looking for a "what would you do?" scenario on my 8.2L 380HP inboard engine / water intrusion

[desperado]

have a 2011 sea ray 350 sundancer. both engines have about 385 hours on them. Starboard engine oil was milky and oil cap had some condensation in it. 4 plugs had water on them. they pulled the plugs and did a compression test. The wet bank are plugs 1,3,5,7 and the compression numbers were 90, 100, 125, and 85.

The dry bank were plugs 2,4,6,8 with good compression numbers of 155, 160, 170, and 155. The marina wants to do a leak down test to further diagnose the issue.

A good boat mechanic/friend of mine said he would try and save as many $100 bills as possible and tell them to take the good head off that produced the good compression numbers and place it where the bad head was that produced the low compression numbers. Then rerun the compression test on the wet bank side with the good head and see if numbers come up. He said if numbers come up you know it's the head. If they don't come up then it's the engine which is really bad news but at least you didn't waste money on the leak down test.

Any thoughts besides sinking the boat?

Hate this but I just don't feel like putting a new engine in boat lol (obviously)

Thanks for any input!!!!!!!

 

[mrsrobinson]

I'd get the leak down test. You can do one yourself, pick up the kit at Napa.

 

[Skybolt]

Your exhaust riser(s) leaked water into the engine and your heads need to be re-done. Inspect the cylinder walls of 1 and 7 to make sure there is no or little scaring. Use a bore scope or just pull the heads. The exhaust valves in 1 and 7 are burned and probably tuliped.

The exhaust manifold's and riser's need to be replaced if the engine is still good.

 

[desperado]

Your exhaust riser(s) leaked water into the engine and your heads need to be re-done. Inspect the cylinder walls of 1 and 7 to make sure there is no or little scaring. Use a bore scope or just pull the heads. The exhaust valves in 1 and 7 are burned and probably tuliped.

The exhaust manifold's and riser's need to be replaced if the engine is still good.

thanks.... maybe i won't sink it just yet LOL

 

[mrsrobinson]

Why should he pay a mechanic, at probably $150/hour to start pulling parts off, when he is trying to save money? That's why I suggested getting a leak down test, and to save some money and do it yourself:

Amazon.com : leak down tester

I don't disagree with your diagnosis/suggestion, simply stating he was asking how to save some money.

@desperado, I have never heard of switching the heads to validate it's a bad head/valves. I am no expert though. My first thought is how will you get a good seal w/out a new head gasket. My 2nd thought is if you are going to pull the heads off go ahead and send them out to get rebuilt.

 

[desperado]

Why should he pay a mechanic, at probably $150/hour to start pulling parts off, when he is trying to save money? That's why I suggested getting a leak down test, and to save some money and do it yourself:

http://[URL]https://www.amazon.com/leak-down-tester/s?k=leak+down+tester

[/URL]

I don't disagree with your diagnosis/suggestion, simply stating he was asking how to save some money.

@desperado, I have never heard of switching the heads to validate it's a bad head/valves. I am no expert though. My first thought is how will you get a good seal w/out a new head gasket. My 2nd thought is if you are going to pull the heads off go ahead and send them out to get rebuilt.

thanks yeah i'll go ahead with the leak down test. if the engine is bad i'll prob sell boat. i've been thinking about moving up to a 370 anyway. but i love this boat dammit LOL. it's the perfect size. ok now i'm rambling haha

 

[Nater Potater]

The whole purpose of a leakdown test is so you know exactly where you're losing compression before taking anything apart! Just like with a doctor, it pays to get a second (or third) opinion before you (or your boat) goes under the knife.

 

[Nater Potater]

thanks yeah i'll go ahead with the leak down test. if the engine is bad i'll prob sell boat. i've been thinking about moving up to a 370 anyway. but i love this boat dammit LOL. it's the perfect size. ok now i'm rambling haha

Oh-oh; two-foot-itis begins its evil pattern of corruption...

 

[mrsrobinson]

Your best case IMO is it's just the heads. That's not too difficult of a job for a mechanic in my opinion. To pull them off, send them out to get rebuilt, then reinstall them. And I guess if you want to do it on the cheap just do the one head. Others can jump in on that though, I'm not the expert. As a future perspective buyer of your boat though I would question why you only did one.

I don't think you'll be able to sell the boat with the engine in that condition, so I would at least diagnose it.

My second to last boat had the heads redone right before I bought it. They did it to sell the boat because it was not reaching wide open throttle. I had the receipt but can't remember what the cost was.

 

[Skybolt]

Why should he pay a mechanic, at probably $150/hour to start pulling parts off, when he is trying to save money? That's why I suggested getting a leak down test, and to save some money and do it yourself:

Amazon.com : leak down tester

I don't disagree with your diagnosis/suggestion, simply stating he was asking how to save some money.

@desperado, I have never heard of switching the heads to validate it's a bad head/valves. I am no expert though. My first thought is how will you get a good seal w/out a new head gasket. My 2nd thought is if you are going to pull the heads off go ahead and send them out to get rebuilt.

Because what I posted is what is wrong. And yes I know this for sure. Seen this many many times. You want to save money do it yourself. This is what it is.

