7-Bolt Shortblock Failure - Full Diagnosis

If you are your own mechanic, there is no more important character trait worthy of development than the ability to own your mistakes. That's where the line is drawn between good mechanics and bad mechanics. It's not the failures but how they deal with them that measures their ability.
In short, it's not easy to admit you did something wrong or were negligent. But if you don't own it and talk about it, it doesn't get fixed, and nothing positive can come from it. It was my quest to overcome my clutch issue that lead to the creation of a video. That video is the textbook perfect guide for how to correctly install a DSM transmission.
• Trans & Clutch 5 - Ins...
Crankwalk as described is caused by a casting defect. This was not a defect. This was preventable. A lot of people would find something like this and not tell anyone out of embarrassment. I'm not ashamed. It's my fault. I got good use out of this engine and it was tough enough to make it 48K miles since the last rebuild despite my abuse. I'm here to tell you if you bought a used car that's had its clutch replaced, or if you ever pay someone else to do it... make sure it has this bolt. It's stashed away between the starter and the transfer case, so it's hard to see. Make sure all of your bell housing bolts are torqued properly because fastener problems can destroy your shortblock, clutch and transmission. If your car fails because of a mis-aligned transmission, you have no reason to blame crankwalk.
It wasn't until I bought my next AWD car that I discovered there was a smaller bolt on the other side of the block. I destroyed 3 transmissions in the GSX first. With the damage already done to my crankshaft, I then lost a shortblock. It's an ounce of prevention that's worth metric tons on your bank account.
Grade 10 M8x60 bell housing bolt = MD706012. It gets 22-25'lbs of torque.
Owning my mistake permits me to learn from it through con$equence$, and never repeat it. What good would it have done anyone else for me to learn this lesson and not share it? That's why I'm providing this video to all of you. Sharing it can perhaps help someone else avoid this costly mistake. This is the final chapter for my 7-bolt, and this book is going back on the shelf.
Here are some valuable resources if you're trying to read bearing damage:
www.enginebuildermag.com/Artic...
catalog.mahleclevite.com/bearing/
www.studebaker-info.org/tech/B...
And of course, now that I've covered the complete oil system, transmission and driveshaft series of videos, you now have all the tools necessary to ensure your 4g63 lasts a very long time. Whether the casting defect exists?... or it's all caused by a bolt, or the harmonics, or whatever... Sure, crankwalk exists and it's horrible. But with the small amount of movement required for your crankshaft before it contacts the block isn't far enough to make your clutch drop to the floor when you turn. You'd be hearing woodpeckers and jackhammers on the crank long before that clutch pedal would fall to the floor. Some people are going to hate on me for saying that. That's fine. I believe all of the people who experienced the clutch pedal issues had fastener problems on their bell housing.
DSMs get a bad reputation for this but we can change that. Crankwalk is never the cause of your engine failure. Crankwalk is always a symptom of the real problem. It's your disease that makes you deny it's your fault. You've got the 'itis. DSM-itis.
Whenever you dig deeper, you'll discover what applied all of those thrust loads to your crankshaft to begin with, and it's not going to be a casting defect that moves your crank .101". Mine only went .014", but all of the same parts failed.
PLEASE tell me in the comments if you find this bolt is missing from your car.

[@awolo06]

[@rpvilleneuve]

Jafro, I want to say THANK you for owning your mistake. Not to many folks would have done that. That is just awsome. So many folks are so quick to blame something or someone else. Sometimes you should look into the mirror before comming to a conclusion. Also, thanks for all the informational videos. You have taken my dsm knowledge up about 10 levels. That's sad in sad in a way since I have owned, driven, and worked on them for just shy of 10 years. Now all I need is your arsenal of fancy tools. Thanks for everything!

[@user-ft6pe1kv8t]

ThePhantomEvoX c

[@conflagrationTuesday]

I understand almost nothing about what you are talking about: but it is interesting and relaxing to hear to talk about whatever it is! Thanks for sharing :)

[@BayAreaMCs]

Had to take a second to say thank you man. Havent found many other videos that explain the right information im looking for, or take 20 mins to get to the point. This is clear, in-depth, and to the point. Your older videos helped me rebuild the transmission on my ford ranger and now again with my honda. Keep up the good work brother, you got my SUB!

