1996 850 wagon

Cincyken · Post by **Cincyken** » 23 Feb 2010, 14:03

i bought a 1996 850 wagon that did not run for $500 (no compression on on cylinders 4 &5.
Pulled the head, found a broken head bolt between cylinders 1&2 and the exhaust valves for 4 & 5 burnt ( 1 in each combustion chamber, not both). I am sure this is what caused the lack of compression.
The car has 176,000 miles on it and there is no cylinder wall ridge and the original factory cross hatching is still visible (truly amazing for 176,000 miles). Normally burnt exhaust valves means the engine was running too lean(vacuum leak probably),but why 4 & 5? Their fuel/air ratio should be the same as the other 3. Right?

Post by **Ozark Lee** » 23 Feb 2010, 14:15

If the car is a turbo burned exhaust valves usually mean that the car has been running on regular gasoline rather than premium. The N/A models don't normally care but the turbos definitely do. As far as 4 & 5 going first it is likely just the exhaust gas routing through the exhaust manifold.

...Lee

Zeff · Post by **Zeff** » 24 Feb 2010, 11:06

...i'm gonna agree with Mr. Ozark Lee on this one...

Zeff

Cincyken · Post by **Cincyken** » 24 Feb 2010, 14:56

it's a non-turbo.
Exhaust gas routing thru the exhaust manifold? It's a standard head and manifold. Why would i have a problem there?
I guess my concern is that once it is back together (this weekend), and i have fixed the vacuum leaks on the oil trap, anything else i need to do to prevent two more burnt valves in the future? ( i hate pulling heads on dual overhead cam engines).

Post by **Ozark Lee** » 24 Feb 2010, 15:03

I wasn't sure what beast we were dealing with here. The exhaust manifold is quite different on the turbo cars with the runs before the turbo being quite shorter as you go from cylinder 5 to cylinder 1.

As far as why goes, who knows? For some reason my Jet Skis always eat the number 1 cylinder when my kids run them out of oil.

...Lee