4.6is vs 4.8is Common Issues - which is worst?
 

I'm fairly new here, but been a lurker for awhile. I'm finally searching seriously for an X5 and conflicted between a 4.6is/4.8is.

no doubt, both will require big ticket items after purchase. But which is worse? The coolant pipe/valve seals/levers of the 4.8is or the timing chain guides of the 4.6is?

It sounds inevitable for the tc guides on the 4.6is, and coolant pipe on 4.8s... but valve seals, is that certain?

I looked at the diy thread of the tcg, and that does not look fun. While I am a diy'er, that looks pretty tedious. On the other hand, valve seal replacement is big $ from what im reading. Any inputs on what actual costs might be from an indy? I dare not ask my indy because he'll just talk me out of either or instill fear.

I was initially looking for lower mileage cars, but now im thinking of pivoting to higher mileage with big ticket items already done. I did find an 4.8is with valve seals already replaced, same goes for a 4.6is with tcg already done. however they are 130k plus cars.

I'd say 4.6is, beyond the tranny and TC guides it's a solid vehicle. 4.8 tends to have a few more issues that people talk about. The valve seals are a big issue with the 4.8 and from reading what people say it's an absolute expensive PITA. Mileage is a moot point on these really boils down to PM items.

I personally prefer the 4.6is because of the relative simplicity of the M62tu compared to the mess that is the N62. Chain guides might be tedious but they're easier than replacing 32 valve stem seals. If you try to do the valve stem seal job with the engine in place it's horrible, and if you pull the engine to do the valve stem seals then it adds a whole lot of extra labor. You don't get all that much extra power with the 4.8 anyways.

Thanks for the input. Would you consider an 4.8is that had 130k which already had the valve stem seals done?

I would find a 4.6 that has had the timing guides done or a 4.8 that has had the valve seals done. If you can't do most repairs yourself IMO neither is a good choice. 4.8 has newer technology such as the all wheel drive system and trans is more computer controlled (a negative to me) and is 6 speed rather than 5. Lowest mileage, maintenance history, few owners are also important.

All considered, the one that you like how it looks inside and out the best should be your choice. You are taking about a vehicle that is 10-15 years old, stuff is going to wear out or fail. I have had very few problems with my 4.6 (118,000 miles or so) that I bought new but it could just as been otherwise. I believe there are owners of 4.8s, especially if they bought them new, that have had just as great an experience as I have had with my 4.6

That's what I'm thinking. I can wrench, but the TCG looks more involved than I'd want to do. Plus, I don't mind routine maintenance and occasional items. What I don't want is a project car. I already have one of those.

Project car and x5 kind of go hand in hand. Love my 4.6 but would never have it be my daily. It is a labor of love though. I dont mind having to work on it and it has its fair share of small issues Im always needing to address. TCG, tranny and suspenions are all big items on the to do list, but once they are done its a HUGE weight lifted off the mind. Thing is a beast to drive and honestly nothing really compares to it.

Eh, a 4.6 can be a daily just as well as any other old BMW. You just have to do a little bit of preventative maintenance and fix things as they come up instead of letting them get bad.

:iagree:

You may note what I have in my garage... All I drive are V8 BMW's... I have two N62's that I rebuilt the motors completely... The 540i has a different untouched block, but rebuilt heads... And the 4.6is is pretty much the same as I purchased it... Then there is the 2001 that in slowly turning into a RWD 6MT... That will be my daily driver, until I convert a nicer one to replace it...

My vote is for the 4.6is personally... And I know that is really all it is... You might want to borrow versions of both to fully get the experience from both... I hear the 4.8is handles better than the little brother... I have only driven my 4.6is and the 4.4L versions of the N62...

Having done both jobs is the reason I like the 4.6... It can be done in the car with just a minor back ache when I'm done... To do the VSS in the 4.8, I would recommend pulling the heads, if not the entire motor... And rebuilding the heads on the workbench... The kit to do the seals IN the vehicle is, IMHO more of a cost than pulling the motor, but I do my own labor... And since the motor is already out, may as well go thru it and clean it up completely...

Other aspects for both... I prefer the front end of the 4.8is... I prefer the non-electric transfer case of the 4.6is... I absolutely HATE (can I use that word on here?!)... I HATE the 6-speed automatic in the 4.8is (4.4)...

But I love the X5 so much more than my 540i that I am squashing them together and making my X5 more like my 540i... The one BMW should have made, IMHO!!! The RWD is just a by-product of the conversion, but the V8's should have a three pedal 6-speed!!

This is just my two cents... Well, maybe like a dime....

Cheers!!!!

I agree with Danny on this 4.6is can easily be a daily driver but I assure you I addressed all of the maintenance and refresh items that make it as trouble free as can be expected for another 100K miles.