1998 90HP Evinrude Problems!

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
I do my own boring the old fashioned way.------But I saw a video of a machine that quickly locates the bore and does this work FAST.----But that shop may still charge $100 / hole to help pay for this machine.
What’s the old fashioned way? Lol
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Use a dial indicator to line up the spindle / boring head to be true to the bore.-----The machine I saw in operation uses a probe where you touch the bore in 3 random places and touch a button and BOOM the machine knows the center.----Takes but seconds instead of 10 minutes.
 

healey8390

Petty Officer 1st Class
Joined
Nov 19, 2010
Messages
215
Yeah that’s what I was originally thinking... but what about the cylinders, just get them bored and run oversized pistons? Any estimate of how much machine shops usually charge to bore out the cylinders?
$30-$60ish a hole depending where you are.

You probably won't need the main crank bearings unless you can tell they're smoked. They're pretty stout bearings..... I was stating them for price comparison....

How long are you planning on keeping it??

Who is to say the three "good" holes need boring? If you're not going to keep it long I'd just get one bored and three good hone jobs assuming tolerances aren't too far off on the three. I honed all four on mine. My damage wasn't as deep and ring end gap is a little over factory but it runs great and if it's lasts me a year or two then blows up I'm good with that. Some will scoff at this but my budget and the fact that I don't fish off-shore is what guides my decisions.

For kits powerhead express seems cool but I've never used them. Just google and shop. I'd stay away from auction sites those.
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
$30-$60ish a hole depending where you are.

You probably won't need the main crank bearings unless you can tell they're smoked. They're pretty stout bearings..... I was stating them for price comparison....

How long are you planning on keeping it??

Who is to say the three "good" holes need boring? If you're not going to keep it long I'd just get one bored and three good hone jobs assuming tolerances aren't too far off on the three. I honed all four on mine. My damage wasn't as deep and ring end gap is a little over factory but it runs great and if it's lasts me a year or two then blows up I'm good with that. Some will scoff at this but my budget and the fact that I don't fish off-shore is what guides my decisions.

For kits powerhead express seems cool but I've never used them. Just google and shop. I'd stay away from auction sites those.
Probably have the boat for the next 2-3 seasons
 

ct1762@gmail.com

Senior Chief Petty Officer
Joined
Jan 17, 2019
Messages
761
going back to your older post: Sunbirds, especially the early ones, were nearly throwaway boats OMC made to get their motors sold as a package. lots of pine wood used in them up until1996 or so. if your seat has rot around it, I can almost guarantee the whole floor needs to come out and re-do the stringers. Not cheap. I have a 1991 Sunbird Skier... extremely rare. But i had a soft spot in the floor just aft of the pilot seat. whole floor had to come out ! oddly enough the transom was as solid as new. I was shocked at the build quality to the point of laughing histerically at the foam they just sprayed all behind the helm to get it to pass coast guard regs. they sprayed wires in! the fittings and screws for the pitot tubes (it has 2 speedos being a tournament ski boat) had no sealer on them. i stopped laughing at that point.
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
Got the motor mostly apart this weekend, sure enough the top ring on the affected piston is gone. Where is the ring now? I know that some of the junk on the piston head is probably ring debris, but shouldn’t I have some bigger pieces somewhere?
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
Also,
Looking ahead, all other pistons and cylinders look good. The affected cylinder only has two vertical scores, one I can barely feel with my finger nail, the other is more noticeable.
my thought is, can I get away with honing out the cylinder a little bit and then just get a replacement piston (original size) and skip the boring?
The only other damage seen inside the cylinder is a small chip taken out of the edge of the exhaust port.
 

healey8390

Petty Officer 1st Class
Joined
Nov 19, 2010
Messages
215
Also,
Looking ahead, all other pistons and cylinders look good. The affected cylinder only has two vertical scores, one I can barely feel with my finger nail, the other is more noticeable.
my thought is, can I get away with honing out the cylinder a little bit and then just get a replacement piston (original size) and skip the boring?
The only other damage seen inside the cylinder is a small chip taken out of the edge of the exhaust port.
My guess is the ring material was expelled through the exhaust. I haven't heard of any rings breaking so small that they got into crank and rod bearings. Seasoned vets may have seen otherwise.

