Effects of momentarily deadheading impeller pump?

[Boomyal]

Here is the deal. I recently posted regarding water puddles in the opening of my exhaust manifold ports. It did appear to be small puddles in the front six cylinders. This occured uniformly on both sides. After much fretting, questions and pressure testing the mani's, the conclusion was that a small amount of water was reverting from the *ss end of the mani's.

It was also stated that Merc had put out a bulletin that recommended that you run the motor up to fast idle before shutting down, to blow out any water that had come in the back door.

I suppose that that is probably an effective method but I had another idea. What if I installed a ball valve on the line from the impeller to the heat exchanger and shut it off 15 seconds before I killed the motor. Whether on the hose or in the water the impeller would stay wet, albeit deadheaded while the the mani's would go dry, allowing any reverted water to be blown out with the exhaust.

What say y'all?

 

[Don S]

Re: Effects of momentarily deadheading impeller pump?

I would stick with the recommended method. Putting a valve in there that you have to shut off and turn on is going to be a lot more hassle than just running the engine at 12 or 1500 rpm for a few seconds.
Besides. That time without water is hard on all those exhaust hoses that would be without cooling water for 15 seconds everytime you shut the engine off.

 

[Don S]

Re: Effects of momentarily deadheading impeller pump?

One other note about running at 1200.
That was something that came out with the Vortec engines due to the increased valve overlap. Your 302 shouldn't be suffering from that problem.

It did appear to be small puddles in the front six cylinders.

How many cylinders do you have, that you have 6 front ones?????8)

 

[Boomyal]

Re: Effects of momentarily deadheading impeller pump?

It's a V????? exotic. Come on now. It is a VEIGHT. It has 4 cyl's on the left and 4 cyl's on the right. If you are right minded (Fooooooooooooooord), the front six cylinders are #'s 1,2,3 on the right and 5,6,7 on the left.

Originally the water puddling in those front six was a mystery. With all of the input on the subject and my Sherlockian powers of deduction I figured that the back two cylinders (#'s 4 & 8) were dry because the boat was always signifigantly bow down when I had the outdrive lowered to run off the hose, at idle, on the trailer.

This of course, Dr. Watson, left the rear two cylinders high and dry.

As to valve overlap (or LSA?), I think that is the root of my issue. In seeking to push the limits of marine tolerance, in my post theft 302, I used a rather aggressively torquey, pre-smog factory automotive grind to orchestrate my motor. Point being, I am not running a stock OMC 302 351 firing order camshaft.

I'd like to think that I have bested the GM Vortec, whose specs they heralded 10 years after Foooooooooord employed them.

All that being said, I will heed the advice in your previous post.

 

[mercrewser]

Re: Effects of momentarily deadheading impeller pump?

I think you need to put the right cam in there before you ruin your motor.

 

[JasonB]

Re: Effects of momentarily deadheading impeller pump?

Hmm, with the cam in my 302, I think I'll follow Merc's bulletin.