98 Tahoe Engine & Drive Train R & R

[G&R's57GMC]

I'm replacing the engine and rear axle in my '98 Tahoe along with the Rad, hoses, water pump, belt & tensioner, O2 sensors & etc.

So I'm in the process of going about disconnecting the wiring from the trans & cat converters. Removing the nuts & bolts on the trans crossmember, header pipe and muffler.

Then I notice how tight things are around the starter area and what a pain it will be to just R&R the trans while supporting the engine and dealing with the head pipes.

I go topside and look at all the wiring connections on the engine and can just see myself in the engine bay screwing around for hours undoing just the harness.

So I think about how the Tahoe was assembled at the factory and came to the conclusion that it may be easier to lift the body with front clip, hood and A/C intact. After all I have a lift and I'm not afraid to use it.

Looking at the connections to the chassis, fuel system, steering & engine from the body it looks easier to unmarry the body from the chassis.

Pull the engine & trans as a unit off the chassis. Separate the engine & trans on the bench, then mount the old engine on its stand next to the new engine on its stand will make the transfer of parts a piece of cake.

Any thoughts on this idea ?

[BarryB]

It isn't that hard to pull just the motor. I've done a few of these, more recent, swapped motor into my 99 4wd suburban. the wiring harness can be off in about 30 minutes and thats taking your time. tie wrap up. those bell housing bolts are easy to get with wobble extensions. once the starter is out of the way. all in all, I've had these motors pulled,and sitting on the stand in about 2 hours. 2 or 4wd. so taking body off, I wouldn't do it, but thats your decision.

[bighaas79]

ditto. pulling the motor or the trans either one is not hard especially if you have a lift. like barryb said few hours at the most.

[jrr344]

Really isn't that hard I usually just unbolt the starter and leave it hanging it is easier then taking the wire off, and on my 2 door tahoe 4x4 I unbolt the transfer case from the trans and unbolt the crossmember and just slide it back instead of pulling the t-case completely out. Most of the wiring is on the top side of the engine that will need unhooking there is not very much left once you get that all unplugged.

[G&R's57GMC]

Thanks guys for the input.

If this was a non computer truck I would just pull the engine and trans separately.

I’m just getting too old for hangin’ over fenders anymore.

Looking at the starter and its electrical connections tucked in so tight between the frame, body, and exhaust manifold I think what a P.i.t.A. this is going to be let alone the engine harness connections.

So rather then fight with all this in the engine bay I decide that the factory had the body off when they set the engine and trans on the chassis.

So I took a hard look at whats needed to be unhooked from the body to lift it off the chassis.**

** 10 bolts hold the body to the chassis (remove grill),
** a few electrical connections at the rear,
** fuel filler to body 3 screws,
** fuel filler ground strap,
** Park Brake forward cable from rear cable (along side of chassis),
** Pull left inner fender and disconnect electrical at firewall (let dangle),
** steering shaft 1 bolt,
** master cylinder from booster (2 nuts) and anti lock system from fender bracket (4 bolts) (system intact)
(zip tie to oil filler tube).
** Remove Glove box (unhook strap) and disconnect electrical connecter from HVAC,
** Remove Rad overflow bottle unbolt electrical connecter from firewall and HVAC drape over engine,
** Unbolt body ground (next to starter on chassis
** Unbolt & disconnect electrical from A/C Compressor ( place support across fenders and zip tie A/C
compressor with system intact )

Things you’ve got to do anyway *

* Throttle cable (drape over left fender)
* Remove air filter assembly,
* Battery cables (zip tied to engine),
* Trans cooler lines & Rad hoses from rad,
* Remove fan and shroud,
* Shifter cable
* Heater Hoses (zip tie out of the way)
* Disconnect A.I.R. & Evap. hoses

Lift Body off Chassis.
Now I can strip the electrical off the engine, pull the trans and swap parts to the new engine in comfort.

Work Smarter Not Harder !

[G&R's57GMC]

More Pic's

[G&R's57GMC]

and more pic's

[G&R's57GMC]

1 more

[G&R's57GMC]

More to come as I progress this week .....

[Boog]

Well dang'd if you didn't. Sure looks like way more work doing a body off to me but if it works for you then, well, alright.

[502ms]

Originally Posted by Boog

Well dang'd if you didn't. Sure looks like way more work doing a body off to me but if it works for you then, well, alright.

+1
pretty hardcore. Now I can imagine if you were actually doing a frame-off resto!

Might as well touch up the frame while body is in the air...nice finishing touch

[cjracing15]

I like it! Now you are not crawling all over the motor unhooking stuff. Plus u have room to work. Great job.

[G&R's57GMC]

Without a lift pulling the body would not be an option.

But with a lift its easy and beats hang in' over the fenders for an hour disconnecting the harness from the engine. And it still needs to be held out of the way to clear the engine.

Scraping your hands and arms trying to disconnect the wiring and cooler lines from the trans.

Disconnecting the small wiring and ground strap from the starter and chassis then threading it out of the heat shield still leaving the starter dangling or not.

Detaching the trans cooler lines from the engine.

Not to mention discharging and opening the A/C system so it can be draped over the right fender.

Removing the hood.

