2.8L V6: Hi-Mileage Life Expectancy and 'Weaknesse

[pgtr]

I've got an '84 2.8L V6 w/ 175k miles and (knock on wood) it seems to be running quite well... It's dependably driven daily - more hwy than city. It gets 26-29mpg. Change oil (10W30) about every 6-7k.

I'm wondering what I should keep an eye out for as far as wear/age related/mechanical issues as it goes beyond 25 years and 200k miles hopefully...?

Timing chain? Other?

I appreciate any input so I might do some preventative maintenance or have an idea what to be on the look out for in the future.

Thanks!

[Superdave]

my old 2.8 lost the oil pump at about 225K miles. Timing chain after 100K is a good idea. Intake gaskets/head gaskets/valve seals will all start to act up soon.

From my expierance once you take a wrench to a hi-mileage engine you are opening up a can of worms. If you are at 175K now i'd leave it alone till something goes wrong.. lol

[Canyonero]

I have two Troopers w/ 2.8L here that are down at about 200k. One had a LIM gasket failure and picked up a bad knock, the other had a burnt valve and cracked head (I'm sure one came before the other, I bought it that way).

My other Trooper 2.8 had 162k and was still running good. I'm about to swap it into one of the above Troopers (I had pulled it in favor of a 3.4L).

Seems these engines will clear 200k in most cases. YMMV after that. I agree with Superdave. Just keep driving it. Keep a closer eye on the vitals though - oil pressure and oil quality. If the oil gets higher and looks like a milkshake, you better get the tools out before some damage is done.

[3100 MPFI]

The 2.8 in my 1988 Cutlass Supreme had 313,368 miles on it when I pulled it out. When I pulled it out, it was because the transmission was going out, and I had finally finished building my 3100, so I felt it was time to do the swap. Yes, the engine was tired, but it still ran, and was reliable.

IF you open it up, you are potentially opening a can of worms, but I recommend doing it anyways. Under the lower intake on mine had almost totally filled up with carbon build up, and I was afraid that if I didn't do something soon, the failure would be catestropic.

If you feel like opening it up, I would do a complete gaskets set from the lower intake set upwards, and then replace the timing chain. If you do it all at once, you might want to check your camshaft for wear, and if it looks bad, replace your cam. I replaced the cam and timing chain set in my 2.8 when I did the lower intake, and it really helped perk it up some.

[torq455]

A timing chain at 100K??! Wow! I have 151K with a "few" hard runs. I'm not worried about the chain. If it had a bigger non-roller cam, it would have been changed a while ago. These engines really don't eat chains, just lower intake gaskets. Just keep an eye on that part of the engine. If it seeps that's normal, but if things are getting wet (more so at the top of the tranny) then it's time for a gasket. I have always used Mobil 5w-30. 10-30 is a little thicker when cold and has potential to cost you a slight mileage drop.

[pgtr]

Thanks everyone for the responses!

Lower intake manifold gasket seems to get mentioned a lot. Silly question but what is a 'lower' intake manifold gasket. Are you referring to the gaskets that mate between the intake manifold and heads?

Thanks for the other tips. This particular Firebird came w/ the factory guage option though I wouldn't consider them all that accurate. Oil pressure and water temp remain quite steady and predictable at least.

I use 10W30 and change between 6-7k (7500 recommended by owner's manual). Typically the oil is just 1 qt low by about 7k. The valve cover gaskets seep a little and some oil eventually drips onto the exhaust and burns off.

Car gets good gas mileage 25 to 27 and on long distance trips closer to 29mpg (700R4 tranny w/ OD). Other than having to accelerate at WOT to get on one specific hwy in the mornings only - it spends almost all it's time at cruise a bit over 2000 rpms or so. Not a lot of city driving, idling and rarely WOT.

Thanks again for the tips. At some point if/when I were to do the chain - I might also consider renewing the intake manifold gaskets too.

[bszopi]

Components and gaskets in order:

Throttle Body
TB gasket
Upper intake manifold
Upper intake manifold gasket
Lower intake manifold
Lower intake manifold gasket
Cylinder head
Head gasket
Block

[pgtr]

Thanks

FYI no throttle body - It's a 1984 2.8L longitudinal V6 in a Pontiac Firebird with Rochester VaraJet II carburetor. There is of course a gasket-spacer between the throttle plate and the intake.