WP Gauge to 70 yamaha

JADED · #1 November 24th, 2006, 11:34 AM

Where is the best place to 'T' in for a water pressure gauge on a 70 yam.?

rodbolt · #2 November 24th, 2006, 11:42 AM

actually a WP guage is not reccomended on that motor.
its a low pressure high volume system and yamaha does not reccomend the use of a WP guage.
whats funny is that was actually a test question some years back.
I would prefer a temp guage over a water pressure anyway.
its just to easy to melt a motor down and still have water pressure.
thats what is so wonderful about audible alarms, you dont have to be watching them for the alarm to get your attention.

JADED · #3 November 24th, 2006, 11:51 AM

Any one want to buy 2 water pressure gauges?

I'have jackplates fitted to twin 70's and I'm testing heights and props so I want to keep an eye on the pickups as they are standard.

What would you suggest?

rodbolt · #4 November 24th, 2006, 04:34 PM

I would suggest a single 150, would go faster.
were it me and I was hell bent on a pressure guage I would drill and tap into the top of the block on the water passage from the exhaust plate to the block.
use whichever tap and tap drill size to fit the threaded fitting.
not saying it cannot be done there are just to figgues on what water pressure will be.
I cant remember if the 70 block has the 10mm threaded port but I dont think it does as it was never intended to have it.
if your 70 has a hose between the exhaust plate and tell tale restrictor you can tee it in there and run with the engines full down to get a base line pressure.

JADED · #5 November 25th, 2006, 07:59 PM

I havn't seen a port as I have been looking, there is a bolt on the block side of the thermostat that looks like it cold be a port though.
I was going to t in to the tell tale but thought that taking the pressure at the open end of a hose wouldn't be the best. I have never taken off a lower unit, is there any where just after the water pump?
If I drill and tap the block would I need to take off the exhaust cover to see where the water passage runs? Is the gasket re-usable? Sorry about all the questions.

I get you about the temperature gauge but will a pressure gauge give a quicker indication if I am running to high. The gauge i am looking to use is 0-20psi

Twin or single is another issue as I do alot of offshore fishing. Just looking to maximise rig I have.