2.8 rod bearing replacement (Page 2/2)
Nytfury JUN 27, 02:46 AM

quote
Originally posted by fredtoast:
It is not necessary unless there is a problem. Since you have one I would try this before tearing the engine apart to replace a bearing.




The work of tearing at the engine to get to the bearings is not the problem, I want to do a fix that will last and not fail immediately. Which as of now no one has given any useful insight towards.
Patrick JUN 27, 02:54 AM

quote
Originally posted by Nytfury:

Which as of now no one has given any useful insight towards.



Several of us were first trying to determine whether or not the bearings actually required replacement... but if you're gung-ho determined to change the bearings, just go ahead and do it.
Nytfury JUN 27, 03:02 AM

quote
Originally posted by Patrick:

Several of us were first trying to determine whether or not the bearings actually required replacement... but if you're gung-ho determined to change the bearings, just go ahead and do it.



yes, i do understand, however, the engine has over 130,000 miles on it and dubious maintenance history so I figured a bearing replacement would be quite beneficial, especially given their seemed propensity to fail. I did see a couple of people saying that replacing the bearings and installing a high-volume oil pump could be detrimental to the engine, so that was my main concern.
82-T/A [At Work] JUN 27, 08:38 AM

quote
Originally posted by Nytfury:


yes, i do understand, however, the engine has over 130,000 miles on it and dubious maintenance history so I figured a bearing replacement would be quite beneficial, especially given their seemed propensity to fail. I did see a couple of people saying that replacing the bearings and installing a high-volume oil pump could be detrimental to the engine, so that was my main concern.




People generally do not recommend replacing the rod bearings - by themselves - simply because the amount of effort involved in pulling the engine and doing so, kind of negates the benefit. It's kind of like... if you're going to go through that effort, you might as well do everything else. I remember someone on here did that with the car on jack stands... and my God... I can't imagine doing that, even when I was 19.

You'll want to remove the engine (my opinion) to replace those bearings, and then while you're doing it, you might as well also replace the main bearings and piston rings, and then hone the cyl walls as well. I'm planning on doing a "garage" engine rebuild soon myself, and what I've been reading essentially states (mostly common sense). That is... you don't generally need to have an engine machined when you replace the bearings. The bearings will wear out over time, and that may ALSO result in the surface area of the contacting component (crank, rod, etc.) also wearing down somewhat as well. If you replace the bearings in-kind, meaning the same size as what was in there previously, it's only going to improve your oil pressure and the engine life. To clarify, that means if your bearings say 0.00 STD or whatever, then you replace them with the same kind. Now, that won't correct any wear that actually exists on the crank or the rod itself. So when you take it to a machine shop, they'll size it, grind down if necessary so that they can go to the next bearing size. But you can still get away with replacing the existing bearings with the correct replacements that your engine is already sized for, and that will improve oil pressure.

Keep in mind, on some engines, the bearing sizes are not all the same. I've not personally seen this (done very little work here myself, but have been reading a lot)... sometimes engine builders (from the factory) will have standard bearing sizes for all but one piston (or two, or three, etc.), and they'll have a .010 or whatever it is increase... simply because that's how it ended up getting machined.

It's a lot of work to rebuild an engine, and a lot of cost. You might be better off just buying a rebuilt 3.4L V6/60 that basically drops right in. You can get a "long block" where everything you already have bolts up to it... you just need larger injectors (17# instead of 15#). And you have to drill/tap one hole for the starter. I just bought a 3.4V6/60 for $2,400 bucks shipped.
Nytfury JUN 28, 10:33 AM

quote
Originally posted by 82-T/A [At Work]:
People generally do not recommend replacing the rod bearings - by themselves - simply because the amount of effort involved in pulling the engine and doing so, kind of negates the benefit. It's kind of like... if you're going to go through that effort, you might as well do everything else. I remember someone on here did that with the car on jack stands... and my God... I can't imagine doing that, even when I was 19.

You'll want to remove the engine (my opinion) to replace those bearings, and then while you're doing it, you might as well also replace the main bearings and piston rings, and then hone the cyl walls as well. I'm planning on doing a "garage" engine rebuild soon myself, and what I've been reading essentially states (mostly common sense). That is... you don't generally need to have an engine machined when you replace the bearings. The bearings will wear out over time, and that may ALSO result in the surface area of the contacting component (crank, rod, etc.) also wearing down somewhat as well. If you replace the bearings in-kind, meaning the same size as what was in there previously, it's only going to improve your oil pressure and the engine life. To clarify, that means if your bearings say 0.00 STD or whatever, then you replace them with the same kind. Now, that won't correct any wear that actually exists on the crank or the rod itself. So when you take it to a machine shop, they'll size it, grind down if necessary so that they can go to the next bearing size. But you can still get away with replacing the existing bearings with the correct replacements that your engine is already sized for, and that will improve oil pressure.

Keep in mind, on some engines, the bearing sizes are not all the same. I've not personally seen this (done very little work here myself, but have been reading a lot)... sometimes engine builders (from the factory) will have standard bearing sizes for all but one piston (or two, or three, etc.), and they'll have a .010 or whatever it is increase... simply because that's how it ended up getting machined.

It's a lot of work to rebuild an engine, and a lot of cost. You might be better off just buying a rebuilt 3.4L V6/60 that basically drops right in. You can get a "long block" where everything you already have bolts up to it... you just need larger injectors (17# instead of 15#). And you have to drill/tap one hole for the starter. I just bought a 3.4V6/60 for $2,400 bucks shipped.



