Jump to content
SAU Community

Recommended Posts

Hi gurus,can anyone tell me why I have to replace my exhaust Mani every 3 or 4 years due to cracks,getting a bit boring now.Coming up to my 4th one this year,any way of sorting this I know I do a lot of ks every year 30000 plus but its mostly long hwy trips pissing me right off it is. :-)

Link to comment
https://www.sau.com.au/forums/topic/456126-cracks-in-exaust-manifold/
Share on other sites

Reweld it ?

Or buy a good one ...

Rewelding it id a waste of time and money considering how cheap another stock one is..

Its the heat cycles that kill them.

Do you get in the car and give it a hard time straight away or let it warm up first? If you even give it a hard time!

Reweld it ?

Or buy a good one ...

He asked why it cracks.

I can only imagine it's getting hot possibly because always on boost on the freeway and it's tuned? Everyday on boost for hours would take it's toll on a lean tune. Only speculating though.

Rewelding it id a waste of time and money considering how cheap another stock one is..

Its the heat cycles that kill them.

Do you get in the car and give it a hard time straight away or let it warm up first? If you even give it a hard time!

Ha ha,I never thrash a cold engine on any car,I warm up for 20 seconds then drive sedately till it gets to operating temp,

then drive it like I stole it , :-) :-)

He asked why it cracks.

I can only imagine it's getting hot possibly because always on boost on the freeway and it's tuned? Everyday on boost for hours would take it's toll on a lean tune. Only speculating though.

Safe PFC tune 220 at the rears for many years now perfect afrs. PS me lady lil ol lady. :-)

My mechanic is the one doing the work I assume he uses a torque wrench to the right specks.

I'd be speaking to him then; don't assume. Check what gaskets you're using too - those cheap cardboard-ish ones don't transfer heat well, and like to leak.

EDIT:

Also, check that you have the front exhaust hanger installed at the gearbox cross member, it's the only real form of support the turbo has. Even without it, it shouldn't really cause cracks on the manifold.

Edited by colourclassic
  • Like 1

Thanks heaps guys,my 33 is serviced every three months,and up on the hoist as well I like to be safe,I'll chat to him when I get back from brissy in a couple of weeks.Far as I know exhaust supports are all there in good condition.I'm just thinking there must be a reason for the Mani to crack have to find out why. :-)

Are you running a flex pipe in your dump and has your dump got a solid mount to the body near its flange like the std ones do? they play a big part in saving manis, gaskets, loose bolts etc.

^^ This. The exhaust is a 5m long breaker bar, and your manifold is very soft at that temperature. A flex join in the front pipe isolates the forces caused by your muffler swinging around.

  • Like 1

^^ This. The exhaust is a 5m long breaker bar, and your manifold is very soft at that temperature. A flex join in the front pipe isolates the forces caused by your muffler swinging around.

I used a few of these as exhaust mounts:

http://www.ebay.com.au/itm/Toyota-Landcruiser-HZJ80-HDJ80-Series-Exhaust-Mount-Rubber-Set-3-/201205416170?pt=LH_DefaultDomain_15&hash=item2ed8c700ea

Had to fabricate my own brackets, but they make a great semi rigid mount. The exhaust cant swing around anymore.

I used a few of these as exhaust mounts:

http://www.ebay.com.au/itm/Toyota-Landcruiser-HZJ80-HDJ80-Series-Exhaust-Mount-Rubber-Set-3-/201205416170?pt=LH_DefaultDomain_15&hash=item2ed8c700ea

Had to fabricate my own brackets, but they make a great semi rigid mount. The exhaust cant swing around anymore.

My exhaust grows in length by 1 1/2 inches at the track, I would be surprised if those would give enough movement to last long term, unless the bracket can bend...

Later model Nissan cars have a fixed rear bracket to stop the muffler swinging around, but they still run a flex joint stock.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • How complicated is PID boost control? To me it really doesn't seem that difficult. I'm not disputing the core assertion (specialization can be better than general purpose solutions), I'm just saying we're 30+ years removed from the days when transistor budgets were in the thousands and we had to hem and haw about whether there's enough ECC DRAM or enough clock cycles or the interrupt handler can respond fast enough to handle another task. I really struggle to see how a Greddy Profec or an HKS EVC7 or whatever else is somehow a far superior solution to what you get in a Haltech Nexus/Elite ECU. I don't see OEMs spending time on dedicated boost control modules in any car I've ever touched. Is there value to separating out a motor controller or engine controller vs an infotainment module? Of course, those are two completely different tasks with highly divergent requirements. The reason why I cite data sheets, service manuals, etc is because as you have clearly suggested I don't know what I'm doing, can't learn how to do anything correctly, and have never actually done anything myself. So when I do offer advice to people I like to use sources that are not just based off of taking my word for it and can be independently verified by others so it's not just my misinterpretation of a primary source.
    • That's awesome, well done! Love all these older Datsun / Nissans so rare now
    • As I said, there's trade offs to jamming EVERYTHING in. Timing, resources etc, being the huge ones. Calling out the factory ECU has nothing to do with it, as it doesn't do any form of fancy boost control. It's all open loop boost control. You mention the Haltech Nexus, that's effectively two separate devices jammed into one box. What you quote about it, is proof for that. So now you've lost flexibility as a product too...   A product designed to do one thing really well, will always beat other products doing multiple things. Also, I wouldn't knock COTS stuff, you'd be surprised how many things are using it, that you're probably totally in love with As for the SpaceX comment that we're working directly with them, it's about the type of stuff we're doing. We're doing design work, and breaking world firsts. If you can't understand that I have real world hands on experience, including in very modern tech, and actually understand this stuff, then to avoid useless debates where you just won't accept fact and experience, from here on, it seems you'd be be happy I (and possibly anyone with knowledge really) not reply to your questions, or input, no matter how much help you could be given to help you, or let you learn. It seems you're happy reading your data sheets, factory service manuals, and only want people to reinforce your thoughts and points of view. 
    • I don't really understand because clearly it's possible. The factory ECU is running on like a 4 MHz 16-bit processor. Modern GDI ECUs have like 200 MHz superscalar cores with floating point units too. The Haltech Nexus has two 240 MHz CPU cores. The Elite 2500 is a single 80 MHz core. Surely 20x the compute means adding some PID boost control logic isn't that complicated. I'm not saying clock speed is everything, but the requirements to add boost control to a port injection 6 cylinder ECU are really not that difficult. More I/O, more interrupt handlers, more working memory, etc isn't that crazy to figure out. SpaceX if anything shows just how far you can get arguably doing things the "wrong" way, ie x86 COTS running C++ on Linux. That is about as far away from the "correct" architecture as it gets for a real time system, but it works anyways. 
    • Holy hell! That is absolutely stunning! Great work!!!
×
×
  • Create New...