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I think I blew up my freshly rebuilt 5.7.....

S

speakrdude

Member
Rick, Here is my story......

Where do I start. (the timeline for all
of below is 20 hours on engine)

Engine info: 1990 Merc 5.7L, had cracked
everything when I bought. Shop replaced heads, block, long block (typical
marine)rebuild. I installed Seakamp (half cooled) cooling system.
(Note*) Checked with Seakamp. No difference in Heat exchanger (radiator) caps shipped with the H/E or the expansion tank.

In
the beginning, I had a fresh new rebuild, new mans, water pump, fuel pump,
everything. Then, we noticed the dribbling fuel from the venturies, causing a
hard warm start. (seemed to be flooded)
But ran OK. Rebuild carb twice, every
trick in the book. Same thing, but seems to idle good and be pretty crisp.


Was at that time, I checked a vaccuum gauge, a little at 12~15 in, but
farily aggressive RV could cause this, so I'm told.

A couple of engine
hours later, I noticed there is quite a bite of tapping noise coming from the
rockers. Removed covers, sure enough, there were several loose rocker arms. (Did
the reman shop not do a thorough job?) Shop said the rocker studs are pressed in
and could be coming loose or nuts are going bad?
Took all back to -0- lash
and tightened half a turn (by-the-book)
Sounds great now! (Runs
OK)

LAst week, Sold boat. Delivered to the customer. While I was out of
no wake area of the marina and by myself, took her up on plane, 4400RPMS,
Denotation! Engine dies.
Tried to start, only running down #1 battery.
Opened hatch, looked down carb throat, getting gas, good. Must have been trash
in the tank and now in the fuel filter. Switched over to #2 battery, holding
throttle wide open because by now, is flooded. Starts up! Idle back to dock.
Tell customer about the stall and change fuel filter/seperator and check things
over for his next outting.

Hear from the customers first outting, (he
just fast idles around the lake a little) that all is well, still kind of hard
to start when warm and idle seems a little low. (dies when manuevering foward to
reverse into slip)
No problem, I run up to slip the next couple of days,
increase nuetral RPMS to 850, in gear solid 650) check timing, all good. Engine
sounds great, life is good. However, I did notice the coolant expansion tank is
almost full and a little bit of spill over in the bilge! (full cold should be
about 25% full)
I checked the heat excahnger and it is low. I poured some of
the coolant back into tank, really puzzled.

Customer now ready for his
Saturday out on the water with the kids.
Saturday afternoon rolls around,
and you guessed it, customer calls and is stranded down lake, engine wont catch.
It almost does but wont quite. I instruck (again) the flooded starting
proceedure. Still no go.
Off to the rescue I go.
I reach the clients
boat at almost sunset and sure enough, wont quite start. Almost but not quite. I
notice the expansion tank is full again with a little spillage. Hmmm.
Also,
when I crank over the boat to try start, I am seeing, what looks like steam,
coming out of the port side rocker cover vent tube on every strock of of the
engine!
I tow them back in.

My next course of action is a compression
test, Tuesday. That is where the beginning of the trouble shooting process
begins.

I am guessing, I have a hole in a piston (or worse), causing the
blowby and no start condition, but wont know till I begin the investigation.
Lots of possibilities I suppose.
Any thoughts?
 
If marina replaced engine it should be under warrenty, Get a new one and start over...........you should have done this with the loose rocker arms and stopped there. This was a manufacturing defect......

what you needed to do was a specific gravity test on the antifreeze to see if you have water intrusion. If so then something internal in the motor (head gaskets, bad torque on heads etc etc.)

More diagnostics is needed on your part.

Also the continued gas seepage is a real concern!!!! you need/needed to resolve this before handing off to a customer.....very dangerous.

buying rebiult is luck of the draw, they are not allways perferct.....

just my opinion
 
kghost said:
If marina replaced engine it should be under warrenty, Get a new one and start over...........you should have done this with the loose rocker arms and stopped there. This was a manufacturing defect......

what you needed to do was a specific gravity test on the antifreeze to see if you have water intrusion. If so then something internal in the motor (head gaskets, bad torque on heads etc etc.)

More diagnostics is needed on your part.

