Advice on Removal of manifold Mercruiser.

[YOBE]

Hi,

Engine Mercruiser 165HP, 6 cyl in-line from 1970's. Engine is in the boat.

To fix a crack I started removing the manifold. The nuts and bolts are removed and the manifold is "loose" from the block.
But I still have the U-shaped elbow that keeps it connected to the exhaust. I removed the 4 nuts but elbow still "sticks" to the manifold. If I gently try to "disconnect" the elbow from the manifold, will I be able to remove the manifold (with some twisting)? Or do I also need to disconnect the elbow from the rubber bellow. Looks like this is a relative stiff part. So wondering if I can twist it sufficient.

Just asking advice before disassembling too much stuff. These rubber bellow's are not always easy to put back on. Certainly with engine in boat.

 

[Scott06]

Hi,

Engine Mercruiser 165HP, 6 cyl in-line from 1970's. Engine is in the boat.

To fix a crack I started removing the manifold. The nuts and bolts are removed and the manifold is "loose" from the block.
But I still have the U-shaped elbow that keeps it connected to the exhaust. I removed the 4 nuts but elbow still "sticks" to the manifold. If I gently try to "disconnect" the elbow from the manifold, will I be able to remove the manifold (with some twisting)? Or do I also need to disconnect the elbow from the rubber bellow. Looks like this is a relative stiff part. So wondering if I can twist it sufficient.

Just asking advice before disassembling too much stuff. These rubber bellow's are not always easy to put back on. Certainly with engine in boat.

yes you have to separate the rubber bellows/exhaust connector from the elbow. Usually over years of heat the rubber gets stiff and it sticks to the elbow so some persuasion is needed.... loosen the upper clamps on the rubber drop them down and stick a flat screw driver pick etc to get the rubber loosened from the cast elbow. You may be able to spray some silicone or power tune in behind the rubber to lube it as you work your way around.

Then loosen the elbow from the manifold and remove. May need to carefully hammer a chisel in there to separate them. Usually the gasket is pretty glued on there. Again will require some personation, beer, and cursing...

where is the crack ? in the manifold or block? either way make sure it isn't into the crank case if its the block or the inside of the manifold as they will be junk if so.

 

[Bondo]

Ayuh,...... Use a hose pick to free the rubber boot from the riser/ elbow,......
To reinstall the rubber boot onto the riser/ elbow, squirt the rubber boot with Quicksilver Power Tune,......
It'll slip right back together,....

 

[YOBE]

yes you have to separate the rubber bellows/exhaust connector from the elbow. Usually over years of heat the rubber gets stiff and it sticks to the elbow so some persuasion is needed.... loosen the upper clamps on the rubber drop them down and stick a flat screw driver pick etc to get the rubber loosened from the cast elbow. You may be able to spray some silicone or power tune in behind the rubber to lube it as you work your way around.

Then loosen the elbow from the manifold and remove. May need to carefully hammer a chisel in there to separate them. Usually the gasket is pretty glued on there. Again will require some personation, beer, and cursing...

where is the crack ? in the manifold or block? either way make sure it isn't into the crank case if its the block or the inside of the manifold as they will be junk if so.

Okay, I know what to do. And I'm really interested to see why it has 2 clamps on each side.
Related to the crack, I saw it was repaired before and some water is leaking. Did compression test on all 6 cyl and measurements seemed fair to me. So I hope its just the water circuit.

 

[Bt Doctur]

couple of whacks with a dead blow hammer will work to free it up

 

[Lou C]

If the rubber exhaust are really stuck which can happen if there was a past overheat you can CAREFULLY heat them with a heat gun monitoring the temp with an IR temp gun, about 125* is hot enough. The double clamps are normal; this prevents leaks due to engine vibration & movement.

 

[Scott06]

Okay, I know what to do. And I'm really interested to see why it has 2 clamps on each side.
Related to the crack, I saw it was repaired before and some water is leaking. Did compression test on all 6 cyl and measurements seemed fair to me. So I hope its just the water circuit.

2 clamps is the factory set up.

On the crack so you used it and confirm no water is getting into the oil? these and the similar lineage 3.0 crack just below the manifold on head side when not drained. if you are lucky it doesnt go into the crankcase and you can make a halfway decent shade tree repair with epoxy. it will last for years if done reasonably well and if in fresh water it seeps a bit who cares...

 

[YOBE]

I believe to also saw a drain plug on the end of the elbow. Could this be right?
For the moment I am aware of 2 drains. The one on block (in the back) and also one on the bottom backside of the manifold.

 

[YOBE]

2 clamps is the factory set up.

On the crack so you used it and confirm no water is getting into the oil? these and the similar lineage 3.0 crack just below the manifold on head side when not drained. if you are lucky it doesnt go into the crankcase and you can make a halfway decent shade tree repair with epoxy. it will last for years if done reasonably well and if in fresh water it seeps a bit who cares...

But you're right. Still a risk that water can enter oil or vice versa. The original oil was milky :-(. But no clue at all how long it was in the engine.... We will see

 

[Scott Danforth]

But you're right. Still a risk that water can enter oil or vice versa. The original oil was milky :-(. But no clue at all how long it was in the engine.... We will see

Pull the motor, pull the pan and look

 

[Scott06]

But you're right. Still a risk that water can enter oil or vice versa. The original oil was milky :-(. But no clue at all how long it was in the engine.... We will see

So if you havent run it before investing a bunch into it I would pressure test the cooling system on the block. just block off the water in and out hoses to the block and rig up fittings to fit compressed air it should hold 15 psi or so.

 

[Scott06]

I believe to also saw a drain plug on the end of the elbow. Could this be right?
For the moment I am aware of 2 drains. The one on block (in the back) and also one on the bottom backside of the manifold.

those are the 2 drains for this engine