Intermittent Telltale

[hodywvu]

I have a 1999 Mercury 200 EFI. It has an intermittent stream out of the telltale. I have had the issue for the past 2 years and have had no luck fixing the issue.

I have replaced the poppet valve, thermostats, and water pump.

I did a compression test. I had 120 to 125 on all 6 cylinders.

I also removed the lower unit and connected the hose directly to the copper water pipe that goes from the water pump to the bottom of the motor. When I did this water was coming out of the motor where the drive shaft goes in. This seems odd to me. When I started the motor at first I had a steady stream. But when the engine came up to temp the telltale became intermittent.

With the lower unit installed and using the water pump to push water into the motor (using the hose or while the boat is in the water) the telltale varies from intermittent to occasional spurts at idle, as the engine is revved up the telltale becomes intermittent.

When the boat is in the water the water out of the telltale becomes very hot at idle. Can only briefly put my hand in the stream. Revving the motor up cools off the stream and it becomes steadier.

Any advice is appreciated.

Thank you.

 

[Texasmark]

Trace the tell tale tube back to the origin. If it comes off the T stat housings (Y'd) the/a stat has to open to get water. If cold weather that could take some time and it would be on again off again till the block warmed up. You may have the 143F stat which I had in a 90 and son in a 150. The temperature of a domestic hot water heater with the temperature set to normal is 140F. You and I know you can't hold your hand under the faucet with just hot water on.

 

[hodywvu]

I borrowed a friends bore scope and took a few pictures inside the cavity that the water tube and the drive shaft are in.

The photos are the upper right of the water tube/drive shaft cavity. With the motor trimmed up and looking in from where the lower unit attaches. The first 3 pictures are with the water running, the last picture is with the water off of the same location.

I am assuming that I need to remove the power head and replace that part. I believe water should not becoming out of there and no water should be in the water tube/drive shaft cavity.

 

[Texasmark]

There is a seal there between the powerhead and mid section and I do see it referenced on here from time to time as needing replacing. With cooling water added to the exhaust housing cover, and to cool the exhaust through the mid section and out the lower unit, and to have an exit point for engine block cooling water, there will be water in the mid section with exhaust.

 

[Faztbullet]

You have a 2.5 L motor and the "P" stream is tied directly to t-stats. It will not "P" correctly till motor reaches full temp and stats open. At above 2500RPM you will have a good stream...at idle you will see it pulse as stats are opening and closing. You also have a water wall that cools the water pump housing and exhaust can from factory holes in adapter plate. If your hot alarm is working and not sounding you have a normal operating 2.5 motor.

 

[AF Marine Services]

have you checked that all the seals are in place on the water pump especially the supply pipe to the pump housing this seal can get old and fall apart causing this issue lack of water flow and boiling air pockets hence the intermittent tell tail

 

[Faztbullet]

You have a PM...