No oil flow to valve train.

5.7L • V8 • 4WD • AUTOMATIC
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LRMOORE89
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  • 1 POST
This vehicle has been sitting for many years after experiencing overheating problems. A few months ago after purchasing it, I took off the intake to clean it up and install new gaskets as the previous owner suspected it to have a bad seal. After putting it together, it ran great and got good oil flow but the transmission is shot which I found out later after the first test drive when I noticed it was leaking everywhere. I plan to replace that later. Well, what ended the test drive was two pushrods breaking in half and so I decided to pull off the heads and replace them with another refurbished set I had purchased elsewhere. I also got a new set of pushrods. After putting it all back together, it has a vacuum leak somewhere and the timing and carb need adjusted which I plan to do. However, while adjusting the timing, I realized after seeing smoke emanating from around the valve covers, I wanted to take them off to make sure I have enough oil flowing to the valve train. There wasn't a single drop. There is a leak near the oil pan which I also plan to take care of but after checking the oil level, it apparently isn't significant enough to have drained the oil. So with the right oil level and pressure, what could be causing this? I inspected the lifters and they all looked just fine but the block is from a 1971-73 Chevelle or like model vehicle and the heads are from a 70-71 corvette so I got pushrods for a '70 corvette therefore I can't imagine the pushrods would in some way block oil flow. Any help would be appreciated.
Nov 9, 2015 at 2:48 AM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
if t lifters get oil and none upstairs to rockers check for blocked pushrods that is how the rockers are oiled. if lifters are not getting oil there is a plug that blocks oil flow below main cap. if that is not installed your oil pressure will be low and that may be the problem. if you have a vacuum leak it' s either the intake gaskets or a hose or something is broken like the manifold. if it' has a Rochester 4 barrel they had internal vacuum leaks. use choke cleaner to find the leak. it should have about 20" of vacuum at idle unless it has a really high performance cam in it then it will be lower. I am talking about a high lift cam over .500"
Nov 9, 2015 at 4:13 AM
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