cure for sticking valves? add bend/trap in exhaust?

[CamaroMan]

Hi all - im still new here (and to atomic 4s)! I still getting to know these little guys..

It seems sticking valves is a common thing - im doing some light work on someones yacht and he told me he never fresh water flushed until i met him and told him too.

Either way - I removed the head yesterday as 2 cyls showed 0 compression and no amount of oiliing/tapping helped -

Turns out both exhaust valves were REAL stuck - they never even dropped back after tapping them down.

I notice the exhaust manifold (at least on this model) goes straight up, surely the salt water will drip back down?


So im wondering if theres a way to prevent this? Perhaps adding in a bend before it goes up to trap a tiny bit of water and stop it from making its way back to manifold/valves?

Judging by the condition of the valves id say this motor has been run without much care for a LONG time - and no acid flush has been done. Im almost worried the block might be bad so doing a psi test on the system after assembly..

[lat 64]

The answer is yes.

I have a dry exhaust, so Im no help but to say there are different solutions for all the different kinds of boats with A-4s.

Many good ideas will be forthcoming from forum members with similar boats as you.
With that said, can you give more particulars like the boat manufacture and maybe some photos or detailed description of exhaust layout.

"Straight up" might mean several different things to this crew.

Cheers,

Russ

[edwardc]

I notice the exhaust manifold (at least on this model) goes straight up, surely the salt water will drip back down?

So im wondering if theres a way to prevent this? Perhaps adding in a bend before it goes up to trap a tiny bit of water and stop it from making its way back to manifold/valves?

In a properly designed exhaust system, the exhaust should first go up as high as possible (space permitting), then go down at least 4 inches before injecting the water. This is a minimum. More is better.

This both protects against splash migration, and provides a larger "volume buffer" in the event of prolonged cranking with the water intake open.

Take a look at my exhaust rebuild photo album to see what I mean.

[Chris Simenstad]

What kind of boat do you have?

On my Ericson 32, the hot section leaves the manifold, goes up a foot to about 1/2" of the cockpit floor, turns 90 degrees, aft another 4", then another 90 degree bend down, meeting the water injection, and then a hose section that drops down to a big waterlift muffler. I always start the boat with the through hull closed, and open it after the engine starts.

My engine hasn't suffered from sticky valves, but I have had to rebuild the hot section. On my boat the hot section seems to last 6-7 years before decaying. I also run 5 gallons of fresh water every time I put the boat back in the slip. I'm not sure if this is beneficial to the valves, but I do think it helps keep the cooling passages clean.

I do put MMO in my fuel religiously, and I make sure I run the engine at least every two weeks, year round. I wonder how many engines develop problems via disuse (or if not properly winterized if not used year round).

[CamaroMan]

I dont have a sailboat now - but im working on one.. Was just curious - im posting up a thread on progress on a head gasket/ sticky valve job with some tips -

have a peek here:

http://www.moyermarine.com/forums/showthread.php?t=10482