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

Wildboating

Update:  Merc says that due to wearing impellers and a small leak in the water drain bulb that happened at the end of last season the reduced water flow is what cracked the exhaust manifold.  When i took the boat for a test run the mechanic overlooked that small leak and apparently the new exhaust manifold cracked again on the test run.  They are replacing the manifold again, and replacing the impellers and the leaking water drain bulb.   Then we retest again....   This is getting out of control.  I am going to be so deep in ultimately exercising this demon.  I truly am getting a new boat one part at a time..    

Handymans342

This is crazy

Black_Diamond

One would think an over temp alarm would have gone off if the water flow was that low. 

Raw water pump:  Hardin Marine.  If you ever have to replace the originals due to wear.  I bet the impellors are not worn, but the side plates it runs against. Broken impellor parts excepted. If the sides of the pump are scored up, a new impellor will not help. 

rasbury

What is the water drain bulb? How long have you had this boat? This is awful......i really feel for you...

GMSLITHO

The drain bulb do you mean the plug on the bottom of the water pump 

Black_Diamond

Rather hard to believe that manifold cracked that easy/fast. Especially with no overtemp alarm. I’d think you would cook the rubber boots on the exhaust connections first. 

212rowboat

Over torqued and it would break easily by vibration or expansion either or... 

Wildboating

I don't like these answers either.  Seems like bs to me but this saga of me getting destroyed by these shops continues.  I need merc's help and they would not help without it being at a certified merc shop.  That is where it is.   The stories are all over the place.  Remember right the gate they told me they set the base timing until i called that out as not possible with the 555 motor then they switched to they indexed the dist.   They did not index it, they may have checked it but i had done it several times.   I know it was and is right.  

Im 3 years in to this drama.  You don't want to know at what cost.  I don't want to be reminded.  Every shop that has ever looked at it and 2 of them swore to me they would not leave me stranded with it yet they swapped tons of parts and eventually said they were too busy to continue messing with it.  If it cant be fixed with common part swaps they give up.  True diagnostics is outside of most shops.  This is why i need merc but they only will help with a certified merc shop.   Good thing i like the boat, probably going to have it for the rest of my life.   There has to be away to verify pulse width and ignition cycles.  I want to see real hard data.  The synchronizer buries to port with small equal amounts of throttle until higher rpms.  Then it stays over or comes about half way back.

The water bulb is the blue drain plug on the front bottom right of motor.   Grey bulb that has a blue plug.   I cracked it at the end of the season, it has a small pinhole style jet shooting out.  No overtemp alarm, does not even get hot.

Wildboating

I just talked to them again, they are saying it is not so much as the manifolds are overheating as it it a hot manifold that receives surges of cold water to a hot manifold that caused the cracks.  Again, this is them guessing with Merc but no one knows any of this to be true however we are fixing the leak and replacing impellers before retesting.

Wildboating

skennelly

Yeah that plastic part is like $180 to replace.

212rowboat

Talk to the admins and get a copy of this thread zipped up... Will serve as documentation.  When the cause os found and most likely on the builder, you need to be reimbursed.  

There is a way to look at pulse width and duty cycle.  A hard way and an easy way. Easy way involves a computer which is costly unless you have a shop with high volume.. Hard way os with osciliscope, calculator, and a notepad.  Plus several pencils and patience. Thing about it is, though, is the system is simple.. Pressure, no obstructions, delivery.  The pcm manages the pulse width/duty cycle but is reliant on proper pressure and flow to do so.  

So... Swap pcm's between motors.  If it follows, you jave a corrupt tune.  If the engine won't close loop it could explain your issues... If it wont open loop under wot then that could explain your issue (and the lean burn).  Your ten minutes from comfirming if its management related by simply swapping brains.  

By the way, lean runs hotter as your aware... Also more susceptible to detonation as your also aware.  This could cause hot manifolds, and could also cause pcm to restrict timing advance. Werent you matching timing advance though engine to engine? 

Wildboating

ECMs have been swapped earlier in this thread.   Problem existed pre swapping long block.  I am looking at buying a fluke DMM that measures duty cycles.  No timing retarding.   Ecm sees 24* wot same as the port motor.

212rowboat

This is where I go back to camshaft timing/dialing. 

Can you get the cam card or do you have it?  That timing cover needs to come off and that engine indexed... You dont want to be mpre than maybe 4* off what each position is declared on the card.  The builders could have timed it wrong (you said long block, right?) Or the cam grind itself could be way off (which is far more common than you'd think).  The push rods could be short/long.  Compare them to good engines... There could be lash in the valve train or lash was set on a deflated lifter... 

