86' 85hp powerhead swap

[jason32038]

Threw an 88 powerhead on an 86..spark on all 3 cylinders. Havent checked compression yet but did a quick finger in the hole/rotate flywheel test and felt good compression on 3 Cylinders look fine and head gasket was barely used when I put it back on from last year. Doesnt seem to be getting enough fuel if any...or too much? Put stabalizer in the fuel last august but doubt it ever made it to the carbs. Maybe gummed up? Also fuel is squirting out while cranking on the middle carb from the vent. Can turning one of those carbs upside down cause the float pin to come out? Also can excessive fuel pressure from a closed tank vent on a hot day cause the float needle to be forced open and flood the engine without me knowing it? I've seen no smell or sign of flooding. Had it in a big tote of water and didn't notice any sight of fuel in the water. Plugs still had wd40 on them that I sprayed in the plug holes earlier..didnt smell fuel on them. The fuel pump that came on the used block was very clean so I used that at first. Still no start so I put the pump on from the old engine and changed the middle valve gasket,pump gasket and diaphram. Still nothing. Sounded like it wanted to start a handful of times but never fired up. Took the fuel outlet hose off of the pump and cranked and noticed a small trickle stream coming out. Timing was at 0TDC in neutral when trying to start. Did a good job on splicing ignition and wiring it up.

 

[john from md]

Re: 86' 85hp powerhead swap

Did you look at the reeds before putting that powerhead on? Excessive fuel blowing out of the carb is an indicator of a bad reed. It can also be from a bad diaphram but you said you changed it.

Even if you have a little fuel in the carbs, the engine should start. Did you make sure all the choke plates are closing? Are you using the cold start throttle position?

John

 

[jason32038]

Re: 86' 85hp powerhead swap

Did you look at the reeds before putting that powerhead on? Excessive fuel blowing out of the carb is an indicator of a bad reed. It can also be from a bad diaphram but you said you changed it.

Even if you have a little fuel in the carbs, the engine should start. Did you make sure all the choke plates are closing? Are you using the cold start throttle position?

John

No I didn't look at the reeds. The block was already assembled. Had old 84' carbs on it that were dirty behind the shutters when I put the clean carbs on. Maybe it is the reeds. I guess i'll have to pop the intake off and inspect maybe put the reeds in from the 86'. I did notice a light mist of fuel pushing out the front of the carbs and has a light squirt out of what looks to be a jet on the side of the carb. Choke plates work great and are closing. Negative on the cold start position. Tried it but would not move throttle I need to adjust it but I did bottom out the idle screw and pumped the throttle a bit before starting and still nothing. Almost started a few times. Everytime it did I could hear 2 cylinders firing and not 3 but 3 cyls are getting spark. Did a finger compression test again after trying to start and 3 has ZERO COMPRESSION. I was trying to avoid taking off the intake because some of those lower bolts are a pain but oh well. I did a visual inspection of the bore and pistons before I slapped the head on and they look good. There was slight scoring on one cylinder but nothing bad.

 

[john from md]

Re: 86' 85hp powerhead swap

If your linkage is not moving when you go to the cold start position, you may never get the engine started. These are cold blooded engines and really need that additional plate opening and timing boost for starting.

The jet on the side of the carb is the bowl vent. If you are getting fuel out of this, your float level is too high.

Your loss of compression can be a blown head gasket.

Removing the intake with the carbs attached is problematic. I always remove the carbs before removing the intake.

John

 

[jason32038]

Re: 86' 85hp powerhead swap

Ok I guess the first thing i'll do is pull the carb off and look at the float on the one carb and do an actual compression test with a tester and get the linkage fixed. Thanks John!

 

[john from md]

Re: 86' 85hp powerhead swap

No problem, get back to me if you run into any snags.

John

 

[jason32038]

Re: 86' 85hp powerhead swap

Ok I wont get a chance to work on it until sunday or sometime this week. I'm storing it at my parents house until I get it running again. I have a couple of more questions though...When I pulled the carbs last year they worked great with no leakage. Do you think that a float pin or something could have come loose in the carb if I layed it on its side or upside down? Also the hose that connects to the powerhead that operates the fuel pump diaphram is actually blowing air while cranking. Is that normal or is it supposed to be vacuum?

 

[john from md]

Re: 86' 85hp powerhead swap

You can't disloge anything in the carb if it is assembled correctly no matter which way you turn it.

The hose from the crankcase operates the pump diaphram in conjunction with another port inside the pump body. The action of the # 2 and #3 pistons going up and down is what makes the pressure and suction to move the diaphram from side to side. It is not a cause for alarm.

