Smarty pants, I really could use your help! 350 Mag trouble SOLVED?? MAJOR UPDATE

Wildboating

Ras if you recall we bought the boat after a inspection and sea trial via a highly touted surveyor.  Unfortunately I was not able to attend the sea trial.  Boat arrived to me with problems the second it was delivered.  During my completion of purchase the surveyor had a heart attack and passed away.  Former owner, swears to no knowledge of any issues.   Week one I had to have someone rebuild both motors heads due to tuliped valves on number 5 cylinder.   

dalek

The very first thing I would humbly suggest is to remove the TPS on the good engine and see if you get the correct error. Repeat with the bad engine. This would take five minutes and cost nothing. I must confess I am somewhat bemused by all your Rinda screenshots showing no problems whatsoever.

Wildboating

Great idea Dalek!!

rasbury

Good luck buddy, sure wish I had some answers for you. Sucks to start with problems as a few others have had as well....

Wildboating

Thanks Ras.  This is the year, im convinced we will figure it out.

Wildboating

I called services shop and he said boat is good to go, they found the issue and fixed it.  According to them both engines easily turned 4400 rpm.  They are writing up what the found and will be calling me back but what he mentioned on the phone makes no sense at all yet makes 100% complete since or about as much sense as my last statement....lol   

Dream_Inn

oh come on, you are killing me!  What was the problem?   inquiring minds want to know!

Wildboating

I am dying for him to call me back with the full write up but they figured it out with Mercrusier.   It is something i have paid many places to go thru and I also did to the full extent of knowledge i was given but a few of you have said it several times over.

Dude_Himself

Glad it's running finally, but we better get a full write-up! Otherwise a few of us might have to visit and tinker a bit to reconstruct the issue...

Carsnmorellc

Well hot ****!!  Hopefully we get a video of this beast cruising on the water ASAP!!

Black_Diamond

Hamsters. lol

Handymans342

If you had diesels this thread would have never started. Just sayin LOL

Dream_Inn

Handymans342 said:

If you had diesels this thread would have never started. Just sayin LOL

Neither would the boat!!  LOL!  (sorry, it just fit right with the statement Handy)

Glad to hear it is fixed!  But, the truth will be when you are out on the water very soon!

reneechris14

20 months and almost 22 pages of comments. Glad to here it right now. ?? Pics,videos and write up??   

J3ff

Man is hoping to see the answer

J3ff

You going to go back to those places you paid and demand some cash back or what?

dalek

Glad it eventually appears to have been resolved, don't leave us hanging with the results.
I was beginning to fear you had grown a little like Bogart in "African Queen" where he says to Katharine Hepburn about his boat engine:-
"You know, I'm gonna fix it one of these days. The only reason I ain't done it up to now is that I kinda like kickin' it."
I don't think it was a 350 Mag though.

Liberty44140

Handymans342 said:

If you had diesels this thread would have never started. Just sayin LOL

Handy, my buddy’s parents had a 70’ fly with huge twin diesels. For two years the stbd would cut out from nowhere. Then restart and run fine. Going from Naples to Bahamas no problem but coming back two shut downs, next trip ok. Had dealers on it, flew in mfg rep, took years to solve. Diesels are the same. Wish I could remember what the issue was! 

Liberty44140

Wild, awesome!!! Hope that all is well and you have a great summer on her. Looking forward to seeing what the issue was. 

Handymans342

Liberty44140 said:

Handymans342 said:

If you had diesels this thread would have never started. Just sayin LOL

Handy, my buddy’s parents had a 70’ fly with huge twin diesels. For two years the stbd would cut out from nowhere. Then restart and run fine. Going from Naples to Bahamas no problem but coming back two shut downs, next trip ok. Had dealers on it, flew in mfg rep, took years to solve. Diesels are the same. Wish I could remember what the issue was! 

Lib that is rare as getting hit by lightning

Wildboating

So i finally got the full details, Im glad i waited as there was more to the story then i initially had been told.  They are telling me that the base timing was off on the engine and they made some adjustments to that.  They took the boat out and was able to get up to around 4400 rpm them the engine pulled back.  After a few more rounds of testing they were on the phone with mercruiser when they decided to pressure check my exhaust manifolds.  They have determined one side is cracked or defective from the factory and is spraying water into the combustion process under load.   A new manifold arrives today and we are going for a follow up test ride shortly.  

