3.0 milky oil/knocking

[Tahoe Charlie]

Sorry for the long post in advance. Your website has been a great help with other projects. But my entire experience below seems unusual compared to others I could locate in the forum. Really hoping someone can give me advice.

We have a 3.0L engine that was refurbished by Quicksilver in 2003. The engine appears to be vintage ~2000. We purchased the boat in 2010. For the last several years, we would occasionally find water had somehow entered the oil, creating a milky mess. Each time, we changed the oil multiple times, running briefly in between and then replacing oil and filter. We suspected water entered the engine when the bilge filled with rain water. On other occasions, we suspected it might be a head gasket or possible exhaust baffle. We replaced the head gasket last month, but shortly after discovered water in the oil again! This week, we installed a new exhaust baffle--the old one was completely missing.

Compression tests: All measure around 140 psi, except cyl #3, which was 170 in April. Last night I checked again with a warm engine: All cyl measure 140 psi except #3 now measure 125??

A substantial knocking noise developed after we re-installed the head in April. We goofed on our interpretation when adjusting the valves and tightened 1 AND 3/4 turns past no lash. The engine ran for maybe 2-3 hours, both on the lake and muffs, before we discovered water in the oil again! Our bilge pump seems to be working fine, however we can't be sure if this is rain water or lake water that has contaminated the oil. This week I drained and replaced the oil twice. Presently, there is straight SAE 30 oil. Still slightly milky. I plan to switch to 25W40 over the next day or so. All the valves were re-adjusted to 3/4 turn past lash, according to manual (#1TDC--5 valves, then rotate engine 360 degrees and 3 remaining valves).

The knocking really sounds like valve train noise, based on other videos. Last night, I removed the valve cover and started the engine. I applied downward pressure on each rocker arm--no change. I then tighten each valve 1/4 turn, hoping to hear a change in sounds. No change. The only rocker arm that reacted to this adjustment in tension was #3 Intake valve. I also noticed more substantial oil spitting-up from the engine in this area. After a few minutes, oil began to stream about 2' in the air coming thru the push rod center hole. None of the other push rods are spewing oil. While tightening or loosening this particular rocker arm nut, the engine RPM would increase or decrease a bit. The valve appears to be moving up/down like the others. I suspect this valve is our problem, but not sure what to do next? Remove the head and reinspect all valves? Start exploring lifters?

I'd love to hear advice anyone can share. Thank you in advance.

 

[Scott Danforth]

knocking is bad. could be something simple, or the water in the oil took out a bearing

water in oil, specific cylinder #3 is a leaking exhaust manifold, pouring water into cylinder #3. the high compression is a tell-tale

is this a salt water boat?

pressure test the manifold, however you may have to remove it to do so

 

[kenny nunez]

You have a “pinhole” leak that is probably at the bottom of the water jacket that is the thinnest part of the block. Try to put some air pressure in the engine only to see if it will hold. That may help to diagnose wether it is the manifold or the block.

 

[Tahoe Charlie]

You have a “pinhole” leak that is probably at the bottom of the water jacket that is the thinnest part of the block. Try to put some air pressure in the engine only to see if it will hold. That may help to diagnose wether it is the manifold or the block.

Thanks for quick response and suggestion. What is the best method to put air pressure into engine? Thru #3 cylinder spark plug?

 

[Tahoe Charlie]

knocking is bad. could be something simple, or the water in the oil took out a bearing

water in oil, specific cylinder #3 is a leaking exhaust manifold, pouring water into cylinder #3. the high compression is a tell-tale

is this a salt water boat?

pressure test the manifold, however you may have to remove it to do so

Thanks for quick response! Manifold was checked for leaks with acetone, on bench. Acetone poured into water passages and level dropped about 1/8" after 30 minutes. No leak was visually recognized however. Now that compression in #3 has dropped most recently, does this still point to leaking manifold? Boat is strictly used in fresh water. I'm happy to pull manifold and check with pressure. How do I seal-off all the ports/passages?

 

[Scott Danforth]

you get creative on sealing off ports in the exhaust elbow, use the inlet hose to pressurize.

to pressure test the block like Kenny mentioned, you drain the water, plug the line to the manifold and from the drive, pressure test to 15 psi. it should hold forever.

 

[Tahoe Charlie]

OK--I'm in the process of becoming "creative" on my pressure tests, both on the engine and the manifold. I will test and report back this weekend.