John

 

[jason32038]

Re: 86' 85hp powerhead swap

Alright I haven't had a chance to take the carbs off and check the floats and reeds. Only had about an hour and a half to look at it today. Trigger is sticky and wont travel back to idle which is causing the shifting mechanism and towershaft to collide preventing me from shifting back into neutral. Even after trying to force the trigger back using the linkage it wont go. Looks pretty tight and dry up there. Gonna have to pop the flywheel and see what's going on maybe lube it up. Original compression readings...cyl 1-130 cyl 2-90 cyl 3-30...readings after adding 2 stroke oil in the plug holes ...cyl 1-142 cyl 2-120 cyl 3-30...I also noticed that it was cranking differently on cyl 2 like it was struggling. Compression tests were done with carbs wide open and all plugs out. Non screw in compression tester which worked pretty well to my surprise. I didn't feel like grounding all the plugs wires so I just cranked with the ignition off. I used jumper cables and jumped from the solenoid to the starter. Hopefully that won't do any damage. Head gasket was fine when I put it on but ya never know. Maybe my overtightening damaged it. I'll check the reeds first...those '84 carbs that came with the powerhead were very dirty and grimy behind the shutters and if that fails ill check head gasket.

Thanks for the help!

 

[jerryjerry05]

Re: 86' 85hp powerhead swap

Used gaskets are never a good idea.Money might be tight but your only asking for trouble.Which it sounds like you have.
You need good tools to work on an outboard.A good screw-in comp tester is necessary.The other style will give readings but never consistent.
If the trigger won't move right the linkage is in't alligned right.
Low comp will cause the motor to turn over hard.Remove all the plugs and mave the throttle full forward.Then do comp test.
The tourqe should be 20 ft#s. J

 

[john from md]

Re: 86' 85hp powerhead swap

Jason,

Compression readings of 30 pounds only comes from one of two reasons. One is the head gasket not sealing and two is mechanical damage to the engine. It looks as if you are going to have to do some disassembly to determine what the problem is.

Using the jumper wires on the solinoid will keep from frying the CDI modules and only cause some arcing pits on the studs and nuts. Just make sure there is no raw gas in that area when you do it.

Regards,

John

 

[jason32038]

Re: 86' 85hp powerhead swap

Finally brought the boat home today. Haven't got a chance to look into the compression problem but i'm pretty sure i've discovered it has sour fuel. I cut the fuel line and caught some in a small container and then dumped a tiny bit into another container. The fuel did have a kind of weird smell to it. It has been sitting since the end of last august. Put stabil in it that my dad had but maybe it wasn't the right stabil. It did ignite but not aggressively. When I had it in the container and after I blew it out it smelt even funkier. Could explain why it only sputtered a couple of times but didnt start. Monday I plan on checking reeds,clean carbs and check float and seat on middle carb,draining the tank and cleaning it. Check headgasket and do annnother compressionn test. I have one question though...on my old powerhead I couldnt get the flywheel off at all. Is it easiest to use an impact gun on the puller and use a rubber mallet?

 

[jerryjerry05]

Re: 86' 85hp powerhead swap

A good 3 jaw puller.Loosen the nut but don't remove it.Install the puller and use the impact.Put a lot of pressure on it.Then a 3-4# hammer on the puller bolt.Keep you hands away.J

 

[jason32038]

Re: 86' 85hp powerhead swap

Where can I rent a 3 jaw puller anyone know?

 

[john from md]

Re: 86' 85hp powerhead swap

Buy one from sears, they aren't that expensive.

 

[jason32038]

Re: 86' 85hp powerhead swap

Took the head off and everything looked fine....took the water jacket cover off and..........severely scuffed piston on 3 and medium scuff on 2. 1 is fine. Also...top ring on 2 is stuck. Cyl 3 is screwed...both rings stuck which explains the 30psi. Looks like I paid for a powerhead that was more trouble than the old. Top 2cyls are great on the other powerhead..bottom is scuffed. Can I just have the bottom one bored and install a new piston or will it throw the engine off balance? One more thing to ask...when I move the pistons side to side in the bore is it supposed to have play and make a light clunk noise when I move it side to side or should I just bore em all. Hopefully I can get by with 30over.

 

[jason32038]

Re: 86' 85hp powerhead swap

Drained gas and removed tank yesterday. Fixed the middle carb...the tab on the float that pushes the pin back up was bent possibly from over squeezing the primer ball. Tank is tanning in the sun right now to remove all fuel and vapor from the tank.