Outback H6 Aluminum Crankshaft

[G.R. Aydelotte]

Well, I thought I had my wife convinced of an 05 outback, but she
drove a 2001 LL Bean H6, and she likes it. I've been reading on these
engines and came across a reference from a Subaru site that this
engine has an aluminum crankshaft. Is this good, bad or indifferent? I
did notice it had a timing chain vs belt. Engine is plenty powerful
for me, and the leather interior doesn't hurt etc.

Gregg

 

[Jim Stewart]

Well, I thought I had my wife convinced of an 05 outback, but she
drove a 2001 LL Bean H6, and she likes it. I've been reading on these
engines and came across a reference from a Subaru site that this
engine has an aluminum crankshaft. Is this good, bad or indifferent? I
did notice it had a timing chain vs belt. Engine is plenty powerful
for me, and the leather interior doesn't hurt etc.

In my humble opinion, the timing chain is a good thing.

I have never in my life heard of an AL crankshaft
in *any* internal combustion engine. I would have
to seriously doubt the veracity of this data. Find
me a link.

 

[Jim Stewart]

Aluminum crank pulley maybe? but then, not with a timing *chain*...
Which, by the way isn't infallible either. Plus, it adds mass, sort of like a
flywheel. Isn't that why they put a timing *belt* into the Lamborghini Diablo?

There's really nothing wrong with either
one. I'd just give a chain a slight
preference over a belt because the
chain does not have a changeout schedule.

As the the crankshaft, I'm guessing they
meant crankcase.

 

[Florian Feuser /FFF/]

In my humble opinion, the timing chain is a good thing.

I have never in my life heard of an AL crankshaft
in *any* internal combustion engine. I would have
to seriously doubt the veracity of this data. Find
me a link.

Aluminum crank pulley maybe? but then, not with a timing *chain*...
Which, by the way isn't infallible either. Plus, it adds mass, sort of like a
flywheel. Isn't that why they put a timing *belt* into the Lamborghini Diablo?

florian

 

[oothlagre]

Not just that, but it adds to engine noise as well. True, chains are not
indestructible. The Nissan Sentra 4cyl. models have a chain that goes out
around 100k. My mechanic said labor for timing chain on that model is 13
hours. Motor swap is only 7.........

Henry

 

[Rick Courtright]

engines and came across a reference from a Subaru site that this
engine has an aluminum crankshaft. Is this good, bad or indifferent? I
did notice it had a timing chain vs belt. Engine is plenty powerful

Aluminum crankshaft? Not saying it's not possible, but I've never seen
or heard of one. Sounds like a recipe for short life if true. Cranks
experience a lot of flex, and aluminum's not the best material for that
type of app. Aluminum "crankcase" as someone suggested sounds more like
it.

On timing chains--properly designed and lubricated, chains should be
much longer lived than belts. Poorly designed (particularly in the
lubrication department) they'll fail early like the Nissan example. BTW,
100k on a chain is absolutely criminal in my book--they should be good
for double that or more. Sounds like a lube problem?

Subaru's timing belt life has always seemed a bit short to me, but my
first experience with timing belts, on the first water-cooled VWs, might
have spoiled me. ISTR seeing something about steel cord in the original
VW belts. I only know there wasn't a recommended change interval in the
book at the time, and I got 190k miles on one of mine. Even if I had to
change a belt, it was only a 30 minute job, not the exercise my Subie
belts are. My guess is Subie went with a chain on the H6 cuz of the
longevity issue?

Rick

 

[G.R. Aydelotte]

In my humble opinion, the timing chain is a good thing.

I have never in my life heard of an AL crankshaft
in *any* internal combustion engine. I would have
to seriously doubt the veracity of this data. Find
me a link.

Well, I hadn't either; I have misread the specs
athttp://www.cars101.com/outback2001.html which say aluminum
crankcase not crankshaft. My apologies, I'll double check next time.

