how do I check for flapper valve parts in the transom housing

HI all:

I'm convinced I have broken off flapper valves stuck in the transom assembly on my engine and am looking for suggestions on how to determine if this is true.
twin 2001 5.7 2bbl with Alpha 1 Gen2.

the starboard engine overheated july 2017. not too bad though... I was doing a WOT test and was on the pins for about 4 min and the temp reached 200 and triggered the alarm so I shut it down.

to remedy the overheat condition I changed out the manifolds, risers, all hoses, water pump and flapper valves. overheat condition is gone and engine has run another 170 hours with no overheat condition.

when doing the manifold job I found that both petals of the starboard flapper was gone and one petal of the port flapper was gone. I reached down into the y but never found anything and nothing was in the outdrive either. Also there was blistering on the large rubber joints between the risers and the Y pipe indicating the high temp.

ever since that day the engine has started rougher and smoked black smoke on start up and refuses to run to WOT either under weigh or at idle. the risers on the starboard motor are also noticeably hotter than the port engine. too hot to keep your hand on. The port motor never gets too hot to hold your hand on.

Once warmed up however and when run at normal cruising speeds the starboard engine never misses a beat and performs flawlessly

I just pulled the boat for the winter and ran it on muffs to flush it. there was a lot of black smoke till it warmed up and it took forever for water to come out of the two exists on the transom assembly and when it did come out it was only a trickle. the port engine on the other hand pumped lots of water out all opening within a few seconds of starting.

at this point I believe that my missing flapper valves are restricting exhaust somewhere in the transom assembly.

I have the outdrives removed now and still can't see antthing. I can reach my hand down the Y pipe till it bends aft. there's only about 12" of the transom assembly that I can't feel or see and I believe my 3 missing petals are in there.

Love to hear your recommendations on how to dermine if this is true and if so how to remove (is this an engine out situation?)

thanks
John

Look into both sides of the Y-pipe with a bore-scope.

Pull the prop and see if they are behind the prop and adjust the choke a bit leaner ,(more open when cold)

................

outobie said:

I'm convinced I have broken off flapper valves stuck in the transom assembly on my engine and am looking for suggestions on how to determine if this is true.
twin 2001 5.7 2bbl with Alpha 1 Gen2.
Like I suggested earlier, use a bore scope.

Also there was blistering on the large rubber joints between the Elbows and the Y pipe indicating the high temp.
These should be replaced!

ever since that day the engine has started rougher and smoked black smoke on start up and refuses to run to WOT either under weigh or at idle. the Elbows on the starboard motor are also noticeably hotter than the port engine. too hot to keep your hand on. The port motor never gets too hot to hold your hand on.
You likely have a restriction somewhere within the "spent" seawater side of the system.

I just pulled the boat for the winter and ran it on muffs to flush it. there was a lot of black smoke till it warmed up and it took forever for water to come out of the two exists on the transom assembly and when it did come out it was only a trickle. the port engine on the other hand pumped lots of water out all opening within a few seconds of starting.
You may have an issue with the seawater pump system on the Stbd side.

at this point I believe that my missing flapper valves are restricting exhaust somewhere in the transom assembly.
I have the outdrives removed now and still can't see antthing. I can reach my hand down the Y pipe till it bends aft. there's only about 12" of the transom assembly that I can't feel or see and I believe my 3 missing petals are in there.
Again..... go into the Y-pipe as far as you can with a bore scope.


John

Click to expand...

outobie said:

HI all:

I'm convinced I have broken off flapper valves stuck in the transom assembly on my engine and am looking for suggestions on how to determine if this is true.
twin 2001 5.7 2bbl with Alpha 1 Gen2.

the starboard engine overheated july 2017. not too bad though... I was doing a WOT test and was on the pins for about 4 min and the temp reached 200 and triggered the alarm so I shut it down.

to remedy the overheat condition I changed out the manifolds, risers, all hoses, water pump and flapper valves. overheat condition is gone and engine has run another 170 hours with no overheat condition.

when doing the manifold job I found that both petals of the starboard flapper was gone and one petal of the port flapper was gone. I reached down into the y but never found anything and nothing was in the outdrive either. Also there was blistering on the large rubber joints between the risers and the Y pipe indicating the high temp.

ever since that day the engine has started rougher and smoked black smoke on start up and refuses to run to WOT either under weigh or at idle. the risers on the starboard motor are also noticeably hotter than the port engine. too hot to keep your hand on. The port motor never gets too hot to hold your hand on.