[@J0cK3rFr3aK]

You are doing your videos in a very analytical and detailed way, I am not even involved with mechanics, heck, I don't even have a licence but I still watch your videos because they are very informative and you explain the relationship between cause and effect very good, thank you for your videos.

[@ScrubyMcBubble]

My bellhousing bolt was missing too!! i had bought the car with a blown clutch and replaced it. May have never been there or maybe i misplaced it but its definitely on me for not knowing it was missing on reassembly. 7 years later you're still saving DSM's with this video!! Your videos have been a life saver so far trying to understand my car as the previous owner has 6bolt swapped it. It was a long forgotten project ive had for 9 years that i have neglected after the water pump failed. The pandemic has given me time for self isolating hobbies again and ive been steadily fixing the rust and got the waterpump, belts, and pulleys replaced. Now it turns out i need a gasket due to overheating when the pump went. Got a small leak on 1st cyl into the coolant (leakdown test proved this). I notice it already has an MLS gasket so im hoping the block is still flat and smooth because i dont have much time or space to be pulling the block to get the RA right for a new MLS gasket. Anyways thanks for the videos, ive been binging the channel like netflix haha

[@warusweims]

I think 48K miles on a build that put down as much power as your engine was is pretty good. Stuff happens. I've done it too. Most people can't do a better job so they can't talk trash. I have faith in your ability. I'm a Subaru guy and I just love your videos because you use tools that most people can afford and are not overly complicated. You prove that you don't need a laboratory to build a great power plant and car.

[@Jafromobile]

warusweims What you said has many truths. Unemployed military aircraft mechanics proved all of it in the late '40's salt flats. I look up to those who came before me for inspiration. Anything that has been engineered can be re-engineered. You get better at it when you break stuff. You and I have both been bitten by the same bug. There's no cure for it, but you can treat the symptoms. "Auto racing was invented 5 minutes after the second car was built" - Henry Ford

[@kainhall]

i blew up my first dirt bike rebuild 10 mins after i put it together..... i didnt have the right tools, and to get the nuts off the crank, i put wood under the piston skirt/on top of the crankcase....and made a TINY crack heard.....SNAP RATTLE RATTLE RATTLE..... and shut if off.....(been working on cars from 6 years old....seriously) piece of piston skirt ended up in the combustion chamber.... but didnt take out the ports! fucking winning! lol 2nd rebuild has 3000 miles on it....and i need a new clutch (i ride that 100cc like a 1000cc), so ill probably check out the top end soon lol on the...sorta the flip side...i guess my dads got a 1997 buick lesaber with the buick designed 3.8L v6.....250,000 miles, still running the gaskets known the fail.... kinda gotta see how far it can go now..... the tires have almost come off the thing.....(ball joints, struts, sway bar links).....trans went out at 200k (just lost OD and still made it home) BUT. THE. MOTOR. WILL. NOT. STOP. and it runs great....

[@Wondering_Wobble]

I have to say every single one of you're videos has expanded my knowledge. You are very thorough in each video and bring to light any and all misconcepted info regarding what it is you are doing. I enjoy and look forward to all future videos and I hope to be a DSM'R for a long time to come. And with you're videos to help guide thee to have a properly built DSM!

[@autofixation]

I don't even own a DSM engine or car, but I still found this to be very informative! There are a lot of things that you pointed out that can be applied to any car. I learned quite a bit, even thought that may have not been your intention. Keep it up.

[@Jafromobile]

autofixation No actually, that was exactly my intention! ;) Remember from which community you learned it. I was raised on classic and collectible Fords, but it was the DSM crew who actually taught me anything about cars. Sort of why I stick to it. Theres so much you can do with 'em. Much more affordable performance than a Judge, Shelby or Yenko. Plus it's more fun to me to be responsible for that performance than having to keep someone else's dream alive. There's at least a little bit of that in all of us.

[@crazyDIYguy]

Your videos are the best, if I see your channel I usually click the video, regardless of whether it's something specific I'm working on or need to know. There's always a plethora of good useful information that can be applied to a wide range of things. Gracias amigo 😎👍💯

[@bitcoredotorg]

Very informative video. Thank you for creating and posting this! Your comments and method of explanation whilst actually showing the steps of dis-assembly/re-assembly without being boring is great - I look forward to more videos!

