Slab Slayer
Cadet
- Joined
- Jul 29, 2023
- Messages
- 10
I have been researching many posts on multiple forums about adding a Tell-Tale to my '76 Evinrude 70HP. The preferred location is on top of cyl #1, where the nomenclature disc is pressed in, with an alternative on the top of the head.
I see in iwombat's post that the V4 engines have a cast-in round boss on the starboard side which can be used for the installation of the adapter. The 3 cyls also have a cast in round boss on the starboard top rear. One hole is threaded ⅜ UNC while the other is unthreaded. Both would lead into the water jacket surrounding cyl #1 if drilled thru.
Short of not fully eliminating the air pockets that may form at the very top of the water jacket, what are the disadvantages to using this for the tell-tale port? Or, is the advantage of it being on the top of the jacket just too great to not put it there?
Backstory... I toasted the last '76 Johnson 70HP because of mechanic error (ME) and a faulty\corroded overheat horn. I picked up this very clean Evinrude exact match for $100, swapped out all the new bobbles and bits on the outside and ran it. I replaced the overtemp horn with several redundant sirens and added a digital head temp gauge. It ran great but never got up to temp. Then it didn't run so great. I scoped it and found evidence of water in the pistons. I pulled the power head, cylinder head, and exhaust manifold and found a host of issues. There were a couple blown gaskets, but more troubling was that there was more old gasket residue on the block and head than the new gasket which was a different color. One of the head bolts had been previously broken off in the block and not extracted so there is no possibility of torquing it properly (I extracted it and will be replacing the bolt). There were no pressure relief valves, grommets, or springs in the thermostat housing which is why it wouldn't get to temp.
I have cleaned up all the surfaces and I am currently waiting on delivery of the gaskets and parts. So, now would be the best time for me to drill the block and install the tell-tale.
I see in iwombat's post that the V4 engines have a cast-in round boss on the starboard side which can be used for the installation of the adapter. The 3 cyls also have a cast in round boss on the starboard top rear. One hole is threaded ⅜ UNC while the other is unthreaded. Both would lead into the water jacket surrounding cyl #1 if drilled thru.
Short of not fully eliminating the air pockets that may form at the very top of the water jacket, what are the disadvantages to using this for the tell-tale port? Or, is the advantage of it being on the top of the jacket just too great to not put it there?
Backstory... I toasted the last '76 Johnson 70HP because of mechanic error (ME) and a faulty\corroded overheat horn. I picked up this very clean Evinrude exact match for $100, swapped out all the new bobbles and bits on the outside and ran it. I replaced the overtemp horn with several redundant sirens and added a digital head temp gauge. It ran great but never got up to temp. Then it didn't run so great. I scoped it and found evidence of water in the pistons. I pulled the power head, cylinder head, and exhaust manifold and found a host of issues. There were a couple blown gaskets, but more troubling was that there was more old gasket residue on the block and head than the new gasket which was a different color. One of the head bolts had been previously broken off in the block and not extracted so there is no possibility of torquing it properly (I extracted it and will be replacing the bolt). There were no pressure relief valves, grommets, or springs in the thermostat housing which is why it wouldn't get to temp.
I have cleaned up all the surfaces and I am currently waiting on delivery of the gaskets and parts. So, now would be the best time for me to drill the block and install the tell-tale.
