B230 engine only happy with timing ~20deg?

Krampus · Post by **Krampus** » 13 Jan 2013, 22:53

My refurbishment of my '88 240DL wagon continues. I pulled the throttle apart yesterday and cleaned everything (replaced gaskets both where it meets the intake manifold and between the idle air bypass and the throttle) and what a world of difference that made. One thing that I'm noticing though, I have to set the ignition timing well past the 12 degrees the service manuals specify for the engine to run anything resembling smooth. The vacuum gauge I got from harbor freight suggests that I'm in the "late ignition timing" zone if I'm at spec timing, but goes into the green zone if I advance it (of course, not volvo specific, but the engine sounds better in the green). I'm at about 20 degrees or so (jumps around a bit even with the vacuum advance hose disconnected). Is there a common mistake I'm probably making?

I haven't tried taking it on the road yet to see if there's a noticable problem running with the advanced timing. I forgot that the power steering pump is driven off the AC compressor. The AC Compressor is currently sitting on my workbench in pieces.

- Jack

lummert · Post by **lummert** » 14 Jan 2013, 05:56

Maybe the crankshaft pulley has slipped. This would cause incorrect timing when using a timing light.

Krampus · Post by **Krampus** » 14 Jan 2013, 10:53

You mean slipping around the vibration damper on the crankshaft pulley? Hmmm... So the timing marks don't "drift" around like I'd think they probably would if it was slipping intermittently. Is there a way to tell if the inner and outer parts of the pulley are no longer aligned? Should the inner notch line up with the timing mark on the outside of the pulley? I'm wondering if maybe it isn't "jerk slipping" but slowly becoming more and more out of alignment. It's the one that was original to the car, so I'm not going to be surprised if that's the case.

If *is* what's happening, I can probably get away with setting the timing "by ear" and looking a the the readout from the vacuum until I have the cash to spare to get a replacement pulley.

Post by **billofdurham** » 14 Jan 2013, 11:44

The harmonic balancer, otherwise known as the crankshaft pulley, is made up of two metal plates sandwiching a rubber isolator. The expected life of the rubber is 150,000 miles.

A quick check to see if the rubber has given up is to paint a white stripe across the two pulley halves and rev the engine. If one stripe moves out of place the rubber has failed.

Setting the timing by ear will be the more effective way if the balancer is shot.

Bill.

Krampus · Post by **Krampus** » 14 Jan 2013, 12:39

Oh, good idea! I'll give that a try next time I'm messing with it. Any thought on how the notch that lines it up with the crankshaft gear aligns with the timing notch? On mine, the timing mark is offset... actually, probably about 8 degrees now that I think about it.

Krampus · Post by **Krampus** » 22 Feb 2013, 16:46

Something that occured to me when I was (unsuccessfully) scouring a junkyard for a replacement harmonic balancer; The crankshaft spins twice for every turn of the camshaft, correct? I'm pretty sure that when I changed the broken timing belt, I only verified that the timing marks on the camshaft and crankshaft gears lined up wtih the approriate marks on the belt guard. I didn't make sure that the cam and crank were in phase (camshaft pointing upwards when piston #1 is at TDC), so I've got a 50% chance that i did it wrong. Would the engine even start if this were the case? I'm thinking that if it would, maybe my advanced timing isn't because of the harmonic balancer shifting but because the camshaft is out of phase! Thoughts, anyone?