Telltale or gauge?

[Jeremy90bay]

Ive been through so much with this motor I dont want to overheat it. what is better a telltale or guage. and if it is the gauge where do you connect it to the motor? I have NO gauges on my dash now. what do you suggest?

 

[john from md]

Re: Telltale or gauge?

Tell tale only tells you that your water pump is pumping. The gage will tell you then temp of that water or, if you install the sender on the head, the head temperature.

If you are handy, you can install both. They are very easy.

The gage is good if you run on lakes because it is easy to partially block your intake and it will notify you before the engine quits.
(if you look at it that is)

John

 

[Jeremy90bay]

Re: Telltale or gauge?

Ive ready the sticky at the top of the forum so im pretty sure I know how to do a telltale. you say I can do both. would I just use a tee on the head or put the gauge somewhere else?

 

[john from md]

Re: Telltale or gauge?

I don't think you can use a 'T' at the head as there is not enough room.

I attached my sensor to the head cover near the overtemp switch. The Sierra kit has adapters for several methods of mounting. Mine uses a z type mount to hold the sensor 90 deg to the head cover and the sensor is coated with heat sink compound where it touches the head. You can get a small tube of this from Radio Shack.

I also ran a separate wire to the gage as I wanted to keep my overtemp sensor. I just used 18ga speaker cable and it works fine.

I calibrated the sensor and gage using a pot of water on the stove and a digital thermometer. Mine was about 20 off from the gage printed readings. I just remarked the gage face with a thin black marker.

John

 

[pnwboat]

Re: Telltale or gauge?

I installed a water temp. and a water pressure gauge. Here are a few pro's and cons's with my set up.

Water Temp.
Pro - Reads actual temp of water flowing through the head.

Con - Gauge starts out at 100 degrees. I have a 130 degree thermostat. Needle on gauge barely moves while under way. Only time I've really seen it move is after I shut the motor off after a long run. Temp. rises up to around 140 - 150 degrees. I've looked for gauges that start out at lower temp. but they are few and kind of pricey....$60 - $90. Seems that most standard gauges start out at 100 to 120 degrees.

Water Pressure
Pro - You can see that the water pump is working as soon as the motor fires. If any blockage occurs, you will see it instantly (if you're looking at the gauge). I replaced my impeller and noted water pressure at idle and WOT. Hasn't changed in over a year so I know the pump is working.

Con - Can't think of any really.

I think the water pressure gauge was more useful than the temp. It also boils down to individual preference depending on what your set up is. Just my observations.

 

[Jeremy90bay]

Re: Telltale or gauge?

PNWboat where did you hook these up too? im new to outboards but im pretty handy I like the pressure idea. cuold you show a pic of your setup?

 

[pnwboat]

Re: Telltale or gauge?

I have a 1988 125 HP motor. First picture is where I hooked up for the water pressure gauge. It's located just below the exhaust cover. There is a 1" pipe plug in the water passage in the divider plate that goes directly into the block from the water tube. Kind of hard to get to. I chose this spot because it comes directly from the pump before it enters the block. If there is a drop in water pressure, this eliminates any variables in the block itself.

Second picture is where I installed the water temp gauge sending unit. There is a 1/8 inch pipe plug fitting close to the thermostat housing in the head. I unscrewed it and installed the sending unit. If temperature goes up and water pressure is OK, then I know I have an issue in the block itself. Thermostat or blocked water passage in the block.

NOTE: Second picture is the spot where many folks install the fitting for a telltale. You could also use this spot to install a fitting for a water pressure gauge.

 

[john from md]

Re: Telltale or gauge?

If your engine has been operated in salt water for most of its life, you will play hell getting that raw water plug out.

John

 

[forceboy]

Re: Telltale or gauge?

pn - what does you pressure run at?

 

[pnwboat]

Re: Telltale or gauge?

At idle 800 RPM's 6 - 7 LBS. At WOT 5300 RPM's it's at 20 LBS.

 

[forceboy]

Re: Telltale or gauge?

Thanks PN - may try and put both in as well. I have an 85HP - is it safe to assume values should be relatively close? What do low values tell you - blockage and or bad pump?

 

[pnwboat]

Re: Telltale or gauge?

I would assume the readings would be similar. Low pressure readings could be either blockage or worn out/bad impeller. Should check both if you notice a permanent drop in pressure.

Same idea as a tell tale. If water stream starts to drop off, time to check pump/blockage.

The reason I like the idea of a pressure gauge is you have an actual numerical pressure reading. Looking at a stream of water and determining if you're pumping enough water is kind of subjective. One person may thinks it's OK, another may not.

I've inadvertently cruised through shallow spots at half throttle where there were weeds and stuff and actually seen my water pressure drop 4 or 5 LBS momentarily and go back to normal after I clear the weeds. Maybe more information than I need to know....LOL! Certainly catches your attention!

 

[forceboy]

Re: Telltale or gauge?

Is your gauge on your dash? How do you transfer the pressure from motor to gauge?

 

[pnwboat]

Re: Telltale or gauge?

Gauge is on my dash. There is a hollow plastic tube that you run from the fitting on the motor to the back of the gauge. I secured the tube at both ends with heavy duty zip ties. Couldn't find a hose clamp small enough.

First picture that I posted above shows the black plastic tube attached to the brass fitting running off to the left.

 

[forceboy]

Re: Telltale or gauge?

Ok I get it - sorry a little brain fart! It must take a couple seconds to get reading? Could I not hook up pressure gauge on top (where you have temp) instead?

 

[backyardangler]

Re: Telltale or gauge?

I have a 3 way tee on mine. I have the pressure, temp and a port for the telltale. I'll post a picture tonight (note to self). I love having the two gauges. I may not do the telltale.

 

[pnwboat]

Re: Telltale or gauge?

Yes Forceboy, you can install a fitting for the pressure gauge where I've got my temp. gauge sending unit mounted.

 

[forceboy]

Re: Telltale or gauge?

Thanks for all your help pnwboat - one more question and I promise I will leave you alone - probably a stupid question, but i am going to ask it anyways! If i have low pressure at the gauge it should be blockage or bad impeller (which i just replaced), if I have good pressure but still overheats, it should be a bad thermostat, correct?

 

[pnwboat]

Re: Telltale or gauge?

Only stupid question is the one that is not asked. Yes, most likely cause for low pressure is blockage or worn/bad impeller. If still overheats with good pressure, most likely the thermostat.

 

[forceboy]

Re: Telltale or gauge?

Thanks again, i'll give er a go this weekend and post my results!