 Mass produced engines are always tricky.  For instance I just bought a perfect classic f150 with a 302... It had zero go go..  Broke out timing light and discovered the base timing was a measly 4*... ????... Advanced it to 16 before it knocked .Backed off to 14.5 and its a new beast... An angry one... Nothing but ignition timing on bone stock engine and likely up from the listed 190 to likely 230-240hp if my levis branded dyno is properly calibrated... Point being, those engines are mass produced and set to a parameter theyve discovered all of them can run on.  I wager donuts to dollars yours wasnt dialed in, as every engine should be... No two are alike.  You can tune them to be similar, and get real close... But there is too much going on in there for them to be the same. 

If you dont find your issue,  and its not a deficiency mechanically that is flat wrong, it may come time to play with timing... Fuel pressure... Map/mafs... Ect.. To squeeze more out of a lessor built engine... Maybe new engine has thicker head gaskets increasing volume? Maybe it has rings that have yet to seat causing greater blow by?  Maybe the pushers are thousandths of an inch short or long?  Maybe cam indexed wrong or bad grind to begin with? 

If you cant find a glaring issue, it may be time to dial it in . 

Dude_Himself

@212rowboat: you're missing where this existed BEFORE he swapped the longblock. So he had a problem -> replaced longblock -> still has problem. That has me questioning what is still in common. I'm pretty sure we've swapped sterndrives without changing symptoms too - so it's not that. Something that wasn't addresses with a new longblock...

212rowboat

Accessories?  Maybe swap belt to one just bog enough to run the waterpumps.  Eliminate ps pump, alternator, ect... See if one of the parasites are killing it.  Things that draw torque at crank have exponential ability to kill engines power.  One of those could be freezing under load... Not fully froze, there is no mistake about that, but freezing instead... Causing great loss of useable power.  He'll, we questioned everything else, right? 

Black_Diamond

This thread is so long now. Jeese. Connections at the injectors all clean?  Flawed/cracked intake manifold?  

The accessory idea is worth checking from Rowboat/Drew. The power steering pump, if the culprit, would be easy to check based on the oil: be burnt smelling/looking. 

dalek

Wildboating said:

ECMs have been swapped earlier in this thread.   Problem existed pre swapping long block.  I am looking at buying a fluke DMM that measures duty cycles.  No timing retarding.   Ecm sees 24* wot same as the port motor.

The ECM outputs the 24* to the coil module, it does not read it. The figure is calculated from the manifold pressure and the RPM.

212rowboat

The throttle body and dizzy are not bound by vacuum.  The advance is a function of cps and ckps and monitored and graded by knock sensors. Monitoring these sensors is far superior to the old vacuum advance relationship between dizzy and carb. Base advance, unless you use computers to alter mapping/strategy on the pcm/way, is the only way to manipulate timing advance. Well, you cam notch your your cps bit that is a hack .

rasbury

Shame none of you guys are close enough to give him a hand, I thought I had problems...

Wildboating

dalek said:

Wildboating said:

ECMs have been swapped earlier in this thread.   Problem existed pre swapping long block.  I am looking at buying a fluke DMM that measures duty cycles.  No timing retarding.   Ecm sees 24* wot same as the port motor.

The ECM outputs the 24* to the coil module, it does not read it. The figure is calculated from the manifold pressure and the RPM.

Correct, I stated that wrong.  How can you verify that the distributor actually is advancing. 

Handymans342

You used to be able to watch advance with a timing light

dalek

Wildboating said:

dalek said:

Wildboating said:

ECMs have been swapped earlier in this thread.   Problem existed pre swapping long block.  I am looking at buying a fluke DMM that measures duty cycles.  No timing retarding.   Ecm sees 24* wot same as the port motor.

The ECM outputs the 24* to the coil module, it does not read it. The figure is calculated from the manifold pressure and the RPM.

Correct, I stated that wrong.  How can you verify that the distributor actually is advancing. 

The distributor itself does not advance at all. The coil module is just fired slightly earlier to create the advance. As Handy says, you can check with a timing light. As I have mentioned before, please pop the connectors off the TPS to see if you get the correct error before you do anything else, just to confirm your error messaging is working. I fear you may be wasting a lot of time and money on a simple comms problem between the ECM and the rest of the boat.

Handymans342

But he switched PCMs and the other motor ran fine. 
I think you will have to pull the motor and tear it down to check the valve timing. 

Handymans342

What if chain is off one tooth??

Black_Diamond

Might be time to pull that engine and take it to Al. He’s only 4-5 hrs away from you in Indiana. Super knowledgeable. Super honest!  

rasbury

There is the ticket !

aero3113

Could the issue be with the outdrive, and have nothing to do with the engine??

aero3113

Is there a chance your drive was swapped with one of a different ratio??

Black_Diamond

Have you checked the oil for water in it after this last go around?