EGR and manifold removal tips-78 280Z

[One Way]

Continuing the tear down on my project.  I have been slowly removing components to evaluate and refurbish as the project slowly moves forward.  The engine is still in the car-less storage space needed.  I have been struggling with the manifolds.  i have been spraying the hardware with Blaster everytime the hood has been popped for the past several weeks.  The rear exhaust stud is missing and I snapped off the front one with barely any force. The center bolt did come out OK.  The factory service manual simply states remove the EGR valve, etc.  The valve has been successfully removed with the Blaster and a bit of heat but the connecting tubes are a different story.  Any tips or suggestions will be appreciated, even an elimination of the EGR system if that would not cause performance or driveability issues with the engine after we get it rebuilt and running.  Thanks for the help in advance.  John-Lugoff, SC

[Namerow]

You can forget about PB Blaster (or any other 'penetrating' oil) having any useful effect in getting stubborn exhaust manifold fasteners loose -- even if you add a bit more every day for two weeks.  What you'll probably need is heat.  Not just any heat, either.  You need to get the fastener just close to glowing.  I've read that an oxy-acetylene torch provides the best flame for this purpose.  However, I've never had access to a gas welding kit, so I use a special torch head (provides an air bleed-in just downstream of the tip) on a regular propane cylinder to get the flame temp up.  A regular (plumber-type) propane torch set-up won't get the job done.

Even with this kind of heat, you'll probably only succeed at breaking the threads free.  Let things cool a bit and add some oil to the threads before you do any more wrenching.  You'll need to coax the fastener out.  Loosen two increments, re-tighten one increment.  Repeat until the fastener either starts to turn freely (good luck) or is fully out, adding a bit more heat and a bit more oil from time to time.  Do not give in to the temptation of trying a power impact wrench.

I -- like you and many other Z owners -- have had to deal with a snapped-off rear exhaust manifold stud.  Mine snapped off about 1/16" below the surface of the head.  I started a thread on this about six months ago and got lots of helpful input.  However, there are no 'silver bullet' solutions.  I you're handy with a MIG welder, that may offer the best solution.  Fill the cavity on top of the stud with weld and then -- using a flat washer as a spacer -- weld a nut on top of the stud.  The combination of heat shock and restored leverage gets the job done.  Drilling the core of the stud out for follow-up with an ez-out is usually the road to hell (although some claim that using a left-hand drill bit works wonders).  I would only let a competent machine shop try this -- and that means taking the head off.  I certainly wouldn't try it with the engine in the car  (limited access, no arm support, tiny stud diameter, engine mounted on an angle -- 'What could go wrong?').  The 'perfect world' solution is to have the stud material vaporized using an electric induction process.  However, this isn't something a hobbyist can do and you may have difficulty finding a shop that has the equipment (unless you live in/near a major urban centre).  Once again, the head will have to come off the engine.

I believe that one of this site's senior members did a write-up (some time ago) about getting the air injection pipes loose from the exhaust manifold.  Use the 'Search' tool to locate.

Edited August 4, 2016 by Namerow
cleaned up the explanations

[siteunseen]

I removed my EGR and the BPT valve.  You have to remove the heat plate that's under the AAR valve with the two heater hoses and the vacuum switch then plug a vacuum hose that runs from the BPT valve to under the TPS to close the system back up.  I have some pictures, when you get closer let me know and I'll post them up.  Those broken studs, the first one and the last one, can be tapped and the next size exhaust stud put in.  I bought mine from Nissan, it's for their 8 cylinder Titan pickup.  

 

Remove this heat plate  and keep this AAR     

[One Way]

Thanks for the tips.  Broken stud removal is definitely a chore to be done with the cylinder head removed.  That will be a separate project down the road.  I am sure the head will need to be milled, machined and gone through thoroughly.  This project was purchased knowing it had been sitting over 19 years, so I kind of expected a complete mechanical rebuild on all areas of the Z.  I am just trying to refurbish some of the smaller components, like the manifolds, cleaning, media blasting and painting as we go.  That kind of stuff is not too hard on the checkbook right now.  I have a bit of time off from work tomorrow so my game plan is to try and get those manifolds removed.  I have the pro grade nozzle and will try some of the MAPP gas on it.  That is supposed to get hotter than the propane.  The propane set up I have has done very well on the stubborn fasteners I have encountered so far but not as well on the EGR tubes and exhaust manifold fasteners.  The oversize exhaust studs may be an upgrade I will do as it seems there have been numerous comments about them failing, especially the rear one.  I will keep you posted and looking forward to more input from the Z experts.  Thanks, John-Lugoff, SC.

