87 175 Johnson vro

[Mikered3500]

Bought a boat with this motor, just got it running again, they had the thermostats off and never changed them...had it on the hose for the start up .the port side got warm pretty quick and had clean water coming out of the thermostat port. Starboard side took forever to warm up and had milky exhaust filled water coming out of that bank. Any suggestions?

 

[Faztbullet]

Need to do a compression test. Does it has the bubble exhaust??? If so these are bad about scuffing cylinders due to sleeves being so thin.

 

[Mikered3500]

I did a compression cold and hot. The numbers are slightly higher hot. Lower 2 cylinders were 85-86, middle were 88-89, top were 90-92. What do you mean bubble exhaust? I'm new to the outboard world

 

[Bosunsmate]

Bubble exhaust has a bulge at the back between both sparkplug banks, the flat one is flat.
Id check that its firing on all cylinders

 

[Rustywrench]

Pretty sure 1986 was last year for big block motor? Guess we need a model number to be sure what we are working with.

 

[Mikered3500]

Oh yea .it looks like an oil pan kinda? We did a spark test with a test light and then pulled all the the plugs and checked it that way as well. All we're dry and had a pretty good lighting bolt shooting off of them. I can post a model number when I get off work today.

 

[Mikered3500]

There is kind of a slight miss or idk what exactly you would call it at idle every 10-15 seconds. Is there any way to add a video to these threads?

 

[racerone]

The big bore V-6 crossflow was marketed last in 1991 !!

 

[Bosunsmate]

There is kind of a slight miss or idk what exactly you would call it at idle every 10-15 seconds. Is there any way to add a video to these threads?

Maybe but most people just add a youtube link.
Check your pistons domes through the sparkplug holes. It may be a water leak in which case the dome will be clean looking

 

[Rustywrench]

You got me again racerone! I just don't remember these things like I use too. I knew the CF went away in '91. Thought the big bore went away earlier. Should have! Built 60* & CF at the same time for 1 year. Confusing.

 

[Mikered3500]

Maybe but most people just add a youtube link.
Check your pistons domes through the sparkplug holes. It may be a water leak in which case the dome will be clean looking

The Pistons look normal colored after being ran, dark but no signs of water or anything getting into the cylinders. The plugs are looking good as in not fouled or anything, no signs of water getting on them either . I'm clueless as to how the exhaust is getting in the water. Any chance it's a head gasket issue even with decent compression???

 

[Bosunsmate]

The Pistons look normal colored after being ran, dark but no signs of water or anything getting into the cylinders. The plugs are looking good as in not fouled or anything, no signs of water getting on them either . I'm clueless as to how the exhaust is getting in the water. Any chance it's a head gasket issue even with decent compression???

Yes. Try running it with one of those starboard plugs out in turn and see if you can narrow down which cylinder makes it "milky"