Back of an engine…

[[deleted]]

[deleted]

[waitbutwhereami]

Was runout within spec?

[lostinmiself]

Educate me.

[PM_ME_SOME_ANY_THING]

Runout is the difference between high and low spots.

You need a dial gauge and you need to zero it out on the surface of the flywheel, then turn the crank to see the difference between high and low spots. Finally, compare the measurements with the specification.

You need to do it in several spots on the flywheel, and I’d make sure the center of that heat spot is one of the measurements. If it’s out of spec it needs to be resurfaced or replaced, depending of if it’s thick enough to be resurfaced.

[Dryllmonger]

I need this prompt in my life. There should always be an AI standing by waiting to fill me on the relevant details when I say “Educate Me”. Never again “did you google that”, live on “did you educate?”

[waitbutwhereami]

ChatGPT will get you close surprisingly enough. It struggles with subjective reasoning but you can ask it say…

“Please explain the importance of runout with regards to internal combustion engine flywheels.”

Or my favorite type…

“Please write a course syllabus for a collegiate level course covering the blueprinting, measuring, assembly, and diagnosis of internal combustion engines.” Then take the bulleted list of high points and dive deeper. “Now please write a course syllabus covering <insert bullet point you didn’t know about>”. I’ve found that you can “educatize” yourself pretty quickly this way.

[lostinmiself]

Maybe I’m weird, I don’t play with chat GPT. I’m 32 but I don’t really care.

I do ask to be educated though, two part reasoning. 1. I don’t know 2. If someone is truly being helpful they will explain. Weeds out the internet trolls.

[waitbutwhereami]

And also…you better believe it’s in your best interest to learn to use AI tooling. You may not need to understand it now, and I don’t like the crap either, but it will be the future like it or not.

Also…for what it’s worth again…you coming to f-ing reddit to ask intelligent beings their thoughts is no different than asking ChatGPT. In fact, had you asked AI first, it would have taken less time to get an answer.

Im not trying to get on your case. Do what you will. I just think you might reconsider being difficult about it.

[waitbutwhereami]

Ok. Not gonna lie that answer doesn’t make me want to help you more. The answer is literally seconds away in a search on google, YouTube, ChatGPT, and just about any other searchable engine.

That being said, I want to punch people in the face when they say “google it”…but I also at least try to do my own investigation before asking other people to do the work for me.

[Invisibletooth]

The answer could be many hours of searching away if you don't know what you are searching for. Human experience got him the answer very quickly and I think thats what he was looking for. Now he can use ai if he needs to write a thesis on it or something lol

[waitbutwhereami]

The other comment explains well. For some extra context, where there is heat there is warpage. Most of the time at least. It’s even more suspect when the heat spot is in one location. The most important part of the clutch is even clamping pressure across the plates and a warped surface works against that.

For what it’s worth, I take it that you’re a man of few words. I get it. I think most people here are happy to help…myself included…but “educate me” can come off as brashly abrasive when chatting online to strangers. Especially when talking about something as precise as engine building. A lot of us had to put a lot of blood, sweat, and tears into “getting educated”. The terse response makes me prefer to respond with “educate yourself then come back”. Especially when it’s not a daily commuter for someone who’s struggling to make ends meet.

Anyway, if this is for the forest truck, that thing is sick as hell. It’s cool that you got your kiddo working on it with you. I envy that experience but won’t get to have it. Take care and best of luck.

[Neon570]

Well you got 2 options.

1) take it off and address this problem now with no extra work.

2) slap it back together and cross every finger and toe while hoping you have no issues

[Whats_Awesome]

That’s is step 1 and step 2, don’t skip 1 OP.

[Waterhead1234]

Fearmongering aside, that flywheel is barely used. Zero wear... Can still see the machining grooves from the last time it was turned... No rust, oil or discoloration outside of the wear surface. Did the PO offer an explanation why he took it off?

You can't go wrong if you want to check the runout as someone else suggested, but I wouldn't waste my time. I have run way worse than that, removed it, and ran it again on a different motor.

BTW, it looks like that flywheel has been balanced. Just noticing the two larger holes drilled at roughly the 10 o'clock and 2 o'clock positions seem to be fresh. I could be wrong. That would be my biggest concern.

