Cracked Exhaust Manifold

[Drew Bru]

Originally Posted by mmoore6856

that should be a 3 piece manifold. you only need the center

Yeah, that's a good point if the bolts are a real PITA it would save a bit of trouble on the hard to reach ones.

[cadillackid]

I like tapping with a hammer when I dont have impact.. I have gotten many loose with hammering on a wrench.. hammering on a ratchet some success.. of course 6 point wrenches would be nice as 12 point on rusty bolt heads can strip em off but likely wont.. I say open the dog house and go at it.. .. also for me it would be worth a trip to storage to get my impact.. i never leave home without my trusty 20 volt impact

[Drew Bru]

Originally Posted by cadillackid

also for me it would be worth a trip to storage to get my impact.. i never leave home without my trusty 20 volt impact

Problem is storage is several hundred miles away. It'd be worth it to buy a new one if it's essential, but maybe I'll give it the old college try before I call for reinforcements. When I was messing around with it at first, the closest/best fitting socket I could find is 15mm, does that sound right?

[cadillackid]

im not sure of the size but make sure your socket is 6 point and dead on size.. slop i nthe socket is easy ay to strip the head off the bolt.. mine is a DTA360 so likely not the same

[Danjo]

Originally Posted by Drew Bru

Problem is storage is several hundred miles away. It'd be worth it to buy a new one if it's essential, but maybe I'll give it the old college try before I call for reinforcements. When I was messing around with it at first, the closest/best fitting socket I could find is 15mm, does that sound right?

Impact tools sure come in handy especially when its close quarters, but the vast majority of wrenching I’ve done has been with ratchets and wrenches.

Going at that rusty stuff is best done with 6 point sockets whenever possible.

Lots of good advice on here. You’ll be fine doing that yourself.

So far we’ve all focused on getting it apart, but reassembly is important too. If you can find them, having the proper torque values and a torque wrench for reassembly is good to have.

If you haven’t assembled something with multiple fasteners, the general rule is to work from the inside to the outside, in a cross pattern with a gradual torque.

[Booyah45828]

To weld it, it will have to come off. You might get someone to braze it installed if it's easily accessible, But you should still drill the ends and v the crack with brazing, so if you can't drill the crack installed, I wouldn't try to fix it installed.

How big your crack is, and how it's situated, I'd say replacement is your best bet. You can get a manifold "kit" that contains new bolts and gaskets and the 3 manifold pieces.

I don't think an impact would be necessary with yours. I wouldn't bother with a hammer either. A good half inch drive breaker bar and a snug socket should work. You'll have to work at getting the turbo bolts off though. That might be a job for heating with a torch and spraying with your favorite penetrant. Christopher said aerokroil, and I agree that it's good stuff. Kimball midwest sold us some of their "torq cb" stuff that seems to work good and smells 10x better then kroil. I had a customer drop off a can of "free all" from o'reily auto that he said is the best he's used. I haven't used it yet to try though.

Best thing I've used for rusty fasteners is heat.

The "ya never know" is a biggie. I'm confident from your picture that you won't have trouble with the manifold bolts. But, if you would, you'd then be stuck trying to remove a busted bolt. Which would require torches, welders, drills etc. to repair. I've never had luck with extractors or ez-outs. In all the cases where I've had broken bolts, if an extractor would work, the bolt wouldn't have twisted off to begin with. Unless the bolt wasn't twisted off and was sheared or snapped. Turbo bolts might be different, simply because you can't get directly at them. But with heat and penetrant, you should be able to get those too.

Mobile mechanics are iffy. Some are competent and could do it, others you'll find have less skills then you have. I'd try it yourself first.

[TJones]

Even though the threads are in the engine block I would put a little PB Blaster on the bolts just to free up the bolt in the manifold. The worst part of the job will be if a bolt breaks off in the block. You could try getting the engine warm then spraying a bolt with one of the freezing penatrating oils and then immediately try removing it.

I would be careful if using an impact not to twist the bolt off. If a bolt seems likely to twist off I set my impact to the lowest torque setting and let it gently hammer away at it. If using a breaker bar with 6 point socket tapping on the breaker bar may be less likely to to twist off the bolt.

Ted

[turf]

i swapped out a cracked manifold on my cummins.
i did twist off the 1st bolt off when removing the manifold and had to dig the stud out with lots of different tools... easy outs/end mills. that was no fun.




i'd second the use of an impact for stud removal.

after the hardware is out. its an easy job.

the new manifold was good excuse to put an egt gauge. when its off the truck is the best time to put it in


good luck!!

[Native]

Also, if you want to wrap the manifold, off the engine is really the only way to go, I'd imagine.

[Bus'n it]

So the question is, why do these crack?

