Water Pressure & Capping Off Lower Unit Intake Holes

[DavidNC50]

Sooo... The water plugs are capped off on my Mercury 135 because this helps to prevent sucking air when trimmed up & running jack plate?

Currently with all 4 holes on each side capped off I am pulling water through the small hole in the front of the lower unit?

If I am correct about the above statement... can it clog or be blocked up easily? and how should I go about making sure the water intake passages are clean as they should be?

I have a water pressure gauge but am not seeing the 12-15 numbers that I think are desired... especially at idle. When I am running full speed the pressure seems to be much higher but I'm not sure if it should be more. (NOOB) Seems to me more is better when it comes to water flow.


If I were to remove them I could have problems when running at top speed and a lot of the motor is not in the water?

I am interested in the scoops I hear you guys talking about also... Do they kinda give you the best of both worlds... water intake fast & slow / speed performance?


Motor Facts:
Mercury 135 V6 black max
4 left & right side intake holes capped off by metal plate that is screwed on.
water pressure gauge
jack plate lifted at least 3"
New impeller on motor.
Water pump has NOT been replaced
Pisses after about 1 min of running. (Maybe a little longer) Not sure if it should be stronger stream or not but seems OK.

 

[Rob B]

Sooo... The water plugs are capped off on my Mercury 135 because this helps to prevent sucking air when trimmed up & running jack plate?

Currently with all 4 holes on each side capped off I am pulling water through the small hole in the front of the lower unit?

If I am correct about the above statement... can it clog or be blocked up easily? and how should I go about making sure the water intake passages are clean as they should be?

I have a water pressure gauge but am not seeing the 12-15 numbers that I think are desired... especially at idle. When I am running full speed the pressure seems to be much higher but I'm not sure if it should be more. (NOOB) Seems to me more is better when it comes to water flow.


If I were to remove them I could have problems when running at top speed and a lot of the motor is not in the water?

I am interested in the scoops I hear you guys talking about also... Do they kinda give you the best of both worlds... water intake fast & slow / speed performance?


Motor Facts:
Mercury 135 V6 black max
4 left & right side intake holes capped off by metal plate that is screwed on.
water pressure gauge
jack plate lifted at least 3"
New impeller on motor.
Water pump has NOT been replaced
Pisses after about 1 min of running. (Maybe a little longer) Not sure if it should be stronger stream or not but seems OK.

When I had a merc motor I installed those scoops. They actually worked great, plently of water pressure. I would unplug those holes and install the scoops. Here's the link with the part number in post #7. http://checkmate-boats.com/forums/showthread.php?t=12310&highlight=mercury+scoops

 

[SKATR186]

Water pressure should be roughly:

2-5 PSI at idle

over 5 while running.

pressure should never go over 25 PSI, if it does air pocket most likely in powerhead.

I will better quote this when i get home and I get my manual out. This is what I remember off the top of my head.

 

[DavidNC50]

Thanks for your input guys! This is my first outboard and it has some "performance" things done I assume by the original builder Wickedrister. The guy I bought it from did not seem to know much about the mechanics of the boat and directed me to contact Wickedrister to get solid answers to motor questions. I have some contact numbers but figured I would ask around here first.

I have a lot to learn so everyone please chime in if you have any advise or suggestions.

 

[john lamon]

It almost sounds like you already have scoops, the scoops are just a flat plate that covers the intake holes, at the front of the plate there will be a very small gap, when water spray hits this gap it forces the water in, I've had people ask me why my holes are capped off and had to explain they were scoops, have a second look at it, they work great, I put them on all my boats, if you run shallow water with lots of weeds or sand they can get plugged with crap though, easy to remove the screws and clean it out, I never lose pressure even jacked all the way up, I swear by them.

 

[DavidNC50]

I looked really good at those plates this weekend while I had the boat out. They do appear to be total block off plates. I will try to take some pictures and post tonight when I get home.

Can anyone tell me if I am right about where the water is drawn into the motor other than the holes on the side.

Has anyone ever heard of completely blocking off the side intake holes or just covering a few?

Assuming they are completely blocked off... can anyone think of any negative drawback to removing them? Am I correct that it may draw in air or reduce top speed? I think I would like to install the scoops mentioned above if it will increase water flow... more is always better right.

I DO NOT have a temp gauge which is why I am trying to be very cautious with tampering with what seems to work OK already. Temperature gauge is coming soon I think.