Logo
FULL SITE MENU

1988 40 HP mariner

N

Newboater14

New member
So first off, my outboard has a tendency to kinda bog down and stop when your starting it cold. It would also take some time to get to full speed.


About a month ago we had it out on the lake for a week and it ran great with only that problem.


I recently took my boat out of the garage and put muffs on it to test it out and make sure everything’s running good. For some reason it seemed like it was idling harder and it wasn’t peeing so I immediately stopped it.


I only ran it for about 25 seconds and noticed the water coming from the motor was milky/creamy. I took out the spark plugs and noticed that only the bottom one had milky substances on it.


I also unscrewed the oil plug to see if the oil had water in it and the oil was pure and good.


I’ve heard it could be a blown gasket but I’m hoping it’s anything else.


I’m new to motors so any guidance would be super helpful.


Thanks

 
Last edited:
Compression test before anything else,If test is bad,pull cylinder head,Take lower unit off and investigate waterpump watertube, and related parts,check the thermostat also
 
johnnygjr said:
Compression test before anything else,If test is bad,pull cylinder head,Take lower unit off and investigate waterpump watertube, and related parts,check the thermostat also
Click to expand...

Thanks,

i ended up running it more and it did start to pee, although the motor would die of it wasn’t fully choked. Also there was the creamy color but a big puddle of it hours after running. The water comming from the prop was creamy too. Does that sound any different?
 
johnnygjr said:
Your engine is ingesting water, like I said compression test
Click to expand...


Hey johnny sorry for the late response I had to get a compression test from my brother. Anyways I recorded each test 3 times. The top spark plug hole was just over 100 psi, around 101 each time with a pretty quick build up. The bottom spark plug hole was just under 100 psi, around 98 with a quick build up. Any idea on what’s next?
 
?---Is it a 4 cylinder motor or 3 cylinder motor ?-----Those smaller MERCURY / MARINER do not have a cylinder head.---A water jacket cover is found on them.
 
racerone said:
?---Is it a 4 cylinder motor or 3 cylinder motor ?-----Those smaller MERCURY / MARINER do not have a cylinder head.---A water jacket cover is found on them.
Click to expand...


As as of right now I don’t know if my outboard has 3 or 4 cylinders im just kind of learning as I go. I’m sorry I’ll keep looking. Is there anything you suggest to do?
 
Back
Top