1988 Suburban "MOBY"

tgdoumit

Adventurer
Yup, another build thread... A cummins 6bt is involved, a suburban and motivation.

my name is tim, i'm proud to introduce you to my new to me 88 3/4 ton suburban "MOBY". no, i didn't name him, someone else did.

this suburban currently has the standard issue drive train and engine that likes to mark its territory. the last guy deleted the tbi system which has me scratching my head. the rear axle houses a "locking differential" (GM speak) that came factory and we also are rigged with 4.10 gears. the fella who originally purchased this beastie had enough sense to add dual batteries and a 40 gallon fuel tank. everything is power and it all works except for the ac (front and rear) which will get disco'd for a while during the swap. it appears to have a 4" lift and rides like a buck board. cheap shocks, cheap springs, i dunno. they will all get replaced anyways. it has 33" wild country all terrains "D" on rusty wheels. this rig is decomposing into a nice chalky patina. heh!!

the interior is in pretty good shape, drivers seat has been ravaged by fast food gas emissions since the late 80s and is completely broken down. at least the inside stays dry!

plans include 6bt swap along with an nv4500, both waiting patiently in my shop. some sort of low visual impact of a kangaroo catcher functional/non peepee extenuation type. maybe one cucv'ish...
i'd like stock type steel wheels with dog dishes if i can find them. i also have a dana 60 and a dana 80 in the shop geared at 3.54 which might play into things. some kind of lighter functional roof rack could be in order too...

ultimately this will be a multi functional vehicle. go to work, camp and tow my TJ on a 16' open trailer. maybe a moderate trail from time to time but for the most part my jeep will do the hard stuff. thats been it's job for the last 19 years :) i am sure the suburban would be fun off road too though...

this is also a project that never happened 5 years ago. i sold off the rigs i was going to use to add on to my shop.
then, i bought my 96 cummins salvage title (guy i sold it to got hit on I-5) and a 84 grand wagoneer the same day, i was set to swap but then decided it was not practical enough for my needs. so here we are today...

good talk, nice to see you all. been here before but didn't stay long for some reason. must have something to do with work n kids and 5 other projects :D

here is a picture the day i brought MOBY home:

 

tgdoumit

Adventurer
thanks guys!
it will be a bit before i go after it as i dropped all my mad money just to get it...
so... i will tackle little things as i go to stay busy, there is plenty to do.

i thought that i would try to see why he's not running so good and take a closer lookit at a few things.

first thing i did today was inspect the spark plugs:



i noticed all the spark plugs were gapped around 0.035 or so except this one which was gapped at 0.000. wonder why this thing was missing. next i gapped them all at 0.045 (no tbi) and it seems like its working pretty well.


hmmm... not really something i would do... someone probably made too many cars with legos.


repurposed a tag for moby, its official, he has a key fob now.

went for a drive and everything seemed fine except for the thin smoke screen behind me. the exhaust y and tranny are well lubed on the outside and the scent of burning oil is in the air. it is quite refreshing to know the skeeter population is on the decline now.

the ride went well. the temp gauge hung out around 210º and the truck tracked very well. i can't say there was a ton of power but i am used to driving a 05 CTD with a programmer.

over all i am pleased.

can improperly gapped spark plugs cause overheating?
i read it may be the fan clutch too. it seems fine though.

the overheating thing bothers me and I'm not sure why its doing it.

also, i need to study up on carburetors so i can get this thing really reliable so i can take it apart. i really want to drive it until i amass all the major swap parts, the ones i dont have already.

until then ill be looking for some sort of headliner replacement, going to clean the interior so mrs. doumit will ride with me and try to stay on the cheap side for a while and maybe throw in a few camp outs here and there while I'm saving pennies.

thanks for looking,
drive safely,
:)
 

tgdoumit

Adventurer
thanks!

looking for the leak tonight after work and in the process i changed out the oil pressure switch up behind the intake manifold. I'm not sure if that was the problem or not.
after talking to a friend, he thought it might be the china wall seal. so the manifold might be coming out for a re seal.

once again, any repairs i do to this engine will benefit my wagoneer project later :) this one is something my son and i are doing.

something else i was following up on was the overheating issue.
a friend told me to get the rig up to operating temperature, shut it off and feel the radiator.
4" down - cold... top 4" hot!

just to try not to fool myself i ran it longer and went through the same dance.
everything south of about 4" was cold.... awesome :(

a new stock suburban radiator will probably work just fine with the cummins swap. they seem to run cool anyways...
 

tgdoumit

Adventurer
today after work i started after the intake. i wanted to be sure it was sealing up well.
here's what i found today:


looks like a poor goop job on the rear seal area.


looks like they tried to dam it up after the leaking was discovered... there was an actual permatex dam!
the front was not sealed all the way across.


the old gaskets, I'm pretty sure "the reused gaskets"
by the way, why block off the rear most openings for the water jacket?


ready for a good cleaning when i can get to it..
 

tgdoumit

Adventurer
did some cleaning, scraping etc. was going to put it all together tonight but my "tube of right stuff turned into a brick. guess it layed around for a few years too long, hehe!
everything is nice and clean and i hope to put it together tomorrow after work.

yup.. about 5 minutes on these... the po wasn't much of a mechanic..


things are ready for reassembly.
 