Then putting all that back to gather, aligning the hood, charging the A/C, hanging over the fender connecting everything, hooking up the trans stuff and cooler lines, etc.

All that extra working around the body takes way longer and is more frustrating than the few easy to get to connections to R&R the body. Of course being in California, 'What's rust ?'

I've been an Auto/Medium truck mechanic since 1970.

Since front wheel drive and fuel injection came along having a lift is one tool you can't do without. Just for maintenance alone you've got have one.

Prep time to remove the body took 40 min. part of that was to figure out the heater wiring going through the firewall (looked like a disconnect) and needing to pull the glove box to get at it.

[Mr_Rich]

I'm pulling the engine in my '89 and thankfully it doesn't have that level of complexity that your '98 has. The last time I pulled the engine in my truck was in '94 so you can see that it dates me. I don't have a lift and I'm just planning on pulling the engine out from the top. I have to brace the bracket for the accessories to the rad support and unbolt the trans and I'm good-to-go.

[G&R's57GMC]

Mr Rich,

Its amazing what 10 years can do to the complexity of the same basic vehicle.

See my next post for the strip down of the engine in prep to remove it.

I can't believe how heavy the wiring harness is now that is off.

[G&R's57GMC]

Now for the Strip .... of the wiring harness, exhaust manifolds and accessories.

I started on the passenger side and went around the engine to the front then drivers side and finally the rear.

Picture #17 : Passenger exhaust manifold prep. Note tools to keep from shrinking.

#18 : Easy access to small wires on starter and knock sensor.

#19 : Small wires removed.

#20 : Note ground wire and strap at back of head. Note heat shield for wiring.
Note bolt on chassis for ground straps from head and body.

#21 : Ground wire and strap removed from stud. Note bracket retained by stud.

[G&R's57GMC]

#22 : Heat shield & starter removed. Note easy access to torque converter bolts.

#23 : Negative battery cable to stud. Heat shield loom for ground, crank sensor and
power steering pressure switch.

#24 : Neg. bat. cable and another ground wire removed from stud. Idler pulley, tensioner
and water pump pulley removed. Note 2 bolts & 1nut retain Alternator bracket.

#25 : Alt. Brkt. Stud. Hose clamps being removed in prep for water pump removal.

#26 : Water pump removed. Screw driver releasing loom retainer.

[G&R's57GMC]

#27 : Power steering brkt. retaining nut on stud. P/S pressure switch just below.

#28 : Crank sensor wiring disconnected. Note P/S pressure switch. Hidden in the
shadow is another P/S brkt. retaining nut.

#29 : P/S brkt nut removed and P/S switch wiring disconnected.

#30 : A/C & P/S brkt removed and set on P/S box with bungie cord to chassis.
Retained by 3 bolts & 3 nuts on studs.

#31 : Yet another ground wire at the thermostat housing.

[G&R's57GMC]

#32 : Drivers side Exhaust Manifold. Note steering shaft.

#33 : EGR tube from exhaust to intake manifold. Note fuel line and wiring retainer.

#34 : Drivers side exhaust manifold, starter & bat cables, water pump, alternator & brkt
Pulleys & tensioner laid out.

#35 : Wiring loom draped over chassis.

#36 : ‘Split personality’ or ‘Out of chassis experience’


I hope this helps someone doing an engine swap on a '98 Tahoe Base model 2 w.d. be it body on or off.

This may also be typical for '96 -'99 Tahoe / Suburban and pick ups & GMC versions.

More to come later.

[Mr_Rich]

I picked up on those "spreaders" you have on the ex. manifolds. When I replaced the engine in my truck in '94 I couldn't fit the manifolds on again and I was using ARP bolts on my engine. I gave up and installed Borla headers which were very new at the time. They've held up all these years and I'm going to re-install them on my fresh engine.

This was my project last year:


It was a difficult swap, but your truck seems even more detailed...phew.

[benoit454]

I have to ask why pull the body for an engine and trans removal?I never seen anybody do it but nice work I like it and like the pics.

[Mr_Rich]

I think you missed his phrase about being too old to bend over the fenders anymore. I'd have to agree since I'm the same age. My truck is much easier to work on being an '89 and I am okay leaning over in to the engine compartment.

[G&R's57GMC]

Todays doin’s ...

Pic. : 37 Fuel lines off, intake bolts out manifold ready for lift off.

38 : Manifold off, lift chains on.

39 : Trans supported by jack stand, We have engine lift off . Note relation of mating
surfaces. I love good tools.
BTW its unnecessary to disconnect anything from the trans, except the shift cable
when doing a body off engine swap.

40 : Flex Plate removed, Old engine on cart, coolant drained from block, knock sensor,
oil pressure sender, oil filter adapter, coolant sender and factory lift hook swapped
to new engine.
Note : Drivers side lower water pump bolt goes into cooling system. Use thread
sealer on it.

41 : New engine bolted in.

[love my 72]

WOW!

Im so jealous!!! Great work!!! why not!

I tip my hat to you sir!!!! I love the way you kept the a/c system intact!!!

[speedygonzales]

One last major chore I would suggest for anyone that is going to keep their vehicle for a long time.

One quart goes a long way

One last thing, I hope your steering wheel didn't get turned while it's disconnected, or you're gona have clock spring problems.