Rod knock...

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May 1, 2001 | 02:45 PM

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Rod knock...

I've seen a few interesting posts on "rod knock" and whether it's rod bearings or maybe some vacuum pump knock. I have an ur-quattro that has a knock that appears to be coming from #1 cylinder and gradually silences as the motor warms up. This sounds like rod bearings to me, but I was curious if what else I could check in case it's not.
Thanks,
dB

May 1, 2001 | 09:04 PM

Evilclown

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Could be several things....

For starters, check the vacuum pump per the directions posted earlier. If that doesn't solve it, go ahead and change the lifters, if it's not that, they'll be replaced and you won't have to worry about them, at least. If it does turn out to be the rod bearings, trust the voice of experience, fix it now! If the lifters and vacuum pump don't fix it, park it until you can get the rod bearings done. Trolling your engine bay with a magnet looking for sray bits of block isn't nearly as much fun as it sounds.

May 1, 2001 | 10:03 PM

®ob

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If it's an Ur-Q most likely it is the cracked manifold

Those crack all the time. See if your car also has the manifold brace. Some had it, some didn't. The ones without seemed to crack more often. So if it ends up being the manifold, see if you can get the brace

May 2, 2001 | 07:35 AM

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I've heard about cracked manifolds, but it sure doesn't sound like it. Sounds more like it...

is coming from inside the block.

May 2, 2001 | 07:39 AM

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I bet it's a rod, but I'll check the vacuum pump and see if I get lucky. This is a WX motor and

has solid lifters. I don't think solid lifters make the sound that hydraulic lifters do even if they needed adjusting, would they?

How hard is it do change the bearings out? Can it be done without removing the engine? (i.e.: if I had to remove the engine I might as well update it with an MC.) I suppose you also have to get the right size bearings and do all that crazy measuring and stuff???

Thanks,
dB

May 2, 2001 | 09:34 AM

Evilclown

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A good way to save yourself all the measurement....

...is to pull the crank and have it turned. When they turn it, the machine shop will mark the measurement on it and you can go buy the rods and mains that they mark. It's a bit extra work, but it really is simpler than trying to get an accurate measurement of a worn crank. It can be done with the engine still in the car, you need to remove the head and the oil pan, and knock the pistons out from the top of the block, which means you'll need new rings, too. For what it costs for bottom-end parts on these things, you probably are better off finding an MC engine that's been run recently and freshening it up and swapping it in. I did the bearing replacement in my Scirocco, took about 12 hours total, and I later swapped in a new motor/trans, which took about the same amount of time. I haven't yet pulled a 5-cyl motor, though I'm about to(see previous posts), so I don't know yet how much work it is.