I pulled my motor back apart because Im getting coolant in teh oil, and this is what I found when I pulled the passenger side cylinder head off. This is pistons 8, 6, 4, 2 from left to right.



The water in #8 got in there from the car beign on an incline and the water jacket wasnt completely drained yet. So when I loosened up all teh headbolts some water got into it. I'd have assumed that's what happened to #6 also, except the water in #6 looks.... rusty? Like it's been there a while?

I cleaned it out a little bit to see if the ... stains or whatever tehy are on teh cylinder wall would wipe off...


From near to far, 8 6 4 2.

You can definitely feel it with your fingers. So I got a close up shot.



So I decided to have a look at the cylinder head to see if the chamber looked any different and this is what I found:



And then Iwent back to get another look at the pistons and you can see #6 is just a little cleaner than #4 here...




Am I barking up teh wrong tree here, or have I found my problem?

I cant tell if the #6 chamber is damaged, or just a little rusty... but I'm abotu to go drop the valve out of it in a minute to see if he valve seat looks damaged. I dont think anything got dropped in the motor... but I suppose it's possible?

 

If you can feel it with your fingers, you might have found your problem. If there's a crack or pinhole there, that could explain how water is getting in. Have a look at this video for an example:
http://youtube.com/watch?v=W34H0QmgbWk

 

Looks like a broken cylinder wall. How much was it bored out?

 

It's .060 over.

I mean you can see where hte machine shop honed it for me just recently, so you'd think that if there was a problem it woudl have been pretty noticeable then... Right?

You guys may remember me as the guy with the bum Vortecs, so I'll reiterate, this motor has about 30 minutes of run time and about 3/4 of a mile on it. I took it around the block once. It's just a baby. So this thing is fresh out of the machine shop. It sould be perfect. Whatever that is, clearly wasnt there before.... Unless those kinds of things are just hard to catch until soemthing like this happens?

 

If you go more than .030" over on a factory block, it's best to get it sonic checked before starting. After, pressure test.

Many people have gotten away with it, but the mid-70's/early-80's blocks were particularly poor quality.

 

This is a 1972 block. It was already .060 over before it got to me without any problems. Didnt have many miles on it (And I trust the guy I bought it from) so all it got was a hone job and then it was assembled.

So whatever this thing is, is it possible that just a hone job could take it a little too far?

Im thinking about sleeving it and putting it back together.

Is this a fairly typical failure, or should I be looking for some other culprit that caused this?

 

hate to say this but , if i were you i'd start looking for another block . good luck .

 

Old blocks tend to have decay issues especially in the water passage areas
that did not use distilled water, or improper coolant mix.

The hone job would normally not cause a failure due to the minimal amounts
of material removed.

This is probably a case of boring + decay + pourosity (which is common with
cast iron blocks).

I agree with the previous post that finding another block is likely your best
option as other cylinders are facing similar conditions. The cost of sleeving
and boring is not much different. The current block may be too weak to
even attempt this repair?

Be sure to have your new block sonic tested before buying.

 

ooh, that SUCKS!
Looks like you were right to look at the block being the first culprit. Hmm, was #6 one of the heads that had a lot of water in the exhaust port as well?
I'd strip that block down to bare and bring it back to the machine shop and get their opinion. Tell them it got water in the cyl #6 and ask them about that spot.
I'm imagining you can get #6 sleeved and rebored to .060" over for less than $200.
I think a whole new block, decked, bored, cam bearings, freeze plugs, etc etc would cost a pile more then that.
Then again, if #6 is punched through, how close is #5? #8? etc etc?
I'd be asking my machinist if he looked at it closely when he honed it out

 

looks like some cracks to me. bummer man

 

That close-up shot sure looks like a crack to me.

 

Machine shop should be able to magna flux the cylinder and tell you for sure if it is cracked. You definitely are getting water in based on clean appearance of valves/pistons. A good visual inspection of gasket/head/cylinder should show problem (crack or blown gasket)

 

i agree with five7.. a stock block should never be bored to .060.. .040 max.. best bet for longevity, get a new block from GM and standard pistons.. clean slate to work with..


whatever you decide to do, good luck

 

So who all is in favor of ditching the block?