[@revolutionzerox]

once again I've learned something. I wouldnt have thought about un-even load with missing bellhousing bolts. makes perfect sense and is good to keep in mind, I look forward to seeing more vids and your gsx back on the road. keep up the good work

[@myesantos5824]

Thank you very much for your videos! I've really learned tons from these, and I'm gonna start my own rebuild on my engine for the first time.

[@ferrumignis]

In an oil filter the bypass valve and the anti-drain valve are two separate things. The anti-drain valve is usually just a circular rubber 'washer' that's located at the mounting end of the oil filter, and covers the oil inlet holes. This effectively forms a one-way valve that prevents oil draining back when the engine is stopped, which is a problem on some (but not all) engines.

[@ZombieSixShot]

When my TOB went out i discovered that hidden bolt missing, im so thankfull i have a good bolt in there now because if my car suffered the same fate as yours i couldnt afford to put her back together right now. Jafro, thank you for your videos i love them and have learned so much. Please keep it up!

[@davidpotter3777]

This was like a Sherlock Holmes Watson thing you must sleep better at night having figured this out and great explanation of the forces applied at the end I can't stand a bad clutch God bless you and your family

[@TangoOne]

I learned....so much. Thankyou. I'm gonna go check for my hidden bolt

[@paulhenry8560]

Thanks for taking the time to do these videos on the misdiagnosed crank walk!! 😉

[@jesterkid99]

You share alot of great information I can't remember how many times I have learned from you videos on how I should work on my engine I am currently working on. Keep up the great work and useful info coming :)

[@gnaloin]

Nice video, great narration and good reasoning. This is very educational. I like it when people challenge generally accepted "because it says so in the book/internet/whatever" knowledge and find out stuff by themselves.

[@nickc2052]

This guy is so on point. Everything he explains is exactly what went wrong on my 3000gt vr4.

[@ODMIJ084]

Wow Jafro another awsome video. I can honestly say that I am absolutely interested in the build now, and can't wait for it. Keep those videos coming.

[@kennethcohagen9037]

No 3 Rod journal looks like a no7 journal on a 350 Chevy when the soft cams they used in the 80's wore flat. In those cases the no 7 cam lobes wore out completely, sending shrapnel through the engine. No 7 Rod journal gets wiped in the process and you see a lot of metal from the Rod bearing imbedded in the crank. Glad you found the cause of your failure. I would have guessed wrong due to experience rebuilding so many chevys back in the day.

[@strykerhorse]

This exact method of failure occurred on my 6-bolt...the "crank walk bolt" fell out and then the engine started loosening the others+the starter bolts. I caught it after replacing the clutch and it's shifted like butter since. Thanks for posting this...hopefully it saves a few engines (and broken dreams).

[@limowreck2612]

Outstanding video, and I love that big blue Wilton!

[@blksentra2]

Taking the transmission off this weekend, very anxious to see what's going on in there armed with this new information. Thanks!

[@aperioguitar]

That was very informative. Thank you for sharing your in depth knowledge and expertise.

[@thaiexodus2916]

This video helped explain what went wrong with my engine. Blown oil line, #3 cylinder raped, and rebuilt the engine. But the thrust bearing surface of the crank was trashed and went un-noticed. I had no clue why the engine ran rough and vibrated. Was ready to have the flywheel turned and balanced when I saw this video. Checked the crank shaft end play: 50 thousandths. Crank was bent like a pretzel, block bearing surface shot as well. Uncontrolled torque thrust. A boat anchor in the form of an engine.

[@asetech1962]

Great video!! This has always been one of my favorite motors.

[@DJDevon3]

This is what makes you a good videograher. You're just as willing to show the mistakes as the triumphs. Live and learn. I do it all the time. Just last month I busted up a brand new radiator during the install. Man enough to show what I did and yeah I'll never make that mistake again. Sucks learning things the hard way but you're much better for it.

[@ChaseTruCutLawn]

Information overload, thanks for the great video.

[@JPilot2]

Dear Jafro, I found the 7-Bolt Shortblock Failure video, with your Full Diagnosis to be extremely useful, and very valuable. Thank you kindly! Cheers! :-)

[@EDIAutoChannel]

Thanks so much Jafro, For that missing bolt ! Right when i watched this video i went out of my house jacked up my car and made sure that this bolt was in there ! Even if its -19 out side !

