell (where the engine mounts) to the very bottom of the transom at the lowest part of the keel. Directly down from the splashwell. Likely the transom is either close to 20" or very close to 25". If your boat has a 20" transom, you need to consider an alternative mounting solution or convert the engine to a 20" lower unit.

 

[KRH1326]

Found something yesterday, in the daylight, that I did not notice before.... Took boat to the harbor, to set timing. I noticed copious amounts of oil coming from exhaust passages. Engine fired up, ran , still smoking heavily, but soon stalled, and could not get it running again. Pulled the plugs, and found them to be soaked with oil. I either misunderstood or didn't think of the breakin "double oil mix". There is still a few gallons of it in the tank. Will have to cut it with straight gas. I bet she stops smoking, and runs with some more "smack" lol