Leaking exhaust valve after winter storage??

[Ricky_rich]

I recently bought a boat with a Volvo Penta 5.7GL that had not been used for a year. Now it turns out that an exhaust valve is leaking. Previous owner states that there should not be any kind of problems with the engine.
So my question is, can such a problem accour after engine just not beeing used for some time. Can a valve spring break or suddenly goes week?

 

[Scott Danforth]

valve springs can break, however most likely a valve is sticking

is this a salt-water boat?

 

[Ricky_rich]

Yes boat has been used in salt water upp untill now. But could that have an inpact on the valves?

 

[Scott Danforth]

yes, most likely the manifold/elbow joint is leaking (manifolds and elbows need to be inspected every year and usually get replaced every 5). the joint has most likely been leaking water and you now have a rusty mess of a cylinder head. hope the rust isnt in the bore requiring a new block

 

[tpenfield]

Wonder how the valve leak was determined- cylinder leaks test :noidea: Do you have the leak % ???

As Scott stated, once you have an exhaust gasket leak between the manifold and riser salt water will tend to reach the exhaust valves and cause some pitting of the valve seat.

Just one valve . . . Or a few?

 

[Ricky_rich]

Thanks, this was good information. I'm going to take the manifolds and engine heads off this weekend. The heads are going in for a restoration, but I'll have a close look at the manifolds and elbow as well.

 

[Ricky_rich]

Wonder how the valve leak was determined- cylinder leaks test :noidea: Do you have the leak % ???

As Scott stated, once you have an exhaust gasket leak between the manifold and riser salt water will tend to reach the exhaust valves and cause some pitting of the valve seat.

Just one valve . . . Or a few?

Yes, did a leak down test. 35% lekage on cylinder number 6 exhaust. The rest have a leak between 3-10%.

 

[Scott Danforth]

cylinders 5 and 6 are the first to get hit with a trickle of water from a failed manifold/elbow joint.

 

[Lou C]

In salt water you should figure on taking off the riser to check at the five year mark, or sooner if you see rust trails emanating from the riser/manifold joint. If it leaks on the outside, it could be leaking on the inside. Also, Volvo has re-vised their exhaust riser gasket material several times, make sure you use the correct OE gaskets, and install according to their latest instructions. If the risers/manifolds sealing surface is eroded and has been used for 5+ years in salt, I would not chance using them, I'd replace with new. Barr Marine makes a good set of exhaust manifolds & risers for these engines. I used their stuff when I converted my '88 OMC from the one piece batwings to the Volvo style center riser exhaust and used the Barr gaskets installed according to their instructions. They sealed well and the exhaust parts fit perfect.

 

[Lou C]

No Title

 

[Ricky_rich]

No Title

I got everything off today. I can not see any obvious cause of the problem. But my guess is that the manifolds have been on for a long time. A lot of rust pieces in the water canals.
One interesting thing is that cylinder number 5 has a leakage of 11%. So number 6 is worst with 35%, and 5 is second with 11%, the rest just have a few % leakage.
So head restoration and new manifolds and knees are the next step. Engine has been used in salt water by previous owner. But I will only use it in a sweet water lake from now on.

 

[Scott Danforth]

Look at the exhaust port on cylinder 6. Do you see rust in the port? Around the valve?

 

[Lou C]

For a salt water used boat it looks VERY good. I don't see any evidence of water getting in the center gas passages of the manifolds & risers and the cooling passages in the heads, are remarkably clean and free of heavy rust. You may just have a valve that is not seating 100% and can be freshened up with a normal valve job.

​Flip the heads around and take pix of the intake and exhaust ports. Sometimes you can see the corrosion on the valve stem. If the engine was not fogged and sat for a long time in a damp climate, that alone could cause a valve to stick. This is why fogging engines helps with storage if it has to be kept outside in a damp climate.

 

[Ricky_rich]

No Title

I live in Sweden and the boat has up until now been used in the Gulf of Bothnia. The water there is not as salt as in the Atlantic or the Pacific Ocean. Here are picture of cylinder six exhausts and intake. Looks good to me, but I?m not used to dig this deep into an engine. I think all ports looks about the same when it comes to carbon oxide.
I have no idea if the previous owner used fogging spray before storage.

 

[Lou C]

The pix look good, I'm wondering though what that darker spot is on the exhaust valve stem. Ports have no sign of rust that I can see. Have a valve job done and put it together with set of Fel/Prom marine engine gaskets

 

[Scott Danforth]

the valve with a darker spot is oil seeping down. the valve looks to be stuck and soot covered. the second pic looks normal

were any of your pushrods bent?

 

[QBhoy]

Is there water evident in the oil or oil filler cap underside ?
Could it be a sticking piston ring ? I?d fire some 2 stroke oil down each plug hole, turn it over with plugs out and leave it overnight. See what happens then...if it?s not a valve problem.

 

[Ricky_rich]

No Title

All pushrods look ok. There are some darker areas on several of the exhaust valves. I?ve attached pictures of them all, not so easy to get a good pic. Can it be that I have bad valve seals?
Engine oil looks good, but under the valve covers there were some gray goo.
Engine heads are off now, but I could drip some two stroke oil on the piston tops, and leave it there for the whole winter.

 

[Ricky_rich]

Problem solved!
I took the heads in to a mechanic for restoration. After removing all the valves, he said all the valve seats were more or less bad. Turned out the seats were not hardened, should be a ring mounted in the head for marine use said the mechanic.
So the solution is to change the heads to proper marine ones. Or have new seats installed.

 

[Scott Danforth]

non-hardened valve seats were pre 1978.after that all heads have hardened seats. cast iron is usually induction hardened, aluminum has inserts

no such thing as "proper marine ones" the same heads are found on trucks.

I would simply get a valve job done or if you want, a set of vortec heads is $500 new.