Mercruiser 5.7 problems

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Thanks again all for the replies.
The manifolds and elbows are coming up to 5 years old, I would have to wait u til I next go down to the boat to check the log to see how many hours are on them but I would estimate somewhere in the region of about 100. All salt water use.

salt water and corrosion dont care if you used the motor or not. the 5 years in calendar time is the issue, not how many hours you did or did not use the boat.

Yes, easy peeze since you have closed cooling
Remove HE cap and install radiator pressure tester cap and pump it up

AD, I dont see where he has closed cooling. he stated he "ran up on antifreeze", which I take as Im trying to winterize by sucking AF up thru the muffs.
 

alldodge

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AD, I dont see where he has closed cooling. he stated he "ran up on antifreeze", which I take as Im trying to winterize by sucking AF up thru the muffs.

Your correct, was another thread

You can tell him how to check
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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pressure testing the cooling system is in the stickies.
 

alldodge

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Remove and plug hoses going to exhaust manifolds
Remove hose coming from drive at the thermostat housing and connect hand pump and gauge. Pump up to (15-20) psi and see if it holds
 

ukstu

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Nov 25, 2018
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Thanks all, Thanks AllDodge, before I start the strip down I will certainly do that.
wont be for a while now though. I will come back with results and some pictures of what is evident inside.
 

ukstu

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Nov 25, 2018
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Could i get some advice on gasket options, i have found these:
http://www.topspeedautomotive.co.uk...fel-pro-gasket-kit-set-small-block-chevy.html

Are they sufficient? i am unsure if they are car or marine, is there a difference?

These are what i have used in the past:
https://www.keypart.com/stock/18-1267

And i have just seen the sets in the iBoats page:
http://ww2.iboats.com/Chevy-Marine-...2486904--session_id.729438352--view_id.174851

Whats the general advice on this please? I want to fit decent gaskets in the hope that i don't get any further issues but at the same time i don't want to spend a fortune on them if there is no real difference?
Any links of recommended would be gratefully appreciated.
Thanks once again.
 

alldodge

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I recommend only FelPro Marine gaskets and which ones depends on if its stock or being bored

Standard Fel Pro 17230
 

ukstu

Seaman
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Nov 25, 2018
Messages
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Hello again all. Well i finally got the time to strip the engine down. Today, i pressure tested prior to stripping and all seemed ok. I inspected the manifolds and elbows and can see that i did have a slight leak on one of the connecting surfaces so will get those skimmed. I'm assuming this is the cause of water in Cyl 2. Condition of the manifolds is otherwise very good.

On removing the rocker covers, i have found that i have 3 exhaust valve springs cracked and one inlet. The cylinder with no compression was the one with both inlet and outlet cracked. They were all new springs last year!! Can anyone advise what would have caused these to crack?

Finally, as i expected, i still have major water mixing into the oil in the top of the 'V' under the inlet and under the rocker covers. It is thick thick milkshake, however, the oil in the sump is not bad at all.. Very confusing and i have no idea where it is coming from.

I've taken the inlet manifold, heads and exhaust manifolds to a head workshop to be inspected, skimmed, pressure tested etc

I did have a slight pass on the head gaskets but it only seemed to be between cylinders and not the water ways so i cannot for the life of me figure out where the water is coming from in the oil!

I realize this is potentially 2 separate problems (or not..?) but please please help me out as its starting to get the better of me and simply replacing the block / engine is not a financial option for me at the moment.

As always, thanks in advance for any advice!

Stu
 

ukstu

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I've added a couple of pictures, you can see how much gunk has accumulated after about 7 months use last year..

Also, please set me straight as its confusing me, the end port on picture 2, i assume is a water outlet from the inlet manifold, is it correct that this water discharges out over the top of cyl 1 & 2 exhaust valves into the exhaust manifold?
I have a hose in pic 3 which comes from the main water hose, splits off and supplies water to the inlet manifold.
 

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alldodge

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The end port on the head is the water cross over port into the intake manifold to the thermostat housing. The port in pic 3 is used for a water heater. Does the boat have a water heater?

I would look close at the bottom of the intake manifold for a crack. This is the most probable cause for water oil mix
 

ukstu

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So with that, is it correct that the water cross over is exiting straight over the exhaust valve on cyls 1 / 2?

Also, no engine does not have a water heater..?

Intake manifold is in for pressure testing and inspection now.

Thanks,
 

Bondo

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Also, please set me straight as its confusing me, the end port on picture 2, i assume is a water outlet from the inlet manifold, is it correct that this water discharges out over the top of cyl 1 & 2 exhaust valves into the exhaust manifold?

Ayuh,..... The water port in picture #2 is the water Outlet from the motor, which goes to the t-stat housin', where it's expelled to the exhaust manifold, or riser,.....

Other than through hoses, there are no water ports from the motor, to the exhaust manifolds,.....
 

ukstu

Seaman
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Nov 25, 2018
Messages
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Hey all, thought i would give an update on this, for no other reason as it may give some answers to others with similar issues further down the line.
Both heads and manifolds went into the cylinder head shop for inspection, all came back fine with the exception of one of the heads.
One of them had a crack. This will explain why i've been getting the water ingress. New head time and back together. Fingers crossed that will sort it.

Thanks to all for the input received.
 
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