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'89 renix intake manifold gasket Q's

sonic reducer

NAXJA Forum User
Location
ft. collins, co
just started disassembly to replace the intake gasket(bolts are torqued and it still leaks) then it got dark. not really sure which way to attack this job; pull the mani's off completely or just pull the bolts and pull them back a bit leaving most things attached to the mani. havent got to the lower rear bolts yet and not really looking forward to it. one thing that is giving me problems right now is the power steering pump bracket. i need to get that whole assembly pulled right? and how the hell do you even get to the bolts under the manifold? like even see them? jeeps are put together a bit differently than i am used to.

if someone that has done this particular job before could give me a pretty basic procedure and a few tips about it that would be awesome.
TIA
 
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Nö doubt about it a pain in the rear. Take the air box out if you haven't already. Take the aux fan out, if you haven't already. watch out for hidden bolts on the power steering pump, some are hard to see and not in obvious locations. When you find them all and get them removed, set the pump where the air box used to be, maybe use a piece of wire to help keep it in place.
Getting enough slack in the harness to move the Renix intake out of the way is hard (not possible?). The connectors on the injectors break easy. I usually disconnect the O2 sensor, the knock sensor and engine temp sensor and any other connections in the rear of the fuel rail harness (being careful to mark them with tape and a pen for future reassembly). I usually get a new "O" ring set and pull the injectors and fuel rail as a unit, though this probably isn't absolutely necessary.
The bottom bolts are a whole lot easier with two people, one on the bottom to guide the extension and swivel and the other to turn the ratchet from the top.
If you take the heat shields off of the intake and throw them away it sure makes reassembly and the next gasket change much easier, as you can then see most of the bottom bolts. There is some argument whether the heat shields are necessary or not, I say no.
That isn't all of it, but just some of the trouble spots.
 
8mud, thank you for the reply.
yes, the heat shield is a problem. once i get it out i might cut it up a bit to make it easily removable as i am generally against removing them completely.
 
Another tip is to be careful of the last bend in the fuel rail harness near the firewall. Years of the motor moving around can cause under the insulation wire breakage from stress or at the least some sort of stress fatigue of the wires under the insulation. Bending the harness up and kinking this bend can cause grief.
Be careful of how the fuel rail harness runs down the front of the motor and replace it like you found it. If you run it the wrong way the chances of it cooking on the exhaust manifold increases.
Chances are you'll need to readjust the TV cable when you done.
I tend to remove more than I absolutely have to for various reasons. The exhaust manifold flange can shift a little making it a bit difficult to reinstall and I just feel more comfortable having most of the junk off of the intake so I get a better feel for how it is seating.
Making sure the exhaust manifold to down pipe studs are back in the flange before tightening everything back down can also make life a bit easier.
 
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I find it most helpful to have a 9/16" 'flex' socket (socket w/inbuilt universal joint) for those rear lower screws. Having done this job a couple of times now, you can belive me when I say it's worth having!

Disassembly -
Yes, you need to remove the power steering pump at least - not necessarily the bracket.
Removing the EGR is a pain in the arse (and you should service that gasket as well, while you're about it) due to the Torx screws. Screws are threaded 5/16"-18, so you can replace with hex heads or socket head capscrews - I used hex socket heads, since I always have an easier time finding hex keys (probably because I have so many more of them.)
Bear in mind that if you break any sealed fluid connection on the fuel rail, you'll want new seals. If you take the two QD fittings off at the ends, you just need to replace those two - if you pull the rail, you'll be doing injector seals (although that may not be a bad idea. In fact, depending on vehicle Hx (read: if it's been done yet...) you may want to just change your injectors while you're there anyhow. Easy enough to tell - OEM RENIX injectors are plastic and metal crimped together to form the body, while replacements typically are not. Small Block Ford, Small Block Chevvy, and Chevvy LT1 injectors are all suitable replacements - and usually cheaper than OEMR. And, they won't leak at the body seam (like RENIX units eventually will.)
You're going to need to disconnect the electrical harness connectors. Make sure you label them before you do so - it's a pain sorting those out (it can be done with FSM wiring diagrams and good light to sort them by colour, but why do work you don't have to?)

Sourcing replacement parts -
EGR gaskets is OEMR only - the manifold gasket is easy enough in the aftermarket. I typically use Fel-Pro - it's easier to find than Victor-Reinz.
While you're getting your manifold gasket, pick up a tube of RTV copper.
See if you can source some LocTite #272 - it's the only grade that can handle exhaust heat, and save you some work. If you can't get #272 (or equivalent,) don't bother with anything.
Copper-alloy screws (I usually use silicon bronze) won't go amiss, either.
Get a couple of brass 3/8"-16 nuts for the collector flange studs as well, and for the downpipe-to-catalytic converter flange studs (if you take that apart as well.)

