Bought 1987 Evinrude 90 HP - questions

[bang4dabuck]

1) Is there anyway to tell if head gaskets need to be replaced ? Only asking because I heard someones horror story in a similar situation. Compression test (already checked - good) or cylinder leak down test find any problem ? Can I replace myself with a book, new gaskets and a torque wrench ?

2) Carbs - not winterized and been sitting for 2 years. Any chance running fresh gas with Merc Quickleen (somebody mentioned Valvtect also) and CMC Marine Stabilizer for Ethanol + spraying carbs out with carb cleaner, I CAN AVOID CARB REBUILDING ?

3) Where are all the zincs and anodes ? I think some clown painted over them. The 2 anodes on the lower unit and the skeg are painted.

4) Automatically change out THERMOSTATS ?

Lower unit oil was good/changed and will change water pump.
Stainless prop is a little stuck but will try.

 

[emdsapmgr]

Re: Bought 1987 Evinrude 90 HP - questions

Head gaskets need to be replaced when they fail. Failure is when there is no/low compression on one hole, or they leak water. If your compression is ok-leave them alone. If the carbs were sitting for two years with old gas in them, likely the fuel has long since dried up and the gel from the fuel is still in the carb bottoms-possibly clogging the jets. You run the risk of starving a cylinder for fuel/oil if any jets/passages are restricted with dried fuel. Your call. I'd pull them apart and clean them with a can of aerosol carb cleaner. The trim tab over the prop is an anode. There is a second (393023) anode just above that trim tab. Thermostats need to be changed if either side of the block overheats at idle. A laser temp gun is handy to check both heads. They should normally be around 145-155 degrees at idle. Replacing them is not expensive and the housing is readily accessible on these 90 hp models.

 

[bang4dabuck]

Re: Bought 1987 Evinrude 90 HP - questions

Thanks
Trim tab - I just read on Continuous Wave board it is a permanent part of engine and is aluminum but I will check. I am used to the trim tab being sacrificial. I see an anode (1, I thought it was 2)and an anode kit do you know what is in the kit ?

Okay I will face my demons and learn how to rebuild carbs.

I heard sometimes there is a water leak into cylinder but is not visible. Makes sense about the compression being a sure sign of a leak. I do have a leakdown tester but not sure if I know how to use it properly. Maybe they got a demo video on YOUTUBE or DIY.

Not sure I want to invest in laser temp gun. Maybe cheaper to replace but I will check with my shop at work, Advance Auto (loaner tool) and some friends of mine for the gun.

 

[tashasdaddy]

Re: Bought 1987 Evinrude 90 HP - questions

this little sensor is more than adequate, i keep one in my boat bag. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93983

Read this: http://forums.iboats.com/showthread.php?t=299680

 

[emdsapmgr]

Re: Bought 1987 Evinrude 90 HP - questions

You can also get water into the cyls from an exhaust cover leak...

 

[aclmvh]

Re: Bought 1987 Evinrude 90 HP - questions

FYI, I created my own cheat sheet from my shop manual:

All V configuration motors have one tstat for each cylinder bank. The purpose of the tstats are to prevent cooling water from reaching the powerhead until the powerhead has warmed to normal operating temps. This increases engine performance, reduces emissions, lugging and carbon buildup.

In most cases the thermostat should open by 125F (53C) and it MUST be fully open by about 136-144F (58-62C). Specs for closing temperatures are not provided by the manufacturer, but typically a tstat must close at a temperature close to but below the temperature for the opening specification.
A slight modulation (repeated opening and closing) of the tstat can occur at borderline temperatures to make sure the powerhead remains in the proper operating temperature range.

The cross flow motors are equipped with pressure relief valves in the tstat housing that allow additional water flow at higher engine speeds by providing an additional exit passage, allowing for increased pump flow and pressure at those higher speeds.

 

[krogie]

Re: Bought 1987 Evinrude 90 HP - questions

in reply to the carbs , dont let it woop ya. these 2 strokes have fairly simlpe carbs to rebuild. firsy buy a manual for this motor . the carb kits generally have a float , needle valve , gaskets , and a few other small parts. cleaning a carb justtakes a little time. there is a post on this site explaining how to go threw a carb. good luck!!

 

[bang4dabuck]

Re: Bought 1987 Evinrude 90 HP - questions

Thanks
Good old Harbor Freight. I might replace thermostats anyways. They don't cost much and this is a salt/brackish water motor. I confirmed with Fairwinds Marina that the trim tab was not an anode but originally the counter guy also thought it was. I think the only other anode is on the prop shaft. Anybody change those out ? I think my prop is stuck. I'll get my 8 lb. hammer and some PB Blaster and see what I can do.