Water Pressure Gauge

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Montauk Guy
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Joined: Sat Jun 20, 2020 8:34 pm

Water Pressure Gauge

Postby Montauk Guy » Sat Jun 20, 2020 9:51 pm

Hi All. I'm having a problem trying to get my water pressure gauge to work on our 2004 Montauk with a 2006 Mercury 90-HP FOURSTROKE EFI . We have owned the boat since 2007. Just prior to launching it the gauge was working perfectly. A week latter and it is only reading zero.

I tested [the gauge itself] by putting air into the gauge. The gauget displayed and held the pressure value. I found that the 16-year-old hose had two cracks. I replaced the old hose with brand new hose connected to the water pressure port on the exhaust cover on the block (but ran the hose above deck) to the gauge. Nothing.

The thermostat tested fine, opening in hot water and closing in cold.

I removed some salt and corrosion from the poppet valve cover and replaced the mounting gasket and spring with new.

I replaced water pump impeller prior to launching since the boat runs in saltwater. The confidence stream has been strong the whole time.

I ran the engine in the water and saw no water leaving the water pressure port. I also fed water into the confidence fitting to flush. Again no visible water. Is there supposed to be water coming out of the port in order for the gauge to work?

I am running out of avenues to explore. I should mention that we lost the bulk of last session due to a bad misfire. During the off season, I rebuilt the VST and had the injectors cleaned and rebuilt. The engine was purring and we were looking forward to enjoying it this year. I am concerned about not having the water pressure gauge and nervous about any possible cooling problems with the motor.

Any advice would be greatly appreciated.
Thanks so much.
Steve

jimh
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Re: Water Pressure Gauge

Postby jimh » Sun Jun 21, 2020 6:36 am

Montauk Guy wrote:I ran the engine in the water and saw no water leaving the water pressure port. I also fed water into the confidence fitting to flush. Again no visible water. Is there supposed to be water coming out of the port in order for the gauge to work?


The port that a conventional water pressure gauge is connected to via a hose should be into the engine cooling system jacket. If you remove the hose from the port, cooling water should flow out of the port.

Since your narrative describes that no cooling water flows out of the water pressure gauge port, there must be some obstruction in the cooling system. Perhaps some mud was ingested into the cooling system, and when the engine was shut off the mud settle in some part of the water cooling jacket and dried. And it is now obstructing the flow to the sample port. Or maybe some small bugs got into the cooling system over the winter and built a mud nest.

Montauk Guy
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Joined: Sat Jun 20, 2020 8:34 pm

Re: Water Pressure Gauge

Postby Montauk Guy » Sun Jun 21, 2020 12:33 pm

Hi Jim and thanks for the speedy reply. I have used a piece of wire through the pressure outlet fitting but nothing was dislodged. I tried running a garden hose at full pressure into the inlet fitting on the water jacket--no luck.

Aside from taking it apart, any recommendations?

Thanks,
Steve

biggiefl
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Re: Water Pressure Gauge

Postby biggiefl » Mon Jun 22, 2020 10:36 am

Use a [non-contact thermometer] gun to check engine temperature. If [the engine temperature is] cool, run the engine and make sure alarm works.

You do not need a water pressure gauge to enjoy your boat' most people do not have them.

Did you use the OEM hose for the gauge? If not, that is most likely your problem.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

jimh
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Re: Water Pressure Gauge

Postby jimh » Mon Jun 22, 2020 10:42 am

Montauk Guy wrote:Aside from taking it apart, any recommendations?

Exactly what is "it" you are considering taking apart?

jimh
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Re: Water Pressure Gauge

Postby jimh » Mon Jun 22, 2020 10:49 am

Advice to remove the water pressure gauge and abandon its use is somewhat akin to cutting off your toe if you have an ingrown toe nail. As a solution to the problem it seems a bit drastic.

Re-reading the narrative, another cause of the water pressure port having no water flow could be due to the cooling system ingesting some debris. This would explain how the engine this season initially had the pressure gauge operating, and now it has stopped. Did you operate the boat in shallow water with sand or mud bottom?

The factory service manual should offer more details about the path of water flow in the cooling system and the relative location of the water pressure port to the water pump.

Montauk Guy
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Joined: Sat Jun 20, 2020 8:34 pm

Re: Water Pressure Gauge

Postby Montauk Guy » Fri Jun 26, 2020 1:09 pm

BiggieFl,
I did use the Mercury tubing (grey and very pliable). Good idea with the [non-contact thermometer] gun. What is the best place to measure temps on the motor? On the exhaust side of the head, on the block between the spark plugs, on exhaust water jacket cover or somewhere else?

Jim,
The boat went from being blocked in our yard (where I did all the work on it) to being lifted with a crane and docked in our canal.

It was on land and on muffs initially when everything was working properly. I did use some Salt Away before launching - don't know if that had anything to do with the gauge problems or not. Perhaps it loosened up a deposit that found it's way to the lowest point at the pressure test port?

As far as the "it", I am hesitant to pull the exhaust water jacket off due to the 12 bolts that have to come out and will probably need to be re-taped.

After going over the water flow chart in the service manual, I believe the blockage is at the water test port that the gauge was hooked up to.

To do this correctly, the boat would have to be hauled out and the side cover of the outboard removed. There is next to no room to get my skinny hands, let alone tools into the space with the cover on. I don't have a trailer either. I'm leaning towards living without the gauge for now, but want to be cautious operating the boat.

Any other suggestions about what to look or listen for while running the boat that would indicate the beginning of an overheat situation (other than the alarm or smoking confidence stream) ?

Thanks so much guys for all your thoughts and advice.

--Steve

biggiefl
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Re: Water Pressure Gauge

Postby biggiefl » Fri Jun 26, 2020 1:45 pm

Alarms usually kick on way before [the engine block temperature rises to] 200-degrees-F. If [the engine is] shut down in reasonable time, [the high temperature incident] will not hurt the engine.

I never said to remove the gauge. I just advised to disregard it until fixedm but still enjoy your boat.

I have owned probably close to a hundred boats. I can count on one hand how many had water pressure gauges.I am a big advocate of them, especially if running high on the transom or jackplate, but water pressure gauges arem by no means, necessary.

Enjoy your limited time on the water and make sure the alarm works. Where you put the laser is up to you. You can also just use your hand.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).