Also the continued gas seepage is a real concern!!!! you need/needed to resolve this before handing off to a customer.....very dangerous.

buying rebiult is luck of the draw, they are not allways perferct.....

just my opinion
Click to expand...

Totaly agree the second you saw the studs were pulled out it means a sloppy job of pressing them in ( mushroom hole ) or no locktite poor fit tolerance to loose etc.
 
I actually didnt notice they have pulled up. I just had to retighten the rocker arms, (zero lash + half)
Could be a bum cam, could be several things.

I checked the oil today, no signs of water. Coolant, no signes of oil.
All 8 spark plugs look identicle.
Compression 150(ish) on all BUT #6, 75 lbs. (Ah Ha!)
Could still be a valve, havent pulled the rocker arm cover yet.
 
The more you work on this yourself, the more ammunition the re-builder will have to deny you warranty. You are building a list of reasons why he won't honor the work they did. IMHO
Bert
 
I doubt they will cover 100% if it is their fault at all. Is already past the 12 month warranty, since it sat in my shop for a little while I was working on other things on the boat. (I have 3 boats I am currently restoring)
They are pretty stand up guys. If they find an obvious fault, they will take care of me. (they have before)
This is probably the 12th engine I have had them rebuild.
 
speakrdude said:
They are pretty stand up guys. If they find an obvious fault, they will take care of me. (they have before)
This is probably the 12th engine I have had them rebuild.
Click to expand...

Find another builder.

Is it possible you wiped the cam during the initial start break in? I cannot see a few rockers coming loose (if the studs did not come out) from bad lock nuts, unless the assembler ignored the fact that there was no resistance while setting lash.

If #6 has 75 lbs, remove all rockers and check to see if all valves are at the same height, if yes, do a leak down on that cyl. A hung open valve will cause a major vacuum leak and the engine will not run.
 
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Both head gaskets bad, (builder said look defective) # 6 intake valve bent, (possibly due to water in cylinder) Checked everything else, Magnafluxed heads, intake, resurfaced, reassembled, will test run this am.
 
So far, every professional I have spoken with have said that the "too much pressure from a factory stock type fuel" is probably around 1%.
We rebuilt carb twice, lowered the float levels, the second time, same proiblem. Have brand spanking new Edelbrock sitting here ready to go in.
 
Something else came to my attention today when we put the boat back in the water at the customers slip. (seperate issue from dribbling fuel at idle)
While at the shop on the muffs, risers stayed nice and cool. (half closed cooling system), at the lake running at 2500 Rpms or less, most of the time, Risers are hot to the touch. Temp gauge still around thermostat range, 180ish. If I try to get boat up on plane, anything above 3000 rpms, detonation! (lots of pings) so I quit, for now. Timing is dead on spec, and didnt really want to retard much, making it harding to start.
Replaced impeller and assembly last fall. Lots of water pressure coming from lower unit (forgot to tighten plate on side of cooler at spring commisioning! Water went everywhere!)
Any Ideas?
 
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Is it possible the gas is crappy? I'd start by draining the tank and fuel system first, assuming it had no detonation prior to the most recent issue. Or even easier fill a 5 gallon remote tank with some gas from another source and see what u get.
 
speakrdude said:
Something else came to my attention today when we put the boat back in the water at the customers slip. (seperate issue from dribbling fuel at idle)
While at the shop on the muffs, risers stayed nice and cool. (half closed cooling system), at the lake running at 2500 Rpms or less, most of the time, Risers are hot to the touch. Temp gauge still around thermostat range, 180ish. If I try to get boat up on plane, anything above 3000 rpms, detonation! (lots of pings) so I quit, for now. Timing is dead on spec, and didnt really want to retard much, making it harding to start.
Replaced impeller and assembly last fall. Lots of water pressure coming from lower unit (forgot to tighten plate on side of cooler at spring commisioning! Water went everywhere!)
Any Ideas?
Click to expand...

1990 model year, still a first generation Alpha?
Crappy aftermarket and some quick silver replacement impellers have a brass hub and they slip at higher RPM's causing a slow over heat. Use only Mercury Impellers with the fiberglass hub.
 
The shop did the valves (yesterday) Did compression test yesterday, (150 all around, you forgot with good battery :rolleyes:) Havent done a vaccuum test since before the incident. Was previously always around 12, very steady.
 
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