Mercruiser 5.7 tuliped valves

[TilliamWe]

Re: Mercruiser 5.7 tuliped valves

if the valve is/was tulip'd loosening the rocker nut wont help it any...once it's tulip'd it will still leak because it wont seal...

if you loosen the rocker nut and it seals that means the lash was set too tight..

Re-read my post. I said, "if the compression goes up" not "if the compression returns to normal". I know the compression won't go back to normal. On my motor, it had 550 hours on it, and had ZERO compression on #2. I loosened the rocker arm, and it went to 60psi. So it was not the lash set too tight, jesus, the motor had run that way for 7 years! Loosening the rocker allowed the deformed valve to seat higher up in the head, creating a little bit of a seal (60psi worth).
And I can tell you from first hand experience, on a Vortec engine, valves will tulip LONG BEFORE a piston will melt. That's a fact you need to know.
Tulipped valves are caused by high combustion chamber temps. That's what happens to boat motors that are over propped and can't reach their WOT RPM range. The motor is working way too hard, at all RPMS, and the chambers get hot and deform the valves.
For a guy who knows a lot, and put "dr" in relation to Chevy engines, you sure are missing some pretty basic boat motor 101 info. I hope this thread helps.

 

[gadget73]

Re: Mercruiser 5.7 tuliped valves

Last time I saw this condition, it was caused by a popped head gasket following an overheat. The cylinder filled with water under load, causing the spark plug to fire out of the metal base, the rings to break, and both valves on that cylinder to tulip. Only reason I know it was caused by an overheat is the customer had us put a water pump in the boat the week before because he overheated the engine severely, though we weren't told the "severely" part until after the engine blew up. It checked out OK immediately after the pump install, but about 2 hours of run time later, it was no longer OK.

 

[Polar_Bus]

Re: Mercruiser 5.7 tuliped valves

This thread has some interesting comments.

I've rebuilt, tuned, raced , and daily driven severall SBC engines, and my personall opinions is they are NOT the same comparable service application. Marine applications IMO will far more heavily load the crankshaft for far longer periods of time, vs. a street, or race service engine.( Especially from what I am reading about correct, and incorrect engine to prop relationship) Street and race engines also have the advantage of multi-speed transmission multiplication to lessen the torque loading.
Heavy , consistant loading festers detonation. From my experiences, I can easily hear detonation in street and race engines, but not the case in marine. There is no way I would ever hear detonation piloting my boat, between the wind rushing past my ears, and the engine behind you, detonation will destroy and engine and the only thing I would observe is the engine crapping out to a stop..
In street applications detonation is more easily heard, and also street WO throttle is always intermittant, so detonation damage is more easily minimised if not adverted.
We are going to read a lot of continuing granading engines stories stemming from bad E10 Ethanol fuel, especially in excessively "wet" marine applications..

(just my thought's) I do NOT pretend to be marine well educated...

Rich

 

[rodbolt]

Re: Mercruiser 5.7 tuliped valves

it does seem that the vortec heads are particularly prone to valve face issues when over propped or lugged.
and yes the ethanol issues are not going to go away but just get worse.
there is some interesting reading to be had on some of the petroleum engineering web sites.
seems the base stock of gasoline designed to be blended with Ethanol is a lower octane rating as ethanol has a given octane of 100.
therefore WHEN phase seperation occurs from sitting your fuel will at first contain to much ethanol,hopefully shutting down the motor BEFORE damage but then the gasoline at the upper layer may be as low as 65 octane crating issues all its own.
we finally had to post signs and on workorders WE are not responsible for fuel system reoccuring problems or damage due to melted tanks,lines,fuel level sender floats or debris coming from the tank and overwhelming fuel filters.
seen all of the above on a reoccuring basis.

 

[TilliamWe]

Re: Mercruiser 5.7 tuliped valves

Simple solution to E10 separating... Use your boats more, and burn up the fuel! That's what I did for 8 years and never had any trouble with ethanol. When it only sits in the tank for 2 weeks max (55 gallon tank), it's not a problem. Once again, the product is not the problem, the users are!

