Telltale not telling!

[CraigDiver]

Hi,

I have a Mariner 40M outboard serial number 6E9S007614. On starting the engine, the engine starts easy and idles well and revs smoothly but only the odd drip out the telltale at idle or revving. There is a great deal of flow from the outlet half-way down the leg. I have taken the telltale small bore pipe off the casing and it is not blocked. Someone has mentioned that it is probably salt deposits blocking internal telltale pipework due to age of motor and to run the unit using my hand as a guage to check not overheating.

The telltale goes onto a cover on the side of the engine, if this is removed will it expose the internal pipe or is it worth trying to shove a bit of wire (paperclip etc.) through the telltale hole in the casing to unblock.

Any thoughts??

I have searched the forum and looked at the FAQs before posting.

CraigDiver

 

[Silvertip]

Re: Telltale not telling!

At 25 years of age, my guess is the engine is due for a water pump impeller replacement. I would suggest you do it now as if it disintigrates and migrates into the engine cooling system you have a lot of work to do. Chances are the tell tale is not plugged. If this is/was a saltwater engine, there may indeed be a corrosion problem. But running with no tell tale points initially to a bad impeller.

 

[CraigDiver]

Re: Telltale not telling!

At 25 years of age, my guess is the engine is due for a water pump impeller replacement. I would suggest you do it now as if it disintigrates and migrates into the engine cooling system you have a lot of work to do. Chances are the tell tale is not plugged. If this is/was a saltwater engine, there may indeed be a corrosion problem. But running with no tell tale points initially to a bad impeller.

It has only been used in sea (salt) water. Does the fact that copious amounts of water are coming out the outlet on the leg not show the impeller is doing its job?

I am mechanically minded but have little knowledge on outboard engine cooling systems, so please help me find probable cause, Thanks

 

[CraigDiver]

Re: Telltale not telling!

Would I do any damage by running high pressure water/air through the telltale outlet on the engine head to check for obstruction. Incidentally, I tried to put my hose up against the telltale outlet (engine switched off) and I don't think water was getting through - should there be resistance or should water flow through?

 

[Silvertip]

Re: Telltale not telling!

I'm not familiar with the cooling system on that engine so I have no idea where you see water coming out on the leg. Besides, if you are running the engine on muffs, the impeller could be almost toast and you'd get a little through the engine because house pressure is forcing water through the system. If the engine has through-hub exhaust, that's where water should be coming out. Pull the tell-tale hose off the nipple and stick a wire in that fitting to see if there any clogs.

 

[CraigDiver]

Re: Telltale not telling!

Well, thanks to you guys I carefully removed gearhousing and opened waterpump housing - Impeller looked not too bad and still rubbery not brittle, however a few chunks and tears and not sitting in correctly (see pic below). I then put my garden hose (only turned on slightly onto the water pipe to the powerhead and lovely flow of water through telltale (see pic below).

Can someone confirm that it does seem to be a worn impeller?

Also, please can I have some guidance on how the impeller should sit in the housing when re-installing the new one?

Thank you all, Kind Regards from Scotland

 

[AMD Rules]

Re: Telltale not telling!

That impeller is cracked/worn out. They should be replaced every other year. You'll notice that one of the impeller vanes (on the right) is pointing the wrong way. It wouldn't be long before that impeller began to disintegrate. You can see the cracks in most of the vanes. This weakens them and allows water to pass under the tips rather than being forced through the cooling system. Loose bits of an old impeller can lodge themselves into cooling passages causing your grief. Be glad to inspected it now, before any damage was done.

 

[Silvertip]

Re: Telltale not telling!

Every blade on that impeller is toast. It's not only the sides but the top and bottom of each vane that needs to seal otherwise there can be no delivery.