New Guy Here - Is the 2.8 V6 that bad?

[Jimmy]

Hey Guys and Gals.

 

My name is James, I just signed up for the forum, looks like a lot of good information here.

 

I just bought an '86 Comanche 4wd with the 2.8 liter V6 with a 5 speed transmission. I have very little experience with Jeeps in general - or 4wds for that matter - but I have been wrenching on cars for nearly 20 years.

 

From the various things I read before going to look at the truck, it seems like most people have a generally unfavorable view of the 2.8 liter V6 model Comanches, but I couldn't really find much information on what's bad about the V6 other than Wikipedia mentions it has bad fuel economy.

 

I don't have plans to make a trail rig or anything like that (although I do think that stuff is really cool), I mostly just need a truck for hauling stuff around and the Comanche seems like it's just-right sized and this one was cheap for a good, solid runner.

 

So, what's wrong with the V6 and can anything be done to make it better? If it's just that it doesn't have any more power than the 4 cylinder but drinks more gas, is it possible to improve either of those issues with a different carburetor or maybe a fuel injection swap from one of the plethora of other vehicles that use the GM 60degree V6?

 

Anything else I should know about the truck, anything else to look at upgrading or replacing? Did I make a mistake buying it?

 

I won't have the truck in my posession until Monday, it might not be too late to back out...

 

Thanks for reading and any information would be apreciated.

 

BTW. I tried to search for information on the V6, but "v6", "2.8", "GM", are all too short to work in the search field so if I missed a good thread and am beating a dead horse, I apologize in advance.

[BLHTAZ]

Just wanted to say welcome to the Club... :cheers:

 

I know the 2.8 has issues, but I have no personal experience so I will allow the guys that do to respond with particulars on what they are. I don't think you are making a mistake in getting it as long as your expectations are not high for power and MPG without putting a lot of money & time in to it. :D

[j440]

My brother has an '83 S-10 2wd with that engine. It has over 250K on it and is still going. The only major problem was an oil pump bolt came loose and locked up the engine. From what I gather the bolt dropped out and caught on a crank counterweight. It took out the oil pump but the engine was idling when it came out so there was no other damage. As far as I know the carburetor has never even been off........ But these results may not be typical. :dunno:

[jeepcoma]

I agree, it has a bad rep most everywhere you read. I'll say straight off, I have no personal experience with this specific engine, but a good deal with similar old engines and carbs. I ended up with a 4.0 HO motor but I was actually looking for a first year 86 with the manual like you have, I just happened to come across my '91 before I found a decent '86. In any case, lots of people complain about EVERY carbureted motor from this period for, in my opinion, the simple fact that 99% of people don't know how to properly set up and tune carbs anymore (especially mechanics). If the carb isn't right, then yes you will have poor driveability, poor fuel mileage, poor throttle response, throttle surging, dieseling after shutdown, and all sorts of other complaints. They do take time and experience (or a willingness to learn through trial and error) to set up properly (most mechanics don't because of the first factor... TIME!), but when you do, man they are sweet. Lots of engines from this time period are based off smog-less designs from the 60s to which the American manufacturers threw a heap of vacuum lines and hoses and canisters to catch up to mandated smog rules. They work great at first, but it doesn't take long for lines to plug up, hoses to fall off, and less-than-knowledgeable mechanics to bypass and jury-rig things they shouldn't. (Those crappy (or lazy) mechanics are the worst, because you'd take your car to the mechanic to get a tune-up and expect it to run right after. So when winter comes around and it's hard to start, you figure that's just the way it is because it's got a crappy carb, and not even consider that the guy tuning it had no clue and butchered the fast idle circuit settings and automatic choke is open an inch too much.)

 

When I was reading about the 2.8 most things I read said don't bother with it and get the 4 cyl instead, the power ratings are almost the same. That's true, but the 2.8 does make a significant deal more torque at lower RPMs than the I4. Even with my HO 4.0 I rarely rev past 2.5k RPM, and the extra power really only comes into play around the rev limit. For the most part, the way most people drive, you're better off with lots of low end torque than high end power, simply the way most peoples' driving habits are.

 

I think if you're knowledgeable about tuning engines the old fashion way (you know how to use a timing light, a vacuum gauge, and a dwell/tach under the hood, and ideally know how to do a plug chop, adjust an automatic choke, follow vacuum diagrams, and maybe even have a colortune plug), you'll have great success with the 2.8. I'd still like to get my hands on one to see what it's really like and see what some careful tuning will result in. Hey! Anyone wants to drive out to my place in RI for some free tuning, you're more than welcome. Just bring some cold ones! :cheers:

[Eagle]

Aside from being underpowered and using atruly awful carburetor, the 2.8L engine has a propensity for sticking connecting rods through the side of the block. It really is a pretty terrible engine.

[Pete M]

Change the oil every 2000-2500 miles and treat it kindly and it might last a good long while.:D Or it might explode tomorrow. :dunno: It's really hard to say. Mine has over 200k on it. It sucks, but it still pushes the truck forward. eventually.

