Found oil pressure problem, Out of round crank Options

[Chad911sc]

So when I built my engine, I took the crank to a local central Florida machine shop. I asked for it to be checked in every way and turn it down .010 if needed. They called me back up a week later for pickup, and said it was all good and my mains were well within spec for standard bearings. All they did was micro polish it. Before putting it in the case, I checked with a set of micrometers that I had purchased and it was in spec. The car had 85lbs of oil pressure on start up, but would fall to 5lbs after up to 220. I tried everything from different oil pump to the tangerine oil pressure valve, but nothing helped, so I tore it all back apart and started over. The bearings on the ends of the crank looked perfect, but the middle bearing was wiping on both thrust sides. So I bought a bore gauge and checked my case after torquing it back together, and it checked out perfectly. I thought I was going to need a line bore of the case due to stretching, but that wasn’t the issue. So I took my crank to another shop to get it checked out and he put it on the machine right in front of me, and wouldn’t you know the crank was out of round on the middle bearing by .008 ! So I see now why the middle bearing had such extreme wear and my oil pressure was disappearing. They are going to turn it down .010 on the mains and straighten it for me.
I am also putting an o-ringed oil pump back in as well to solve the improper fit issue with the type 1 pump. When I checked the bore of the case and the oil pump that came out of it, they were the exact same size. So the press fit was lacking a bit. Hopefully will be putting back together in a couple weeks once the parts are back in and the machine work is done.

[Chad911sc]

Main bearings

[friethmiller]

That sucks but it makes sense. At least you know and are now fixing the problem. Hope it all works out this time. I'm waiting word on my machinist but I think I've got the same problem with my aftermarket crank.

[930cabman]

Do you recall when assembling the case of the smoothness/tightness of the crank while turning by hand? ie, any indication of a tight fitting main bearing?

[Chad911sc]

No not really…everything felt smooth and normal…

[Superhawk996]

Good find

(IMG:style_emoticons/default/smilie_pokal.gif) for doing the deep dive to get to root cause

[930cabman]

Good find

(IMG:style_emoticons/default/smilie_pokal.gif) for doing the deep dive to get to root cause

the best way to go, otherwise you are picking up the (probably broken) pieces and mucho $$

" crank was out of round .008" with the precision required here thats a mile

[stownsen914]

Yikes what a story. Good you figured it out, you should be on the right path now.

To get .008" out of round, the machine shop must have done some righteous polishing job ...

[Chad911sc]

Exactly!
Or dropped it off of the counter and wiped off the dirt before handing it back to me!
Either way I feel good that I actually found something to be the cause of the pressure drop. I was beating my head against a wall trying to figure it out.

[porschetub]

Yikes what a story. Good you figured it out, you should be on the right path now.

To get .008" out of round, the machine shop must have done some righteous polishing job ...

(IMG:style_emoticons/default/agree.gif) you would think the machinist would have checked for runout BEFORE anything more was done ?? pretty much standard proceedure ...strange .

[trojanhorsepower]

Glad you figured it out.
Sorry you had to deal with this.

[Chad911sc]

The “machine shops” around central Florida have changed drastically over the past 10 years or so. My best friend is a Toyota Master Tech that builds mud race truck engines every weekend, and he always points me to the right direction for my machine work needs. But he couldn’t give me a good place for my crank work, because his guy moved out of state and the work that he had to have done lately, had been hit and miss. All the air cooled gurus have retired and or passed away. When I moved here in 1992, there were quite a few very good air cooled machine/build shops here. Now there are none. I rolled the dice with a machine shop I had never used, but had very good reviews from all different types of engines. I figured any machine shop could easily check and turn a crankshaft. I will take nothing for granted this time and will check it all. I am very disappointed to have this engine back apart in my living room, but also I love to learn and see how things work. Having it apart again and being able to tweak a few other things that I would have done differently, it’s a great learning experience and a chance to overcome some adversity.

[bkrantz]

The “machine shops” around central Florida have changed drastically over the past 10 years or so. My best friend is a Toyota Master Tech that builds mud race truck engines every weekend, and he always points me to the right direction for my machine work needs. But he couldn’t give me a good place for my crank work, because his guy moved out of state and the work that he had to have done lately, had been hit and miss. All the air cooled gurus have retired and or passed away. When I moved here in 1992, there were quite a few very good air cooled machine/build shops here. Now there are none. I rolled the dice with a machine shop I had never used, but had very good reviews from all different types of engines. I figured any machine shop could easily check and turn a crankshaft. I will take nothing for granted this time and will check it all. I am very disappointed to have this engine back apart in my living room, but also I love to learn and see how things work. Having it apart again and being able to tweak a few other things that I would have done differently, it’s a great learning experience and a chance to overcome some adversity.

Good attitude!

Too bad so many people working in supposedly expert jobs don't have it.

[930cabman]

The “machine shops” around central Florida have changed drastically over the past 10 years or so. My best friend is a Toyota Master Tech that builds mud race truck engines every weekend, and he always points me to the right direction for my machine work needs. But he couldn’t give me a good place for my crank work, because his guy moved out of state and the work that he had to have done lately, had been hit and miss. All the air cooled gurus have retired and or passed away. When I moved here in 1992, there were quite a few very good air cooled machine/build shops here. Now there are none. I rolled the dice with a machine shop I had never used, but had very good reviews from all different types of engines. I figured any machine shop could easily check and turn a crankshaft. I will take nothing for granted this time and will check it all. I am very disappointed to have this engine back apart in my living room, but also I love to learn and see how things work. Having it apart again and being able to tweak a few other things that I would have done differently, it’s a great learning experience and a chance to overcome some adversity.

Good attitude!

Too bad so many people working in supposedly expert jobs don't have it.

I have found basically ALL working people are 1/3, 1/3 or 1/3. The first 1/3 really care, are knowledgeable and get a good result generally, the second 1/3 have some desire to get a god result but often don't and the other 1/3 just don't care. they are in it for the $$ and the results show. This goes for doctors, lawyers, barbers, postmen, 914 guys, you name it

It's often a crap shoot

[Chad911sc]

You are exactly right..
I’ve worked with Drs in the Critical Care stetting for over 30 years, and that is a solid truth even when it comes to people’s lives.