Is the 2.8l really that bad?

[nolehynaws]

I’ve been looking at a 1986 Comanche with only 60000 miles on it, but it’s got the 2.8l motor. Everything I’ve read says they’re bad, but in what way? I’m not going to be off-roading this truck (that’s what the CJ is for), I’m just going to be driving around town and occasionally going on trips for an hour or two. If I change the oil on time and take care of it, is it really gonna be that bad?

Also, if i end up getting the truck in the future, what motor should I swap into it? I don’t really care about power, just reliability and cost and ease of getting it in. Thanks!

[Eagle]

No, it's not really that bad ... it's much worse.

 

The best/easiest swap is a GM 3.4L V6 out of a rear-wheel drive car like a Camaro or Firebird. It's the same basic block, but a MUCH improved engine.

 

[BeatCJ]

I remember the 80 Buick Skylark my mom bought new with that engine. It was perfect for a 50 year old accountant.

 

Biggest gripe was the lack of power, then poorly designed main bearings, and overheating/ head gasket issues. Well maintained, you could get by. Be prepared to have it towed some day. And be thankful if it never happens to you.

 

And there is really no other sensible choice than to upgrade to a much better later model 60 degree V-6. GM increased them incrementally over the years, but 30 or 40 years of improvement goes a long way.

[Pete M]

In a small defense of the engine, my 2.8 went 200k before I sold it.  but it didn't get there quickly, that's for sure.  that carb suuuuucked.   

 

there's a bunch of info on the 3.4 swap in the link in my signature  

[omega_rugal]

it has  alot of problems, swap it out ASAP

[Chad R]

My mom bought a 84 Xj new and it had that engine in it . Went threw 27 quarts of oil in the 7 months we owned , because  it leaked it out! Jeep dealer put every gasket you could think of but amc would not let them put new engine in. 

lucky for us the dealer bought it back and we got a 85 xj with the 2.5 .

[nolehynaws]

8 hours ago, Eagle said:

No, it's not really that bad ... it's much worse.

 

The best/easiest swap is a GM 3.4L V6 out of a rear-wheel drive car like a Camaro or Firebird. It's the same basic block, but a MUCH improved engine.

 

How much do you think that will cost?

[cruiser54]

Just buy it and drive it. 

[coheed]

It is not an good engine, but some can be reliable. The current Comanche I have has the original 2.8 as far as I can tell, and the unhooked odometer had 330k miles on.  It'll take it about 10 minutes to hit 60 but it'll do it.

 

Take the chance. Buy the truck. Drive it till the motor does or does not explode, and swap when you have the time, money, or need.

[JustEmptyEveryPocket]

1 hour ago, coheed said:

Take the chance. Buy the truck. Drive it till the motor does or does not explode, and swap when you have the time, money, or need.

Best advice right here.

[88towmanche]

3 hours ago, coheed said:

Take the chance. Buy the truck. Drive it till the motor does or does not explode, and swap when you have the time, money, or need

 

Buying my first house, got notified the day before closing I needed to cough up another $8k in cash - (we had thought we needed $12k and had that but someone miscalculated and we needed $20k) - sold the S10 Blazer I had for wholesale price to get some quick cash and bought the house but had no vehicle or money to buy one.....

 

Borrowed $500 from my brother and bought an 84 S10 pick up longbed with the 2.8 - truck was straight but paint and interior were trashed - motor sounded like a bag of marbles in a washing machine on spin cycle.

 

Thought maybe it would last a couple of months - kept an eye on the oil and temp and just drove it.....for 2 years!  Thing spewed oil like you couldn't believe - finally got that somewhat under control - was a banjo bolt that I think held the oil filter on - remember trying to cut a complicated gasket after tearing the $5 dealership one - finally said screw it and forgo the gasket for a $#!& ton of RTV - stopped that particular leak for rest of the time I had the truck.

 

Gutless and noisy, but it ran until I sold it to some kid for the same $500 

[Eagle]

4 hours ago, coheed said:

 

Take the chance. Buy the truck. Drive it till the motor does or does not explode, and swap when you have the time, money, or need.

 

Absolutely. If it's running, drive it. Just keep in mind that when the 2.8L dies, the 3.4L (NOT 4.3L) is the easiest, simplest, and probably the most economical replacement. Just be sure you get a 3.4L out of a rear wheel drive vehicle.

[AMC86Kid]

I have a 86 and it’s upgraded to 3.4 

i agree with eagle 

if you can drive and deal with the 2.8’s problems then go for it but once your done putting up with it, I recommend upgrading to the 3.4 

 

the 2.8 is super underpowered especially if you have 4wd and it has a stupid design with 3 belts on it and vacuum switches and a super complex varajet carborator 

you can tell that it’s outdated 

and for around the same money you can upgrade to a much simpler design 

also with the 3.4 you don’t have to worry about everyone passing you cause your going to slow 

 

the 2.8 gets around 110 hp and 150 lbs torque and the 3.4 gets around 160 hp and 200 lbs of torque 

[Pete M]

bonus points if you retain the 3.4's fuel injection system  

[coheed]

3 hours ago, 88towmanche said:

 

Buying my first house, got notified the day before closing I needed to cough up another $8k in cash - (we had thought we needed $12k and had that but someone miscalculated and we needed $20k) - sold the S10 Blazer I had for wholesale price to get some quick cash and bought the house but had no vehicle or money to buy one.....

 

Borrowed $500 from my brother and bought an 84 S10 pick up longbed with the 2.8 - truck was straight but paint and interior were trashed - motor sounded like a bag of marbles in a washing machine on spin cycle.