Identifying the water entry is primary, but I still am worried about the knocking and valve behavior (RPM change, excess oil, etc). What is the explanation for the #3 cylinder valve behavior I experienced last night?

 

[Tahoe Charlie]

UPDATE:
Manifold: Manifold on the bench. Removed riser and carb and reinstalled these items with temporary rubber gasket. Capped 1" intake fitting. Pressured manifold thru 1/4" NPT fitting at bottom of manifold. Pressurized to 60 PSI, with entire manifold under water. No bubbles from emitted from intake or exhaust passages. Tiny bubbles from my rigged fittings of course. So I believe my manifold is good!?

Engine: Drained water from bottom quick-release fitting. Removed this fitting and installed 1/4" compressed air fitting. Blocked-off 1" fittings at t-stat housing. Introduced 20 PSI thru the 1/4" compressed air fitting near bottom of engine using a leak-down test rig. Checked for leaks with soapy water. Tightened a couple of clamps and then no more bubbles. Leak-down test rig is now disconnected from compressor, set at 20 psi. It dropped 1 PSI in the last hour. Waiting to see if this trend continues or levels out.

Have I done the above tests correctly?

 

[Tahoe Charlie]

Bump.
I would greatly appreciate getting some feedback on what I've done so far.
Thank you.

 

[Bondo]

Ayuh,...... Yer tests sound good,...... 60 psi is plenty high, I usually go 15, maybe 20,.....

 

[ibrw1]

Knocking sound more like cluck? Neighbor got water inside cylinder. Water does not compress. Connecting rods do. Lower compression may be due to reduced piston travel. Use fiber optic scope cheap at harbor freight. Stick it in spark plug hole. Sometimes people spray ether in carb to start engine. That cracks block. Then water leaks through hair line cracks. I’ve fixed 2 of these so far. Many things cause cracks, still lots of possibilities, low compression, followed with knock, Not good news. Rip off the bandaid. Summer is here. GOOD LUCK!

 

[ibrw1]

Anyway, the key here is to look for piston travel. Pull all plugs, possibly flash light, spin engine, look through spark plug opening. ensure piston reaches “max travel up” like others. Bearing spin and or bent connecting rod reduces Top Dead Center max travel. It’s fast easy test. Or, Pop the head off. You will notice difference with eyes.

 

[ibrw1]

[No message]

 

[achris]

quick-release fitting[/b]. ....

Another name for this fitting.... Block splitter....

If this is the method used to drain the block for winter, it's likely the block is cracked from water left in over winter and freezing. The ONLY way to correctly and fully drain a block is to remove the plug, let the water out, then pock and prod the hole with a nail or small screwdriver until ALL the water is out.... Anything less leaves water in there.

I'd be looking at the engine block as the chief suspect, just because of this 'quick release' fitting....

As for the knock, possibly a wiped bearing due to continuous water in the oil. Bearings really do not respond well to water....

The reaction of the valve adjustment on #3 can also be attributed to water... A gummed up, water damaged lifter...

Just my thoughts....

Chris......

 

[Tahoe Charlie]

Update:
Finally had time to put everything back together. Since the manifold and engine block tests were acceptable, I'm leaning towards water accumulation in the bilge, which is somehow getting into my oil. Boat is a Tahoe Q3 and the bilge area is small--wouldn't take much water to rise above oil pan gasket. My theory anyways...

I tried to restart engine, but got that awful starter grinding noise. Pulled starter. Bendix is worn along 2/3 of length of each tooth. Is this normal? Also 1 tooth is broken. Starter is relatively new (it is OEM, not aftermarket). We suspect our oil/water situation may have included a hydroloc and possible excessive wear on the starter. Starter motor itself bench-tests fine. Should I look for a local show to just replace bendix or just replace entire starter??

After looking at the ring gear, I see it is worn. Some teeth worse than others. Based on my other issues with the engine, I decided now was the time to pull the engine. It was much simpler than I expected.

Although my starter and ring gear are compromised, I'd still like to see if I can get the engine running on the stand, to help further diagnose my overall engine condition. No point buying another starter and new ring gear until I know I don't have very serious issues from the milky oil issues (again--see my post from last week).

How do I start a Mercruiser 3.0 (refurb 2008) on an engine stand?