[@blindabinda1234]

KeepinIT_StockG35 was it in there?

[@facundolopez7346]

Congrts for the fine analysis. Keep It coming. Thanks!!

[@tomrodgers1596]

Thoughtful, insightful, informative - good postmortem!

[@AlchemistLair]

Excellent video!! Tough lesson but I love the way you analyzed it out!!

[@FrostD3mon]

I must admit man, AWESOME video!! Subscribed!

[@Ryan_1997]

wow I noticed THAT wen I purchased my 3rd dsm. my.gst didn't. have that bolt wen. I did inspection,... thank God. I put one in years ago. but very great information jafro. had I not put a bolt into that part of the transmission. would of had this problem commonly as others. like we all say" thank u so much! Im glad I learned something new!!!

[@figifister]

You the man. Thanks for the explanation. Props on being humble.

[@1InfinityShade]

But it did teach me. Thanks for the video. My buddy wants me to get into DSMs because he has two and thinks i would enjoy a change of platform. I asked him about the differences in 6 and 7 bolts when he brought it up but this was more visually educational.

[@PheazibbleKneads69]

Great video ! Keep up the clean work ! I loved the tips.

[@AATopFuel]

Jafro, good job! I don't build little engines like these, but it is fun to watch you do stuff. At least you are man enough to know that you screwed up and you probably saved a couple of people in the process. I build Mopar's and we have a one similar to that and that would be an oil galley plug in back that we all miss when new at it. Like your engine it is hidden in the back of the engine and if you get in a hurry and place the outer plug in not thinking or seeing that there is a second one behind it, well I bet you that you can imagine what would happen. Thanks again, have fun. JBL

[@natenut]

i am checking this on my car tomorrow morning! i'm pretty sure the bolt is not there. Thanks for your priceless videos and advice!!

[@lucascournoyer11]

dont worry i still got faith in your skills thank you for your very good vidéo.very helpfull and welldone.wish i have your habilities,maybe after your 213 vidéo.thanks again.

[@TripAMD]

this video was so easy to watch, nice job man👍

[@kafoure93]

Your still awesome. Your full of knowledge and thanks for sharing it for everyone to learn.

[@jb2zero0six5]

I meant on my jenk motor Lol. Though, that was last Saturday, very well could been #3! Hell, I don't know what clutch is in the car yet. I'm also directly following the alternator rewire and battery relocation video while everything is out. I love wiring, and your videos are of course gold! Starting over someone's half-assed project is always fun!

[@FeeeshEP3]

'maybe I'll build another 7 bolt some day soon' --- clean room ready! really looking forward to this :)

[@ChristmasCrustacean1]

6 bolt, 8 years in the making coming tho but I would really like to see jafro rebuild this engine some day

[@MainyMitsu]

Great video Jafro! I'm going to verify all transmission bolts are in the correct place as well as there torque as soon as I get home!

[@catocaster2985]

Dude i like the way u doing your video, thats really nice.

[@jorgegomez4668]

Amazing video! Learned a lot... Thanks

[@Kraals]

Great failure analysis. I suspect 99% of this type failure are misdiagnosed.

[@jerryware2500]

hey jafro I put that hidden bolt on and put everything back to gather and my car shifts into the gear right I took it out for a drive yesterday thanks man for helping me you made my day I even looked at your other video how to adjust the clutch I did that too everything good thanks great videos

[@senia.samoata.7607]

True original stuff that is carelessly handle by bush mechanic's Thanks for the video

[@christophersaa]

Awesome video! you gave me a much clearer understanding of what could have happened to my engine. My car is a 1997 STi with an ej20k engine which has a center thrust ( old engine ) the thing is that my center thrust failed causing crank walk, which then lead to wearing on my bearings. All this happened after I push and pull the clutch ( like a clutch kick) to powerslide the car ( stupid driving habit I had). I wonder if by reducing engine and tranny movement this might help? the addition of stiffer engine and transmission mounts, what are your thoughts? considering that the engine and tranny moves forward and backwards in a subaru... I was thinking about installing this for an improvement but if this will compromise this i would rather not. Thanks in advance, Chris

[@justsaiyansteve]

Amazing analysis!