Once warmed up however and when run at normal cruising speeds the starboard engine never misses a beat and performs flawlessly

I just pulled the boat for the winter and ran it on muffs to flush it. there was a lot of black smoke till it warmed up and it took forever for water to come out of the two exists on the transom assembly and when it did come out it was only a trickle. the port engine on the other hand pumped lots of water out all opening within a few seconds of starting.

at this point I believe that my missing flapper valves are restricting exhaust somewhere in the transom assembly.

I have the outdrives removed now and still can't see antthing. I can reach my hand down the Y pipe till it bends aft. there's only about 12" of the transom assembly that I can't feel or see and I believe my 3 missing petals are in there.

Love to hear your recommendations on how to dermine if this is true and if so how to remove (is this an engine out situation?)

thanks
John

Click to expand...

Boats on the hard....Pull the drive. Look in the pipe from the drive side, look in the drive, if you do not find what you are looking for, separate the drive and inspect the water dam, the filler block and the lower housing under the pump. If it looks like this,

You need a new lower unit.

Who manufactured the pump that you installed? Did you change the seal carrier (the yellow part in my picture) when you changed the pump?

Why yes my drive does have corroded dam exactly like that

noticed it it when I had the water pumps replaced

oem mercruiser by by the way. The mechanic and I discussed st the time and we used some sort of sealant there which still looks intact and not leaking.

can you explain to me what you think is going on so I can understand better

ive not been able to wrap my head around this

A bote scope is on my Christmas list��

all burned parts were replaced. The drives are off for the winter so I was thinking I’d try to use the bore scope from the drive side first.

outobie said:

Why yes my drive does have corroded dam exactly like that

noticed it it when I had the water pumps replaced

oem mercruiser by by the way. The mechanic and I discussed st the time and we used some sort of sealant there which still looks intact and not leaking.

can you explain to me what you think is going on so I can understand better

ive not been able to wrap my head around this

Click to expand...

When the water dam rots it lets exhaust gasses into the cooling water stream and puts air pockets in the engine block that will give you erratic temp readings and will crack a cylinder head.

It does not matter how much sealer you put on it. The lower case needs to be replaces.

What does the plastic filler dam and rubber block look like?

This is the first thing you repair when you have a cooling issue.

No, you cannot weld it or add more sealer.

Docksidemarineservices said:

When the water dam rots it lets exhaust gasses into the cooling water stream and puts air pockets in the engine block that will give you erratic temp readings and will crack a cylinder head.

It does not matter how much sealer you put on it. The lower case needs to be replaces.

What does the plastic filler dam and rubber block look like?

This is the first thing you repair when you have a cooling issue.

No, you cannot weld it or add more sealer.

Click to expand...

the thing that is difficult to comprehend is that there is an open cavity above this that connects the same chambers...why is it important to seal hear when it's open above it?

my drives didn't come with the rubber blocks...we added them when we identified this issue last year along with the sealant per a service bulletin we found. the plastic dam is intact and looks fine to me.

would you think this is the primary cause of my rough running issues or only related?

also do you have any thoughts on where to source a replacement...2001 Alpha one Gen 2 drive for a 5.7 with 1.47 gears?

I'm convinced I have broken off flapper valves stuck in the transom assembly on my engine and am looking for suggestions on how to determine if this is true.
twin 2001 5.7 2bbl with Alpha 1 Gen2.
Like I suggested earlier, use a bore scope.

I have one on order and will do

Also there was blistering on the large rubber joints between the Elbows and the Y pipe indicating the high temp.
These should be replaced!

This was done when manifolds were done

ever since that day the engine has started rougher and smoked black smoke on start up and refuses to run to WOT either under weigh or at idle. the Elbows on the starboard motor are also noticeably hotter than the port engine. too hot to keep your hand on. The port motor never gets too hot to hold your hand on.
You likely have a restriction somewhere within the "spent" seawater side of the system.

Can you direct me more specifically...on where to look

I just pulled the boat for the winter and ran it on muffs to flush it. there was a lot of black smoke till it warmed up and it took forever for water to come out of the two exists on the transom assembly and when it did come out it was only a trickle. the port engine on the other hand pumped lots of water out all opening within a few seconds of starting.
You may have an issue with the seawater pump system on the Stbd side.

please help me understand terminology a bit better. "seawater pump"...is that the one in the outdrive (which is new but has the drive corrosion issue mentioned above) or the the one I normally call the water circulating pump on the front of the engine.

at this point I believe that my missing flapper valves are restricting exhaust somewhere in the transom assembly.
I have the outdrives removed now and still can't see antthing. I can reach my hand down the Y pipe till it bends aft. there's only about 12" of the transom assembly that I can't feel or see and I believe my 3 missing petals are in there.
Again..... go into the Y-pipe as far as you can with a bore scope.