Im thinking if I get another block, the entire shortblock is gonna be ditched. That's a 2 pc RMS crank balanced to fit those pistons and rods and with the pistons at .060 over Im not sure how confident I feel about boring another block over that far.

I've got a T56 swap that was waiting in teh wings (now postponed for a while... obviously) so I figure now that I have the oppurtunity, I should move to a 1 pc RMS block so I can use the normal T56 flywheel (Which I already have) as opposed to the $380 or so conversion wheel for a 2 pc RMS crank. So it would save me $400 on a flywheel, but I'd still need to get the one I have resurfaced plus all the machinework I need to get done to a new block or just buying a new block.

So I'm trying to compute the cost comparisons here but it's getting a little difficult to figure out.

What do you guys think I should do?

 

My old 350 block was bored to .060, not to many hours were put into it and cylinder 8 developed some pits about halfway down the cylinder. If you really want to keep the block, then you can sleeve all the cylinders...i'm guessing $700 with the re-decking...

 

Great video! That was very interesting to see.

 

Yes, I'd be in favor of ditching that block. I'm about 95% sure that's a crack. Looks like a crack. Feels like a crack to your fingernail. Ergo, it's probably a crack.

A fresh GM block in standard bore would not be all that expensive. A good used one, even less expensive.

Sell the 60-over pistons on ebay or whatever to recoup a few bucks against a new set of standard bore (or 30-over) units of the SAME manufacture and design. The difference in weight between a 60-over piston and a standard bore one is not very much. Not enough to throw the balance off by more than a few grams- negligible, really. Then reuse all the rest of the bottom end stuff you've already got.

I swap rotating parts into different blocks semi-regularly. It DOES make sense to do so when you have a matched and balanced bottom end. Beats the heck out of buing a complete fresh set of part that haven't run together before and spending the time to make sure they all fit together and then pay even more to have them balanced as a set.

 

I'd show your local (trustworthy!) machinist before making any rash decisions. See what they think. They honed it out, so i'd be going back there and screaming at them for not noticing that. I'd be getting them to sonic check the block for me for FREE (no parts are needed, so they're only "donating" 1hr of their labor due to their previous incompetence, which ensures my repeat business in the future). Then ask if THEY would recommend a single sleeve, bored out to .060". If the rest of the cylinder walls are too thin, and they recommend against it, find another block and go .030" or so. If they think this block is usable, grab the guys business card on the way out, so you know who to blame later if something goes wrong.

 

ditch it!!!!!! Just to throw this out there I have a Lt1 block and crank, pistons, it will need to be cleaned up, the block has only 45k on it bore I spun the bearings. Let me knnow if you are interested. would be a cool carb project.

 

and remember once a spun bearing always a spun bearing!

 

What does that mean?

 

Spun Rod or Spun Main- big difference. One is replacing a couple con rods, other is line boring, which is not great unless only minor damage done. Prob. better finding another block if main spun.
GJ

 

if you are speeking about my block you need to learn about engine rebuilding before you post....

 

Hey Sean, I didn't mean to say anything bad abt you or your engine. I have been building engines, trans, axles, etc for abt 30 yrs - probably couple thousand of every variety by now (cars, mcycle, lawnmower, boats, etc, etc). BUT, I don't have experience in building performance engines, just stock stuff. When I looked back at your post, looks like that is what you have. Sorry I mis-spoke. Your stuff is probably in a whole different catagory and everyone please disregard my comments -just trying to help.

 

oh i know plenty about engine building... haven't had to do much rebuilding....

i was simply stating the fact that the bearing spun for a reason.... which needs to be corrected which is going to cost $$$ because you have no idea why it spun or if it will happen again... that whole block would need to be done over....

as opposed to a block that has never spun a bearing... that would be fine with a hone or 030 over bore....