Why a 3.2 over a 3.0? Plus Many Questions.

[Macgyver]

I get the obvious displacement, but are the 3.2's better? Do they have better oiling systems? Do they share the same rod bearing issues? Do they hold up better simply because they spent their life behind an automatic and likely suffered less abuse? Has anyone cross-drilled the crank to help with the oiling issues? Why do the rod bearings starve? Can the oil pump/oil galleys be ported or smoothed? Has anyone documented a full rebuild?

 

[Racer X]

I get the obvious displacement, but are the 3.2's better?

The torque is a nice bonus.

Do they have better oiling systems?

http://www.shoforum.com/search.php

Do they share the same rod bearing issues?

http://www.shoforum.com/search.php

Do they hold up better simply because they spent their life behind an automatic and likely suffered less abuse?

They're no more or less durable than the 3.0L, save for the oil pump differences. They do tend to see as easier life when placed behind an autotragic.

Has anyone cross-drilled the crank to help with the oiling issues?

I'm sure someone may have, personally I can't say for sure who has.

Why do the rod bearings starve?

http://www.shoforum.com/search.php

Can the oil pump/oil galleys be ported or smoothed?

Yes I'd imagine so, however these oil pumps flow remarkably well, so it's not a common practice.

Has anyone documented a full rebuild?

A few people have. They can be found here. http://www.shoforum.com/search.php


I know most of those replies are sort of *******, but 3.2 swaps have been discussed ad nauseum here, a few minutes searching would reveal a wealth of knowledge on the subject.

 

[jimtash]

I'll never go back to a 3.0L. Best part of the 3.2L is the torque. These cars become descent in traffic especially if it's a manual. Less gear shifting and without the lugging.

I highly recommend using the 3.2L injectors and getting a computer tune if you do the conversion.

Using a 3.2L oil pump should take care of the rod bearing issues at least where spinning them is concerned. But only if you keep in mind that the design of the rotating assembly does put strain on the bearings themselves and they do wear quicker than in other engines. Both versions of the pumps are designed for low pressure and high volume but the 3.2 is the one you want because it outflows the 3.0L. And as long as the oil is kept up the rod bearings should wear good. But they will need replacement eventually as merely a preventative maintenance issue.

 

[Macgyver]

Thanks for the reply. I've read about 3.2 swaps, but I'm not really interested in them. I have a good running 3.0 that is loose upon cold start. I'm interested in the root cause of the problems and addressing them. I've read plenty about rod bearing swaps, but I've never read anything about keeping it from happening again.

 

[intimdatr]

Somethings to help is dont lug the engine as much as possible, raise the idle, run good oil, and use 5/30 oil.

 

[jimtash]

The only to do is change the bearings out and keep the oil changed regularly. If you can score a 3.2L oil pump, consider that as well. The rod bearings should be thought of as strictly a maintenance issue. They will not see the mileage that the rest of the components in the engine will.

 

[rubydist]

I am convinced that the rod bearing issue is largely due to quick clutch engagement at low engine rpms. The oil pump is high flow and lower pressure, so the oil pressure at 1500 rpm is not much, and its possible to break down the oil film with a quick clutch engagement. I have yet to see a 3.2 with rod bearings that needed replaced prior to 200k miles, while I have seen 3.0s with under 100k with spun bearings. The slight change is oil pump volume is not likely to make that kind of difference.

 

[AREA 91]

I am convinced that the rod bearing issue is largely due to quick clutch engagement at low engine rpms. The oil pump is high flow and lower pressure, so the oil pressure at 1500 rpm is not much, and its possible to break down the oil film with a quick clutch engagement. I have yet to see a 3.2 with rod bearings that needed replaced prior to 200k miles, while I have seen 3.0s with under 100k with spun bearings. The slight change is oil pump volume is not likely to make that kind of difference.

FWIW I have seen 3.0 and 3.2's with spun bearings under 200K.
It's all about your driving style and mantainance program.

 

[jayro]

I see replacing the bearings on these engines as part of the maintinance due to the age of them. It seems like every family of engines have there "weak points". My 3.0 had the oil changed religously with Castrol 5w30. I did the bearings at 170K during a clutch job. While they had some wear, they were not in bad shape.

I would only switch to a 3.2 oil pump if I was rebuilding the engine and only then because it's easy to do. And if you are rebuilding, why not use a 3.2 block and rotating assembly?

If you are really worried about oil pressure, you can always install a guage. Bumping the idle could also keep the pressure a little higher.