1985 Black Max 150 Hp Leaks oil out of reservoir cap. I replaced the cap and still leaking.

psilver145

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I have a Black Max 150 that is leaking oil from the reservoir cap at the top of the engine. I saw a small crack in the lid so I replaced it. The new cap and float assm is still leaking and it appears to be coming from around the threads the cap screws onto. Can anyone give me some new ideas on what it could be?
Thanks in advance for your help.
Pat S.
 

dingbat

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I have a Black Max 150 that is leaking oil from the reservoir cap at the top of the engine. I saw a small crack in the lid so I replaced it. The new cap and float assm is still leaking and it appears to be coming from around the threads the cap screws onto. Can anyone give me some new ideas on what it could be?
Thanks in advance for your help.
Pat S.
The nylon deteriorates and threads deform over time. Had change my oil permeated oil tank that starting leaking through the walls

Having said that…are you missing a gasket by chance?

You’re lucky it just cracked. Mine cracked and blew off 12 miles offshore. Got home with a sandwich bag and a tie wrap
 

Chris1956

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Gee, I always carry a gallon of 2 cycle oil with me. If the oil injection fails, I dump the oil into the fuel tank and rock the boat a bit to mix it.
 

psilver145

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The nylon deteriorates and threads deform over time. Had change my oil permeated oil tank that starting leaking through the walls

Having said that…are you missing a gasket by chance?

You’re lucky it just cracked. Mine cracked and blew off 12 miles offshore. Got home with a sandwich bag and a tie wrap
Thank you. I am looking for a new tank. I did notice that after running it a few minutes and it started leaking at the cap, the reservoir was full to the top of the neck. is this normal or is there a check valve in line somewhere that might be clogged up, causing it to overfill?
 

dingbat

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Thank you. I am looking for a new tank. I did notice that after running it a few minutes and it started leaking at the cap, the reservoir was full to the top of the neck. is this normal or is there a check valve in line somewhere that might be clogged up, causing it to overfill?
It’s been a while, but I believe both tanks are pressurized when in use
 

Dukedog

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there is a 4 psi check valve that could be bad also... its tha "T" fitting right ahead of tha tank cap
 

QBhoy

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I’d absolutely say (from horrible past experience personally and knowing of many others who suffered the same), that you should almost certainly do away with the oil injection system on that engine anyway. Wouldn’t normally say such a thing about most other injection systems on mercs and Yamaha engines…but that particular engine and the other similar engines in the v6 black max bracket, are just simply infamous for failing. Unless you are religiously and rigorously removing, replacing and checking all the components on the system. Most other systems you can get away with just checking and maintaining the oil lines and fittings. But on those the pump drive itself can simply randomly give up the fight without too much warning.
Since my first one of these failed on me decades ago…any of the handful I’ve had since and currently have had the system done away with in favour of pre mixing the fuel. Quite sure most old school merc guys will likely agree…mostly. 50-1 for a normal v6 of that era and a little richer for the XR models
 

psilver145

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Thank you. If what I am about to do to it doesn't fix the issue, I will delete it and remove the tank.
 

QBhoy

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Thank you. If what I am about to do to it doesn't fix the issue, I will delete it and remove the tank.
No worries. Best of luck. But honestly…I’d strongly urge you to do away with it altogether. Absolutely well known for failing horribly these things. Totally up to you of course. Best of luck either way. All the best.
 

Dukedog

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QBhoy i gotta disagree with ya on tha oiler.. merc kept tha basic design around for over 21 years so ta me thats not a bad design.. tha main reasons for failures was/is ta poor maintance and/or over heat of tha motor which weakens tha ring gear. so ta me generlizin' tha thing as a whole is not an actual fact..... how many have you owned that gave up tha ghost???. i've run tha V6 since 1976 and only problem i had and or dealt was for above reasons............ jmo
 
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jimmbo

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QBhoy i gotta disagree with ya on tha oiler.. merc kept tha basic design around for over 21 years so ta me thats not a bad design.. tha main reasons for failures was/is ta poor maintance and/or over heat of tha motor which weakens tha ring gear. so ta me generlizin' tha thing as a whole is not an actual fact..... how many have you owned that gave up tha ghost???. i've run tha V6 since 1976 and only problem i had and or dealt was for above reasons............ jmo
1976? Merc didn't put the Premixing System on until the Mid 80s...
 

Dukedog

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oiler '83 ta '05 same basic design............. i've run nothin' but merc production and high performance v6's FROM '76 ta '08
 
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jimmbo

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Reading the Post, I couldn't tell if you meant
...I've run the V6 since 1976...
or
...I've run that V6 since 1976...

I thought 84 was the 1st Year for the Mixing System on the V6
 

Dukedog

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'83... only year that had oiler and single ram TnT.... may have been mid year tha oiler was added.... lotta dead brain cells ta remember for sure....
 

Dukedog

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'82 ta '84 was different things happenin' with merc.. kinda like tha '90 ta '91 changes jus messed with everything..........
 

Dukedog

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still kickin' huh!... tha little second gen. 2.0 motors were/are jus 'bout as bullet proof as ya can get...............
 
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