[siteunseen]

Rebello heads have all studs replaced with the bigger size. I just did the first and last. My MSA header already had those holes enlarged. It's a very common upgrade.

With the head on a work bench, R&R those studs will be 1,000 times easier.

[Chickenman]

There is a modern alternative to heating. Handy for the DIY who may not have torches. It is extreme cooling sprays.

Various " Freeze  " sprays are available  from CRC and Weicon that freeze a bolt down to -30F or lower in seconds. The bolt shrinks, the rust crystals are broken and the Penetrating fluid now has room to " wick " into the threads by capillary action. This stuff works amazing and is used by a lot of Industrial firms. I've used it on frozen turbocharger bolts and flanges on Marine engines ( Salt water corrosion ) and the stuff works extremely well.

CRC Freeze Off:

https://youtu.be/b0BaowQvL6c

Weicon Rust Shock:

http://www.weicon.com/pages/ca/products/spray/dissolving-separating/rust-shock-spray.php

 

 

 

 

 

[One Way]

I have seen the FREEZE sprays available now but have never tried any.  Great to hear an advertisement from a real user rather than just the promised amazing results printed on the can.  Over the years I have had good success with PB BLASTER, some heat, and a lot of patience.  Looking forward to tackling this segment of the project.  Thanks again, john-Lugoff, SC.

[Namerow]

I've had mixed success with freeze sprays.  Worked like magic in one case (frozen brake line connection), but failed miserably in another (snapped-off distributor clamp-down bolt).  In the latter case, I had the part on the bench and worked away at it for a week, using various sequences of heating, freezing, shock, and penetrating oil.  I finally had to drill out the remainder of the stud and re-tap the hole for an oversize bolt).  My theory (and that's all it is) is that the freeze sprays work well to break up ferrous-metal rust, but not so well to break up the thread bonding that occurs between dissimilar metals (i.e. aluminum casting / steel bolt).  Nevertheless, your results may be different -- and I hope they are!

One warning:  Freeze sprays are quite flammable, so be careful about spraying a part that you've previously heated with a torch.  You'll end up with a dandy little fire and you better have an extinguisher close by (ask me how I know this).

[One Way]

Both manifolds removed.  3 exhaust studs snapped off right at the nut so there is something to work with there when I remove the head.  The back stud was already broken and appears to be snapped off inside the head.  That will be the major concern.  The large EGR fitting also snapped off  in the intake manifold.  Also another project for another day.

Looking for recommendations on exhaust options.  Keep the stock manifold, remove the EGR fitting, replace the 3 intact but looking pretty poor exhaust pipe studs, blast and hi-temp paint-or purchase an aftermarket header ?  The exhaust pipe looks pretty good, although I have not removed the heat shield around it yet.  Center muffler not the greatest, rear pipe and muffler defintely bad.  This is a budget project and most likely keeping the engine basically stock.  Thanks for any advice from the Z  experts.

The MAPP gas definitely gets things hotter and faster.  The exhaust pipe nuts came free rather easily after a little torch time with the MAPP gas.  I will see how it works trying to remove the EGR fittings out of the exhaust and intake manifolds.  Thanks again, John-Lugoff, SC.

 

[siteunseen]

See if you can find a n2 an intake, before egrs or n47 and a block off plate. I got mine for $40. I know your budgeting but msa header and 2.5" premium exhaust is $500 & you'll love it. It'll flow more air so you can open up the head's ports to match the gasket. Round them out or "bugle" shape the ports. More air moving through is always best. The motors are a air compressor more or less so the more flow the better.

Stock is good for efi. They don't like mods because of the ecu stays the same. My $.02

[Zed Head]

I've read that the stock manifolds flow pretty well.  It's the pipes after the manifold that offer the most potential.  Bigger from the manifold back.  It would be a bit pointless to go with headers but stock size pipes to the back.  No offense to those that have done that.

Those three exhaust studs are really difficult to remove.  If you try it use lots of heat.  I've had some that would only move when everything was hot.  As it cooled I couldn't turn it any more.  If they look like they'll last a while just clean up the threads and leave them.  You'll probably break them trying to remove them.

[siteunseen]

Remember Zed, heat from cast iron equals vapor lock potential. Just saying that. Headers clean up the engine bay too. The OE manifold does flow just as good from what I've read but $250 ain't bad for ceramic coated header. $.04 now.