Left head won't prime with oil

b4black

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May 24, 2001
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I purchased a rebuilt 4.1 a few years back and I'm finally ready to fire it up. I pulled the valve covers and I am priming the oil pump with a drill. It's getting oil through the right head and the turbo oil feed, but nothing on the left head. :(

Engine has a new timing cover and a roller cam. What's most likely wrong?

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ScottHeidinger

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May 2, 2015
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dank GN

BlackArts Automotive (661)993-8277
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If the oil gallery plug behind the timing chain on the passenger side is to deep it will prevent oil from getting to passenger side lifters . I’m not certain on what side it is but I know that if that freeze plug is to deep it can ruin your day you can see in the picture the crossover port
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b4black

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Well, the engine was lower mileage and I don't think the freeze plugs were changed. That would leave an issue with the cam bearing. The rebuilder has experience with 4.1, so I'm not sure what happened.

If it is an issue with the cam bearing, will adding the crossover at the back be good enough? (That's seems like the easy solution)
 

ScottHeidinger

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The issue is the roller cam doesn’t have the oil groove in it like the original cam did and normally the simplest solution is the rear oil crossover. You could get different cam bearing that are grooved from TA performance or groove the block but normally people don’t want to pull the cam back out. There are plenty of threads that list the proper size fittings for the crossover on the rear of the block.


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earlbrown

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May 26, 2001
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Non grooved block with a non grooved cam (roller) and you've got no oil on the DS lifter rail. If someone tapped the front lifter galleys for pipe plugs, you can choke off the DS by going to deep (giggidy).


The best answer is to pull the front cam bearing and groove the block. (that's assUming the reason isn't improper installation of the pipe plug)


A 'fix' is to build a connection on the rear cam journals. The main issue with that is getting it right, and hoping it doesn't crack in the future. Once the engine's in, getting to that area is a real bitch.
 

Chuck Leeper

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^^what Earl said. Additionally, you create 2 more potential sources for leaks.
Fix it right.
A. Cam brg.
B. groove the cam. Either way, the ft of the engine has to come off, and the cam out.
While the cover is off, do Earls cover/oil pump mods.
 
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earlbrown

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Well, the engine was lower mileage and I don't think the freeze plugs were changed.

Two problems with that statement. First, 'low mileage' is not a good thing when it comes to rebuilt Buick V6s. Every fresh rebuild I look at is a POS until it has a chance to prove itself. They either have problems right off the bat (like yours), or they last forever.

Second, if someone rebuilt your engine and didn't clean out the oil galleys, they built a grenade with the pin pulled. Behind those welch plugs are basically a debris trap. Crud will build up and sit there..... ...until someone tears the engine down and starts letting the degreaser and parts cleaners fly.


It's easy enough to figure out if an improperly installed pipe plug is your culprit. All you have to do is pull the fuel pump plate and look in there with a boroscope. These engines didn't come with pipe plugs, they came with welch plugs. If the builder didn't tap that location, that's not your culprit.


Being a 4.1 with a roller cam, my money's on lack of cam bore groove.
 

No disintegrations

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This happens a lot. Odd all the cams don't have the groove which seems important. Lol Why ? more bearing surface area or oversight?
 

earlbrown

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More bearing surface area. And less damage to the actual bearing.

It was just a crutch for an ungrooved block. Then it stuck after block were grooved. When roller cams came out, they weren't made from the same blank, so they didn't come with that same weakness/flaw.
 
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