Eoughphilly
Cadet
- Joined
- Jul 13, 2019
- Messages
- 28
Hello,
I obtained a non running 1990 mercury 8hp. The compression is really low, 40psi. After inspecting the gaskets and finding no real cause for low compression, I decided to crack it open to inspect further. There is very minor scouring (not enough to feel withy finger nails) and all in all, looks pretty good on the inside. The lower seal was totally shot. I figure since I have it open I'll replace the rings and home the cylinders. However, I noticed that none of the piston ring grooves have a locating pin. Nor can I find any marks of where a pin once was. The service manual says there is a locating pin. It also says the lower ring is squared and the upper is tapered, but I cannot visually see a difference between the two.
Do some of the smaller hp engines not have the locating pin?
I obtained a non running 1990 mercury 8hp. The compression is really low, 40psi. After inspecting the gaskets and finding no real cause for low compression, I decided to crack it open to inspect further. There is very minor scouring (not enough to feel withy finger nails) and all in all, looks pretty good on the inside. The lower seal was totally shot. I figure since I have it open I'll replace the rings and home the cylinders. However, I noticed that none of the piston ring grooves have a locating pin. Nor can I find any marks of where a pin once was. The service manual says there is a locating pin. It also says the lower ring is squared and the upper is tapered, but I cannot visually see a difference between the two.
Do some of the smaller hp engines not have the locating pin?
