1984 johnson 90hp carb leaking fuel out air cleaner

[racerone]

For me a leaking carburetor is a simple float valve repair.-----Compression in a cylinder or lack of compression has nothing to do with a carburetor leaking.-----On your first inspection you said ---" things look fine "-----I would take about 1/2 a second to determine that piston was JUNK.-----Sorry to be blunt here , but it is time to invest in a manual !

 

[ct1762@gmail.com]

there are a bunch if idle air bleeds on these carbs. and 2 idle main jets in the bowl. i'd need to have one infront of me, but the 2 tiny brass ones port and starboard are air for the idle circuit under the top horseshoe shaped cover, and 2 more inside the carb for fuel to exit

 

[Catchafish]

by "gash" in carb do you mean that little hole that's part of the idle circuit and has another one on the other side, or is there a crack somewhere?

If you look at post number 3, see gash in carb image here . This does not appear to be an idle circuit as I believe they are on the other side of the throttle valve.

 

[Catchafish]

I have been reading the service manual from johnson evinrude from boatinfo.no , a lot to get through but interesting for sure. Some more pics of the other piston and part of the cylinder. This is actually the port side that compression was at 120psi. The exhaust is.......wow....

 

[ct1762@gmail.com]

yeah might as well start looking for another block...

 

[racerone]

Not sure what the pictures are trying to show.-----Just take in all apart and post some pictures of the pistons !

 

[Catchafish]

Not sure what the pictures are trying to show.-----Just take in all apart and post some pictures of the pistons !

Just showing the exhaust visual state. Disregard
Finally got it apart, see attached pics.
Stuck bottom ring on the top starboard piston.
Top ring took chunk out of the bottom starboard piston.

 

[racerone]

Fact-----The basic engine design is very good if it was still able to start run in that condition !!-----I do not have enuff fingers and toes to count how many times I have seen this damage.-----That is why I suggest compression testing all the time.-----The top ring is a bad design.-----And folks destroy motors like this every day and find new ways to do so too.

 

[Catchafish]

Yes, it seems the manual stresses he importance of compression testing, then if any cylinder is not within 5psi, take it all apart..

What are my options please. Or are you saying this is no longer salvageable.

 

[racerone]

Easy rebuild for me.---Have any and all parts on hand new and used.-----Any markings on those pistons to suggest pistons are O/S now ?----Or is the bore 3.500" now ?

 

[Catchafish]

Easy rebuild for me.---Have any and all parts on hand new and used.-----Any markings on those pistons to suggest pistons are O/S now ?----Or is the bore 3.500" now ?

I am glad to here that. No need for a new block........had me worried, seemed costly at $3500 and every site was out of them except used on eBay.
The pistons markings on the inside are 49003-a , 328 355. They all measure right around 3.5. Does O/S mean original standard??

 

[racerone]

Good one------But no ---O/S ---Generally refers to OVER SIZE --------Your motor is still standard size so easy fix in my opinion.----Far cheaper option if you supply the labour .

 

[Catchafish]

Good one------But no ---O/S ---Generally refers to OVER SIZE --------Your motor is still standard size so easy fix in my opinion.----Far cheaper option if you supply the labour .

Great!! So do I need to bore the cylinders and go .030 OVERSIZE, or hone the cylinder just stick with replacing with new standard size piston and rings.
Thanks for your help!!!!!

 

[racerone]

Everyone works to different standards !----On a 36 year old crossflow you would be wise to rebore all cylinders for 0.020" O/S new pistons and rings.-----Put those cylinders back to factory new specifications on clearance.

 

[Catchafish]

Would you advise on NOT going 0.030 inches out, it seems piston and ring kits are easier to find for this rebore size. 0.020 inches is not as common, from what I am seeing.
Thank you

 

[ct1762@gmail.com]

i'm doing an 86' 110hp as i write this. The cylinders all need bored, as usual but the issue is the same 2 pistons... #1 and #3 both lost their top rings on factory 30 over pistons (obviously rebuilt before). which means if those grooves it made don't clean up with another .010", i'm screwed. but they do sell plenty of .040 and .030'' kits no problem. Just call Bill at Mastertech marine.

 

[racerone]

Lots of good used standard bore blocks available if you know where to look.

 

[Catchafish]

i'm doing an 86' 110hp as i write this. The cylinders all need bored, as usual but the issue is the same 2 pistons... #1 and #3 both lost their top rings on factory 30 over pistons (obviously rebuilt before). which means if those grooves it made don't clean up with another .010", i'm screwed. but they do sell plenty of .040 and .030'' kits no problem. Just call Bill at Mastertech marine.

Yep, I know. I can find .030" everywhere, but it was advised for me to only go .020" out. I found a complete powerhead rebuild kit on ebay that allows you to select .020" out.

 

[racerone]

Looked at a 1990 model 90 HP yesterday.-----Looked at the sparkplugs.---- Then popped off the cylinder head..----Found cylinders scored on #1 and 3.---Likely 2 and 4 as well.----Bone dry cylinders with no sign of oil.-----Winter work with 0.020" over WISECO pistons.----Nothing to it.

 

[Faztbullet]

Yep, I know. I can find .030" everywhere, but it was advised for me to only go .020" out. I found a complete powerhead rebuild kit on ebay that allows you to select .020" out.

The WSM kits you can go in .010 sizes..you can get .010 /.020/.030/.040 OS pistons. 020 is usually the norm as it will clean up most cylinders except deep grooved ones.