 

[rodbolt]

Re: Mercruiser 5.7 tuliped valves

Tillam
not an issue if you live on the water.
quite a few of my customers live over 400 miles from the marina dry stack and may only use the bout 10-20 hours a YEAR.
they still have twins and 200 plus gallon fuel tanks.
one grady 26 coastal I put a brand new F225 on in the summer of 03, engine now has 29 hours on it and the fuel tank holds 165 gallons.
my personal 21 sea pro I placed a new F150 on in july of 07, it now has 115 hours on the command link.
I fix them for a living and dont have time.
my 175 Etec I bought in nov 06 I blew up in march of 08 at 15.4 hrs and since the new powerhead I may have put an additional 8 hours on it.
this summer I have taken 3 days off since about may.
it IS a fuel issue not a consumer issue.
E-fuels, its the greatest kneejerk reaction ever foisted on the american public,unless maybe your a senator from Iowa.
check with the FAA and see what they say abouut E fuels for aircraft

 

[TilliamWe]

Re: Mercruiser 5.7 tuliped valves

Ethanol has been in use for YEARS and it's not nearly as big of a problem as you "professionals" are making it out to be. Yes, in extreme circumstances it can cause problems, but not in the vast majority of cases. And I'll still bet the original poster's issue has nothing to do with fuel or ethanol, it has to do with lugging his engine.

 

[rodbolt]

Re: Mercruiser 5.7 tuliped valves

I tend to agree with the lugging issue.
I disagree with the Ethanol fuel issue altough so far this summer I have made almost 30K over it .
it DOES dissolve polypropalyne tanks,it DOES disolve the black foam sender floats, it DOES dissolve fuel lines even though the line has fire cohol printed on it.
I have a sample hanging on the shop wall where the inner rubber liner seperated from the hose and would collapse after 30 min or so at or near WOT shutting off fuel supply.
I also have 26 fuel tanks we have replaced manufactured by moeller from 2000-2006 with dissoveled draw tubes,tank materiel itself and floats as well as the black plastic fuel tank caps.
so far this year we have pumped out bover 2000 ngallons of bad or phase seperated fuel.
more than the past 5 years combined.
we have replaced more contaminated VST and fuel water seperators this year than any of the pst 2 years combined.
its not the e-10 per se its the effects of the hygroscopic nature,large tanks sitting in the pond at relativly high humidity and the fact ethanol is a very good organic solvent.
for those not understanding what a solvet does, add 4 tablesppons of sugar to 1 pint of water, mix thoughroughly, pour said mixture through a coffe filter.
inspect the filter for surgar and see if it filtered out 4 tablespoons worth.
the water was the solvent the sugar was the solute.
happens the same way in your hull fuel system the ethanol is the solvent and anything it can dissolve is the solute.
something about when the fuel vaporizes in the carb or injection system that now the solute falls out of solution and does the nasty .
if you dont belive me start googling Ethanol fuels for marine use.

 

[pocrain]

Re: Mercruiser 5.7 tuliped valves

Some folks might see some confusing opinions here but the street level guy like myself gets alot of info very quickly when these differing opinions are posted. Thanks to all who post and help us keep our ancient crafts afloat !

 

[JustJason]

Re: Mercruiser 5.7 tuliped valves

Just curious... what company do you get to dump 2k gallons of gas? Any ideas of what they charge to take it and ultimately what they do with it?

 

[rodbolt]

Re: Mercruiser 5.7 tuliped valves

there are some very good sites by most all major manufactures about E-10 its self life the effects of it and so forth.
and yes the e-10 base fuel stock is lower octane then it was with MTBE and other oxygenates.
so its possible when you fueled up you had 87 octane but when it let go it was 75 or less.
in our area we have seen blends as high as 50%, those that got it were lucky as the engine shut down.
those that had in the 20 % range blew engines.
gasoline burns at roughly 14 parts air to 1 part fuel.
Ethanol burns at roughly 7 parts air to 1 part fuel.
ECU doesnt know the percentage of Ethanol and the mechanical air inlet(throttle plate) is fixed.
the computer map simply cannot compensate for the lean air to fuel ratio now induced due to a fuel that needs twice the fuel for the shutter opening.
runs lean now.
couple that with some over propping and maybe a bit of cooling system degradation and you just smoked the intake valves.

 

[Polar_Bus]

Re: Mercruiser 5.7 tuliped valves

Ethanol has been in use for YEARS and it's not nearly as big of a problem as you "professionals" are making it out to be. Yes, in extreme circumstances it can cause problems, but not in the vast majority of cases. And I'll still bet the original poster's issue has nothing to do with fuel or ethanol, it has to do with lugging his engine.

You need to do more reading on the serious disadvantages of E10 when used in powersport applications. It's a BIG issue. Not so much of an issue where consistant fuel turnover is the norm. I have a boat, a snowmobile, and a leaf blower, chain saw, and so on and in these non-constant applications E10 based fuel, if left untreated WILL wreak havoc with your fuel system......

 

[rodbolt]

Re: Mercruiser 5.7 tuliped valves

justjason, find some local crabbers and give it to them. I guess they use it to thin the tar they dip pots and nets in.
as long as it disapears from my place I really dont care.
and it disapears for free.
local fuel service guy disposes of it the same way and chages 3.50 a gallon and a 150 dollar pump setup fee.
hate to cut someone but I have my customers intrests to look after as well.