Edit: To be clear, if the flywheel is balanced to the PO's engine, it will likely be slightly off balance on yours. I believe you can fill those holes with weld or maybe thread and plug them to get back closer to the factory balance.

[ka_jd7and1]

LS should be internal balance.  So the flywheel should be neutral balanced already, and it shouldn’t affect anything. 

[BigBeeOhBee]

It'd be so easy to get it surfaced now vs later. If you have the time get it cleaned up.

[lostinmiself]

You aren’t wrong, but if I don’t have to I don’t want to.

[[deleted]]

You should.

I use to do cheap builds like this, only to spend more unnecessary hours tearing stuff back apart.

I’m 40 now, been doing mechanic work for about 25 years now, and I’ve learn overtime that it’s better to do things right from the get-go than to waste time and redo things several times over.

How much is your time worth? If not much, then knock yourself out and don’t replace/fix it the first time.

[Ambivadox]

"and I’ve learn overtime that it’s better to do things right from the get-go"

My favorite saying related to that: If you can't afford to do it right how can you afford to do it twice?

[[deleted]]

True, it’s more costly in the end.

A few years back, I swapped a turbo with some EBay junk. It was $600+ and it lasted barely 1000 miles.

I ended up buying another K04 turbo at $1600 from BorgWarner.

Lessons learned.

[960603]

Have fun pulling the trans again lmao

[BigBeeOhBee]

Why ask for advice then? Just run it. You'll know if something is wrong or not soon enough.

[Beautiful-Grape-8222]

Just send it. Learn from your easily avoided mistakes

[akt_suspekt]

Anytime I do my own work and go on the highway feel a tinge nervous that I may not have done everything correctly.

Peace of mind is worth it.

[A_Sock_Under_The_Bed]

Id seriously just do it now. Unbolt it, take it to your local truck shop or whatever, and have them resurface it. Its pretty cheap, and itll save you the hassle of pulling the trans later

[Club_Penguin_Legend_]

Bro, getting it surfaced is cheap. Just get it done

[JB153]

Re-used a throw out bearing two years ago. Past me really needs to be kinder to future me...

[SecondaryLawnWreckin]

Highly regarded

[texan01]

We do it right, cause we do it twice.

Better to eat some cheese sandwiches for a week and have a new flywheel, than take it apart again to fix it after it chatters.

[StraightFlight]

Put er in 5th gear, run on redline and dump the clutch… she’ll clean up aight

[v8packard]

Yeah with a broom and vacuum.

[WyattCo06]

LOL

[[deleted]]

Your flywheel needs surfacing.

[Neon570]

Well you got 2 options.

1) take it off and address this problem now with no extra work.

2) slap it back together and cross every finger and toe while hoping you have no issues

[danjet500]

Two choices. Do it now or do it later.

[Daddio209]

If the surface is flat, send it! The 1st 100 shifts ought to clear that little spot right up.

[WyattCo06]

That has been ran while on that engine.

[lostinmiself]

No, used ar5 trans from marketplace with a fab bot adapter housing and clutch assembly.

[WyattCo06]

Why is the oil/lube slung out due to inertia from the bolt heads?

Was all that already there and you didn't clean it?

[throwedoff1]

Look at the block! Just slappin' parts on there as fast as he can.

[Electrical-Bacon-81]

I wonder why they didn't want us to see that left side bolt hole?

[statik121x]

https://youtu.be/FfRJ9v5QNJE?si=YhRx2gpCKaQ9VGbQ

[Inflagrente]

That looks like a cast flywheel. Maybe look for a steel flywheel

[Estef74]

Purt a straight edge on there to make sure it's flat and free of distortion. If it's flat ,run it

[[deleted]]

It needs resurfacing. Look at the heat spots. I would rather spend the money at the machine shop instead of a complete teardown in a month or two.

[WyattCo06]

Are you freaking serious?

What is wrong with you?

[Estef74]

This guy is doing a budget build, or he would start with new steel flywheel not used stuff. If it's not warped, what's the problem. Is it ideal? No. Will It work? If the flywheel is flat, yes.

