? what does this guage do?

[bobjoe1]

I have a guage on my 17 foot Lowe boat that I have no idea what it is. It appears to have a small tube running from the guage to the engine and T;s in to the tell-tale right before it discharges out back of engine. The guage says water on the bottom and goes from 0 to 30 but does not seem to move. I am at wits end. Help please

 

[carholme]

Re: ? what does this guage do?

bob;

Would help to know which engine, hp and s/n.

Sounds like someone installed a water pressure gauge when they installed the telltale. If you have a resonable flow out the tell tale when the engine is running, water pressure at the telltale "T" should also flow forward to the gauge. If the engine is running now, remove the tube from the gauge and see if you have water flow there and that nothing is plugged. If you have a decent flow with measurable pressure, you can assume the gauge may have a problem.

Gerry

 

[bobjoe1]

Re: ? what does this guage do?

It is a 1989 Evinrude E40 TLCEC. If I disconnected hose at engine and with ignition on blew thru the hose to guage wouldn't it read pressure or tell me if it is blocked or obstructed

 

[carholme]

Re: ? what does this guage do?

I think the first thing you have to do is ensure that the line is clear, If it is obstructed, nothing is going to reach the gauge. We don't know what type of gauge you have, do you have a manufacturer p/n? Is it a direct reading or other type?

As far as blowing through the line with it still connected to the gauge, if it were mine, I would only be blowing water pressure through it. However, you can blow anything through it all day long but if the line is blocked, you are not going to read anything at the gauge.

Gerry

 

[crb478]

Re: ? what does this guage do?

Its a water pressure guage and it may have an obstructed line or the gauge may be broken. You can put a short hose on the back of the gauge and apply pressure that way to see which one is the problem.

 

[bob johnson]

Re: ? what does this guage do?

I would pull the hose off the guage and the t fitting and blow compressed air through it!!

if you are getting flow through the hose, then you know its clear... and reinstall the hose on both ends and see if you can get the guage to read.

the gauge maybe bad..

I wonder if that spot is a good place to pick up water pressure...obviously the size of the area the water is in , at the point of pick up plays a huge role in what pressure should be there..

if it is a small area the pressure will be higher than if it is a large space...

there should be a place to pick up water pressure on the block or head


bob

 

[Silvertip]

Re: ? what does this guage do?

You can blow on that tube and you will not get air to pass through it. If you could your feet would get wet when the engine is running. That gauge is exactly like a speedometer only it is calibrated in PSI rather than speed. Water DOES NOT flow through that tube since this is a closed system on the gauge end. While there may be a little water in it, water pressure in the tell tale compresses air in the tube which causes a bourdon tube in the gauge to unwind which moves the needle. The water pressure gauge tells you how well the water pump impeller is operating. The idea when adding the gauge is to also install a new impeller. You then note idle, mid throttle, and wot water pressure readings. Any deviation down the line means the water pump is beginning to degrade.

 

[bobjoe1]

Re: ? what does this guage do?

I agree with Bob in that it is tied into the side of a tee right above where it drops out of cowling. I don't think it would accuratly show real pressure

 

[bobjoe1]

Re: ? what does this guage do?

what should normal pressure be if showing correctly

 

[bob johnson]

Re: ? what does this guage do?

what should normal pressure be if showing correctly

well I do agree with silver tip about the use of the guage,..it is RELATIVE....

installing a new impeller and then taking a reading is giving you a base to measure against( assuimng the install went good), but I dont agree that blowing the tube clear WONT help..if the tube is clogged...then AIR PRESSURE cant force a reading on the gauge..

yes the water wont make it all the way to the guage, because of trapped air.....you do have to at least attempt to verify the hose is clear!


I have a V4 looper that gives me about 5-10 psi at idle and 20 psi up to about 4000 rpms and 25+ at WOT 5800 rpms

dont assume because you have great water pressure, that you cant OVERHEAT!!

a temp gauge in my view is more important

good luck


bob

 

[Silvertip]

Re: ? what does this guage do?

Whether a water pressure gauge works well in the tell tale or not depends on how the cooling system is designed. A tell tale is nothing more than a pin-hole leak in the grand scheme of things on most engines so it is very capable of measuring water pressure. This should be even more obvious since there is much more water passing through the engine and out the exhaust that through the tell tale. Don't know about the E-tecs, but my 40 HP carbed Evinrude and 75 HP Merc were both plumbed into the tell tale and read 17 PSI at WOT which is perfectly normal. Here is what it looks like on the Merc.

 

[carholme]

Re: ? what does this guage do?

I agree with Sivertip. When I had it happen in my boat, with the engine running, I just removed the tube from the gauge and without the sealed circuit, water flowed out the tube. Simply a matter of shutting down, removing the tube at the telltale and blowing it out again and reconnecting the tube at both ends. With the sediment removed, I could see the gauge flickering but replaced it anyway for the cost and was good as new.

Here is a list of different engines with water pressures based on good impellers, housings and plates, clean internal passages and clean tubes.

http://img41.imageshack.us/i/841c.jpg/

Gerry