water going to back plug at idle

[bigtoe]

Hi I have the 3.0.GL last year ( and previously) i have had change the manifold and riser as water was starting to get to the back plug from either one of them leaking. So last year i tested the manifold and found it to be leaking and dully changed both.
Since then it hasn't really cured it. I still get water building up in that little bowl at the end of the manifold, then when at idle or going really slowly the boat starts running on three until I rev the boat a bit and clear it. You can also smell fuel a bit as well when this is happening.
So my question is, did i fit a faulty manifold or could water be getting there from anywhere else?

Last year i removed the user to check and saw specks of rust in the carbon but not runs of water going down from the riser manifold joint, so I felt the joint was good but hoped the re-joining was what was needed.

Cheers in advance

 

[Bondo]

So my question is, did i fit a faulty manifold or could water be getting there from anywhere else?

Ayuh,..... Anything is Possible,....... only other thing I can think of is possibly a cracked head,......

 

[muc]

Bad exhaust valve can also do it. Maybe time for a compression test?

 

[bigtoe]

ok I was thinking that could be a possibility (hoping it wasn't) Ill do one today

 

[bigtoe]

hi ok id did a compression test. I think its pretty good across them all. 170 to 180. Are we thinking its the manifold now ?

 

[Bondo]

Are we thinking its the manifold now ?

Ayuh,..... Or a cracked head,......

 

[Scott Danforth]

hi ok id did a compression test. I think its pretty good across them all. 170 to 180. Are we thinking its the manifold now ?

check your gauge. 170-180 is water in all cylinders. anything over 150 is suspect.

 

[bigtoe]

scott sorry i don't understand what do you mean anything over 150 is suspect ? To do the compression test I simply removed the coil lead from distributor. removed each plug in turn and turned the boat over. all came pressures came out between 160 and 170.
By suspect what do you mean? gauge is brand new. Regards john

 

[Grub54891]

To do a compression test, you remove all the sparkplugs completely. The motor must be free to spin easily. Try that and let us know the results.

 

[bigtoe]

Ok thanks for that i will. I can see the relevance now, if one chamber leaked to another that chamber would just pressure and hold. Live and learn.
Since my last post I have removed the riser and had a look in side. I carried out a water test on the manifold. Filling it up until the max level against the riser gasket and dried out the exhaust route . An hour later the water level has dropped 1/4 inch and wet inside the exhaust route !
So I've contacted the sales dept and they are sending a new manifold. How unlucky is that !!

 

[Scott Danforth]

a brand new motor would have compression in the 150 psi range. that is also what was posted in the manuals for decades

anything higher than 150 is suspect. it is either a faulty gauge or something in the cylinders such as water or oil

a new gauge does not mean its a good gauge.

also, in post #5, you state 170-180 psi, yet in post #8, you stated 160-170.

after a compression test, you also need to do a leak-down test on any cylinder that is lower than 10% the highest value.

do an acetone test in the manifold.

 

[bigtoe]

scott thanks for the above. I appreciate I have carried out the compression test incorrectly and figures are different in the posts, I checked the gauge before resending in post 8 and realised id read the value 10 higher than it showed.

I have since carried out a water test on the manifold and it is leaking. Using acetone instead of water i assume shows the leak quicker ?

Ill come back with further results once the new manifold turns up tomorrow and its fitted,

All the very best, I must also add a massive thanks, invaluable info you guys help out with

 

[Bondo]

I have since carried out a water test on the manifold and it is leaking. Using acetone instead of water i assume shows the leak quicker ?

Ayuh,..... This is correct,.... Quicker, through finer/ smaller cracks,.....