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ZondaC12

HEYY!!! I'm back....my 248 has an entirely new lease on life...

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Thought this would be the perfect time for an update so some of y'all don't think I dropped off the face of the earth! :P

School keeps me a slave, got my last final next Monday, winding down at long last. But I'm the most excited I've ever been over anything having to do with this car right now.

Some might remember me whining about the tapping/knocking noise that it makes, under load, sometimes under this condition blah blah but not always and it was a theoretical discussion that went nowhere because I didn't know enough about what I was talking about in diagnosing a source even.

I was reading a site purely dedicated to noise diagnosis, and it's funny how there are simple things that work that you'd just never think of. Like pulling plug wires and seeing what happens.

The car has been off the road for a couple months now, but I rolled it out of the garage, started it, and did just that. Figured I'd start nearest the firewall. I pull the wire, rev it........NOTHING. :eek: :eek: :eek: Sounds like a whole new engine. It really to me anyway, makes it sound like it's brand new. After 4 years of wondering and trying not to beat on the car and worrying, the problem is solved. I'm gonna go with wrist pin. No noises exist at the speed of the rotating assembly. Maybe piston slap...but the main point is the head's coming off this winter over break and I'll see what I find! :D

I'm just so in love with the fact that this engine, being this old, is in this condition. KNOWING this. Now I can enjoy the car far more carefree than ever. Can't wait til spring!!!!

Have a good weekend all, hope everyone's doing well.

Edited by ZondaC12 (see edit history)

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Paul,

Glad you're back. I was beginning to wonder if the old girl was taking a back seat for a new one.... You might re-think pulling the head though.

I don't think you can remove the piston and rod from the top, but you can do it from the bottom.

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Really. As in...even with the crank there? It'll fit through? Possibly showing my ignorance some more...is it not up through the block you usually install/uninstall pistons? Why? How do you utilize a piston ring compressor to install it then?

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I'm pretty sure the pistons come out the top of a 38. They did for my 39 and the 38 and 39 engines are very similar.

Earlier Buick pistons had to come out the bottom, the big end bearing on the rod would not fit through the cylinders. This could be done without removing the crank, you just have to rotate it to the right position. On those bottom loading Buicks, there is a generous chamfor on the bottom of the cylinder to help compress the rings. I don't think there is enough room on the bottom of your 38 to get the pistons through.

Your Buick probably has a loose big end connecting rod bearing. These have poured babbitt and are more inclined to failure than the wrist pin bushings. If the bearing is just loose, you may be able to take out some shims and tighten it up. This can be done simply by removing the pan and taking off the lower rod cap. The shims are between the rod and cap.

If the babbitt is damaged or missing (you'll see chunks of it in the pan when you take it off, looks like solder), you'll have to pull the rod and sent it out for rebabbitting.

Good luck

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I have not yet had the pleasure of tearing down my 38 engine. Buicksplus is right the pistons and rods can only come out the bottom of my 31 engine. I have had my 31 engine torn down completely. I also re-babbitted a couple of rod bearings and am now re-assembling it. Today I will be using Plasti-Gauge to check clearances & to correctly shim the rod caps.

Pulling pistons & rods from the top will be much easier....

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Definitely worth checking...especially seeing as two hours ago my semester ENDED!!!!!!!!! Feels great, freedom I need badly. I plasti-gauged 'em all in '07 after going to Rhinebeck twice, and that was there and back twice at 60 mph, so about 3,000 rpm the whole time. Most of them checked out fine, I replaced a couple shims here and there. I would certainly check it again though, seeing as the pan will be off anyway.

I should find something in there anyway! And I'll let y'all know what that something is, when it is found! :D

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Paul I never had a 38 248 apart but when I pulled the pan on my 41 320 I had to jack the frame to give clearance for the pan to come off (tie rod in the way) so as to not adversely effect clearing the oil pump pick up. The oil pump pick up was attached to a swing floating oil filter. Bottom line read carefully your book on pan removal as the oil pump pick up might be cheap pot metal and easilly broken.