Gregg

 

[Jim Stewart]

VW belts. I only know there wasn't a recommended change interval in the
book at the time, and I got 190k miles on one of mine. Even if I had to
change a belt, it was only a 30 minute job, not the exercise my Subie
belts are. My guess is Subie went with a chain on the H6 cuz of the
longevity issue?

I'm just speculating here.

If you look at the front of the H6, you can see that they
were able to shave at least an inch, maybe 2 off of the
overall length of the engine by going to a chain. I suspect
that this was a *big deal* to get the engine to fit. They
would have probably had to use a wider belt to handle the
load of 2 extra cylinders. I suspect that when they looked
at the big picture of shortening the engine, removing the
scheduled replacement and loosing 4 potentially leaky camshaft
seals the chain started to look pretty good.

 

[oothlagre]

Well, in defense of Subaru there are models with shall we say whimpier
timing belts. My brother has a '96 Hyundai and the change interval on those
is 60,000 miles mandatory. They can break within 10,000 or so of that limit
and bend the valves from here to never. I looked at one once that needed and
engine because of that very issue. I called a dealer service department to
see what was involved and he gave me the rundown on it.

So, 105k on a Subie looks better to me. In fact, my dad just got a '95
Impreza with 150k and no belt change yet. I plan on doing that one this
weekend.

Henry

 

[Skweezieweezie]

The H-6 uses TWO chains, slightly offset.
Passenger side driven directly by the crank,
Driver's side from an idler pulley driven from
the passenger side chain.

 

[John M.]

Well, I thought I had my wife convinced of an 05 outback, but she
drove a 2001 LL Bean H6, and she likes it. I've been reading on these
engines and came across a reference from a Subaru site that this
engine has an aluminum crankshaft. Is this good, bad or indifferent? I
did notice it had a timing chain vs belt. Engine is plenty powerful
for me, and the leather interior doesn't hurt etc.

To some of the other posts I'll add this:
1 - The chain definitely was a factor in reducing the length of the engine.
2 - The chains are designed to last the life of the engine, given that
proper engine oil maintenance happens.
3 - Their are 59 (!) bolts of four different lengths that attach the front
chain cover to the rear. It indeed would be a big job to replace the chains.
Of more concern would be any water pump/oil pump maintenance that might need
to occur. Though it looks as if only the RH chain would need to be loosened
(?) to get the pump out, I would dread removing all of those bolts and
getting them back in the right spots.
4 - There are oil ports that spray engine oil directly on each chain to
ensure it receives the proper lubrication.
5 - The LH chain has 148 links, the RH 134.
6 - The oil pump is driven from the RH chain, as is the water pump
7 - I don't know how the noise will work out in the long run, but I know the
cases were designed to minimize chain noise. I haven't notices any
difference from the belt driving cams.
8 - Overall, I would not feel very comfortable doing a chain replacement...
I've had no problems doing belt replacements. I'm counting on the long life,
and believe that will be the case as with all-things-Subaru.
John

 

[oothlagre]

I hope the water pump doesn't leak into the oil if it fails. That's an awful
lot of labor should one of the pumps fail. Has anyone actually had a water
pump fail on a Subaru? I am going to replace mine when I do my timing belt.

Henry

 

[John M.]

I hope the water pump doesn't leak into the oil if it fails. That's an awful
lot of labor should one of the pumps fail. Has anyone actually had a water
pump fail on a Subaru? I am going to replace mine when I do my timing belt.

Henry,
You are right; I guess it would be possible to get water into the oil... not
good.
I have never had a water pump go out (a PS pump, but not water pump).
However, I did replace one when I had the opportunity during a timing belt
change.
John

 

[Rick Courtright]

lot of labor should one of the pumps fail. Has anyone actually had a water
pump fail on a Subaru? I am going to replace mine when I do my timing belt.

Develop a slight leak? Yes. Outright fail (bearing seizure, impeller
lets go with fan digging into radiator type stuff)? No.

Rick