Crankwalk's affect on block without crank contact

Just 300 km ago, I rebuilt my 7 bolt 4g63 in my CE9A evo 3 with ACL race bearings and forged internals. The crank was the original one, and when I got it back from the machine shop, it had a bit of uneven wear on the thrust bearing surface. The shop assured me the surface was fine, so I ran the crank.

Fast forward to last week, and the engine began cutting out when clutched in. It has ~ 2 mm crank endplay, and I've pulled everything apart. The crank has gone through the copper surface of the thrust bearing, and is into the steel. There was no contact between the crank and the block.

I just paid quite a bit getting this block decked and bored over only a month ago. I have an Eagle crank now, and want to make sure I don't have any more problems.

After researching online, some suggest once a block crankwalks, its no good to reuse (but provide no engineering standpoint backup as to why this would be the case), and then there's quite a few others (including shops who've given input on the subject on the dsm forums), who say the block is perfectly fine to be used with a new crank and main bearings.

Anyone with some first hand knowledge on this?

Unless someone has some actual reasoning as to why the block would suffer (heat distortion maybe?), I'd be inclined to pull it down to the bare block, pressure wash the whole inside/oil pump, and re bearing it with the new crank.

Hey Mike,
Watch this YouTube video:
http://youtu.be/hF8iCN7H7DY

I don't have a lot of experience with rebuilding engines (my 240k 7bolt still strong) but bad cranks can lead to crankwalks.

The block is perfectly fine to reuse, been there done that on a few engines already over the years. The thrust simply wasn't aligned properly and it wore.
I'd highly suggest getting your brand new Eagle crank machined 10 thou under on the mains and rods to make sure it is straight. The Eagle cranks are rarely straight brand new from what I've heard. I will not even run a good OEM crank now without getting it machined 10 thou. A few guys I know with high HP setups and myself have been running machined cranks for a few years now with no issues at all.
In fact if I was you, I would have just gotten another used OEM crank, machine it, align the thrust properly and call it a day

Reza,

Can you explain how a thrust is aligned properly? This smacking the crank back and forth thing has left me questioning whats right.

With motor in car, keep the pan off and use the clutch to apply pressure and align the mains. Works for me. Paul @ Rainbow assembled my bottom end right in front of me properly and it still walked. I caught it in a few hundred km's when the thrust wore upto 0.009, and I was good to go with just a new thrust bearing and using the clutch pressure to torque the mains down. I'v seen a motor built by Gord Bush do the same thing. So it doesn't matter where or who builds it. It's not the machinists fault. Same sh!t at the end of the day and it can still walk.

Reza would you do any side to side prying in the opposite direction prior to setting the final clamp area with the clutch while in the car? Ie, would you move the crank as far as it would go towards the transmission side, then push it the opposite way with the clutch pedal pressure before finally torquing it down?

Do you assemble your motor on a stand, plastigauge everything as per normal with required tq values, then back the main studs off to finger tight, lower the engine/trans into the car without a pasepan/pickup tube, then once its on its mounts, bolt on the slave cyl, actuate the clutch fully a couple of times, crawl under the car, and torque the mains to spec?

Sound like I'm planning on doing it the right way? I hope this gd crankwalk never resurfaces

Yes pry towards the transmission side then use the clutch to press it back towards the other side, keep the clutch pressed down, then torque down the center main.
I'm sure there are other methods that people use with great success. Feel free to chime in
The above method works for me.

I double checked the endplay with a dial indicator. First measure the bearing widths (both halves), then measure the width of the opening in the crank, thrust surface to thrust surface. Do the math. That is the theoretical end play you will have. Once it is assembled, check that the endplay is at least close to that number, I'd say no more than 0.001" smaller. Optimally, it would be the same, but due to stack up of tolerance issues I doubt you will get the theoretical number. Move the crank back and forth in the block with a prying tool and measure the movement with a proper dial indicator setup. It doesn't take a lot of force or banging.
If it's off by 0.005", you know there is a problem.

Thanks for the tips guys.

Reza, are you saying to keep the car clutched in with a second person holding the clutch until the mains are torqued?

Rob, I will check the measurements in the way you describe. Any idea where to pick up a dial indicator for a reasonable price? I've always wanted one, but have used feeler gauges instead as I've not come across one that seems decent for a reasonable amount of money.

That is the first time I've EVER heard that method. But I like numbers so Rob's method makes me feel better in that I can quantify it as correct. Makes good logical sense though.



Princess Auto gauge will suffice and they are surprisingly accurate.

Also do people re-torque main studs after a couple heat cycles or km?

Like I said Mike D, choose your own method. I'm just stating what works for me, and keeps my DSM on the road If I did everything the "number and paper way", I'd probably have a non running DSM for a decade just like you! Haha just kidding.

I take my measurements and know before hand if it's likely to walk or not. Your end play should be on the big end of the spec if all is right. If your on the small end of the spec, it ain't right. Think about it hard enough Mike, Rob and I are both looking for the same thing, just slightly different methods Sorry if I am not giving you #'s. That's for you to look up in the FSM I'll also just pressume you know why I am stepping on the clutch too before I torque it down, afterall you are an engineer

I have both a dial indicator and feeler gauges. I use the feeler gauges between the crank thrust and bearing surface to get measurements.