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Well...looks like last time I never looked closely enough, or probably just didn't bother to crank it over and check every cylinder wall. Just so happens to one of interest is plainly visible. Pushing the rod off the crank and wiggling it, you can see and feel the piston move side to side in the bore. :( There are visible scuff marks up and down the bore in at least two locations, about 1/4" wide or so, spaced about 1/4 of the circumference apart. You can also see a haze of rust through the oil film actually. It seems like the wrist pin is quite tight. There are no shims left on the rod cap, and another plastigage showed that its somehwere between .0015 and .002, which is about the maximum tolerance allowed according to the shop manual (.0018). As they all were when I checked some two years ago, the cap and rod babbitt both look GREAT on this cylinder, as does the crank journal.

I dont mean to put myself down buuuut I can't help but think that at 16 I just wasn't nearly cautious enough. I'm sure those helping me back then felt the same way I do now whenever I read or hear about someone unearthing a vehicle from multiple decades of sitting and getting ready to try and turn the motor. Who knows. Maybe I made it get starved of oil, maybe not.

Where the bore was scuffed didn't FEEL very damaged to the touch, I'll say that much. Any chance it could be honed? Can a standard non-oversize piston be put in? I would guess this would accomplish nothing because both the piston and bore are now worn some unknown amount, correct? If the next step is overboring and a new piston, well, then this might be the beginning of another resting period for the old girl. :( I'm certainly not going to drive it with that piston continuing to slap away. The noise is bad enough, but knowing what's going on I just couldn't do it. And yes, "someday" ONLY that cylinder will be bored and that piston replaced. The camshaft looks MINT, everything else looks so nice and is obviously in much better shape...I'll be able to at least say 7/8ths of the engine is original!!!!!;):D

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You can go the old way and GI the Pistons ( knurl the skirts to fit the bore). In my

experience with 1932 engine blocks, the cylinders wear to a taper (ususally less at the bottom. Honing should easily remove the scoring. I would'nt be concerned about the .002 clearance as long as the babbit is smooth. Just run a higher viscosity oil than normal.

In my early mechanic life ( 1950's) It was very common at about 70,000 miles to pull the head, knock out the pistons, hone the bores, GI the pistons, install new rings and put the engines back together and they were good for another 50,000 miles.

Bob

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Hmmm! Did a little reading...interesting. Is this something most machine shops can do? I suppose I'd just ask and find out. I like the idea...new school old school any ideas like that I'll listen to. :cool:

That's pretty neat...thanks for the bit of history. I LOVE stories like that.

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Okay I tore the freakin' thing down Saturday I need to update this thing already....I hate photobucket it's good but it's gotten so crowded now they limit ya and it's dead slow. Don't feel like uploading the pictures now. What a lazy BUM. Doesn't help the college kid stereotype much. Course I am on winter break and pulling at least 30 hours a week at my usual off-school grocery store stocking job. But still....WHAT A LAZY BUM!!! :D:p Hahahaha.

Anyway. Head's off...the upper oil ring is actually broken in two different places. Most of each respective section is broken, not all the way, just a chunk taken out. About 3/8" long in each case. Who knows when this happened. Probably a long time ago, plenty of scoring of the piston. But my buddy and I think a hone should DEFINITELY take care of the cylinder. I wanna see what his dad says about the ring. Only one thats broken. Dunno if all should be replaced or just the one. Don't know about the whole seating thing myself. Probably gonna grab a piston from Kanter, I know they anyway sell 'em each for $38. No clue on bob's or CARS though I'll check.

Plenty of carbon everywhere inside...nothing overly suffocating...actyully starting to clean itself out seeing as the one piston had a lot of its surface showing. Head's gonna get cleaned up real nice in another friend's huge high-tech parts washer. Check the valves do some lapping maybe make sure they all seat. While its out ya know!!!.....

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:) Hi Paul,

Glad to see you're making some progress. After you remove the carbon from the top of the bores, if you have a ridge on the top of any of the cyl. bores, use a ridge reamer to remove it. I'd get a micrometer to mike the bores to see if they're std. size first, and if you're able to hone the 'bad' bore , hone it the bare minimum with a fine stone to remove the 'scrapes in the bore and re mike it before you just order a standard size piston. I'd also get all the rings for that cylinder, and when you install the rings on the piston, make sure you have enough ring end gap and groove clearance on the rings in the piston grooves ( should be about .010 end gap and .0015-.003 groove clearance on all the rings) when you reinstall the piston.

Another thing to make sure of is the fit of the piston pin in the piston and alignment of the rod-pistion assy. Please keep us posted, and make sure you scrub your hands good before you restart school!!

