mercruiser water pressure gauge install

jlmill

Cadet
Joined
Aug 1, 2014
Messages
6
I have '86 Sportcraft 22 w a c, power package MCM190, eng. ser. # 6925425 . This is freshwater cooled 4 cylinder engine.
I would like to install a seawater pressure gauge. I have read a few post here all pertaining to other engines.
First of all my local merc dealer has no parts for this install. Articles I read mentioned sender unit at power steering cooler or at seawater
inlet. Could someone give me guidance?
 

alldodge

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Staff member
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Mar 8, 2009
Messages
40,582
I have '86 Sportcraft 22 w a c, power package MCM190, eng. ser. # 6925425 . This is freshwater cooled 4 cylinder engine.
I would like to install a seawater pressure gauge. I have read a few post here all pertaining to other engines.
First of all my local merc dealer has no parts for this install. Articles I read mentioned sender unit at power steering cooler or at seawater
inlet. Could someone give me guidance?

:welcome: to iboats

Sounds as though you want to measure your seawater pump pressure. If this is the case you can go electrical or mechanical. Need to tap into the line coming directly from the pump. This could be on the inlet side of the power steering pump, or just before the entrance of the thermostat housing. It could be inserted into the cold side of the thermostat housing but the pressure would show a bit less because of the increase size of the housing.

Electrical: Need a sensor and a gauge 0-30 psi. Run a 12V lead from instrument panel to the gauge. Other side of gauge will need a sense lead which will come from the sensor and probably a ground. The sensor most often will need three connection, 12V, Ground and sense (sense goes to gauge).

Mechanical: Need a gauge, some plastic tubing and a fitting teed into same area as the electrical.

Can google and find gauges of both types, and you can use automotive, marine or industrial. Found a little gauge for 9.99 just googling, but it was not a panel mount.

If your looking for the ones currently being used by Merc, they are available but will cost a lot more
Good luck
 
Last edited:

jlmill

Cadet
Joined
Aug 1, 2014
Messages
6
Thanks AllDodge I hope with this type of gauge I might be able to detect impeller wear early... Found pressure gauge install kit on ebay (ordered) and local performance auto parts house has, (if needed) inline water pressure adaptor to fit 3/4" inside diameter hose, (now thats a hard one to find). Mechanical kit. I'll let you know how it turns out when completed. Thanks again for the response/reply jlmill
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Most pumps detonate when they go. A pressure gauge would just go from normal to 0 when that happened. I had it happen. I change the impeller every other year and carry a spare on the boat in case.
 

Speakrdude

Ensign
Joined
Feb 25, 2004
Messages
942
I think it will be more flow than pressure. Seems like I tried this a while back and it was barely enough to show on the gauge. My outboard engine used a small port off the head for the water psi. It was usually around 25-30 psi at 5k rpms.
 
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