2001 Nautique GT-40 Engine Need Help

[ColeNautique]

Hi guys,

New to the forum and I'm coming in needing some opinions.

I have a 2001 Nautique with the 351W GT-40 motor with 300 hrs on it and I'm having some engine issues.

The story is that I bought the boat used, took it out and immediately noticed that it was running rough. Towed the boat home and figured out that it was a burnt valve so I had the head/ valve seats re-machined, and put it back in but now I am getting some excessive lifter noise that is not going away. It's coming from just one of the lifters and I'm wondering what the best thing to do is. I had a mechanic friend help me with the head and he's unavailable so I'm trying to diagnose/ fix this on my own.

The symptoms are as follows:

Tap is present from start up and is only audible at low RPM especially at idle. The noise goes away when any load is placed on the motor beyond just having the boat in gear then returns when I put the boat in neutral or the RPM drops down. The motor did not have this noise prior to the rebuild on the head. Anyone have any ideas? I was going to get in there and see if the push rod is bent but does anybody have any tricks to get that lifter to pump back up? I've tried liquimoly in the oil which helped a little but I'm concerned that if I leave it like this that I'll eventually bend a push rod or even flatten out the cam lobes.

Running SAE 40 Valvoline Racing Oil

Any suggestions or insight would be appreciated!

[Peter6000]

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If the valve was stuck it's very possible that a pushrod is bend. Did you check them prior to putting on the head?
The should be easy to get out just remove the rocker arm.
Check the manual I believe there is a way to test the valve play.

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[Gbracer]

you can try putting a qurt of atf in the oil if you have a stuck lifter this will work fairly quick and well.
You will have to change the oil after . good luck

[ColeNautique]

If the valve was stuck it's very possible that a pushrod is bend. Did you check them prior to putting on the head?
The should be easy to get out just remove the rocker arm.
Check the manual I believe there is a way to test the valve play.

Sent from my SAMSUNG-SM-G870A using Tapatalk

Just a visual inspection and none of them looked bent but I've heard that I need to roll them on a piece of glass to see. I'll check out the manual.

[ColeNautique]

you can try putting a qurt of atf in the oil if you have a stuck lifter this will work fairly quick and well.
You will have to change the oil after . good luck

Does that just clean out the passageways?

[Gbracer]

yes if you got some dirt or something in there it will clean out the muck aft has high detergents in it, it's a trick from auto world on old cars,

[ColeNautique]

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How long would you recommend running it through there? 5 minutes?

[Gbracer]

what was the outcome ?

[ColeNautique]

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So for me it was worst case scenario. I have a slightly wallowed out cylinder causing the knock. Sounds just like a noisy lifter but its the cylinder. The oil pressure drop was from the head/ block/ intake manifold not seating correctly. The motor was sucking oil in from the valley into the cylinders and burning it. Its back to running again with a light knock that I'll probably have to get rebuilt this winter

[Fast351]

Bummer. Good news is 351s are about as simple to rebuild as you can get.

I did it regularly on my race car. I have a (very old) article I did about it a long time ago:

http://www.fast351.com/cartech/enginerebuild/