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| slow oil pressure https://slantsix.org/forum/viewtopic.php?t=46867 |
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| Author: | 65CrewCabPW [ Fri Nov 04, 2011 12:09 am ] |
| Post subject: | slow oil pressure |
Any ideas why it takes 20 seconds in the morning to get oil pressure? I hear the bearings slowly start to make noise after it starts before finally, the pressure comes up. I don't have a gauge right now, just an idiot light. Start and it flickers for up to 20 seconds of idling. After that, during the day, it's pretty much immediate. I changed oil pumps and I literally had to crank and idle it for 1 minute with no oil filter before any oil came from the pump. I had previously filled the pump with oil, so no, it wasn't dry. However, the new pump isn't realy any different from the old one. |
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| Author: | SlantSixDan [ Fri Nov 04, 2011 12:21 am ] |
| Post subject: | |
Service the oil pressure relief valve to make sure it's not stuck and is doing its job, as described in these two threads: thread 1, thread 2. |
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| Author: | Charrlie_S [ Fri Nov 04, 2011 5:27 am ] |
| Post subject: | |
What weight oil are you running? You really don't want anything heavier then 10-30 unles the engine bearings are already toast. The heavier the oil, the longer it will take to get to the bearings, from a cold startup. If you install a guage, even a tempory setup (about $10), and check cold idle/cold 2,000 rpm/hot idle/hot 2,000rpm, pressures, that will help determine the condition of the bearings and the relief valve. I'm thinking not relief valve as you changed pumps, though it is possible. Also might have a crack in the pickup tube. |
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| Author: | Doc [ Fri Nov 04, 2011 8:54 am ] |
| Post subject: | |
Are you using the factory anti-drainback valve at the filter or a filter with a built-in drainback check-valve? DD |
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| Author: | 65CrewCabPW [ Fri Nov 04, 2011 9:40 am ] |
| Post subject: | |
I'm running 10-30, I have no idea what drainback valve (i'll look at the links) and I suppose it's entirely possible I have some kind of air leak in the system. I changed the pump merely because the old one was leaking like a sieve, and I got the new one (brand new sealed power) for near nothing on Ebay. I don't have a gauge becuase the sender was leaking and I don't have a replacement yet. I"m intending to rebuild this shortblock in a year or so, as it seems to have excessive blowby, even though it's recently been rebuilt... but apparently done by some mass production rebuilder shop. I'm going to look for a core shortblock and have the machinework done by my favorite race engine shop, so I get it done right ( torque plate, multi-pass boring, balancing, etc) instead of the crap jobs most machine shops do. Until then, I'm kind of at a loss as to why this thing is so slow to get oil pressure. btw, this is the propane engine, in the morning it takes about 8-10 seconds cranking to start, first to pull the vacuum lockoff, then get fuel in the engine, and finally to actually start and run, which I use slight throttle to get to run about 800 - 900 rpm. Also, what's this about a cracked pickup tube? does that happen often or is it common for it to leak, etc? This is on a truck. |
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| Author: | bigslant6fan [ Fri Nov 04, 2011 11:26 am ] |
| Post subject: | . |
Might be a plugged oil pickup screen too. |
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| Author: | 65CrewCabPW [ Fri Nov 04, 2011 12:03 pm ] |
| Post subject: | |
I've thought of that, but this engine has low miles since apparently being rebuilt (no ridge on cyl walls, no gunk under original rocker cover, etc), so I don't see that as likely. |
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