Merc 9.8 has hot telltale stream

[Boatnug]

I have read many forum threads on this topic, since starting my search for a cause/fix for my problem. I've done all the normally suggested checks (e.g. replace impeller, chase passageways with grass trimmer string, blow air through waterways, etc.) and I still have a telltale stream that is hot to the touch (very soon after starting) and then the volume of the stream decreases to almost no stream, with either steam or exhaust replacing the water out of the telltale hole. If I stop the motor and wait for a short time, then restart the motor, the telltale stream is good again (albeit hot) and the cycle repeats.

I should mention that in checking the cooling system, I found that the thermostat had been removed prior to my buying the motor. (Yeh, I bought it without having the seller start it up...) He mentioned that the motor had been checked out at an outboard shop, that it had been noted that it ran a "little hot" and the receipt said that they did a "flush" of the cooling system and appeared to run OK at the shop.

I don't consider myself to be totally inept at mechanical things, but I've hesitated to dig into this problem any further - in the hopes of getting some sage advice.

Has anyone seen this type of problem? I haven't gotten to checking gaskets or looking for internal cracks.

Thanks for any help you can provide. (The motor is a 1981, serial no. 5638840)

Boatnug

 

[Laddies]

Re: Merc 9.8 has hot telltale stream

The engine has a blocked water passage, air will in some cases clear the telltale but will not solve your problem. There are several places to check and you will have to start by removing the power head, if the engine has overheated there is a plastic grommet on the end of the water supply tube that can melt and cause a problem, the next place to look is under the exhaust cover plates, if a impeller has came apart of the engine has been run in the dirt you may find debris in a passage or even a gasket blown. The last place to look is the passages from under the exhaust plates to the block and that will require removing the water jacket cover. You will need gaskets and patience, when removing the bolts in the exhaust plates and water jacket cover use care not to break them as they are only 1/4" bolts.

 

[Boatnug]

Re: Merc 9.8 has hot telltale stream

Laddies,

Thanks for the reply. I'll bite the bullet, get some wrenches out and get into the innards.

I appreciate your info.

Like they say, "If this was easy, everybody would be doing it."

Thanks! - to you and iboats!