water pressure.

[bbowenb]

I have a 2003 mercury 200efi. I have seemed to have somewhat low water pressure ever since i bought the boat. i have had 2 waterpumps put in by a reputable mechanic but still seem to have low water pressure. It is only a factor when i idle around alot in hot weather. If i idle around for an extended period of time sometimes i will get a continous alarm. i can shut the engine off and restart it back and the alarm is off. I have also replaced both thermostats. What do I need to look at next????

 

[bullbat]

Re: water pressure.

you could have a temp sensor actin a fool. does it seem to be runnin hot when the alarm goes off?

 

[bbowenb]

Re: water pressure.

It has very low pressure at idle and the water coming out is very hot. The water is barely coming out of the engine at idle. It almost falls straight down from the motor. All other motors I see have much, much more pressure at idle than mine. I do not have a guage to know for sure. It has not caused any problems with the engine operation.

 

[hkeiner]

Re: water pressure.

Installing a water pressure gauge would help in troubleshooting. It is easy to do yourself and not expensive.

http://www.diy-boat.com/index.php?option=com_content&task=view&id=151&Itemid=49

Even without a water pressure gauge, the below guide may give you some ideas.

 

[jimc_LA]

Re: water pressure.

I have the 2000 year version of the same engine. While I didn't normally have any overheating issues, I did have the same concerns about my telltale being very weak at idle. After discussing with others on this forum, I learned that this was because certain Mercs (200EFI included) have th telltale piped off of the thermostat discharge. I'm not sure why they did it this way, but it certainly made for a weak discharge since hardly anything came out unless the thermostats were open. Based on instructions from some of the more seasoned members of this forum, I was able to re-pipe my tell tale so that it now comes off of the main line from the exhaust manifold. Now I get a very strong stream even at idle.

This may not solve your overheating issue, if you truly are overheating, but it will give you a much better telltale which will tell you that your water pump is working well. You need to check the sensor or the temperature of the water when the alarm goes off. Keep in mind that the thermostats are probably 142 degree stats and the discharge water may be at least that hot under normal operation.

Also, I do have a water pressure gauge and I believe it usually runs about 4 to 6 lbs at idle.

Hope this helps you some.

Jim

 

[bbowenb]

Re: water pressure.

Who would I talk to about repiping the flow or where might I find that information?

 

[jimc_LA]

Re: water pressure.

Here's a link to the thread I had discussing this back in late June of '07. There is some pretty good explanations for what to do. The the thread is titled "Don't Trust the Telltale" if the link doesn't work.

http://forums.iboats.com/showthread.php?t=203732

Also, here are a couple of photos of my re-route completed. I would expect that there aren't going to be any major differences between a 2000 200 EFI and a 2003 200 EFI. Basically you are going to cut into the hose that comes from the top of exhaust manifold and travels to the poppit valve. You will be teeing into this and routing the hose from the tell tale outlet to this location. You will have to do a splice to the hose coming from the port thermostat where the existing tee is removed. Since this line from the exhaust manifold is independent of the thermostats, it will "pee" as long as the engine is running and the water pump impeller is in good shape. This makes it a better tell-tale for knowing that water pump impeller is working as it always works, not just when the thermostat is open.

After reviewing all of this, if you still have any questions, you can PM me and I'll help if I can.

Jim C