Oil pressure gauge reads low and knock on cold start in small block

[HotRodPC]

At least the thicker grade helped some. That does go to show you do have some bearing wear or the gears in the oil pump are worn. I'd tend to lean toward the bearings since you mention the knock. Never know, it might go another 50K with that knock.

 

[austinado16]

Yeah, now I reeeeeaaaly want to pull the pan and roll a set of rods and mains into it and replace the pump.

Of course there's a bunch of things in the way of the oil pan bolts....hard lines for the engine oil cooler, support arms for the bell housing, lower trans bell housing cover, etc. So it's going to be a bit "fiddly." Was hoping I could just lay on my back and go, zip...zip...zip with my 1/2" drive air gun and have the pan fall off and hit me in the face.

Might do it after the upcoming trip though.

 

[HotRodPC]

Yeah, now I reeeeeaaaly want to pull the pan and roll a set of rods and mains into it and replace the pump.

Of course there's a bunch of things in the way of the oil pan bolts....hard lines for the engine oil cooler, support arms for the bell housing, lower trans bell housing cover, etc. So it's going to be a bit "fiddly." Was hoping I could just lay on my back and go, zip...zip...zip with my 1/2" drive air gun and have the pan fall off and hit me in the face.

Might do it after the upcoming trip though.

uhhh NO. Doesn't work that way. Removing the pan is a chore. If you're doing all that, I'd also consider changing the rear main. But, wait, you have the 1 piece, so no, it should be OK if it's OK now.

 

[austinado16]

So is the rear main, not a 2 bolt affair, where the main cap comes off and there's a bearing shell in the main cap, and a bearing shell still up in the bock above the crank?

If it's not designed that way, then does that mean the transmission has to come out in order to replace the rear main?

 

[HotRodPC]

So is the rear main, not a 2 bolt affair, where the main cap comes off and there's a bearing shell in the main cap, and a bearing shell still up in the bock above the crank?

If it's not designed that way, then does that mean the transmission has to come out in order to replace the rear main?

Yep. Not sure of the exact year. I want to say 86 was the last year of the 2pc rear main where you had the 2 half moons that you could slide up and around the top of the crank. After than, it's a 1 piece and goes on within the bellhousing area from the back of the block. Just another tip, if you are going to do the rear main too and have the trans backed off the block, change your freeze plugs back there too while you're there since you have the high mileage. Actually high mileage doesn't even matter for freeze plugs. Its a matter of being 23 years old.

 

[bucket]

Really close, '86 was the first year for the 1-piece rear seal.

 

[austinado16]

I'm confused (an possibly stupid too)...

When I search for crankshaft bearings for a 1990 V1500 'burb with SBC, I get this:

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Which shows that all of the bearings are standard 2 piece bearings.

I understand that the rear main seal is a standard round seal, like I'm used to seeing, rather than a 2 piece "rope" type seal.

So are you saying that the rear main doesn't have a main bearing cap w/ 2 bolts facing "down" like the other main bearing caps?

 

[HotRodPC]

Really close, '86 was the first year for the 1-piece rear seal.

I knew is right there in the mid 80's somewhere. But I was thinking they help off until TBI for the 1 pc. Apparently not. So the 86 is a bastard. 1 pc rear main wo the center bolt valve cover heads and carbed.

 

[HotRodPC]

I'm confused (an possibly stupid too)...

When I search for crankshaft bearings for a 1990 V1500 'burb with SBC, I get this:

You must be registered for see images

Which shows that all of the bearings are standard 2 piece bearings.

I understand that the rear main seal is a standard round seal, like I'm used to seeing, rather than a 2 piece "rope" type seal.

So are you saying that the rear main doesn't have a main bearing cap w/ 2 bolts facing "down" like the other main bearing caps?

Yes the rear main does have 2 bolts. But notice the bearing for the rear has a flange that wraps ver the edge of the main cap. IIRC, the thrust on the crank rides up against that flange or... wait. Now I'm confusing myself. That flange is for a reason now I'm forgetting. Deeta Dee !!!

 

[HotRodPC]

Well hell. I thought I had a pic of a back of a 1pc rear main block with the crank in it. But guess not. I do have one here though if you want me to go out back and get you a pic. It's from a 94 TBI motor.

 

[bucket]

The rear cap bolts on just like the earlier small block, but there is a rear seal and seal retainer that bolt to the back of the block with a gasket. The seal retainer is also the surface for the pan gasket.

 

[austinado16]

Here's a photo I found online of the earlier rear main:

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Bottom line.......can I change the front and rear mains by just dropping the pan. Or, does the transmission and flex plate have to be removed to get the rear main shells out?

 

[Guardian]

Todd, we are having a communication glitch here. lol...
You are talking about the main bearing and hotros is talking about the rear main seal.

Yes it has a 2 bolt reaer main bearing cap; but is is not as wide front to rear as the one you have pictured. THe blue pieace in that picture is the rear main seal and it is a two piece. Most of the 86 blocks are a one piece rear main seal and it isn't in the main bearing cap. This type seal bolts to the back of the block behind the flexplate.

The one piece rear main seal prevents you from rolling in a bearing shell because it doesn't allow the crank to move downward, and if it does you will need to replace that seal.

 

[austinado16]

Okay, gotcha. That's exactly what I wanted to know.

While I have never rolled a set of mains into a SBC, or any V-8 for that matter, I've never had a problem rolling them into other engines, even the flanged thrust bearings will roll in. Again, not saying that it IS possible on a SBC, all I'm saying is that I've done it quite a few times in other engines.

And yes, I knew my 2 sample photos above were of the early design. I was just using them as a reference, and also, I couldn't find any photos of the later design. I actually had to laugh a little when I read the article that went with those photos. It was an engine that rebuilt not that long ago, and was leaking from the rear main seal. First of all, there's red silicone smeared all over the pan gasket like a 4 year old built it, and then I see the condition of the bearing shells.....hey, guess why it's leaking passed that 2 piece seal. And then the guy just put it back together with the destroyed bearing shell. Hey....knock much on cold start?

I'm sure my rear main looks just like this, and that's why I have a rear main seal leak, even after having the seal replaced when the trans was out last year.