 

Thought maybe it would last a couple of months - kept an eye on the oil and temp and just drove it.....for 2 years!  Thing spewed oil like you couldn't believe - finally got that somewhat under control - was a banjo bolt that I think held the oil filter on - remember trying to cut a complicated gasket after tearing the $5 dealership one - finally said screw it and forgo the gasket for a $#!& ton of RTV - stopped that particular leak for rest of the time I had the truck.

 

Gutless and noisy, but it ran until I sold it to some kid for the same $500 

 

 

I worked with a guy years ago with a similar story. His grandparents gave him an S10 with a 2.8 for a summers worth of work on their farm. He drove it for about five years back and forth from North Carolina to Michigan through high school and working. Was still running fine when he got a newer truck.

 

1 hour ago, AMC86Kid said:

I have a 86 and it’s upgraded to 3.4 

i agree with eagle 

if you can drive and deal with the 2.8’s problems then go for it but once your done putting up with it, I recommend upgrading to the 3.4 

 

the 2.8 is super underpowered especially if you have 4wd and it has a stupid design with 3 belts on it and vacuum switches and a super complex varajet carborator 

you can tell that it’s outdated 

and for around the same money you can upgrade to a much simpler design 

also with the 3.4 you don’t have to worry about everyone passing you cause your going to slow 

 

the 2.8 gets around 110 hp and 150 lbs torque and the 3.4 gets around 160 hp and 200 lbs of torque 

 

Most of the vacuum system can be removed to little to no ill affect. Mine is mostly deleted on my 2.8. Also if you remove the air pump, or just the pulley on it, you can run two water pump/alternator belts for a little extra assurance.

 

110hp for the 2.8 is at the crank, brand new, and optimistic. If you can't deal with a SLOW truck, and I mean slow, swap or buy a newer Comanche with a 4.0.

[AMC86Kid]

You could drop a 4.0 in it 

but it would be a little more work 

also I don’t think it’s compatible with his 2.8 tranny since it has a 60 degree bell housing 

[Pete M]

it is not.  they don't share a bolt pattern.

[omega_rugal]

1 hour ago, AMC86Kid said:

You could drop a 4.0 in it 

but it would be a little more work 

also I don’t think it’s compatible with his 2.8 tranny since it has a 60 degree bell housing 

 

full drivetrain swap

[Minuit]

It's an engine that was used in 3 model years in XJs and one model year in MJs that made less horsepower and only slightly more torque than the base 4-cylinder. It does not justify this shortcoming with reliability, fuel economy, smoothness, or novelty. In fact, by many accounts it's quite possibly the least reliable engine offered in any year of the MJ - that being said, there really aren't enough diesels out there to have a decent sample size. If you dared option the truck up, it came with an automatic with three whole gear ratios, and a transfer case that was similarly dropped after 1986. The factory carburetor is finicky 80s emissions "technology" at its almost worst. You can read accounts from back in the day of there always being one in the shop with a window in the block. The 4.0 that replaced it, and appeared in 6 model years of Comanche and fifteen model years of Cherokee (this is important - parts availability), among others, is better in literally every quantifiable way. The 2.5 that it was an option over is better in most quantifiable ways. I've seen a handful make it to 200k on the original engine, but I've seen literally dozens of 4.0 Jeeps make it into the 300s that only landed in the junkyard because they were about to rust in half.

 

The only saving grace of this engine is that it can be easily replaced with another GM V6 that is only found in 3 model years of rapidly disappearing F-body posermobiles, and is still in many quantifiable ways inferior to the 4.0L that any other year of MJ could come with except for fuel economy. In addition, the full potential of said replacement GM V6 can only be achieved if the fuel injection that came with it is swapped in, which isn't exactly a project for a toddler.

 

You be the judge.

[Pete M]

the 3.1 is also an option.  I believe found in s-10s?

[coheed]

1 hour ago, Pete M said:

the 3.1 is also an option.  I believe found in s-10s?

And early 90s Camaros and Firebirds.

 

Like I said, if you like the truck buy it. If you decide you hate the engine, swap it. I'm really thinking mine will get a diesel once my 2.8 gives up the ghost.

[WesD]

I have to disagree with a lot here - I had a S10 Blazer with the 2.8 V6 and the 700R4 transmission.  The 2.8 made it to 200k and was at the end of it's life when I sold the old beast.

Never had a problem with it other than replacing the intake gasket (common failure), matter of fact I kept the same spark plugs in it for 65000 miles.    Carb worked fine, and one time it even took the family to school when the good ol 2.5 Renix wouldn't even hit it was so cold outside.

 

They weren't fast, but back in the day when the 305 V8 was putting out 160 HP, a 110 HP V6 wasn't terrible.    Parents also had a midsize GM car with the 2.8 that was 150k miles when sold, no problems. 

 

As long as it runs fine, drive it.

 

And the S10 only came with the 2.5 4 (2.2 after 1991), 2.8 V6, and then 4.3 V6.

 

 

[Pete M]

there is a running hypothesis that Jeep got... lesser castings.  just a rumor though.

[AMC86Kid]

Did the 3.1 have the same 60 degree bell housing as the 3.4 ? 

 

Also forgot to mention the 2.8 is not even internally balanced, they had to weld a chunk of metal to the fly wheel to get it externally balanced 

[Eagle]

3 hours ago, AMC86Kid said:

Did the 3.1 have the same 60 degree bell housing as the 3.4 ? 

 

Also forgot to mention the 2.8 is not even internally balanced, they had to weld a chunk of metal to the fly wheel to get it externally balanced 

 

60-degrees is the angle between the two banks of cylinders, it has nothing to do with the bell housing. But, yes, the 2.8L, 3.1L and 3.4L are all based on the same 60-degree block design.

The GM 4.3L is a 90-dgree design, which is why those engines are so much wider.