Last edited:

chaos616

Adventurer
Hey, thats cool. Interesting they converted it to Carb. I have an 88 Jimmy, same engine (except really really really bad shape) and whoever had it before the last owner converted it to carb too, i also scratch my head, it runs like crap (granted i havn't messed with the carb as i don't have time right now).

Looking very much forward to your build and especially that cummins nv4500 swap, exciting stuff!!!

Cheers,
 

tgdoumit

Adventurer
Hey, thats cool. Interesting they converted it to Carb. I have an 88 Jimmy, same engine (except really really really bad shape) and whoever had it before the last owner converted it to carb too, i also scratch my head, it runs like crap (granted i havn't messed with the carb as i don't have time right now).

Looking very much forward to your build and especially that cummins nv4500 swap, exciting stuff!!!

Cheers,

I have been watching videos on rebuilding quadrajet carbs. It is said its not too bad and you can order complete kits online. I'll have to find that video and link it here as it gives details. Some of the videos I watched had some really gummed up carbs that worked awesome after getting cleaned up. There are plenty of hacks out there for this carb.

I plan on keeping it as close to stock and let my kid monkey with (after the cummins swap and the TBI 350 into the waggy swap)
 

chaos616

Adventurer
I have been watching videos on rebuilding quadrajet carbs. It is said its not too bad and you can order complete kits online. I'll have to find that video and link it here as it gives details. Some of the videos I watched had some really gummed up carbs that worked awesome after getting cleaned up. There are plenty of hacks out there for this carb.

I plan on keeping it as close to stock and let my kid monkey with (after the cummins swap and the TBI 350 into the waggy swap)

I think mine has an edelbrock, but whoever adjusted it before adjusted it via their little chart. The bottom left corner of the chart setting was circle, more hp running cooler, its so rich that it gets a whopping 3-4 mpg :). I will be interested to see how your quadrajet cleaning and tuning comes out. That being said, the head gaskets are also completely shot (PO replaced them and isn't much of a mechanic) so it sucks the coolant in through the cylinders.

Awesome having your kid mess with carburetor adjustments, best way to learn how an engine runs and what they need to run.

Cheers,
 

tgdoumit

Adventurer
got it all back together and it seems to be leak free but i won't get to hwy test it till tuesday night, yup, forgot to insure it.
i am tempted but ill wait. i ran it for an hour and putted around my street a bit. MOBY idled and ran real good. the last time i heard a 350 that quiet was on a cadillac... that stock exhaust is really necked down!

here's a pic outside the garage getting degreased again.
 

tgdoumit

Adventurer
keeping up with the old ritual of looking EVERYTHING over before you get too excited about driving around in your new junk:

thats a hefty title, huh

today was yankthewheelsandseewhatshidingbackthere day. i have to say that i was pleasantly surprised to find brakes that are relatively new. the rotors and pads up front look to be in excellent condition and the rears are not so bad either.


the wheels are crap, i know... but i thought id atlas try to get the rust off mostly. the po used a wire cup on them and squirted canned chrome here and there.


after... i knocked out all the plastic rivets that were half burned off by the last owner and chucked the hub cans. i dont much like them even when they are new. the long lug nuts will be d/c'd in favor of standard open lug nuts.


sprayed a little paint on the wms for each wheel.


i dont like shock boots so they came off too.
is that lower shock mount a stock the real deal? i know it came as a option on this rig, it just seems sorta um, not so robust...

finally i pulled the rear diff cover. i dont think i have ever seen anything so used up as the lube in there. it was solid brown like the color of chocolate frosting... there was plenty of spoo stuck to the magnet but no ferrous chunks. however it seemed as if there was some dirt or sediment in there.

there is in fact 4.10 gears back there and a "locker" it looks like some steam punk contraption compared to the arb lockers i am used to seeing.

once again, my beliefs were reenforced when i pulled that diff cover today. you never know what someone has done (or not done) with their junk before they sold it to you...
 

tgdoumit

Adventurer
today i finished up with the rear diff.
also i addressed the problem of the ignition key sliding out at any position and at times you could turn the mechanism with no key.
the nice thing is the part only costs about $12.00 to $18.00 depending on which finish you want etc.
it is a pretty easy repair to do plus you don't have to lay in a puddle to do it!

i have always made some sort of tool to get the small retaining ring off the column and it was always a fight with potential bleeding.
this time i bought the correct tool that pushes the column lock ring so you can effortlessly remove that little retaining ring. all for six bux!
in almost 30 years of wrenching the cheapest tool was the smartest tool of the day and i wish i would have bought it way back.

there you have it, MOBY is just a little more secure than before. other measures will be taken i am sure.

up coming things to do will be a drivers side lower door hinge and a passenger side exhaust manifold. both on order.
 

BBslider001

Diesel Head
Nice work!! That is one good looking older Sub. It makes me miss my 88 and my 93 2500. Kinda wish I had not sold it even though it only got 9 mpg on a good day.
 

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