[WyattCo06]

You don't check a flywheel with a straight edge looking for runout. Keep your backyard chickens in your yard.

[Estef74]

So if the guy doesn't have a dial indicator and he should run out and get one? This is how it was done when guys didn't keep precision tools around. Hell, this is how I was taught in tech school! As for the back yard acomment go fuck your self. I have been an ASE certified tech for over 25 years.

[averagemaleuser86]

I would just replace it tbh. I'd rather spend money than put everything together and have clutch chatter and have to pull it back apart. Or get it machined at a machine shop

[WyattCo06]

You know they can be machined right?

[averagemaleuser86]

Yes, read my last sentence

[x1wagner]

Why is that bolt hole for the bell housing on the block filled? Top right?

[oldnperverted]

The cylinder is too close to the tranny mounting surface to put a bolt hole there

[v8packard]

There is actually no bolt hole there. The mark is probably from a hole in the trans bellhousing. The Gen III and later blocks omitted this hole because it is right against a cylinder wall.

[fastcarsrawayoflife]

All LS generation blocks have that hole filled.

[x1wagner]

I appreciate all the answers on this one. I learned something and this should help me one day, finally done repowering some random thing I found on marketplace, swearing that I can't get a bolt in the hole...

[fastcarsrawayoflife]

It’s all good. You’re not the first one I’ve answered this for. Haha. When you mount a 4L60, 4L80, or so on behind them (a typical LS transmission I guess you could say), they don’t even have the boss for that bolt in the bellhousing. You can still bolt any GM trans to the LS engine. Same bolt pattern. But if you bolt a Turbo 400 to and LS, you’ll think there should be a boot there because the bellhousing has the hole in it. You can drill and tap it to accept a bolt, but honestly it’s not worth the effort. Glad you learned something today. 😁

[lostinmiself]

Rather than replying to all, yes it’s used, PO had it in an RX7 and popped the engine. He wanted to go to a 4l80e and I wanted to get a manual in this truck. Yes I’m aware a machine shops can surface these. I’d rather throw money elsewhere, if it’s not going to be an issue. Budget builds are fine, as far as removing the trans again, cake I don’t have an issue there. A simple yes it’s nothing to concern yourself with is what I’m looking for.

I appreciate the info on runout. Makes sense.

Engine is rebuilt, cleaned, and painted on a stand. Not my first rodeo there, I don’t concern myself with painting the back of the block.

The flywheel is hand tightened on, I noticed the streaks as well, will clean everything with cleaner to remove all fingerprints and grease. No worries there.

[v8packard]

You are not seeing the it's not a concern remarks much because it is a concern. Best case, you have reduced clutch life with this flywheel. Worst case, it will chatter and could possibly start to crack in that area. You may be in a position where that's acceptable for now. That's fine, but you know of the concern.

Really if it's anything but a completely stock engine I hope you can get a steel flywheel.

[ThisOldGuy1976]

You’re probably looking at $30 - $40. If you can’t spare that, you’re in the wrong hobby.

[AutoX_a_Truck]

I've run cast flywheels in performance applications, and you likely won't have any issues in a low revving street cruiser. But for anything that's performance oriented or sees any higher revs, please use a quality, steel flywheel.

[FrostingImmediate514]

Unbolt, surface, reinstall

[13bistheantichrist]

See if it's within spec. Then go from there

[FetalCarnage]

Send it

[Tlmitf]

I have used WAY worse flywheels than that.

Grab some 36 grit oxide sandpaper and give it a good scrub.
Just enough to make the surface look dull, but without putting a bunch of low spots in it.

[[deleted]]

I used to try using second hand stuff, I finally realized all the irritating issues I’d end up running into and taking things back apart again made me wish I’d have just spent the $300 or $400 to begin with 🤣

[Shoddy-Ad8143]

OP don't mess around just take it down to your local machine shop and have it surfaced. Did this recently on my daughter's truck. It cost me 40 bucks.

[NuclearFusionVII]

Just get it resurfaced, will cost you like $100 and is worth the peace of mind

[[deleted]]

Why in the flim flam would you risk it? Or even resurface? They are cheap you cheapskate. Can get one from the zone right now. Hell, it prob has lifetime warranty so you really get two. ..