Wildboating

Where can they have made adjustments to the base timing?  How can so many people look at it and say it is fine then they need to make adjustments.   I paid another mechanic to pressure check the manifold but if his defense we honestly could not get the plugs out of the top.  I wonder how they did.  We spent half a day and gave up as we were convinced we were going to mess them up trying any harder.

212rowboat

you've got to stunt the engine to set base timing. 

there is a lead off the dizzy that has to be bridged.  when it's bridged the pcm will not advance timing.  you set your base in this mode and at 1100RPM- and it should be 10~12 degrees.  the engine should be at operating temperature, stopped, stunted, restarted-timing set, stopped, then you pull the bridge/stunt- and then it's game on. 

the PCM has an advance of 22~24 degrees... this gives you a total advance of 34~36 degrees, and reconciled with the knock sensor, the intake air charge, maf/map, will allow your engine best possible advance all by itself with no user input- except for that base timing.  

glad you got it taken care of!!!!

Wildboating

We will see.  Todays test to confirm.     All these threads and i was always told you can not change base timing on a 555 motor.  Now there was a way to adjust it? 

Wildboating

The exhaust manifold spraying water into the fuel?   I know all 8 plugs are orange, they said only one bank was and it conceded with the side that has a crack or defect.  Im curious to how or where they did a pressure test. 

dalek

Wildboating said:

The exhaust manifold spraying water into the fuel?   I know all 8 plugs are orange, they said only one bank was and it conceded with the side that has a crack or defect.  Im curious to how or where they did a pressure test. 

I was just about to say:-
How can water get "sprayed" into the combustion chamber from a leaking exhaust manifold?
How are the plugs of uniform color throughout the engine if only one manifold is cracked?
I am also curious.

Wildboating

dalek said:

Wildboating said:

The exhaust manifold spraying water into the fuel?   I know all 8 plugs are orange, they said only one bank was and it conceded with the side that has a crack or defect.  Im curious to how or where they did a pressure test. 

I was just about to say:-
How can water get "sprayed" into the combustion chamber from a leaking exhaust manifold?
How are the plugs of uniform color throughout the engine if only one manifold is cracked?
I am also curious.

This is what i want to know?  The exhaust valves when open are under pressure and would be exhausting outward.  How can anything be coming into the combustion chamber?  Hopefully some of the more experienced guys while chime in

212rowboat

i wouldn't get too hung up on the orange of the plugs...  orange isn't a bad thing, so long as it's not layered rust.  orange denotes leaner than stoich, and proper temperature.  it's actually something sought in some configurations.  an item that will cause orange is also found in the fuel- which is an additive to inferior fuel to raise the RON.  

the info about water being injected doesn't sound right to me either.  you gotta figure, at full tilt the engine exhaust pressure should overwhelm the leak and push it out- the danger comes when you're backing off RPM's and the flow of the water is momentarily greater than the exhaust pressure- which will allow leaking into the jug past the closing exhaust valve.  similar to a crower six stroke, as soon as that water is introduced into a hot cylinder it expands- causing what may be misidentified as 'dieseling'.  the pressure of turning water into steam has got to go somewhere, and that is where it's most often noticed- a 'run on' after key off.  

the real issue in this situation is when you go to restart the engine, and it has water resting on the exhaust valve as the only barrier between it and the cylinder- or worse, you caught the stroke with engine off with the exhaust valve left open... the cylinder fills with water- not much, but enough... when you turn the engine it doesn't want to turn at all- almost like a bad starter.  it'll ultimately clear the water in the cylinder after you attempt to turn it several times and start... but there is going to come a time in the very near future if this condition exists that the head gaskets give, the piston rod gives, the piston face gives- or a bearing cap gives.... something will give.  something bad.  

^that doesn't sound like anything you've described.  

what could be happening is 'steam'. 

if you've got steam due to leak in the exhaust water jacket close enough to the head exhaust port, the pressure the exhaust pulse has to push through could be much greater than what is expected, disallowing you to build RPM's, just like what could be experienced with an exhaust flapper lodged and not opening... it would be manifest by heat, though- and that bank would be considerably hotter than a bank not experiencing that situation... I don't recall you mentioning one bank being really hot, though. 

at any rate...... I'm really happy you got it worked out. 

Wildboating

I am not convinced it is actually fixed.  I am joining them later today for the next test ride.  I am convinced that they have picked up where everyone else left off and they are just throwing parts at the problem and saying they found the issues.  Nothing you just mentioned is any of the symptoms.  

Wildboating

I understand the additives, but both motors pull from the same gas.  The port motor plugs are not orange