RE: Issues with Mercruiser 5.0 LX 4 Barrel Carb

[tank1949]

Hello Guys:
Todays Updates... I've had an inspection camera down both sides of the Exhaust Y Piece/Bullhorn and they appear clear.

I've flushed the Bull Horn with Water and Flow is good out the rear of the Alpha Drive Unit. Not saying this is definitive, but its the best I can do at Home currently.

Compression Test Results however are a little bit more disappointing.
Right Side (Front Front of Boat)
Cylinder 1 : 130PSI
Cylinder 3: 50PSI
Cylinder 5: 120PSI
Cylinder 7: 120PSI
Left Side (From Front of Boat)
Cylinder 2: 110PSI
Cylinder 4: 110PSI
Cylinder 6: 115PSI
Cylinder 8 :120PSI

Obviously they are a little low to begin with, however Cylinder 3 is the big concern.

Just in terms of Testing Method to confirm I did the Compression Test with
- All Spark Plugs Removed
- Ignition Leads Isolated in Seperate Plastic Zip Lock Bags Cable Tied
- Carb etc was still connected so Some Fuel was exiting Exhaust Manifolds at Cylinders 7 & 8

(As Both Exhaust Manifolds/Risers are currently removed)

It would be difficult unless checking for leaks, but older y pipes need replacing. "Cancer" eats them at the transom connection.

 

[Bt Doctur]

First, fix the temp gauge and sender or it will just happen again. The "not able to shift" is most likely a melted shift cable where is passed around the Y pipe.

 

[BusinessConnected]

Just an update guys:
I've replaced Intake Manifold/Head Gaskets and Compression is still low on Cylinder 3.

Others have come up to around 120-130 PSI... Cylinder 3 is still 60PSI Unfortunately.

I'm a bit up in the air about the Next Step etc... Seems a little pointless fitting the Replacement Exhaust Manifold/Risers etc when I have the issue with Cylinder 3.

I've replaced Engine Water Pump (Old one was severely corroded) and have New Temp Senders etc arriving shortly also.

 

[stresspoint]

i am assuming you did do a valve leak down test whilst the heads were off ?.

how did the cylinders look ? glazed or lost x scratching . over heat can cause glazing and lower compression ."however' to drop compression that low and after a gasket change still having low comp would indicate compression rings have gone bad on that # 3 cylinder.

there are 3 ways to go about this , providing the valve leak test was done and passed on that real bad cylinder #1 , replace the motor #2 , remove the motor and give it a birthday (rings bearings ,hone , etc) . #3 take a chance and run it with low comp , hope it runs fine without a miss and just lacks power.

 

[BusinessConnected]

Guys:
Just an update again now...
I've managed to get the Boat all back together with a bit of a delay as I didn't realise I needed Riser Extensions (Which I needed to get shipped to me).

Anyhow Boat Engine is all back together and starts and runs well.. Idles fine.

I've got 2 remaining issues of which the first is most pressing/concerning
1) Alpha One Gen 2 Impeller doesn't seem to be pushing water. I've disconnected the Inlet Hose from the Thermostat Housing and left it "Lower" Down trying to see if Water is coming through but it never seems to come through.

I've dropped the Lower Leg Unit and confirmed the Impeller is Seated Properly etc.. Seems fine and moves freely etc. Confirmed the "Key" is latched against the Drive Shaft etc..

Whilst the Lower Leg was down I've connected a Garden Hose Directly to the Impeller Pump Inlet Inside the Upper Leg Unit and that will flow out the Inlet Hose inside the Boat.

I've also flushed it back the Other way and Water flows out Inlet Holes etc on Lower Gear Unit etc.

Any Ideas short of getting another Impeller Rebuild Kit etc?
Also silly question... Should the Impeller work at Idle out of Gear?

2) Shifting Into Forward or Reverse doesn't operate smoothy when Idling on Muffs. If I attempt to Shift into Gear it basically cuts out and Stalls. However if I do it "Harder" into a Higher Rev Range it works and then operates fine...

Appreciate your help guys..

 

[Scott Danforth]

get a whole pump kit, not just the impeller

if the motor is running, the impeller should be turning. unless of course, you have a bad coupler, you broke the upper gear teeth, or you broke a shaft.

 

[Scott06]

Guys:
Just an update again now...
I've managed to get the Boat all back together with a bit of a delay as I didn't realise I needed Riser Extensions (Which I needed to get shipped to me).

Anyhow Boat Engine is all back together and starts and runs well.. Idles fine.

I've got 2 remaining issues of which the first is most pressing/concerning
1) Alpha One Gen 2 Impeller doesn't seem to be pushing water. I've disconnected the Inlet Hose from the Thermostat Housing and left it "Lower" Down trying to see if Water is coming through but it never seems to come through.