[Booyah45828]

Sometimes you can fault broken exhaust hangers. Sometimes you can fault bad castings. But in either case, you have to realize the circumstances this is in with the heat, vibration, and thermal expansion forces at work.

These manifolds will operate from below 0 to 1000+ degrees. It's pretty hard to find any material that will stay flat and not crack or disintegrate.

[turf]

i cracked my exhaust manifold climbing a mountain. monarch pass hwy 50, colorado.

Now........, i know that long climbs with your foot on the pedal will send your exhaust manifold temps into the stratosphere. now that i have replaced the manifold and installed an egt gauge, i can keep an eye on those temps.

WOT on flat ground is easy, no big deal temp wise. WOT while climbing a 7% grade, towing 5k lbs with a slipping 545 will send those temps right up to an exhaust manifold disintegrating territory.

if i lay off the throttle, egt's stay friendly. hill climbs are easy, and i have power left to spare.

it may seem counter intuitive, but slower is faster. turn on the 4 ways and enjoy the ride.

[Drew Bru]

Originally Posted by turf

i cracked my exhaust manifold climbing a mountain. monarch pass hwy 50, colorado.

Now........, i know that long climbs with your foot on the pedal will send your exhaust manifold temps into the stratosphere. now that i have replaced the manifold and installed an egt gauge, i can keep an eye on those temps.

WOT on flat ground is easy, no big deal temp wise. WOT while climbing a 7% grade, towing 5k lbs with a slipping 545 will send those temps right up to an exhaust manifold disintegrating territory.

if i lay off the throttle, egt's stay friendly. hill climbs are easy, and i have power left to spare.

it may seem counter intuitive, but slower is faster. turn on the 4 ways and enjoy the ride.

I suspect driving the Rockies hastened our manifold's demise. I drive pedal to the floor way too often on the hills. Ideally I'd like to install a EGT gauge and a turbo boost gauge, trans temp gauge too, but I suspect that's all beyond my abilities...I wouldn't really even know where to start.

[JackE]

Originally Posted by Drew Bru

I suspect driving the Rockies hastened our manifold's demise. I drive pedal to the floor way too often on the hills. Ideally I'd like to install a EGT gauge and a turbo boost gauge, trans temp gauge too, but I suspect that's all beyond my abilities...I wouldn't really even know where to start.

I have never installed a boost gauge, but the others are pretty simple, I would imagine the boost gauge is too. Drill a hole, tap the hole, and thread the sensor in, run some wire and you're done. If you have the skill set to change the manifold, you can do the other things too.

[Shortbusjohnny65]

Just remember never enough time or money to do it right the first time but always enough time and more money to do it again.

[JodyandRenee]

Originally Posted by Drew Bru

Yeah, if it's going to have to be removed I'll just put a new one on. I can order a new kit from NAPA, probably elsewhere too. I'll use PB Blaster in copious amounts. Just wasn't sure if it's a mobile job but it seems like it should be.

It looks like you have great access to the manifold. I would try and do it yourself first. Take your time, use heat on the bolts and PB blaster to loosen them up. Take the turbo off first since you can get the backside of all its fasteners then concentrate on the manifold.

I agree the manifold can be brazed. Depending on its composition (cast iron vs cast steel) you may be able to just weld it also. If it were me I would look for a good replacement instead.

[Studedude]

not sure where this should be posted but since rusted bolts are mentioned here: google acetone/atf mix as penetrating/rust buster mix. There are some tests done that show this is superior to any commercial spray. It works for me (which is not proof) and its cheap however only mix what you need as the acetone evaps over time

[Danjo]

Originally Posted by Studedude

not sure where this should be posted but since rusted bolts are mentioned here: google acetone/atf mix as penetrating/rust buster mix. There are some tests done that show this is superior to any commercial spray. It works for me (which is not proof) and its cheap however only mix what you need as the acetone evaps over time

Thanks for this. It’s always nice to have homeopathic remedies

[Native]

Originally Posted by Studedude

not sure where this should be posted but since rusted bolts are mentioned here: google acetone/atf mix as penetrating/rust buster mix. There are some tests done that show this is superior to any commercial spray. It works for me (which is not proof) and its cheap however only mix what you need as the acetone evaps over time

I call it "Farm Aide". I keep it in a hand-pump stray bottle. The acetone stays in the bottle that way. Just shake it uptomix and start spraying.

[2po2watch]

Originally Posted by Studedude

not sure where this should be posted but since rusted bolts are mentioned here: google acetone/atf mix as penetrating/rust buster mix. There are some tests done that show this is superior to any commercial spray. It works for me (which is not proof) and its cheap however only mix what you need as the acetone evaps over time

As a professional mechanic of over 25 years, this is by far the best penetrating oil I have ever used.