 

That engine is up there with the Peugeot transmission and Dana 35 as the worst things Jeep put in our rigs. All three have a propensity for failing when you least expect it. My 88's peugeot blew up as I was just cruising along with rush hour traffic on the freeway. Bang! My 88's Dana 35 blew up as I turned a corner. Bang-Bang-Bang-Bang! My 86's 2.8 is still kicking, but she ain't winning any races. Bang! (that bang was the 86's muffler blowing up last summer). :shake:

 

Treat it nice and she should last. But be prepared and read up on the 3.4L swap. :thumbsup:

[tin moon]

I had a 2.8 L and I only got 60K out of it before it dumped a rod and broke the block. I put a new motor in and it ran like a top for the next 140k. It was only taken off the road after getting t-boned by a bigger truck.

 

As I understand and from my own experience is that if you have a good 2.8L it is good and if you don't it is going to violently explode.

 

If it has a knock or the idle is rough, RUN!

If it is velvet smooth you probably found a good one.

 

Good luck

[Jimmy]

Change the oil every 2000-2500 miles and treat it kindly and it might last a good long while.:D Or it might explode tomorrow. :dunno: It's really hard to say. Mine has over 200k on it. It sucks, but it still pushes the truck forward. eventually.

 

That engine is up there with the Peugeot transmission and Dana 35 as the worst things Jeep put in our rigs. All three have a propensity for failing when you least expect it. My 88's peugeot blew up as I was just cruising along with rush hour traffic on the freeway. Bang! My 88's Dana 35 blew up as I turned a corner. Bang-Bang-Bang-Bang! My 86's 2.8 is still kicking, but she ain't winning any races. Bang! (that bang was the 86's muffler blowing up last summer). :shake:

 

Treat it nice and she should last. But be prepared and read up on the 3.4L swap. :thumbsup:

 

Thanks for all the replies!

 

Is the 2.8's propensity for throwing rods related to the same phenomenon on the 2.8L transverse engines? If so, isn't that just a problem of owners letting them run low on oil? Seems like an easy thing to stay on top of.

 

Is there a thread on the 3.4L swap? Seems like it would be fairly straight forward if it's just swapping in the GM 3.4 that is a relative of the 2.8. Is there a way to search for threads about the 2.8 since GM, 2.8, and V6 are all too short for the search engine to work with? Is there something else that they'd be referred to that the search engine will pick up on?

 

Is the 2.8's 5 speed the Peugeot transmission?

 

The guy said that he had been through both axles recently and did all the brakes at the same time, hopefully I'm safe on that one at least.

 

Dealing with a carb doesn't scare me. The owner said that the guy who had the truck before him unplugged and capped a lot of vacuum hoses to simplify the carburetor. It started right up and ran good so hopefully the guy knew what he was doing. My experience with carbureted cars comes mostly from oddball imports, so if the carb gets too flaky, I'll make an adapted and stick a Weber DG series two barrel on it. Nothing simpler or more reliable than those.

 

Overall, I'm pretty excited about the truck. I was looking at crappy little Rangers and such. The Comanche seems much cooler with more long term potential.

[Pollockzrodz]

HAHAHA If the truck is cheap I say buy it just because motors come and go But comanches are getting harder to find cheap! :yes: Ive got an 86 Manche with the v6. Its got 148,000 on it. It idles like crap leaks every fluid it can and the y-pipe has a crack in it so its noisy. I treat the truck like crap! I mean I have my foot to the floor from Point A to Point B still under 45mph :headpop: . I bought it with 145,000 and Have yet to change the oil because it leaks enough to where When I top it off its all fresh oil :rotf: The motor is the worst on gas even when you don't have your foot into it. I have proof of 2 rebuilds on this motor with the book of paper work the fella I bought it from gave me. I don't really care if it blows up tomorrow even though it is my daily driver :yes: Because the sooner it blows the sooner the v8 gets stuffed in there.

[Pete M]

This article should give you a good start:

 

http://jeep.off-road.com/jeep/article/a ... ?id=277008

[Eagle]

Is the 2.8's 5 speed the Peugeot transmission?

Nope. The pewgoat was used behind the 4.0L I-6 from 1987 through mid-1989. The 2.8L 5-speed was probably an Aisin-Seiki AX5, although there's a very remote possibility of a T-5 (which Jeep used occasionally if they ran short on AX5s).

[aemsee]

I personally like the little 2.8. It really gets better with MPI, but that is a lot of work. A different carb would be a great upgrade. The varijet on it now is the absolute worst carb I have ever worked on.

I think the issue with the engines self destructing is that GM sold AMC a bunch of substandard engines, just like they did with the iron duke 2.5.

[oldrusty]

I had 2 s10's with the 2.8. First one was an 85 blazer 4x4 that the wife had when we got married. I HATED that stoopid truck :fs1: :headpop: . It was affectionately known by anyone who knew me as tht little blue mother #@&*$#. It was severly underpowered and never seemed to run right from the day she bought it. It did finally expire one day on her way to work. Engine spun 3 main bearings and broke 2 rods. In its defense it did still run enough for me to limp it home( had 2 put it in low range 4x4 to get up the hill at the end of the road....lol) My other 2.8 experience was in an 83 s10 shortbed 2 wheel drive. That little thing was a trooper. I got the truck with a bad trans for free from a co worker. Put a $50 junkyard tranny in it and beat the snot out of it for 4 years. It finally just got so rusty I was afraid it was going to break in half. That thing ran great, seemed to have good power , and got really decent gas mileage.........That being said if you have ever driven a comanche with a 4.0 you'll understand why no one likes the 2.8.