I've dropped the Lower Leg Unit and confirmed the Impeller is Seated Properly etc.. Seems fine and moves freely etc. Confirmed the "Key" is latched against the Drive Shaft etc..

Whilst the Lower Leg was down I've connected a Garden Hose Directly to the Impeller Pump Inlet Inside the Upper Leg Unit and that will flow out the Inlet Hose inside the Boat.

I've also flushed it back the Other way and Water flows out Inlet Holes etc on Lower Gear Unit etc.

Any Ideas short of getting another Impeller Rebuild Kit etc?
Also silly question... Should the Impeller work at Idle out of Gear?

2) Shifting Into Forward or Reverse doesn't operate smoothy when Idling on Muffs. If I attempt to Shift into Gear it basically cuts out and Stalls. However if I do it "Harder" into a Higher Rev Range it works and then operates fine...

Appreciate your help guys..

On the not pumping of water. Would check that impeller vanes are not spinning on center hub, common defect seen with cheap aftermarket pumps. The oem merc pumps last a long time dont waste money on anything else. Verify the key that locks impeller to shaft is in place, as its easy to miss when reassembling. Also check water tube coming off pump was in place in water pocket in upper drive. If this was not in place you would have a bunch of water coming out of pump area of drive when running on muffs.

yes the pump should be pumping any time engine is running. On an alpha the vertical drive shaft is turning when in neutral. Only the prop shaft is not turning in neutral.

on the shifting into gear if its dying going into gear likely the shift interrupter is being tripped, you can disconnect to verify. This should never be getting tripped on dry land, only in water when there is load on the prop. If this happens on dry land it is evidence of something hanging up and creating drag. Normal areas of concern are worn shift cable, misaligned or bent shift mechanism from forcing drive on or corrosion to shift swivel and linakge in bell housing. If you remove lower shift cable from shift plate you should be able to mive shift cable and shift withjust two fingers on the shift cable , if not pull drive and see where things are getting hung up. A factory merc manual is very helpful for these items

 

[stresspoint]

just wondering if the O ring where the drive joins may have been dislodged or not put in .

 

[stresspoint]

as for the cutting when shifting , is it possible for that to happen if the shift mechanisim didn't locate to the cable when fitting the drive .

 

[BusinessConnected]

I've purchased the complete kit below when we replaced the Impeller.

Mercruiser ALPHA ONE (GEN.II) Pump Kit With Housing 817275Q05 Replacement

Mercruiser Water Pump Repair Kit 817275Q05 Replacement Replaces Mercruiser 817275A4, 817275A5, 817275K05, 817275Q05, 817275Q4, 817275T4, 847275A5 Water pump kit for Mercruiser Alpha 1 Gen 2 drives. Alpha I - Generation II . Rubber Gasket on face plate 8172761. Includes carrier seal 807929a1...

marinepetrolparts.com.au

Obviously it's not the easiest process to confirm the Water Hose has connected with the Internal Receptacle, but definitely second time around that seems to be the case.

Not sure if you have any particular way/method of ensuring its lodging correctly.

"just wondering if the O ring where the drive joins may have been dislodged or not put in "
Not sure exactly what you are referring to with this comment itself..

I'm not massively concerned about the Shifting Issues... I feel this is more likely an alignment/adjustment issue because I've had the Shift Cable off the Engine Risers etc when I was replacing Head Gasket/Intake Manifold etc..

I'll approach that issue once I have some Water Pumping!!!

 

[Scott06]

I've purchased the complete kit below when we replaced the Impeller.

Mercruiser ALPHA ONE (GEN.II) Pump Kit With Housing 817275Q05 Replacement

Mercruiser Water Pump Repair Kit 817275Q05 Replacement Replaces Mercruiser 817275A4, 817275A5, 817275K05, 817275Q05, 817275Q4, 817275T4, 847275A5 Water pump kit for Mercruiser Alpha 1 Gen 2 drives. Alpha I - Generation II . Rubber Gasket on face plate 8172761. Includes carrier seal 807929a1...

marinepetrolparts.com.au

Obviously it's not the easiest process to confirm the Water Hose has connected with the Internal Receptacle, but definitely second time around that seems to be the case.

Not sure if you have any particular way/method of ensuring its lodging correctly.

"just wondering if the O ring where the drive joins may have been dislodged or not put in "
Not sure exactly what you are referring to with this comment itself..

I'm not massively concerned about the Shifting Issues... I feel this is more likely an alignment/adjustment issue because I've had the Shift Cable off the Engine Risers etc when I was replacing Head Gasket/Intake Manifold etc..

I'll approach that issue once I have some Water Pumping!!!

