Johnson overheating - telltale suddenly stopped working

Hello all. Need some help. Have a Johnson 2 stroke 1984 75Hp outboard. Installed a telltale and a new impeller (even though the old one looked fine). Fired up the boat and everything looked fine. Telltale squirting and all. All of a sudden the telltale stops pissing and the engine starts to overheat. Intake not blocked. Removed lower end and impeller looks fine nothing loose or missing. My 1st thought was I installed the impeller kit wrong (but why would it work fine for 5 minutes?) No foriegn objects blocking anything. Cant figure out why its not pushing water through anymore? Any areas to check?

Thanks.

Re: Johnson overheating - telltale suddenly stopped working

Have you tried checking the lines that run to the tell tale for bits of weeds? Another possibility is that the new impeller is bad. Have you tried reinstalling the old kit to see if it works or was it not working before you swapped them? I would try to blow compressed air through the lines to double check for a blockage. Possible thermostat issue?

Re: Johnson overheating - telltale suddenly stopped working

Thanks for the reply. Air travels fine from water tuber to pisser. Telltale was installed before the thermostat, so I dont think the thermo is the issue. Suspecting the key. Is it possible for the impeller to spin around the key if not installed right? Feels tight by hand pressure, but maybe at high pressure or high temp things change? A real head scratcher......Especially being as it worked great for about 5 minutes???

Re: Johnson overheating - telltale suddenly stopped working

If you have the plastic wedge key, have you got both that and the impeller installed in the right direction ??

Re: Johnson overheating - telltale suddenly stopped working

The key is a half circle metal key. Looking at the earlier post, is it possible to get a bad impeller brand new? How would I tell it was defective?

Re: Johnson overheating - telltale suddenly stopped working

a non-functioning or blocked tell tale will not cause a motor to overheat; the problem is bigger and elsewhere.

Re: Johnson overheating - telltale suddenly stopped working

Ok.....I took the lower end off (again)....Im getting really good at that....Everything looks good except for a couple of things that dont quite match up with the manual.

Oring (9) is missing, and Gromet (3) appears to be upside down from schematic.

However when flipping grommet (3) to the position in the picture, it doesnt fit anywhere. It has a groove in it which seats perfectly on to the plastic housing. Not sure what oring (9) does or where it goes?

FYI.....when I opened the LU for the 1st time, neither 3 nor 9 were installed, and it ran like a champ without them. Never overheated until I started messing with it.

Can someone clarify what these 2 pieces do and exactly where they go. The Schematic is very unclear. I will try to post pics of how I installed them later but will have to borrow a camera.

Thanks for all your help so far. I bought this boat cheap so I could learn stuff like this before I investing in a more expensive one.

Re: Johnson overheating - telltale suddenly stopped working

Error in my original posting (this is a 1977...not 1984).....75ELR77S