Had it with the boat - may need a new motor

[vetting]

So after 3 years of only minor repairs, my 25ft Mercruiser V8 I/O has been giving me nothing but grief this year.  

- This spring I replaced the entire outdrive

- Then found that my gimbal steering collar was out of whack so had to replace the gimbal ring.  That was a lovely 19 hour labor bill.  

- Finally got to fish for a bit and then had a bilge pump that failed which lead to the back of the boat dipping at the dock which then let cold water back up through the exhaust and onto a hot head.  Cracked the starboard side head.

- Tore down the entire top half of the motor and replaced the head along with all of the gaskets.  Along with tons of cleaner to get the gunky/frothy oil out and 6 total oil changes while messing with it.  

- Fished another 2 days and got stranded 3 miles out due to my cap/rotor busting the pin off

- After replacing the cap/rotor, the boat wouldnt run.  That lead to replacing all of the wire connectors on the motor.  Boat finally ran well after that.

- Fished a tournament last Saturday and on the race back into the harbor for weigh-in, the boat suddenly went from 25mph to 15mph with no change in throttle.  Backed off a bit and got it to go again, but seemed as though I had to throttle up a bit.  Then the temp went up to 210 so I backed off again.  Limped it back to the harbor and started to inspect what happened.

 

Pulled one plug at a time and did a compression test. Mind you,  before the new head was swapped on - compression was 140 to 150 on all cylinders.  The head was replaced on the 2-4-6-8 side.

 

Plug #8 was not even hand tight and the electode was slightly melted. 4 was also loose and 6 wasnt much better. All 3 plugs had white soot on them from blowby and 4 was dark. 

 

1-150

3-150

5-140

7-150

 

2 -150

4- 5

6 -120

8 - 0 

 

So looks like the new head blew up and may have taken some pistons with it.  Any ideas on what could have happened and where I should go from here?  Would really had to rip the entire thing down again but looks like Im going to have to - just a little difficult with the costs that have added up already.  If it comes down to it, does anyone have an experience with any companies that offer a fresh rebuilt longblock?

 

[Rippin'Line]

michigan motorz

 

http://www.michiganmotorz.com/

[machzrcr]

What motor?

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[vetting]

It is a 89 Mercruiser V8 5.7 260 HP

[skipper19]

Check jasper engines, they do all sorts of marine engine now. Even outboard power heads.

http://www.jasperengines.com/marine-products.php

Edited August 5, 2015 by skipper19

[lost a lure]

Just buy a new boat

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[Roughrider IV]

Brings new meaning to Break Out Another Thousand. You certainly have more patience than me, hope it turns around for you. Good luck!

[Silver Fox]

Go to mercruiser. 3 year warranty. Russian roulette anywhere else.

silverfoxcharters.net

[skipper19]

Actually after looking at reviews on Jasper engines...maybe not. I saw their add today in a publication and saw your dilemma, but yeah, check out mercury cause of the warranty and better quality no doubt!

Mark

[buckboardjr]

All of your data defines that you had a lean mixture or possibly advanced timing or severe retarded timing. These conditions could lead to the melted electrode, white soot, and a hole in a piston from detonation.. The loose plugs I would attribute to not being torqued to spec.With all the problems everyone is having with Ethanol fuel restricting jets and drilled passage ways in carbs maybe your original head got cracked do to detonation, though this isn't usual.I'm sure you had the distributor out during the head swap, and this is a chance for timing to get off. Oh and burnt valves would be idicative to retarded timing. That new head didn't just blow, I believe one of of these items caused it. If the plugs on the other bank look normal then I would lean toward the starboard side main jet circuit of the carb caused a lean mixture.

Edited August 6, 2015 by buckboardjr

[ray koziatek]

just another tip from a old fart,go over the boat 100% before you drop another penny, ..stringers,transom,elect,fuel sys. ect,ect,And the "Dog house" eng cover, if that cover allows rain ,spray to drip on the carb it could allow water to get in the engine. 

[vetting]

So turns out the rockers were all too tight from the beginning. To fix, I replaced all of the plugs that were fouled, then backed off the rockers about 4 turns and got some compression on the 2 dead cylinders. I then warmed up the boat to operating temp with the valve cover off on that side. I then was able to back off the rockers another 2 full turns on average before they started to clatter with the motor running. Then turned them back down to where they stopped clattering and turned them another half turn or so. I didnt do another compression test yet, but its purring like a kitten at 600rmps at idle and in gear with 50 psi of oil pressure. So what I think what happened is that they were all too tight from the beginning and once I did a long WOT run, it heated the oil enough that the lifter cleared out and the lifter finally filled the entire way. Then the push rod was putting too much pressure on the valve and they werent closing all the way hence the 0 compression.  Would also explain why the plugs all looked like they were super dark and why everything heated up.  Its just a matter of any damage was done running it for 2 weeks with the extremely tight valve train. I'll run it like it is for a few days, see how it runs, and then do another compression test.

[buckboardjr]

I'm glad you figured it out. I did not suspect your rocker adjustments because you had 2 days of it running good prior to the failure! The way you adjusted them the final time is the way my dad taught me. It works but there is an easy way while not running. You just bring each cylinder up to top dead center of compression stroke. I start with #1 . Snug rocker nut down while spinning pushrod with your fingers. When you feel resistance to your spinning of pushrod then tighten one full turn. Keep in mind in a few seconds that lifter will bleed off and the pushrod will again spin so you DON"T keep tightening the nut. You do both valves. Turn the crank 90 degrees, "for V8s"  in the direction of operation" Watch the time marks on Harmonic bal." Do the next cyl. in the firing order. Work your way thru the firing order till done.

[vetting]

I think the main issue is we washed the motor down a ton with cleaner and diesel to remove all of the oil/water cake mix.  As a result the lifters were empty when we installed everything and not primed when the adjustment was made.  Plus the guy who did the original adjustment kinda went back and forth with different ways to adjust them so I think he ended up cranking on them more than once.