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Login to post Forums » Grassroots Motorsports » Any info on a '84 GMC S15 V6 auto 4wd?

Dec. 4, 2008 11:08 p.m. Duende Reader

1984 GMC S15 4wd V6 auto with a rear main oil leak, and apparently only running in 2WD/RWD right now. A friend of the family offered it to me for $200 and the body is in actually good shape. I'm going to search for a specific forum tomorrow, but everyone here is so knowledgeable it's my first go-to now, hah. Any information you have on these things would be great. Parts availability, junkyard parts, whether $200 is even a deal for an old truck with issues. I have some pics but they're on my phone, had a long day so I'm heading to bed, I'll post them up tomorrow if anyone is interested.

Alright, night, fellas. Thanks!
Dec. 4, 2008 11:31 p.m. walterj HalfDork

GMC S15 4wd auto you say... Perhaps you are thinking Trebuchet... but I would caution you that you need a very strong struture to throw anything that large very far.

They do make excellent targets for automatic weapon practice, and can also be a lot of fun to just take a huge hammer to on a slow lunch break.
Dec. 5, 2008 12:59 a.m. Capt Slow Reader

That was my very first car.

That car killed GM for me.

I get mad whenever I read worst car ever lists that DONT list this pile of crap.

I second walterj: Its good for target practice.

84s had the early 700r4 transmission that were less than reliable.

The brake proportioning valves tend to leak.

The 2.3 L v6 is anemic by any standard.
Dec. 5, 2008 6:54 a.m. Jensenman SuperDork

I have heard that they make excellent jon boat anchors until they dissolve.

It's probably the 60 degree 2.8 V6 which had a nasty habit of breaking cranks.

The upside: there is a TON of junkyard stuff out there. The 3.1 is a bolt in and IIRC the later 3400 can be done as well but is not a direct swap (it's MPFI, not TBI).
Dec. 5, 2008 7:57 a.m. Kramer Reader

I had an '83 Camaro with the 2.8. It was the worst engine GM ever put in a car, I think. Mine finally gave up the ghost when the gobs of gasket material (silicone in place of VC and OP gaskets) finally clogged the oil pump pickup.
Dec. 5, 2008 8:06 a.m. ClemSparks SuperDork

You'll want to find out if you can pull the oil pan with the engine in the truck to find out how hard the RMS seal is going to be to replace.

IIRC, the actuation for the transfer case on these is a vacuum switch...so the fix for the non functional 4WD could be as easy as diagnosing a vacuum leak or such (note: I said could be...).

They made S10s an ds15s (5 better than an s10?) for ages...so it stands to reason that the parts are cheap and everywhere.

That said, I haven't owned one...just had family and friends who have.

Clem
Dec. 5, 2008 9:22 a.m. rustyvw HalfDork

I've had a couple s-10's, and the ones I had took a surprising amount of abuse. They always have a lot of little things wrong, but they would usually bring you home. If I remember correctly, there is a kit to convert the transfer case to cable operation which should be more reliable than the vacuum set up they came with. Both of my s-10's had head gasket issues, but they aren't that hard to work on and parts are cheap and plentiful.
Dec. 5, 2008 10:04 a.m. belteshazzar Dork

Sounds like a good shell if you've got time and patience. Give up on the 2.8 earlier than later, and count on replacing pretty much everything before it's a useful pickup.

The problem is, you can get the same truck but 8-10 years newer and with a 4.3 for 1500-2000 around here. On the other hand you can spend 1500 on parts for that one and do a ton of work. The result might be as nice.
Dec. 5, 2008 5:53 p.m. Duende Reader

Oh well. I desperately need cheap trans, like, yesterday, so... Oh well, it's $200 bucks.

Thanks for all the info, guys. I guess I'll be junkyard scrounging for the stupid thing but it'll give me something to do.
Dec. 5, 2008 6:14 p.m. bamalama New Reader

I'd let it leak oil. The rear seal in one of those is a bitch.
Dec. 6, 2008 12:34 a.m. curtis73 Reader

I'd drop in a 350. With the tons of aftermarket parts out there, its literally a drop-in.

The 2.8 (in my opinion) is a fine engine. The bad crank issues were a rarity in very early production. They were not an issue at all by 1984. Nothing special about it, but its reliable and parts are dirt cheap. Other 60* V6 swaps are available (like the 3.1, 3.3, 3.4, 3.8, etc) but they have to be RWD sources. The 4.3L can drop in as well, but the crossmembers are different between the early and late S-trucks. The 4.3L is a small block V8 with two cylinders lopped off.

The 700r4 is pretty weak in factory form, but it is also only responsible for 130 hp and 175 tq. It survives fine in corvettes, and in fact a variation of the 700r4 is still used today in full size trucks with 300-hp V8s. It will run forever, or until the valves start sticking and you get really rock hard shifts. Then you'll need a new valve body. Since the 700r4 is the most commonly used tranny that GM ever made, junkyard parts are a dime a dozen.

The transfercase is big-boy stuff; NP203 IIRC. Same as is used in some Jeeps and FS trucks.

The S-chassis is a great setup. Not inspired or modern, but it uses many off-the-shelf GM parts sourced from other trucks and cars. It also has a full frame that is very sturdy.

I'm actually currently actively searching for a truck, and an early S-truck is on my list.
Dec. 6, 2008 1:04 a.m. Duende Reader

I'm fine with dropping in anything that will be reliable, easy to work on, as cheap as possible to swap, and hopefully provide better mileage. So I'll certainly be researching that.

Thanks! I'm a bit stuck into buying it so we'll just have some fun with it and hope for the best! I'm over on http://www.s10forum.com/forum/s10-s15/ right now which is really the only decent forum I've found so far.
Dec. 6, 2008 7:59 a.m. minimac Dork

You could also look here for inspiration:http://www.ad-engineering.com/index.html
Dec. 6, 2008 6:48 p.m. belteshazzar Dork

curtis73 wrote:

The 700r4 is pretty weak in factory form, but it is also only responsible for 130 hp and 175 tq. It survives fine in corvettes, and in fact a variation of the 700r4 is still used today in full size trucks with 300-hp V8s. It will run forever, or until the valves start sticking and you get really rock hard shifts. Then you'll need a new valve body. Since the 700r4 is the most commonly used tranny that GM ever made, junkyard parts are a dime a dozen.

The 700r4 is only junk until around '87 or so. Examples newer than that are just fine.
Dec. 6, 2008 7:23 p.m. curtis73 Reader

belteshazzar wrote:

curtis73 wrote:

The 700r4 is pretty weak in factory form, but it is also only responsible for 130 hp and 175 tq. It survives fine in corvettes, and in fact a variation of the 700r4 is still used today in full size trucks with 300-hp V8s. It will run forever, or until the valves start sticking and you get really rock hard shifts. Then you'll need a new valve body. Since the 700r4 is the most commonly used tranny that GM ever made, junkyard parts are a dime a dozen.

The 700r4 is only junk until around '87 or so. Examples newer than that are just fine.

Agreed. They are typical of GM transmissions; they build a capable box, then mush it up so soft so that old people don't complain about hard shifts. But behind a 2.8 v6, they'll probably outlast the rest of the truck.

Its updated form (4L60E) was the same basic transmission with electronic controls, and it doesn't survive behind the 260hp/330tq that came stock in my 96 Impala SS, but properly built they can launch on slicks with 600+ lb-ft all day and not break a sweat.
Dec. 7, 2008 10:46 a.m. Duende Reader

Well, unfortunately, picking it up today. So we'll see! Thanks for all the input, gents, I'm sure you'll hear some gripes from me about the thing shortly, hopefully not.

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