I don't plan to take the engine out, I've done worse from underneath a car (I'm 18). I still have good compression on all my cylinders and not much visible sidewall wear, so I don't feel it super necessary to replace the rings. I'm really only looking to get maybe another year/15-20 thousand miles out of it, so a full rebuild seems somewhat pointless. And I don't think that changing the engine is economical at all, a better oil pump + rod and crank bearings is only a couple hundred dollars. Next summer I'm gonna try and drop a Volvo T5 in her, but I don't have time this summer, so I just want the engine to last until then. Thanks for the input and info. Also with the different bearing sizes from the factory, I believe that's known as select fit bearings, I've worked on a honda engine with select fit bearings, and it was stamped onto the crank which bearings were needed on which journals. I don't believe the 2.8 does this (I could be wrong obviously)
82-T/A [At Work] JUN 28, 10:55 AM

quote
Originally posted by Nytfury:

I don't plan to take the engine out, I've done worse from underneath a car (I'm 18). I still have good compression on all my cylinders and not much visible sidewall wear, so I don't feel it super necessary to replace the rings. I'm really only looking to get maybe another year/15-20 thousand miles out of it, so a full rebuild seems somewhat pointless. And I don't think that changing the engine is economical at all, a better oil pump + rod and crank bearings is only a couple hundred dollars. Next summer I'm gonna try and drop a Volvo T5 in her, but I don't have time this summer, so I just want the engine to last until then. Thanks for the input and info. Also with the different bearing sizes from the factory, I believe that's known as select fit bearings, I've worked on a honda engine with select fit bearings, and it was stamped onto the crank which bearings were needed on which journals. I don't believe the 2.8 does this (I could be wrong obviously)



The size rating of the bearings will actually be stamped into the bearings themselves. They're stamped or laser-etched on the underside (obviously not surface-side). See image below as an example. The bearings are made specifically for the engine that you're going to be putting them into, so they're generally all going to be STD. It's not common, but does happen where a particular crank journal or rod bearing has a different size. It becomes less and less common as years go on. I've never seen one in a Fiero V6, but have seen it on SBCs and my big block Olds. You will probably be fine buying STD size rod bearings... I only mention it as something you'll want to consider in case you encounter it.

I think a high-pressure oil pump will be fine. It can cause issues mostly if you have bad rings (which I know you said you do not), because you'll have more blow-by. Other issues if you have an external cooler and blowing the oil lines (which you do not have). So you'd be perfectly fine doing it.



quote
Originally posted by Nytfury:
(I'm 18).



Haha... I only quote this because I've literally been there before. Like, it feels like it was yesterday. And I've been on Pennock's since 1999 when I was ~19-20 under a different account. I think if you search, you will actually find a post EXACTLY like yours from me, which is hilarious because it's like I'm going back in time reading this post. If you're me from the past, in the future, let me give you a warning... do not use the Coltec Industries "High Flow Performance" water pump with the plastic impeller, ask me how I know!!!

All joking aside, I think replacing the crank rod bearings are fine... but probably a lot of effort for something relatively unnecessary. Your oil pressure isn't horrible, it's just not great. I'd recommend keeping the oil at 30 weight, but I would switch to full synthetic. Regular oils don't have any of the things they used to have in it back in the 70s... or even from when I started working on cars in the late 90s. So normal oil does in fact not inhibit wear as much as much as it used to. Synthetic oil, if changed at normal intervals and properly filtered... basically completely eliminates engine wear with all other things being good (meaning no overheating or whatever). Most engine wear occurs at engine start-up when the oil is cold and less viscous. With synthetic oils, it has nearly the exact same properties when cold as it does when warm, so it significantly reduces wear at start-up.

If like me at 18... you didn't have a whole lot of cash, but just wanted to do something because this was your hobby and enjoyed doing it, then go replace those bearings. But if you've got a **** ton of stuff to do... like college assignments, or banging that girl that you keep forgetting to call... then I think there's more important things you should be doing than replacing bearings that don't really need to be replaced.


[This message has been edited by 82-T/A [At Work] (edited 06-28-2023).]

olejoedad JUN 28, 12:07 PM
New bearings OR high volume pump, but not both.

HV pumps were introduced in the days when bearing wear occured before 100K miles, they were a band aid to extent the service life of the engine.
Notorio JUN 30, 09:02 PM

quote
Originally posted by Nytfury:


I don't plan to take the engine out, I've done worse from underneath a car (I'm 18) ...



Fury, I recently replaced my rod bearings and crank bearings from underneath, putting in stock sizes, figuring this had to be better than leaving the 100K units in place. I was able to at least inspect all the journals (looked great, no scratches, etc.) and the bearings as they came out (very obviously, highly worn). This refresh completely cured my low oil pressure issue. It's not fun but very doable. You have to undo the motor mounts (I replaced those too) and jack the engine up and block it up a few inches, so you can get the oil pan off.

[This message has been edited by Notorio (edited 07-01-2023).]

Will JUL 01, 01:12 PM
I have replaced 2.8 rod bearings with the engine in the car. Drop the exhaust, remove the engine mount bracket and block the crank pulley up on the cradle rail with a 4x4, then you can get the oil pan off. It's not fun, but doable.

15 *actual* psi at idle is fine. Not sure what rpm it's turning to show 30 psi. Just because the gauge shows that doesn't mean that's what the pressure actually is. Fiero gauges (and every gauge GM built in the '80's) are notoriously inaccurate.

I had a Pontiac 6000 with the 3.1 Gen 2 engine. It was so worn that it would light the oil pressure light at heat soaked idle. I installed a high volume oil pump, but kept the stock regulator spring. That moved enough oil to keep the pressure up at idle, even heat soaked in traffic with the AC on.