Reassembly -
Leave at least two studs in the head - even if you have to cut new ones (if I have to, I cut them from 3/8"-16 threaded rod. Cut to about 2" long, and get new nuts and washers.) Locations are at either end (in the exhaust flange) and about fifty-fifty for the top centre (also exhaust flange) - they're there so you have something to hang the exhaust on while you horse the intake into place.
Apply an even coat of RTV copper to both sides of the manifold gasket. The screws will work loose over time - the RTV will help the gasket stay sealed (check torque annually. This is a known quirk of side-draft inline six engines in general) and also help to prevent gasket burn-through.
Install all screws loosely, until you have all of those wretched things in place.
Once they're all set, you can work one screw at a time - pull out the screw, apply #272, and torque to spec. Repeat ~13 times (handle the stud nuts the same way.)
Treat the EGR gasket similarly. Use copper-based alloy screws if possible (5/16"-18x1")
And the donut packing for the exhaust collector flange. And the catalytic converter flange gasket, if you took that to bits as well. Use brass or bronze nuts for reassembly.

Why the RTV Copper? It will help seal the high-temperature exhaust gas, and help the gasket stay sealed if it gets loose.

Why the brass/bronze screws? They won't seize or corrode anywhere near as badly as the carbon steel ones the OEM used (check a marina supply house, or your local Fastenal. 5/16"-18x1" for the EGR valve, 3/8"-16x1-1/4" for the manifold, and 3/8"-16 nuts for the collector flange studs and catalytic converter flange studs. 3/8"-16 if you cut new manifold studs, or 3/8"-24 if you did not.)
 
got way too many irons in the fire right now but i finished disassembly and got the gasket surface sparkling clean. a nightmare of an intake manifold for sure, the worst i have done. I ended up pulling the fuel rail so i could throw the intake manifold in the parts washer as it was filthy inside. i'm talking 1/8" of gunk from 2" behind the injectors halfway down the head ports. the injector o rings look fine so I'll reinstall with some lube and replace them later if they leak since theyre easy to get to. i chose not to remove the header and just pulled it mostly out of the way. i honestly think this job would be doable without removing much except the airbox and fuel injector harness if you were looking to haul ass.

5-90 have you had good luck with that copper stuff? I have used the spray before with ok results but never RTV. i have heard many opinions on copper gasket stuff.
surprisingly enough the studs on the header where in excellent shape and the nuts threaded right off even though they look old! they were 16tpi at the head and much finer at the nut-about 24 or 26. dunno if that is stock or not.

8mud i did notice that the injector harness looked close to the exhaust at the front although it did not appear to be heat damaged at first glance. do you have any good pictures of how it is supposed to be exactly?

lastly, does anyone know the correct torque values for the manifold studs and bolts?
thanks a million! :cheers:
 
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got way too many irons in the fire right now but i finished disassembly and got the gasket surface sparkling clean. a nightmare of an intake manifold for sure, the worst i have done. I ended up pulling the fuel rail so i could throw the intake manifold in the parts washer as it was filthy inside. i'm talking 1/8" of gunk from 2" behind the injectors halfway down the head ports. the injector o rings look fine so I'll reinstall with some lube and replace them later if they leak since theyre easy to get to. i chose not to remove the header and just pulled it mostly out of the way. i honestly think this job would be doable without removing much except the airbox and fuel injector harness if you were looking to haul ass.

5-90 have you had good luck with that copper stuff? I have used the spray before with ok results but never RTV. i have heard many opinions on copper gasket stuff.
surprisingly enough the studs on the header where in excellent shape and the nuts threaded right off even though they look old! they were 16tpi at the head and much finer at the nut-about 24 or 26. dunno if that is stock or not.

8mud i did notice that the injector harness looked close to the exhaust at the front although it did not appear to be heat damaged at first glance. do you have any good pictures of how it is supposed to be exactly?

lastly, does anyone know the correct torque values for the manifold studs and bolts?
thanks a million! :cheers:

The copper spray is okeh, but I've used the RTV copper for years on this sort of thing with good results.

Yes, the threads on the studs are that way from the factory (3/8"-16 into the head casting, 3/8"-24 on the nut.) Yes, there is a good engineering reason to do so. No, it doesn't apply in this case - I cut new studs out of 3/8"-16 threaded rod without any trouble at all.

I'm wanting to think you torque the manifold fasteners to 19 pound-feet - but you can check my site to be sure. Torque values given there (Technical Index & Reference) are culled from FSMs as I accumulate them.
 
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