1990 V6 Water Pressure Gauge Problem

[dajohnson53]

J200TXESM. I connected the water pressure gauge tubing according to the teleflex instructions. It is T'd into the tube that feeds the telltale, about 2 inches upstream from the telltale itself.

I get 0 pressure on the gauge - idle, cruise, WOT, nothing. This is on the hose and in the water. I do get a strong steady stream out of the telltale.

I plugged the telltale with my finger while the engine was at high idle and the gauge then registered pressure. I was alone so I could only do this experiment from the back of the boat at idle and I couldn't read the exact pressure, but it definitely was registering good pressure at idle.

The telltale hose and the hose that feeds it (into which the pressure gauge tube is T'd) is quite a bit larger diameter than the pressure gauge tube.

Is this the problem? Do I need to reduce the diameter of the telltale tube to the same as the pressure gauge tubing in order for it to work, or is there some error I've made in the installation?

Thanks.

 

[Dhadley]

Re: 1990 V6 Water Pressure Gauge Problem

The instructions are for a crossflow. On a looper you want to T into the line coming up from the adaptor plate to the water control vale behind the throttle arm.

 

[dajohnson53]

Re: 1990 V6 Water Pressure Gauge Problem

The instructions are for a crossflow. On a looper you want to T into the line coming up from the adaptor plate to the water control vale behind the throttle arm.

Thank you - yes that looks better. From their instructions I couldn't tell which tube at the water control valve they intended. I picked the one going to the tell tale but have now changed to the one coming out of the adapter plate. I'll put it in the water soon to test it. Thanks again.

 

[Dhadley]

Re: 1990 V6 Water Pressure Gauge Problem

Don't feel bad. When the loopers first came out a very good boat manufacturer put out a bunch of boats with the gauge hooked up like that. Their explanation was that "an OMC looper doesn't have much pressure". So much for boat builders knowing what they're talking about.

 

[dajohnson53]

Re: 1990 V6 Water Pressure Gauge Problem

Don't feel bad. When the loopers first came out a very good boat manufacturer put out a bunch of boats with the gauge hooked up like that. Their explanation was that "an OMC looper doesn't have much pressure". So much for boat builders knowing what they're talking about.

The guy who rigged the engine onto the boat for me last fall rigged the pressure gauge tube onto a small water fitting near the top rear of the port cylinder bank (left as you're facing forward - just to make sure I'm using the correct terms!). That fitting is for a small diameter tube that ran across the top rear of the engine and then - to I can't remember where, somewhere on the starboard side. He just replaced that 90 degree fitting with a T and added the gauge tube.

That installation gave me a good pressure reading, but evidently it filled the tube up with water rather than just pressurizing it because this spring the gauge was inoperative - pegged at maximum and could not be revived. When I disconnected it at the gauge end, water ran out and it had a very good water flow when the engine was running! (making a mess under the dash until I figured that out!) Brilliantly I guessed that the water froze in the tube and gauge last winter. I never had this problem with my early 80s V6 Crossflow and thus have never considered disconnecting and draining the gauge tube (which I will now do, just to check it this fall). That one was connected at a much lower place on the engine, exactly where I can't now remember - somewhere mid-lower rear water jacket and/or near the telltale IIRC, regardless, much lower).

I think the reason the tube filled with water rather than just pressure is that it was so high on the engine and had a downward route to the gauge?

Anyway, thanks again for your advice. Always a learning experience for me, sometimes getting into more than I really care to!

 

[dajohnson53]

Re: 1990 V6 Water Pressure Gauge Problem

final update - the connection point recommended by dhadley worked great. I just backed the engine into the water and started it up. The pressure didn't register immediately, but in a few seconds went up to 10+psi. I haven't run at WOT yet, but I'm comfident it will be fine. Thanks.