[@cowmilky]

Weather you like it or not i learned quite a bit. Thanks for the Great vid!

[@paopao814]

Hey jafro great informative video. Bitter sweet experience for me because i was praying that once i crawl underneath my car i would find this bolt on that hole however it was missing. I hope its not too late. Ive driven my car for 8k miles for two years now (133k on odo atm) since i bought it. Hard acceleration here and there. I hope its not too late now that i have that bolt in there. Car is stock and its my dd.

[@4G63addict]

Great video BTW Jafo. I really enjoy your professionalism and attention to detail. Go skins!

[@Tugboatpb]

That was an excellent video. Very well done, thanks!

[@philr300]

Excellent video. Thanks Jafro.

[@johndelta00]

The drain back valve you referred to is a separate valve that most oil filters are equipped with and is essentially a check valve made of rubber that blocks oil from draining back through the INLET side of the filter(outer holes). Also, not to be too picky but not ALL oil filters are equipped with a by pass valve either, the by pass valve on GM engines is integral to the oil filter adapter therefore filters made for GM engines are not equipped with one. Awesome video's keep up the good work.

[@omarrserrano9607]

WOW! Thanks, The cars going up and im checking for that mystery bolt!

[@talontsi92]

Glad to see that I am not the only DSM'er to have had someone else's idiocy cost them a part because of this bolt. Mine cost me the entire transmission, as it broke the bellhousing. Luckily the engine never suffered failure due to this.

[@johnestey9041]

excellent video, bravo. as Honda owner and a caterpillar technician and have been thru several failure analysis classes, blew and built 100's of engines and my conclusion is this engine was oil starved at some point whether the engine oil level wasn't adjusted properly or the engine was raped on with low oil temperatures, since 3&4 are the furthest away from the pump they were the last to get lubricated. bending a crankshaft from shock load isn't likely IMO, that don't really don't explain why

[@diggabledork]

Looking forward to it! Keep up the good work.

[@dtiydr]

Im not into cars and I don't even have one but this was interesting to watch. The stronger the engine the more delicate it could be but as long as everything as it should be there is no problems but even an small insignificant thing can destroy but when you know why the thing had to be there then you understand.

[@sethat8e]

Nice carnage, its also nice for someone to talk the honest and sometimes demeaning truth.

[@mitsuturbo]

I've encountered this issue MANY times. Rather than crankwalk, i've seen it all too often result in cracked and broken bellhousings. Two GVR4's came into my possession over the years which each had this "special bolt" as i call it, missing. They both had cracked bellhousings. A word to the wise, if any of you reading this ever have someone ELSE work on your car, make SURE they put this bolt back in! The factory one has a 12mm head, and has a #10 on it.

[@martinda7446]

PS. Hello from new subscriber. Great stuff - Really top quality.

[@crash_override9435]

Awesome narration.

[@SkwerIe]

This video was published the same week I was pulling the transmission out of a neglected 1G I had just bought. I just now saw this, weeks after I sorted the problem out. I wish I had seen this sooner. :D That bolt was broken off in the transmission on the car I bought, and several other bolts were missing. The previous owner had driven it that way, until the clutch gave out. This video will haunt me until I decide to pull the engine and rebuild it...

[@AUTO_LOCKSMITH]

great vids i watched them last night nice one good advice too

[@holton345]

Great video! Thanks for the heads up on this.

[@woodsyeps]

Excellent vid. Thank you!

[@deadman12078]

The best lessons are learned the hard way. As always interesting

[@raimondszunda]

That vid was... ...great! Only now I understand how much I have to learn about cars and engines.

[@02studios]

thanks for the heads up mate, am just about to build a 7-bolt.... just missing a crank sensor..

[@jtmagicman25]

Is there a way to use a 6 bolt crank in a 7 bolt block, seeing as those are the strongest parts of each. 7 bolt comes with a nice built in main girdle

[@sergMpowered]

As I am not into DSM's anymore, I did loose a 93 7 bolt engine to this very same thing. It even broke a ear of the transmission and subsequently cracked the crank do to the torsional twisting of the crank.

