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3.8l plenum removal for rear heat tubes

7K views 6 replies 5 participants last post by  GlenBill 
#1 ·
Hi all,

Sorry for starting so many threads, but I have a lot of work to do an a vehicle I am not too familiar with.

While attempting to replace the rear heat lines, I discovered that there is almost no room to get the old ones out, let alone the new ones in. I removed the wiper assembly, but I can barely get the thing to begin to come out.

I want to preserve the shape of the old lines, because I can put the new ones in the same way I get the old ones out.

I am considering taking the intake plenum out to allow more room. A quick look at it makes me think that it is not too big of a deal, but looks can be decieving. Is it as simple as removing about eight nuts/bolts. and a few tubes? It looks like it should take about twenty minures to me.

Anybody do this one? Is it OK, or a nightmare?

Thanks!
 
#3 ·
I have read some people removing it to clean it out etc. do to build up of black goop inside (from EGR I believe, might be wrong). Hope fully one of those experienced people will chime in with some direction on how to do this.
KC.
 
#4 ·
Hey, I want to reopen this discussion. I need to replace my rear heat pipes on '98 Gr Vygr. What a bear. Have removed wiper cowl, air filter box, heat shield near cat convrtr. Now still have no idea how to remove old heater pipes. Several serious questions:
1. Do I remove the old and put new in from underneath or above?
2. If above, do I have to remove air plenum? What about the alternator?
3. How big of a job is it to remove plenum? Nobody really answered st1100pilot on this.
4. Any other suggestions except "next time take it to a reputable mechanic"?

Thanks. Quick response needed. I have the van in a buddy's garage... we need to get it put back together by tomorrow.
 
#6 ·
Glen, removing the wiper module is EASY find my pictures posted by Ultraman (I couldn't post on here due to dialup). It took me 20 min to remove the module, take the pictures and add directions. It actully took ½hr to download them and send to ultra.

There is no easy way to replace the rear heater tubes. No magic short cut. You have to pull them out the top. So you have to pull the wiper assembly. You have to pull the upper intake plenumn (I've never been able to get around that nor find an easier way). I even tried pulling the front engine mount and rear engine mount an rotating the engine... didn't work so I went back to pulling the intake (that only takes me 15min to pull-- review ALL the other posts on this topic for tips on removal). NEVER use liquid sealers on assembly.

To remove the plenumn:

Disconnect the battery
Remove air inlet tube and air silencer box (you don't need to remove air cleaner assembly
remove coil pack (4 10mm bolts
Remove brace from cylinder head 15mm (it goes from the back head to the plenumn)
Disconnect a couple vacuum lines and electrical connectors (MAP, TPS, IAC)
unbolt egr tube from intake (2 13mm bolts) these are the hardest to get at IMHO
I don't remove throttle/cruise cables but some people do. there's enough slack to lay the manifold over the top of the trans
remove ground wire from firewall by alternator
unbolt intake plenumn to lower intake (2 10mm bolts 2 13mm nuts)
lift intake and pull forward slightly, now there's 2 3/8" self tapping screws on the back that support the alt wires, take these screws out after moving the intake. double check for anyting attached that I might have missed and lay intake out of the way
**** COVER INTAKE HOLES WITH SHOP TOWELS****** so nothing can fall into your engine.

I unbolt the alternator and lay it to the passenger side, that frees up just abit more room. Theres one nut on the firewall for the heater tubes and down below, just pry the tubes off a stud near the end of the tubing. The first one I did, I looked everywhere for how to get at the screw, there isn't. just pry it off.

A cable operated hose clamp tool makes this job A LOT easier. http://www.sears.com/shc/s/p_10153_12605_00947390000P?keyword=clamp+tool
 
#7 ·
Many thanks for helping me navigate through all the removals, etc. Took many long hours, but in the end, have replaced Rear Heater pipes. Wow, what a job. Yes, on 1998 Gr Vygr with 3.3L, had to remove wiper cowl, intake plenum, EGR valve, of course all sorts of hoses, electrical plug-ins, alternator bracket (but didn't touch alt), and battery. Removed old tube assembly from top- only way to go. Also had to remove 4 bolts holding cat convrtr up on manifold- allowing us to move cat convrtr off to one side... otherwise couldn't push new heater pipes down alongside cat convrtr. Was good time to replace all spark plugs, and had to replace air plenum gasket. Otherwise easy job. Heh heh.
:thumb:
 
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