:) kaycee

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:) Back again, Paul,

Another thing I forgot to mention was that according to my old Motors and Chiltons manuals, the piston/rod assy's are removed from the top on '38's.

Good luck!

:) kaycee

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Zonda,

I think you are going down the exact same path I have travelled.

About 15 years back I pulled the head, dropped the pan and removed each piston / rod assembly. Sure enough, I had one bad piston. It's ring land (upper) had failed and the ring was broken, causing some cylinder scoring. So, I pulled the block and had the one cylinder re-sleeved. I bought one new piston, and a full set of new rings and started putting it back together. Well, I always thought I had a bit of high rpm vibration, and attributed it to the one new piston (slightly different weight?)

To make a long story short, I came across some new (1950 vintage) connecting rods, with insert bearings. So, last summer I decided to pull the head and do this quick update. I was surprised to find four more pistons with ring land damage and broken rings. Even though it was still running, it would not have gone on for long. This time, I pulled the block and had all eight cylinders bored .030 over, and ordered all new pistons and rings (and of course, the conn rod bearings). Plus, I had the crank turned so I needed new mains as well $$$.

Anyway, my theory is that the original set of pistons, having an equal number of stress cycles as the first failed one, were not destined to last much longer. I should not have re-assembled with the originals. (the car only accumulated 2 - 3,000 miles in 15 years). So, give that some thought.

If you do want to replace just the one piston, I have the first Egge replacement in my garage, 15 years old, but not many miles! Free. Should be good to go.

Jeff.

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Kaycee--thanks for those tips, I did intend to measure the bores, just gotta get my hands on a mike and that will be done first and foremost!!!

Jeff, as soon as I read the first sentence I knew what was coming! I don't know how but I did! Probably "path" and "traveled" did it hahaha :eek: :D

But yes I see what you're talking about. I really hoped I could leave this engine entirely alone, thought it would be nice to claim I haven't opened it up and it's still fine. I have not removed anythign besides that piston and rod. I intend to leave it that way. If something else goes bad...such as a vibration or whatever, so be it. I'm gonna at least try. If I gotta do this again, oh well. Unlike when I tore down my '87 Cougar for a top end upgrade, this has taken very little time. I love it. Like an 8-cylinder lawn tractor. Also..PM sent.

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Paul,

Hang in there, it sounds like you are getting some great advice. You have done well the last couple of years and are learning a whole hell of a lot.

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Hey thanks a lot Stevo! I definitely have, and the more I know the more I love this car and the hobby in general.

Two things I still want to someday be able to do on my own are to rebuild a transmission either stick OR auto, and set up a rear end aka ring and pinion. Then I can pretty much say I do ANYthing I need, myself. I really REALLY enjoy being self-reliant and able to build/fix/replace whatever I need to. I can't imagine how much money I've not spent over the last several years due to the labor being taken care of my yours truly.

This was something I've wanted to tackle for a long time. I so strongly look forward to being able to drive it without spending a half hour getting up to 40 miles an hour just to avoid hearing that thing slapping!

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Hey Paul, Getting the pistons out from the Bottom of an early engine is quite common for stuff built before the 30's. As far as installation, The bottom of the cylinder had a 45 degree taper cut into it so with a little wiggling, the rings would collaps and slide in one by one. The 15 is this way. Many early stationary engines were also made this way. Glad that you are doing alright, and still at it with the old Buick. :D Dandy Dave!

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Our 39 Special coupe with it's 1947 engine had totally destroyed pistons, and no compression rings to speak of, and still ran! Had to bore it out 0.30. Great fun! Bob's pistons are things of great beauty. I can highly recommend them.

Cheers

Grant

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Spring is here and the car is finally on the road of course....

I am overjoyed to report that it runs and sounds like a brand new engine. I'm amazed. No noises under any conditions at all, not to mention some increased smoothness I think from lapping the valves and cleaning everything while it was apart. These things really have some muscle when you can actually USE it!!! :)

Today is in the mid-60s, and the thermometer won't even break 140 degrees. Equally shocking.

There will be three things still around at the end of the universe. Cockroaches, 1980's ford 300 CI straight 6's.....and this car.

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Any one know what the compression should be in a 1939 Buick 8?

6.1:1 in the smaller ones (40's)

6.25:1 in the bigger ones (everything else)

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