The Dark Side of Volvo's Excellent V8
Not many people know that at one point, Volvo offered a V8 in a select few of their vehicles. It's a wonderfully powerful and smooth engine that has ample torque, spins fast with a high redline, and has an amazing exhaust note once uncorked with an aftermarket exhaust.
The official designation for Volvo's V8 engine is the B8444S, broken down into "Bensin (Gasoline) 8-cylinder 4.4 liter with 4-valves per cylinder that has "suction", meaning that it's naturally aspirated.
The B8444S was first developed by Yamaha Japan in 2005 for Volvo. Mated to an Aisin Seiki 6-speed transmission and Swedish Haldex AWD system, the B8444S was known for quality and reliability (or so people thought). The engine made 311 horsepower and 325 foot pounds of torque, respectable figures at the time.
Interestingly, the engine made another appearance in the Noble M600, although it was heavily modified with two turbochargers and custom internals that allowed it to make 650 horsepower, more than double its original power output!
Traditionally, the inline 5 cylinder engine found in most Volvos has a 90° split. All modern Volvo cars have transverse engine setups because it creates a large crumple zone and allows just enough room for a compact front-wheel drivetrain. To fit a 4.4L V8 into an engine bay designed for an inline 5, the engine has an unconventional 60° split instead of the usual 90° split.
The downside of the 60° split is that it makes the engine difficult to balance and doesn't feel as smooth as a traditional 90° V8 on acceleration. To compensate, Volvo designed the engine with a balance shaft driven by the timing chain.
This balance shaft sits in the valley of the engine, the space between the two cylinder banks. Ultimately, this placement of the balance shaft became the Achilles heel of the B8444S.
Balance Shaft Failure
For some reason, half of the sealed bearing that supports the balance shaft is exposed to the environment. This became an issue in the B8444S as there is a small depression in the block right below where the exposed side of the bearing is.
What does this mean? Well, if you're the type of car owner who cleans your engine bay with a hose, water can and will collect within that little depression, seep into the bearing, and destroy it over time. Consequently, the balance shaft will then begin to rattle and slowly eat away at the mount point on the opposite side where the timing chain is.
Eventually, the sprocket that drives the balance shaft will wear out, the chain will slacken, and the valve train will jump timing. The resulting noise from when the pistons meet the valves in their sudden newfound embrace sounds exactly like your checking account being emptied - XC90 owners have reported quotes as high as $15,000 to get their engine rebuilt out of warranty.
In most cars, the the cylinder head can usually be removed with the engine still in the car. However, in the XC90 and S80, this isn't possible due to the transverse setup of the massive V8. While some people have done it with some coaxing of the front radiator support and engine mount maneuvering, Volvo specifies that the engine has to be removed to remove the cylinder head as per their service bulletin.
When you consider the high labor cost of removing the engine just to remove the cylinder head, expensive parts for a low production run engine, and the cost to refurbish the valve train, it's easy to see why it's still obscenely expensive to repair this engine and why most owners opt to total the car instead of going through the costly repairs.
If you own a 2007-2010 Volvo S80 or 2005-2011 Volvo XC90 equipped with the B8444S, do yourself and your wallet a favor and be careful cleaning the engine bay. Don't use a hose under the hood; instead, wipe down the engine cover with a damp microfiber and never spray water directly at the engine or accessory components. Later models of this engine - namely, the 2006+ models with engine serial number 6833+, have an improved design in the engine block with a hole drilled into it depression to allow water drainage and prevent bearing failure.
When the defect was discovered, a recall notice was put out by Volvo to correct the problem. If you're not sure if your recall was done, call your local Volvo dealer with your VIN ready to confirm. If the recall was never done, get your engine inspected as soon as possible!
Written By: Andrew Peng
Andrew is an aerospace engineer and car fanatic that enjoys working on his garage of Volvos and Subarus. When he’s not busy attending car meets and shows or taking things apart, he enjoys driving his cars and finding interesting new ways to break them. He can be reached via his personal website at http://andrewpeng.net, Facebook, Google+, Instagram, or Twitter.