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1999 Mercruiser 5.0 Tuliped valves

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Firescooby

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That’s the diagnosis I got, cylinder 2 and 6.

Shop is recommending a new motor. Machine shop says that the tuliped valves are caused by the valves being sucked up and shouldn’t have caused any lower damage. He says that head work would fix that.

What do y’all think?
 
Yes head work will "fix" the symptom of the problem but not the problem... are the damaged valves intake or exhaust??? NEED to find out WHY this happened in the first place if you are going to rebuild this one... any number of causes including wrong octane gas, over propped, too aggressive timing...etc IT GOT TOOO HOT in the cylinder.!!!
 
sandkicker said:
Yes head work will "fix" the symptom of the problem but not the problem... are the damaged valves intake or exhaust??? NEED to find out WHY this happened in the first place if you are going to rebuild this one... any number of causes including wrong octane gas, over propped, too aggressive timing...etc IT GOT TOOO HOT in the cylinder.!!!
Click to expand...

It's on the exhaust side. They said that the motor was "way out of time".
 
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Firescooby said:
That’s the diagnosis I got, cylinder 2 and 6.

Shop is recommending a new Engine.
Machine shop says that the tuliped valves are caused by the valves being sucked up
It would be interesting to hear that machinist's explanation.

The term "tuliped valve" refers to the valve face in that is has become distorted (cup shaped) due to excessive heat.
As the face becomes more cup shaped, the effective length of the valve stem becomes longer.
As the valve stem becomes longer, it now allows the properly adjusted rocker arm to prevent the valve face from seating.
The problem quickly perpetuates itself.



and shouldn’t have caused any lower damage. He says that head work would fix that.
I agree with Bob..... you need to FIRST learn what caused the damage.

What do y’all think?
Click to expand...

sandkicker said:
Yes head work will "fix" the symptom of the problem but not the problem... are the damaged valves intake or exhaust???
NEED to find out WHY this happened in the first place if you are going to rebuild this one...
Yes!

any number of causes including wrong octane gas, over propped, too aggressive timing...etc IT GOT TOOO HOT in the cylinder.!!!
Click to expand...

Firescooby said:
It's on the exhaust side. They said that the Engine was "way out of time".

I'm not sure how they determined that without first operating the engine and checking the TA........... but it is very likely the case.

Excessive ignition advance can cause ignition induced detonation.... of which can be very destructive.
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Firescooby said:
That’s the diagnosis I got, cylinder 2 and 6.

Shop is recommending a new motor. Machine shop says that the tuliped valves are caused by the valves being sucked up and shouldn’t have caused any lower damage. He says that head work would fix that.

What do y’all think?
Click to expand...

Unless your engine was used in fresh water, Don't waste your time repairing a 21 year old engine block, there is not much left to the water jacket after that many years. The 5.0 is a crappy boat engine to begin with... Upgrade to a 5.7 if you are going to change the long block.

Now why did this happen, #1 is a lean condition caused by an intake leak or dirty carb/clogged fuel injector if fuel injected. #2 Boat over loaded creating excessive EGT's and heated up the valve, #3 Bad ignition timing, caused by incorrect base timing or a bad distributor pick up. #4 bad fuel.

FYI, overloading the boat=over loading the engine... Meaning the engine throttle is pushed up and the engine is lugging not getting into the correct RPM range for the amount of throttle applied. This happening once will heat up a valve and slightly stretch it causing a slight loss of power, not enough to be noticed by the average boat owner. Once this happens the cylinder will run lean and finish off the valve.
 
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Thanks for the information.

The boat is a freshwater only boat.

The boat was running when taken to the shop, just very poorly. They checked timing and said it was “way out”. Compression on all 8 cylinders was 150, 2 and 6 failed the leak down leading to the tuliped valve diagnosis.
 
Are you in love with this vessel? If you can't imagine life without it, then I would pop for the repower. If the answer is no, then take the ten or twelve thousand that the repower will cost and put it towards your next seafaring love boat. Sometimes you gotta think with your head and not your heart.

Maybe you can sell this to someone who wants a project,
 
o2batsea said:
Are you in love with this vessel? If you can't imagine life without it, then I would pop for the repower. If the answer is no, then take the ten or twelve thousand that the repower will cost and put it towards your next seafaring love boat. Sometimes you gotta think with your head and not your heart.

Maybe you can sell this to someone who wants a project,
Click to expand...

I only bought the boat in late May, and it's been in shop since first week in June...haven't had it long enough to know. Can't hardly remember what it looks like.
 
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