rookie456
Petty Officer 3rd Class
- Joined
- Aug 25, 2011
- Messages
- 81
I have a 1972 50 hp johnson, model 50esl72, on a 1987 17' blue fin s170. I bought the boat 2 years ago. Right after I bought the boat I saw the same engine for sale on craigslist for parts, it had a burnt piston, but I bought it for parts. A few weeks ago I was checking my compression on my good engine. I was using a gauge from auto zones rental. Top cylinder 150, bottom cylinder 155, while removing the top cylinder spark plug I noticed that it was helicoiled, and the helicoil came out with the plug. I got the helicoil off the plug and used jb weld to put it back in the cylinder head, let it sit for a couple days, rechecked the compression, top cylinder 135, bottom cylinder 155. I dont know how accurate the gauge is, or how good of a seal I was getting on the tester, but I think 20 psi difference is a bit too much. I did run it out at the lake, I checked the spark plug area after running it and I didnt see any signs of fuel getting out where the spark plug is.
In order to try to get the compression between cylinders closer to being even, I thought I would take the head off of the parts engine, and put it on my running engine. The head I want to use has 2 issues. 1) the cylinder head is pitted, maybe even gouged, I will attach pictures. 2) The PO must have tried to add a telltale into the water jacket on the head, cause there is a hole with threads thru the top of the head.
So, this is where my questions come in,
1) If I plug the hole in the water jacket, and surface the head to have a flat matting surface, could I use this head?
2) Could I use a brass plug to plug the hole, or would it be bad to have 2 different metals together?
3) Will I be able to tell if the pistons and rings are in good condition when I remove the head? What should I check for?
4) I did see a new head online, but it was not painted inside the area where water cools, is there suppose to be some kind of paint in that area for corrosion?
I am just trying to save some money and use a part I already have, but if it is in my best interest to use a head in better condition I will spend the money for it.
Thanks in advance for any advice.
In order to try to get the compression between cylinders closer to being even, I thought I would take the head off of the parts engine, and put it on my running engine. The head I want to use has 2 issues. 1) the cylinder head is pitted, maybe even gouged, I will attach pictures. 2) The PO must have tried to add a telltale into the water jacket on the head, cause there is a hole with threads thru the top of the head.
So, this is where my questions come in,
1) If I plug the hole in the water jacket, and surface the head to have a flat matting surface, could I use this head?
2) Could I use a brass plug to plug the hole, or would it be bad to have 2 different metals together?
3) Will I be able to tell if the pistons and rings are in good condition when I remove the head? What should I check for?
4) I did see a new head online, but it was not painted inside the area where water cools, is there suppose to be some kind of paint in that area for corrosion?
I am just trying to save some money and use a part I already have, but if it is in my best interest to use a head in better condition I will spend the money for it.
Thanks in advance for any advice.
