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Author Topic:   Weak tell-tale on Merc 200 on 25' Revenge
Eagleman posted 02-12-2003 01:26 PM ET (US)   Profile for Eagleman   Send Email to Eagleman  
The tell-tale stream of water on our 1991 200HP Merc appears to be weaker than starboard engine. Temperature on port engine raises when idling about 20 degree's then holds stabile but cools down under way to match the starboard engine. Is a weak tell-tale and rising temperature always an idication that the water pump is the trouble spot? This waterpump was replaced last summer, I'm beginning to think I may have a faulty impeller or something. I've check for visual debris externally couldn't see anything. Looking for some suggestions. Also the water pressure gauges for both engines show the same pressure while idling and running. Thanks
lhg posted 02-12-2003 02:17 PM ET (US)     Profile for lhg    
Russ, that's just the way those Mercury's are. I remember same situation with my 1989's. As long as gauges are reading OK, it's just some "plaque/hard water" build-up in the telltale hose or fittings, which will often self clear when you run them hard.

BUT, I would have the head gaskets checked (which means once opened up, replaced) on those engines. Have them pull one head, on one engine, and see how the gasket looks.
If signs of corrosion, replace all. If OK, leave others alone. This is the best money you can spend on that vintage engine, and it's a simple job. With exclusive fresh water use, they may be OK, but I'd check.

The temp difference between two gauges is common. It could either be discrepancies in the thermostats or temp sender, or gauge itself. I have yet to see any two read the same. With the water pressure gauges reading correctly, you don't have an impellor problem.

Whoever set your boat did a nice job with the full complement of dual engine gauges. Don't often see that on a Revenge.

Eagleman posted 02-12-2003 02:49 PM ET (US)     Profile for Eagleman  Send Email to Eagleman     
Good to hear from you. Any plans for the North Channel run this Summer, drop me an e-mail. All's well in Wisconsin hope you and your's are doing well.
Take care,
bdb posted 02-13-2003 10:01 AM ET (US)     Profile for bdb  Send Email to bdb     

Have you checked its prostate?

lhg posted 02-13-2003 10:33 AM ET (US)     Profile for lhg    
HarryH - that cold climate must be getting to you up there. You should head south for a few weeks!
bdb posted 02-13-2003 01:41 PM ET (US)     Profile for bdb  Send Email to bdb     
The weather has been brutal! Just told Russ in an email that the Prozac is getting low; may not last 'till spring. At least the sun is out a little longer. They tell me summer will come. But I've heard that before. When people were complaining about the heat last summer, I wrote down their names. I'm having a meeting with them all tonight!

In the meantime, I remain,

Harpoon Harry, giving up boating for February

Monnas Rock posted 02-17-2003 11:09 PM ET (US)     Profile for Monnas Rock  Send Email to Monnas Rock     
My Merc 220 XR-i does the same thing. I just had the lower unit serviced and new water impellar. The Merc service tech. assures me everything is working just fine, but It concerns me.
I'm used to my old Evenrude 70. It always looks like it just finished a six pack of Bud, while my Merc looks like an old man with a prostate problem!
Clark Roberts posted 02-18-2003 10:08 AM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Advice to anyone who thinks tattle tale stream on whatever engine is not strong enough... introduce yourself to your engine cooling system from bottom to top, locate thermostat (remove/inspect and check in water on stove/clean-replace), locate flex tube from block to outlet and remove and clean, including the little plastic nozzle (a small shell or piece of grit/debris can alter flow dramatically). A weed eater string makes a good probe for cleaning while engine is running... Now, the cooling water stream only indicates proper water pump operation and does not indicate that the water is circulating though block and heads at proper flow and pressure. To be absolutely safe a cyl head/cooling water temp gauge and a cooling water press gauge are necessaty. I use a temp gauge on all motors and a press gauge also when power jack plate is used. Another suggestion is to flush cooling sys at time of impeller change by clamping a proper size water hose (fitting must be cut off hose)to the copper "up" tube which carries water up to power head. Most engines have a pressure bypass around thermostat so not necessary to remove thermostat to get complete circulation. Sorry to be so long winded...Others will no doubt have additional suggestions, etc.. blah, blah, blah... happy Whalin'.. Clark.. Spruce Creek Navy
Monnas Rock posted 02-18-2003 12:15 PM ET (US)     Profile for Monnas Rock  Send Email to Monnas Rock     
Is the engine temp guage, that seems to be standard equipment on many boats, reading cylinder head temp, or is that a separate guage? My temp guage showed my engine was running a little warm at low speeds until I had the new impeller installed, now it runs cool, all the time (according to the guage). The drizzling telltale is new to me and it concerns me that after I start the engine, it takes 20 or 30 seconds to start flowing. Then it just seems to sputter water. Even at high rpm's it's not a real strong flow.
Bigshot posted 02-18-2003 01:16 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
You ahve a little clog in there. Try some wire or weed eater line.
Clark Roberts posted 02-18-2003 02:09 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Monnas, whether cyl head or jacket water temp depends on where/how transducer (sender) is mounted. If xdcr is mounted to cyl head surface the gauge reads cyl head temp and if mounted through cyl head and submerged in cooling water then reading is jacket water temp ... (jacket water from engine water jacket--- common expression) .. happy Whalin'.. Clark.. Spurce Creek Navy

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