Honda 8

[lexi]

I have s/h Honda 8 . Just bought on auction. Engine seemed fine on startup ran well. Checked oil when I got home .......little bit black. So changed it cold . Took engine out gave it a good run and then trolled at slow speed for 6hrs.

Drained new oil and noticed emulsion like Mayo in oil....oops.

Took off rocker.......mayo!! Removed cover where thermostat lives .........no stat. Have rigged up leakdown gauge. First possibility is that last owner has removed stat in a foolish attempt to cure an overheating issue. Is there a slight possibility that thermostat removal and slow running could have any bearing on this. Maybe wishful thinking!!

Alex

 

[VicS]

Running cold will lead to water condensation in the oil and the oil/water emulsion you have observed but in 6hrs ? There may have been a lot of water in there already that your oil change did not remove of course.

If it starts easily and runs faultlessly i would discount the possibility of a head gasket failure for now but of course it could leak between a water passage and an oil-way so it cannot be ruled out entirely.

I think you should fit a new thermostat and a new pump impeller and run it again paying attention to the temperature. Then see if the water in oil problem is sorted out. if it overheats or continues to accumulate water in the oil it is probably going to means strip down to investigate/cure.

BTW don't run it dry, that'll wreck the pump impeller almost instantly.

You may find you can get valuable help and advice from the Honda forum at iBoats

 

[graham]

Most definitely agree with Vic ,a cold running engine will cause the "mayo" you describe.I would fit a thermostat then change the oil and filter again then see how it goes. The old stat may have been faulty and the owner binned it mistakenly thinking it wouldnt matter.

Go for the easy solutions first.

 

[lexi]

Thanks Guys
I`ve had better advice on here than i boats. Must be a British thing! Will change gasket housing and Stat.

Put compessed air into cylinders. Bottom cylinder had no obvious air rushes. None out of next spark plug hole which would indicate a blown HG. On the top cylinder with TDC. and valves closed (compression stroke) the piston moves and air obviously comes out of inlet or exhaust ports. Tried it every way...come back to that again.

Alex

 

[graham]

Let us know the result,I have the same engine so very interested to learn from your experience .

 

[Lakesailor]

Whip the head off.
How difficult can it be?
Just because there is no compression leak doesn't mean that oil and water are not mixing at the head/block interface.
It looks as though there is a pressure "O" ring at that joint as well, and as the oil pump seems to be part of the head assembly that means the oil is going to the crank. If that is leaking you could be creating bearing problems.

 

[lexi]

I bought this one on in the hope that while in use I could swap parts with my other one which has a slight intermittent problem. This would help me diagnose instead of going out and payin £I80 quid for my chief suspect ...cdi unit. Turns out the wires and spec on this one are slightly different resulting in different part no........so can`t take the chance.

Alex

 

[lexi]

[ QUOTE ]
Whip the head off.
How difficult can it be?
Just because there is no compression leak doesn't mean that oil and water are not mixing at the head/block interface.
It looks as though there is a pressure "O" ring at that joint as well, and as the oil pump seems to be part of the head assembly that means the oil is going to the crank. If that is leaking you could be creating bearing problems.

[/ QUOTE ]

Not difficult LS. ............until a head bolt that someone may have jumped on breaks while undoing.lol. I have ordered the stuff up including head gasket. Will decide later. Could not do leak down on that No 1 cylinder without locking the Crankshaft......same result no air escaping from one cyl to the next.

Alex