Roger that will do

outobie said:

Why yes my drive does have corroded dam exactly like that

noticed it it when I had the water pumps replaced

oem mercruiser by by the way. The mechanic and I discussed st the time and we used some sort of sealant there which still looks intact and not leaking.

can you explain to me what you think is going on so I can understand better

ive not been able to wrap my head around this

Click to expand...

here's mine from last year before replacing water pump

"I just pulled the boat for the winter and ran it on muffs to flush it. there was a lot of black smoke till it warmed up and it took forever for water to come out of the two exists on the transom assembly and when it did come out it was only a trickle. the port engine on the other hand pumped lots of water out all opening within a few seconds of starting."


Your staring issue with black smoke is most likely carb issues. Choke closed or not set up correctly. Black smoke is un-burnt fuel and/or too much of it.

There are basically three things that drive over heat or hot issues.

1. water coming in, impeller, blockage.

2. thermostat housing, rust, thermostat, diverter if there is one and it is missing or installed incorrectly, hoses routed wrong.

3. elbows, Heavily corroded bad or incorrect gaskets.


Manifolds can be a factor but not as often as elbows except at the gasket area due to corrosion/gaskets issues.

As far as the flappers missing go. There is a lot of free space and if the drive is removed and they are not visible then most likely they are not your issue.

If they were rubber coated metal flappers the metal portion should have remained. The rubber portion most likely melted and was flushed out the exhaust.

If they were plastic with rubber then a similar situation could have occurred and they melted and simply were flushed out.

200 degrees is not a catastrophic failure and should not have damaged much if anything. What was the root cause of the over heat? did you ever find out?

WHat Chris refers to is very important and should not be taken lightly. Exhaust entering the fresh water stream can cause a lot of damage to the engine.

Typically though the engine would get hotter as rpm increases as less water as displaced by exhaust air bubbles would occur.

A bore scope will not solve anything here. Stupid suggestion for this issue.

The "rams horn" exhaust is ~ 3-4 inches in diameter. for both sides. It joins at the bottom and and there is a lot of space for exhaust to flow.

99% of the time where the drive bolts to the bell housing is where you would find the "missing" parts. If not there and they found there way further and then they would be in the drive exhaust cavity. Then you split the upper and lower half's have a good look and use air and or water to flush or a wire to prod.


Even if the "missing parts shut down the exhaust water path at the drive/bell housing the exhaust can easily escape at the two holes at the transom assembly as so many have asked if this is correct when watching while on a hose..........


If one side of exhaust (elbows) is that much hotter then the other then you have a water flow issues.

Either incoming issue as in, not enough, exhaust bubbles or simply air bubbles, elbow blockage, thermostat housing hose routing issues or thermostat housing internal issues such as rust or a large flake of the housing is floating around and blocking water flow (SEEN THIS MANY TIMES especially with salty dogs),

One side is and can typically be 20-30 degrees hotter and that is normal.

There have been no more overheat issues. There was only the one minor (just nudged 200 degrees and triggered the alarm) overheat in July 2017. At the time of the overheat the water pumps were new. I determined the root cause to have been the heavily scaled risers. The joint between riser and manifold was about 70% blocked with scale. The tail end of the risers literally fell apart in my hand when I took them off. I guess they were past their life expectancy by quite a bit at 16 years of service on the Chesapeake Bay J in hind sight perhaps the corroded dame in the outdrive was also a contributing factor. After the overheat I replaced the following parts on both motors with OEM Mercruiser parts (they were all original parts from 2001).