[@fuzzywoz]

Wonderful video, number 6 bearing on a blazer is the worst of mine.

[@mikkomansikka5704]

Silly question. Could we not hone the scratchy crank and then use undersized bearings? I don't know does anyone make undersized bearings. Just wondering would it be possible if they would make such.

[@jamesdouglas6748]

Sweet update jafro. I thought that only OEM mitsubishi oil filters had the bypass valve in them! luckily they are only 6 bucks.

[@crobulari2328]

Excellent Video.

[@Bevoin1970]

Awesome Jafro! simply awesome. As I was taught many times whilst in engineering, anyone can get "in the shit" its how you get out of it that makes the difference. :-)

[@K0nst4nt1n96]

Could a 2 mass flywheel if not installed by default help in reducing the torque on the crankshaft? Very interesting insight! I dont own this car but i am always interested in these kind of videos.

[@lsselects]

jafro your a huge help with my build!! im only 14 and i have a 1996 talon tsi awd!!

[@matteo3893]

What are the symptoms you were having with your clutch for torsional vibrations to you crankshaft? I have been having a vibration on a freshly auto to manual swap Mazda. The vibration occurs with my foot on the clutch, in gear giving revs. If I pull it out of gear or let the revs drop it goes away. I noticed that the crank pulley was wobbling and after investigating realized the crank moves in and out a bit. I been going crazy trying to solve this and actually have the oil pan pulled off and the man caps pulled figuring it may be a thrust bearing failure but all the bearings and journals look pretty good. I would appreciate your input have been following your videos for along time.

[@Jafromobile]

If that "a bit" is more than ten thousandths of an inch, you my friend have discovered crankwalk on a non-DSM. It happens to anything if the crank thrust bearing fails. I've seen a crankwalked civic wagon before. I would suggest researching it thoroughly if this is what happened because the entire rotating assembly would be suspect. The cost, difficulty and reliability of fixing it would negate the cost of its replacement. I don't know how much your crank moved, but the testing procedure is in my videos.

[@djay102687]

So will the bolt be some where around the same place for a FWD 2g?

[@boosted2.4_sky]

Excellent. Good stuff. I think I can learn a thing or six. Lol...SUBSCRIBED...

[@sivucit]

Thanks For Super Fast response. I have a question , not sure if can ask here, i have 2005 Toyota corolla, have changed crank shaft , rod and main bearing.. I have a noise coming from lower end, only when engine is cold, but when it gets hot that noise goes away. i can see that when i hold the engine RPM at 2500 to 2700. any advise, please. also a note, i had this problem even before with my old crank..

[@thundercamel]

Great videos!

[@jth1699]

Interesting - another thing that will cause that type of failure is a failed harmonic balancer...

[@zx8401ztv]

Smashing diagnosis mate :-) No one's perfect and the world would be very very boring if we all were perfect :-) Dont stress if you make mistakes, we all make them, some people more than others lol, but your honest about yours :-) Your wisdom is still intact master yoda :-)

[@jerryware2500]

cool thanks jafro one more question. the bolt u said the M8 by 60 is the bolts in the 2g diff size from the 1g because ur bolt looks longer and when u was tightening it the transmission and the block was joining to gather I got the hidden bolt from the stealer ship and they gave me the bolt for my car but the bolt they gave me looks shorter and when I was tightening mine the transmission and block wasn't joining to gather they gave me the wrong bolt? and wear can I get the M8 by 60 bolt at?

[@lennybasaj1649]

Very well made video.

[@jeffreycastillo170]

Good video, with good information.

[@michaelfrancis3261]

Ok first thanks for this video awesome as always. On to my question, so I am getting ready to drop in my crankshaft in my 1996 Lexus Ls400. I place all of the main bearing in set in the crank, nothing wrong. Place the thrust bearing in and now the crank won’t sit in. I measure it and its 2.44mm so it’s within spec. what do you think is wrong?

[@Jafromobile]

2.4mm? That's nearly a tenth of an inch? Measuring which? The oil clearance or the thrust clearance? In either case that seems huge to me.

[@dsmdtrain97]

Awesome. You are the man Jafro! Thanks

[@nobody1574]

I had that same bolt snap on my 92 talon it didn't trash the motor but it did destroy a clutch and crack a bell housing.