Rich88
02-14-2010, 11:19 AM
The background:
Last September I swapped the worn-out 360 in my '88 using one I'd overhauled, ran for about 5K and then sat for about 5 yrs in an '83 (long story). The last time it ran I had healthy oil pressure: idled at about 20 and steady at about 50 when hot running on the highway.
When I first started up after the swap, the oil pressure max'd and stayed that way for about several minutes, and then blew out the oil filter. It appears that 5 yrs of sitting caused the oil pressure bypass valve to get gunked and wasn't opening. So I removed the cap & spring, but I couldn't get the actual valve out. Again, presumed stuck.
Instead of removing the whole timing chain cover like I should have to do clean-out surgery (lazy me) I squirted a bunch of solvent in the open hole and swabbed out what I could under the inconvenient circumstances. I put the cap & spring back in, fired it up, and behold the cold oil pressure max'd at about 60, but when fully hot it nosedived. Since September, I've been running around with 25 max hot running and around to 2-3 when idling. My theory now is that same gunk is preventing the valve from closing adequately to maintain good pressure. (Yes, I added a mechanical pressure gage, and in fact the electric sensor & gage is pretty close.)
The cure:
Today I finally decided to try something: I removed the oil pressure relief cap & spring and inserted a 3/8 spacer between the cap and spring. With the added spring pressure it was a Great Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley Moogley to get the cap to screw on, but I prevailed.
Behold I'm now running hot at 35 and idling at about 5. So I made progress. But not good enough. I obviously need a longer spacer, but I know I would not be able to screw the cap on with the added spring pressure. So next step will be to drill & tap the center of the cap and insert a fine thread bolt that I can turn to push the spacer I added - and therefore the spring - to increase pressure on the bypass valve. This way I can adjust for proper pressure after a hot run. I just want to get by until Spring. (No garage, and in CT)
I'll report back when that's done, for better or worse.
If anyone else has had experience with this same problem, your comments are welcome.
Rich
Last September I swapped the worn-out 360 in my '88 using one I'd overhauled, ran for about 5K and then sat for about 5 yrs in an '83 (long story). The last time it ran I had healthy oil pressure: idled at about 20 and steady at about 50 when hot running on the highway.
When I first started up after the swap, the oil pressure max'd and stayed that way for about several minutes, and then blew out the oil filter. It appears that 5 yrs of sitting caused the oil pressure bypass valve to get gunked and wasn't opening. So I removed the cap & spring, but I couldn't get the actual valve out. Again, presumed stuck.
Instead of removing the whole timing chain cover like I should have to do clean-out surgery (lazy me) I squirted a bunch of solvent in the open hole and swabbed out what I could under the inconvenient circumstances. I put the cap & spring back in, fired it up, and behold the cold oil pressure max'd at about 60, but when fully hot it nosedived. Since September, I've been running around with 25 max hot running and around to 2-3 when idling. My theory now is that same gunk is preventing the valve from closing adequately to maintain good pressure. (Yes, I added a mechanical pressure gage, and in fact the electric sensor & gage is pretty close.)
The cure:
Today I finally decided to try something: I removed the oil pressure relief cap & spring and inserted a 3/8 spacer between the cap and spring. With the added spring pressure it was a Great Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley Moogley to get the cap to screw on, but I prevailed.
Behold I'm now running hot at 35 and idling at about 5. So I made progress. But not good enough. I obviously need a longer spacer, but I know I would not be able to screw the cap on with the added spring pressure. So next step will be to drill & tap the center of the cap and insert a fine thread bolt that I can turn to push the spacer I added - and therefore the spring - to increase pressure on the bypass valve. This way I can adjust for proper pressure after a hot run. I just want to get by until Spring. (No garage, and in CT)
I'll report back when that's done, for better or worse.
If anyone else has had experience with this same problem, your comments are welcome.
Rich