Water pressure on bbc.
 

My thermostat housings have 2 sending units in each, and a water temp. gauge and a water pressure gauge on the dash. I assume the funny looking sending unit on the back of the thermostat housing is to read water pressure, as I have tested the other senders and determined that both are water temp senders and the temp gauges are working properly. Neither water pressure gauge is reading pressure, so I got 2 manual gauges and put in each intake manifold water jacket beside the thermostat housing. Started each engine independently of the house water hose and neither of the manual gauges show water pressure. Is a boat set up with an open system supposed to have enough water pressure to show it on a pressure gauge, and if so why am I not reading pressure off the water jacket on the intake manifolds?

Also, is there a more reliable sea water pump that the stock pumps with the rubber impellers.

the second sender on the T Housing is a high temp alarm ... sounds a buzzer in your dash at 190-200* ... the water pressure sender should be mounted on the block below the heads ..... you really should not see any pressure at idle .... I run 20lbs WOT .....you should not see more than 30lbs ..if you do you need to relieve the pressure ...

2nd question .... actually the sea pumps are pretty reliable ...dont run them dry ....m

Thanks for the info and the clarification on the second sending unit. I have not knowingly (and I have been very careful not to) run the pumps dry, but have had several failures. That's why I'm concerned about the water pressure gauges. A guy I saw at the docks last time out told me he had similar problems with the stock pumps and he said he bought some type of billet pump from Trick Marine. Of course Trick is gone and I haven't found anything else on the net anywhere that alludes to something other than the rubber impeller setup. I always carry spare impellers just in case.

there was a member on here that was selling blue nitride impellers, said they would run 15 min dry, I was going through impellers like crazy, installed one of these and no more problems, I don't have the link but maybe someone out there does, there pricey but work great.

I've got 2 new motors, and that seems to be the weak link, so I wouldn't consider them pricey against the cost of an engine. If anyone has anything, I'd appreciate a post.

http://www.defender.com/product.jsp?path=-1|311|53460|809302&id=168198