I’ve got my engine fully taken apart, inspecting the bearings at 57k miles. Nothing had failed, I’m just transferring some of the internals on a 1988 v6.
I hear about the v6 getting rod knock a *lot*. Is this problem mitigated somewhat in the 1988 version since the crank is balanced? What can I do other than double check clearances to make sure this doesn’t happen.
From what I know the rod knock is mostly from a poorly designed oiling system, combined with higher rpms. The oiling channels are built into the block, so the most you can do to help that is a higher volume oil pump. You can also replace all the bearings and that will be beneficial. I think the oiling problem is that the camshaft has priority, and it's bearings wear out and gush oil, then very little oil is left over for the crank, and even less for the rods, give it some rpm, and knock knock knock.
Newer 3rd gen 60* v6s like the 3100, 3400, 3500 have mains priority oiling, the 1.5 gen engines (iron head firebird 3.4, 3.1 and the 88 Fiero 2.8 I think) have better oiling and are much more reliable, but they aren't as good as the 3rd gen ones, I think they still have cam priority.
[This message has been edited by 1985 Fiero GT (edited 03-08-2025).]
It's not uncommon for a well maintained 2.8 to get 150,000 miles .
Most wear happens at startup and driving before the engine is up to temperature. Always let the car warm up before driving, even 2 or 3 minutes will make a huge difference in engine life.
Sustained medium rpm at highway speeds (2600-3400 rpm) should not be an issue.
Over revving above 5000 is not good, the engine is out of its power band by then, 4600 rpm shifts will keep it in the power band.
Just because it looks like a racecar doesn't mean you can rev it like a racecar.
I beat the crap out of my 86 2.8 SE, but I didn't overrev it. It ran very well at 135,000 miles but the car dissolved around it . Teardown of the engine showed no noticable wear to the internals.
My son's 2.8 is going strong at 280,000 plus miles.
[This message has been edited by olejoedad (edited 03-08-2025).]
Newer 3rd gen 60* v6s like the 3100, 3400, 3500 have mains priority oiling, the 1.5 gen engines (iron head firebird 3.4, 3.1 and the 88 Fiero 2.8 I think) have better oiling and are much more reliable, but they aren't as good as the 3rd gen ones, I think they still have cam priority.
I’m switching to the 88 2.8 block, I’ll check out my options for higher capacity pumps. Hopefully it will be enough
I’m switching to the 88 2.8 block, I’ll check out my options for higher capacity pumps. Hopefully it will be enough
Thank you!
Melling has a higher volume pump that pumps an additional 20%.
I'd say that the rod knock thing is not really a huge issue... it's just that the engine isn't overly forgiving if you run it low on oil or overheat the motor (which was my problem). A well maintained and good-running V6/60 with good oil is going to last a really really long time.
I had a valve lifter come apart on me, and pulled the oil pan to see what was up. I ended up doing a crank bearing replacement with the engine in the car while I had the oil pan off. That was about 10,000 miles ago and it has 125K on it now and runs about as well as it did when I bought it 20 years ago. I am going to make a bearing replacement a regular maintenance item every 100,000 miles. I think the engine will last a very long time!
Originally posted by olejoedad: Over revving above 5000 is not good, the engine is out of its power band by then, 4600 rpm shifts will keep it in the power band.
Torque is more important in the power band that horsepower, I pushed the envelope when I suggested 4600 rpm. 4000 rpm is a better redline. Even though an engine will rev that high, it doesn't mean the higher rpm shifts will enable quicker acceleration, especially with an 85 V6 mated to the 4 speed transmission.
[This message has been edited by olejoedad (edited 03-09-2025).]
At any given speed, selecting the gear that maximizes whp maximizes vehicle acceleration.
If your shift RPM is too high, then you are spinning the engine for too long where it is not breathing.
If your shift RPM is too low, then your RPM after the shift will be too low, where the engine is not powerful.
If your shift RPM is optimal (for acceleration), then the engine will generate the same horsepower before and after the shift.
From the chart I linked to, and assuming M17 gearing, these are the optimal shift points for acceleration:
1-2 shift: 5100 -> 3000 RPM, 82 whp before and after the shift 2-3 shift: 5000 -> 3108 RPM, 88 whp before and after the shift 3-4 shift: 4900 -> 3200 RPM, 90 whp before and after the shift
4000 or 4600 RPM as shift points are fine if you want to maximize engine longevity, but you will be missing out on acceleration, at least with an engine that behaves like in the graph I linked to.