Stop buying non oem water pump parts way too many issues with them.

 

[stresspoint]

I've purchased the complete kit below when we replaced the Impeller.

Mercruiser ALPHA ONE (GEN.II) Pump Kit With Housing 817275Q05 Replacement

Mercruiser Water Pump Repair Kit 817275Q05 Replacement Replaces Mercruiser 817275A4, 817275A5, 817275K05, 817275Q05, 817275Q4, 817275T4, 847275A5 Water pump kit for Mercruiser Alpha 1 Gen 2 drives. Alpha I - Generation II . Rubber Gasket on face plate 8172761. Includes carrier seal 807929a1...

marinepetrolparts.com.au

Obviously it's not the easiest process to confirm the Water Hose has connected with the Internal Receptacle, but definitely second time around that seems to be the case.

Not sure if you have any particular way/method of ensuring its lodging correctly.

"just wondering if the O ring where the drive joins may have been dislodged or not put in "
Not sure exactly what you are referring to with this comment itself..

I'm not massively concerned about the Shifting Issues... I feel this is more likely an alignment/adjustment issue because I've had the Shift Cable off the Engine Risers etc when I was replacing Head Gasket/Intake Manifold etc..

I'll approach that issue once I have some Water Pumping!!!

the O ring can be seen in the lower part of the pic i posted , it needs to be glued in place before you put the drive on or it falls off , even with glue it can still dislodge .
i found the use of contact adhesive to do the trick.

when you locate the cable in the holder it should be pulled toward you with the shifter in forward gear,(opposite to the pic as that is in reverse gear) the recess at the bottom should be strait to accept the shift arm jigger from the drive.( i will see if i have a pic )

 

[BusinessConnected]

Stop buying non oem water pump parts way too many issues with them.

Hence why I'm bought the genuine QuickSilver Kit now... Not aftermarket.. That was just what I had originally.

 

[BusinessConnected]

the O ring can be seen in the lower part of the pic i posted , it needs to be glued in place before you put the drive on or it falls off , even with glue it can still dislodge .
i found the use of contact adhesive to do the trick.

when you locate the cable in the holder it should be pulled toward you with the shifter in forward gear,(opposite to the pic as that is in reverse gear) the recess at the bottom should be strait to accept the shift arm jigger from the drive.( i will see if i have a pic )

Stresspoint bit confused about this O-Ring you're referring to..
I have the Alpha One Gen 2 Unit that looks like the Image Below (This isn't my particular unit... just a similar image for same unit).

 

[dubs283]

Stresspoint bit confused about this O-Ring you're referring to..

Its the one on the bell housing between the water outlet port on the drive and the bell housing. Which if misplaced or missing would leak at that seam, but probably still pump water up to the t Stat housing.

Like others have said you most likely have a melted lower shift cable and that is what is preventing a sound shift f/n/r.

As to not pumping water I would venture to say based on provided info there is a water tube issue between the drive halves, broken upper gears in the drive or a spun engine coupler

Low compression on 3 would indicate a tuliped valve

 

[stresspoint]

Its the one on the bell housing between the water outlet port on the drive and the bell housing. Which if misplaced or missing would leak at that seam, but probably still pump water up to the t Stat housing.

Like others have said you most likely have a melted lower shift cable and that is what is preventing a sound shift f/n/r.

As to not pumping water I would venture to say based on provided info there is a water tube issue between the drive halves, broken upper gears in the drive or a spun engine coupler

Low compression on 3 would indicate a tuliped valve

i got a call from a mate that had just completed his drive replacement telling me he is getting no water to the engine when the boat is in the water.
went with him to take a look and it was also struggling to get water to the Tstat on the muffs , turned out the O ring had slipped half way and got squashed.
so guessing there is a possibility that it may still get water up that far or not depending on if it is gone completely or just dislodged.
pic is for demo where the Oring is located

 

[Scott Danforth]

Holy corrosion in o-ring groove batman

 

[Lou C]

looks worse than mine, which has been in salt water 6 months of the year, for around 16/17 seasons!

 

[BusinessConnected]

Ok... after some further ready of the schematics we might have managed to determine our problem.
Because when we pulled our Lower Unit and all the Water Items were melted etc we didn't see/know how it was put together.

Basically we were running the Wrong Plastic Joiner Hose between the Upper and Lower Unit. It was too short and Water wasn't reaching the Inlet on the Upper Unit.

Anyhow We've now replaced that with the Correct Tube and Water is pumping great again.

Now just looking into adjustment on Gear Shift Cable now..

 

[dubs283]

Now just looking into adjustment on Gear Shift Cable now..

Check for melting where the lower cable runs next to the exhaust

May be time to replace it, they're good for 5-10 years on average