Help with lightly modified L31-R

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davkenrem

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How about you guys start your own thread about rocker arms so this thread can stay on topic?
 

davkenrem

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OK, so it's been five months since my last update on the project. We left off with me losing all oil pressure to the engine. I was devastated. There was still snow on the ground, but in early April I got some good enough weather to pull the pan and investigate what happened.

Once I go the pan off I could see the problem. The oil pump drive shaft had some how bound with the oil pump and they destroyed each other and damaged the rear main cap.

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davkenrem

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The Oil Pump Drive shaft somehow tore the slot in the Oil Pump in half and cracked a corner of the rear main cap.

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I put the pan back on and though my new motor was going to need to be fully torn down to repair it. That was April. Late in May I took these photos and the damaged parts to the machine shop. In the ensuing weeks I was sure that I would need to replace the rear main cap and have the block Line Honed. Looking at almost what I paid for the engine to have it tore down and line honed for the new cap and reassembled, not including my time to R&R the engine. I was not happy.

Your wondering how this happened. I'm not completely sure but I think it may have had something to do with my attempts at priming the engine oil system with an old distributor. That's all I'm going to say about that. Suffice to say it was my fault, no one to blame but numero ono. And honestly thats the way I prefer it, if something going to get screwed up, I'd much rather I did the screwing up that way there is no one to lie to me about what happened and no fight over who's paying for it.

Anyway after the machinist looked at it he said, "you know the important surfaces on the main cap are fine and there is no damage in any stress area. I'd break off the cracked area of the cap where the Oil Pump drive shaft passes and bolt it back on." I looked at it and agreed and so, that's what I did!!

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I broke of the cracked corner, smoothed out all the edges and bolted it back on. While I was in there I inspected one of the other main bearings to make sure no trash ran through the engine and it looked good. Cleaned the pan really good, new gasket, oil filter and fresh oil and it is running fine, no noise or anything. I will change the oil next weekend and take another hard look at the oil and the filter, but I think it's fine.

Next up 411PCM swap!!

I've got everything ready to do that this coming weekend if the weather agrees. But soon that won't be a problem as I broke ground on a new 24'x32' garage this month so soon weather be damned, I'll have a place to work, Lord willing.

Engine idle is a little low and rich and the shift points are not where I want them, so those will be the first adjustments made after the swap.


More to come, Stay tuned

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Schurkey

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The Oil Pump Drive shaft somehow tore the slot in the Oil Pump in half and cracked a corner of the rear main cap...

...Your wondering how this happened. I'm not completely sure but I think it may have had something to do with my attempts at priming the engine oil system with an old distributor.

So...what happened to the plastic collar on the oil pump drive shaft?

Some aftermarket oil pump drive shafts use a metal sleeve instead of the OEM plastic collar.

Lack of guidance for the drive shaft is what broke the oil pump and main cap. Has NOTHING to do with priming the engine. Either that, or the oil pump gears locked-up due to debris. My bet is on the oil pump driveshaft collar, because there should be no debris in a new engine. Old engines often have pieces of hardened plastic/rubber valve stem seals, or broken-off teeth from a nylon-coated timing set laying in the bottom of the oil pan, smaller pieces can get pulled through the oil pump pickup screen and lock-up the pump.

https://www.summitracing.com/parts/mah-h31354/overview/
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https://www.summitracing.com/parts/mel-is-55e/overview/
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Gramps

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So...what happened to the plastic collar on the oil pump drive shaft?

Some aftermarket oil pump drive shafts use a metal sleeve instead of the OEM plastic collar.

Lack of guidance for the drive shaft is what broke the oil pump and main cap. Has NOTHING to do with priming the engine. Either that, or the oil pump gears locked-up due to debris. My bet is on the oil pump driveshaft collar, because there should be no debris in a new engine.

Melling actually recommends pulling apart their new pumps before installation to check for debris from the manufacturing process.

But aside from that, what pump was used? On the high volume pumps they tell you to use a new shaft with steel collar.

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davkenrem

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The new oil pump has the the shaft with the metal sleeve...
 

L31MaxExpress

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I replaced my stock driveshaft on my L31 after finding the the plastic colar in two pieces in the pan. The factory GM Goodwrench pump was a M55HV in my circa 2005 crate engine.
 

davkenrem

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I replaced my stock driveshaft on my L31 after finding the the plastic colar in two pieces in the pan. The factory GM Goodwrench pump was a M55HV in my circa 2005 crate engine.
I just went with the standard volume. For the rpms this will see it will be fine.
 
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