• Exhaust manifolds
• Exhaust elbows
• All hoses on motor including large 6” couplers from elbows to bends to Y pipes (8 of them, 4 per engine)
• Thermostats
• Rubber coated flapper valves
• Hoses thermostat housing to manifolds, and to the transom assembly and to the steering cooler…everything on the engine that was rubber is new.
• New water pumps in the outdrives

Maintenance done in the last 18 months unrelated to overheat

• New serpentine belts
• New fuel pumps
• Several rounds of new fuel filters and oil filter/changes (about 250 engine hours logged in this timeframe)
• Carb rebuilds done by Carburetor Spe******ts in Alpharetta, GA
  • When I installed them the choke setting was not set to factory spec so I adjusted per the OEM manual
  • Choke seems to open and close as expected
• New Alternator
• New Bellows
• New plugs (Champion)
• New distributor cap, rotor, ignition trigger
• Engines winterized twice with all block drains picked out (there was a good bit of scale that came out of lower block drains…had to remove bronze block where Knock sensor and blue plastic block drain attach to pick it all out.

I am highly confident there are no issue with assembly of hoses or diverters, etc…both motors were done one at a time with the other as reference in addition to following OEM shop manual step by step.
On the Starboard engine, the starboard riser is slightly hotter than the port riser but both are significantly warmer than those on the port engine. On the port engine you can keep you hand on both side risers. On the starboard engine you cannot keep you hand on either side riser.

The drive is unbolted from the transom assembly now leaving the bellows and the pivoting part still attached to the hull. I cannot reach my hand into the bellows to feel anything or see anthing.
The two holes at the transom assembly don’t appear to flow much water at all as compared to the port engine. That’s what I was thinking perhaps the flappers were obstructing flow there. The outdrive has been split in half since the overheat and there are no pieces of the flappers in there.

1. Either incoming issue as in,
   1. not enough,

This is something that I have not ruled out…the water pump is new but there may be other issues

1. exhaust bubbles

I have not ruled this out

1. or simply air bubbles,

How is this different from exhaust bubbles?

1. elbow blockage,

I don’t believe this to be the case as they are new last year

1. thermostat housing hose routing issues or

I don’t believe this to be the issue as they hoses are routed the same way they came off and the same as the port engine

1. thermostat housing internal issues
   1. such as rust or

I don’t believe this to be the case…I’ve had the thermostat housing off and cleaned and inspected it…slightly pitted but otherwise servicable

1. a large flake of the housing is floating around and blocking water flow (SEEN THIS MANY TIMES especially with salty dogs),

Where would I look for this?


At the moment my plan of attack is to:

1. check the two transom outlets and main exhaust passage for blockage
2. replace plugs and do a compression test
3. ??? maybe look at the carb again? But it runs perfect once warmed just won’t get to WOT
4. ??? How can I test to see if the corrosion on the outdrive is causing my issues without dropping lots of $ on a new outdrive?

At the moment my plan of attack is to:

1 check the two transom outlets and main exhaust passage for blockage
2 replace plugs and do a compression test
3 ??? maybe look at the carb again? But it runs perfect once warmed just won’t get to WOT
4 ??? How can I test to see if the corrosion on the outdrive is causing my issues without dropping lots of $ on a new outdrive?

1 . Yes check this.........

2, good to know but not probable for heat issue, if it was fine before and ran to WOT then maybe plugs could be suspect. Make sure they are the correct plug and gapped properly

3.One thing to check is visual on both carbs when WOT with flame arrestors off. See if secondaries are open equally. throttle plate butterfly open 90*/equal between engines and upper butterfly (which is opened by vacuum) are equal and secondary rods are up the same distance. Some may be visual without running but if you are not experienced in looking for this it may it may be easier to running. NOT IN NEUTRAL, under load!!

4 Swap drives...........may make boat act/steer weird but if out in open water it may give you the results needed after a short run.

If all this gives no changes then I would say look at the power steering cooler in line in the incoming water hose and see if blockage.
Pull elbows and see if rust flakes may have caused the water passages to clog. you will need new gaskets......

for the record. A riser is a spacer between the exhaust manifold and the elbow. it is called an elbow because it bends 90* like you arm!!!!!!!!!!!!!! Like a elbow used in plumbing (90*).........

if you have risers then they also can be suspect along with the wrong gaskets used.

If all the water is flowing out the prop vs the two transom holes then possibly the holes could be blocked.
If the total volume is different than the other engine then you most likely have a flow issue either in or out..........

Are these Alpha drives or Bravo drives? I assume they are alpha's based on water pump impeller in the drives and the dam in picture..........just want to be sure because some bravos use the drive pick up and deliver incoming water to onboard engine driven impeller in a similar path, thru transom then by transom hose to to impeller housing. Just making sure

See pic attached.

found a used lower drive in great shape...installed and waiting for spring...I scoped the exhaust and found nothing.
after de-winterizing I'll deal with tuning the carb.