1990 7.4 winterization?

[ericcarr2000]

Ok, I have a question regarding the winterization of my 1990 7.4 motor. While winterizing her this past fall, I had noticed that while I was spraying the fogging fluid into the throat of the carb that the motor wouldn't die or bog down. I guess my question is is this normal or should it have bogged down?This is the first time I've winterized this particular motor and it has approximately 910 hours on her. She runs good.

 

[Chad Flaugher]

I assume the engines you've fogged in the past were smaller... I'm no expert, but I will say this. I have a 5.0 in my boat, and I was surprised how much it took to bog her down. When I fog my small stuff, it's almost instant. My theory is a simple grasp at what seems to be obvious. That 454 big block of yours consumes a massive amount of fuel and air during combustion, and a little fogging oil isn't enough to choke her out. If it makes you feel better, hit it with two cans at the same time until she slows, then have your helper cut the motor while your spraying.

Now I hear two sides to this part. I've heard to actually kill the motor with the fog, but I do not agree this. This practice could lead to severe engine damage through hydro locking. The method I agree with and practice is... Bring the idle up to about 1,500 rpm, bog the motor down to about 750 rpm, and have a helper kill the motor. Keep spraying until the motor stops.

 

[ericcarr2000]

Yeah my last motor I had was the infamous mercruiser 3.7. I know this big block takes a lot more fuel & air. When I fogged her, I had her idling then sprayed the fogging oil into her for approximately 10 or so straight seconds. I assumed from my 3.7 motor it should have bogged her out... I guess I was wrong, lol

 

[tpenfield]

I could never get my 7.4L Mercruiser (1991) to bog/stall with fogging oil. I even sprayed 2 cans at once and it would not die at the slowest idle. I saw a mechanic kill it once, but he poured oil from a container straight into the carb.

On the bright side, if the engine dies too quickly, there may not be enough coverage of the intake and valves. The big question I always had . . . was there sufficient oil coating inside the cylinders. :noidea:

 

[Chad Flaugher]

Here is a good saying to go by... "Doing something about it is always better than doing nothing about it". You're good, no worries.

 

[ericcarr2000]

Lol