The engineer in me says if the numbers work there all is good. Numbers don't lie!

You are definitely doing the same thing. The clutch is nice because it applies an even load much more so then a hammer or pry bar can. That part I like. And yes we're splitting hairs here, both are going to align the bearing.

Can you take the measurements with a feeler gauge is there room?

If your on the small end of the spec, What the hell can be done to correct it?

With the pan off, there is tonnes of room to get feeler gauges in there. What Rob is doing with measuring the thrust and crank is pretty nifty too. I never thought of that.

That will indicate that the thrust is not aligned properly. If one of the halves if off by even 0.001 from the other, your final measurement will be on the small end of things.

Think about it, if the thrust is aligned properly, the crank will have the most end play possible right after assembly.

I understand it will be the biggest possible once its aligned but what if the crank was too narrow or the bearing too wide or a combination of both? Tolerances can stack up. I know bearings are made to tight tolerances but what about these aftermarket cranks, these could throw spec's right out the window! Its why I insisted on a OEM crank for my build.

Do people grind the crank to get to the big end of the spec? Is that the recourse?

I have only ever run OEM cranks and have never run into these issues with the bearings being too wide or the crank too narrow. From the research I have done, seems like all the Eagle stuff that comes out is never within spec, especially the cranks.

If your worried about these tolerances stacking up, then Rob's method of measuring things is definately a good way to get things into perspective.

Just got everything ready for the machine shop tomorrow. Getting the head decked for the MLS gasket, the block gone over for where there's a slight knurl on the mains from the crankshaft touching it when the clutch was depressed. I'm also getting them to go over the main bore to check for roundness etc. If they can align hone it I'd like it done but I hear many shops won't do the 7 bolt due to a girdle design. Not sure what's up with that locally yet...

I have a magnetic base and a couple of Mitutoyo dial indicators (1/2" and 2" stroke). Go with whatever brand you are comfortable with. A decent brand is not crazy expensive. You will also use the dial indicator setup when you degree your cams! So it's a worthwhile investment really.

If the bearings are too tight, I would suspect the thrust halves are misaligned. In my experience cranks are ground to give more oil clearance, not less. If it did end up being too tight and it's verified by measuring the parts as I mentioned, then you can sand down the thrust surface with fine grit sand paper and proper machinist angle plate / surface plate. I have done this with a non-4G63 engine and it worked. If the clearance is too big, then you have to decide if you want to try to get oddball bearings, rework the crank ($$), live with slightly oversize oil clearance (not always a bad thing), or get different parts.

Larger oil clearances causes more oil flow, so you may not need to modify the oil pressure regulator / bypass port in the front cover when you remove balance shafts. This also keeps the bearings cooler and you have a slightly larger cushion of oil. Of course, the oil pump needs to be able to supply the oil for that so you can't be too far off, there are limits. Heavier weight oil may be needed too in this scenario.

Another side bar question. I think i have the thrust bearing thing understood and under control.

How do people replace both side of the bearing with the engine in the car? Doesn't the crank need to come out? but of course its attached to the flywheel and timing belt. I've read some people do bearings as a maintenance item in a sense in there strokers.

I was wondering that too.. Certainly seems like you'd have to drop the crank to me! The bearing MIGHT come out with a few taps on the end opposite its keyway, but it seems like it'd be a sketchy way of doing it.

All my parts are at the machine shop now, and it seems like I had ~ .8mm wear on the thrust measuring one side (2mm) of the bearing lip vs the other side ~1.2mm.

Yikes!

You should subtract the clearance spec to actually show how much it wore.

NO the crank doesn't need to come out unless you need to actually replace it. If you actually get around to doing this you'll get creative. I use my "special tool" the slide/pry the bearings out the backside without touching the crank

Yup hardcore guys do replace their bearings after a few passes or at the end of the season.
If you want to drop the tranny, flywheel, clutch, t-belt etc. in order to do it because it makes you feel better, that works too. I don't.

What Reza said.
You just "spin" the bearing out of the block for the upper half. Care is required. Leave a couple main caps on loose with the bearings in them to prevent the crank from falling too far.

On a side note Mike Degli, I think changing your engine bearings with the crank in the car will probably never apply to you. I mean I know your building a 2.4, but with no car to put it into, do you really think that motor is ever gonna spin, under its own power?

Reza, I ain't fueling the fire.......

So I have the engine block align honed now, new bearings, and the eagle crank. It measures consistently with the plastigauge at .001" on all mains.

I usually find mine measures ~ .002" on rebuilds with stock cranks, but the service spec is .0008" to .002" so it is in the range. I'm bolting it together now, this seem fine to everyone? It's a BIT on the tighter side, but everything is brand new, perhaps it will open up slightly after first use?

shots have been fired! hahaha

I wouldn't expect things to "open up". ANY bearing contact is a bad thing. Rings wear in, journals and bearings do not. They all ride on a film of oil and are never to contact each other but from my limited experience i would say you are okay being in tolerance

Like Mike said, its not gonna open up. Tight motor !

You guys have way too much knowledge..