If they're scores you might not be able to get away with a hone. Going by your calculations on compression the bad hole is about 60. I'm not sure if a hone and new rings will get it to 100+, but with a top ring missing 100+ may be possible with just a ring and hone job.

My damage was piston material on the cylinder and very minimal scoring. It's the weakest cylinder compression wise at 100. The other three are 105,105 and 110. Like I said probably good enough to last a year or two. Maybe more but I'm not worried about that.

From the pics I don't see anything major on the wall but do you have closer pics?
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Looking ahead, all other pistons and cylinders look good.
You do not go by looks but by measurement's...mike the cylinder to see if worn past their limits or ports.
can I get away with honing out the cylinder a little bit and then just get a replacement piston (original size) and skip the boring?
Why??? If cylinder is worn (which 90% are) do you want to hone and make looser? Measure and repair correctly
 

Attachments

  • cylinder.gif
    cylinder.gif
    16.5 KB · Views: 1

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
+++++ on the above.-----Folks have little knowledge of how these parts fit and work I think.
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
Alright so I got the power head off the boat today and into the garage. I want to check my lower unit for any problems. Aside from checking the oil for metal, any other things to check?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Very easy to remove water pump.----Then the bearing housing below the water pump.----Inspection / condition of the thrust bearing tells a lot about lower unit condition.---At least in my opinion !
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
guys I have appreciated the help so far but need some more assistance! So when I found water in the lower unit I did a reseal and inspection. The afterwards everything was good with the lower unit, got the new power head in and slid the lower unit back in.
With no bolts on the lower unit tightened down fully I did a test of by spinning the flywheel to make sure the prop moved and the motor shifted fine. EVERYTHING WAS GOOD TILL HERE.
I went ahead and tightened the lower unit bolts down all the way, maybe 2-3 full turns and now the flywheel is very hard to turn and after some muscle there is about a release and the prop moves but it only moves about a 8th of a rotation and gets tight again. In nuetral it does the same thing... any ideas? I loosened the bolts up and it turned nicely again
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
Well.-----These powerheads all look the same but they are not.-----Contact the supplier of the rebuilt head.------They will know what is wrong and what to do.-----There were slight difference in fit-up of driveshaft and crankshaft spline.----This change occurred in the 93 / 94 models I think
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
Thanks. Will reach out to them asap.
In the mean times Do you think it is wise to pull the power head off and take measurements? I have the old power head here and I should be able to do a side by side on the crankshaft splines.
Do you think this is definitely the issue or is there anything during the install I could have missed? I followed the manual and basically just reversed removal procedures.
 
Last edited:

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
Got antsy and pulled it off, sure enough the internal splines on the crankshaft are completely different. There is a lip about 3/4 of an inch from the bottom of the female portion where the splines end and on the old crank the splines run almost all the way to the bottom and there is no lip.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
The spline is the same count and size.-------The length of spline and sealing arrangement is different.-----Your local expert shops can help you with a " work around "------It is not the end of the world.
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
The spline is the same count and size.-------The length of spline and sealing arrangement is different.-----Your local expert shops can help you with a " work around "------It is not the end of the world.
Yeah. Even counted the splines lol. Took a couple tries. I have called the manufacturer (OBR) and left a message so I’ll see what they say come Monday. Workaround, I assume, probably entails modifying the driveshaft?
 

Cooks

Seaman Apprentice
Joined
Nov 15, 2020
Messages
34
So to sum up the last couple weeks. turns out it was boxed wrong and they sent out a 88-91 powerhead. I was able to return the wrong one and get the right one shipped out.... after a few days of hassle, but that’s irrelevant here...
now I am back to putting it all together and it’s going smooth. My problem now is I am trying to run all my fuel lines and I am having trouble figuring out how to route them and where to connect them. I have the manual but i can’t find any diagrams. Anyone able to help with this?
 
Top