Curious what a leak down test would do here and how would it save money? The compression test was already done. Holes 1 and 7 are dead. A leak down test is useless at this point. A leak down test will tell you where the issue may lie. In this case it is very evident and this is what it is and the work is what needs to be done.

Where did you get switching heads from?

 

[mrsrobinson]

Because what I posted is what is wrong. And yes I know this for sure. Seen this many many times. You want to save money do it yourself. This is what it is.

Curious what a leak down test would do here and how would it save money? The compression test was already done. Holes 1 and 7 are dead. A leak down test is useless at this point. A leak down test will tell you where the issue may lie. In this case it is very evident and this is what it is and the work is what needs to be done.

Where did you get switching heads from?

Difference of opinion on how to save money. Reread his post, he's the one that mentioned switching the heads not me.

 

[Skybolt]

The whole purpose of a leakdown test is so you know exactly where you're losing compression before taking anything apart! Just like with a doctor, it pays to get a second (or third) opinion before you (or your boat) goes under the knife.

If there wasn't water in the engine I would agree. But there is water and two dead cylinders.

A quick test to back up what I am saying is put marvel mystery oil in those two cylinders and re-do the compression test. doesn't change that much it's the valves.

 

[desperado]

Your best case IMO is it's just the heads. That's not too difficult of a job for a mechanic in my opinion. To pull them off, send them out to get rebuilt, then reinstall them. And I guess if you want to do it on the cheap just do the one head. Others can jump in on that though, I'm not the expert. As a future perspective buyer of your boat though I would question why you only did one.

I don't think you'll be able to sell the boat with the engine in that condition, so I would at least diagnose it.

My second to last boat had the heads redone right before I bought it. They did it to sell the boat because it was not reaching wide open throttle. I had the receipt but can't remember what the cost was.

no my apologies didn't mean to imply i would sell boat without diagnosis or repair. that was me rambling. i'll at least get the diagnosis and then make a decision depending on what needs to be done. I guess this happened just sitting in the slip i ran it 2 weeks ago and both engines were humming at 4200 rpm with a WOT test. oh well. it's a boat and it's paid for.

 

[Nater Potater]

If there wasn't water in the engine I would agree. But there is water and two dead cylinders.

A quick test to back up what I am saying is put marvel mystery oil in those two cylinders and re-do the compression test. doesn't change that much it's the valves.

That's a very good point. A change in readings with oil in the jugs would sure point to rings (or the inverse, if the valves). I'm spoiled after having done this on a number of engines, and I get a kick out of pinpointing the cause prior to a teardown. It's an OCD thing...

 

[Skybolt]

Difference of opinion on how to save money. Reread his post, he's the one that mentioned switching the heads not me.

Not sure anyone is trying to save money, except fixing this engine and not buying a new motor. But doing a leak down test is wasting money. It's another 1-2hrs in the wrong direction. That same 1-2hrs is all that is needed to take the head off, which needs to come off anyway.

At the end of the day that head needs to come off and you will see the story. Compression of 85-90 will be self evident as to what's wrong. Any skilled mechanic will be able to see burnt tuliped valves and/or scared walls.

 

[Skybolt]

That's a very good point. A change in readings with oil in the jugs would sure point to rings (or the inverse, if the valves). I'm spoiled after having done this on a number of engines, and I get a kick out of pinpointing the cause prior to a teardown. It's an OCD thing...

You mean an engineer thing, we all (engineers) seem to be OCD to some degree I think.

But yeah, if you have the time to diagnose and then prove your diagnosis was right, is always a good day.

 

[desperado]

I really appreciate everyone’s input. I’m a guy who knows what I know and I know what I don’t know (which is important in life).

Anyway I thank y’all very much so I can talk sensibly with marine shop tomorrow.

 

[Bill Curtis]

This is just my opinion and the route I would take.

I saw a comment asking if rebuilding just one head is OK. I would say no.

Reason? if both heads are done at same time, they age the same as time goes on. Plus you now know thay are both good. If only 1 is done, then there is a possibility that head #2 (the one that wasn't rebuilt) fails in near future and you need to do everything all over again.

And while apart, have the exhaust manifolds and risers checked for leakage, also. This can be done on your work bench with some compressed air pressure and / or acetone. 10 or 15 PSI should be sufficient.

Also, before removing the engine parts, pressurize the cooling system (block off the exhaust manifolds from the cooling water) w/ about 15 PSI of air and see if the cooling system leaks into the engine.

 

[370Dancer]

Don't forget the 10+ hours of removing all of the top end electronics/mechanics and front bolt ons to get to the heads. In the middle of this right now.

 

[Skybolt]

To do this job right, both heads need to be re-done and valves checked. Both Manifolds, riser(s) and elbows need to be replaced. That is, if the cylinder walls are not scored to badly. If there is light scaring, then, after both heads are back on, I would do another compression test to validate the scaring isn't an issue.

A knowledgeable mechanic can disassemble down to the short block in a few hours. Re-assembly will take some time. Hard to say how much, but I would think the complete tare down and re-assembly would be around 10hrs, maybe 12.