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Knocking Sound


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16 replies to this topic

#1 mikeshoup

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Posted 10 July 2006 - 06:17 PM

So, I proceeded today to change the driveshaft on my 88 GL wagon. Simple enough procedure. Was easy to do. I top off the transmission oil. I looked, the motor oil was about a qt low, just where I wanted it. So I dumped in the can of seafoam I'd been waiting to add (the lifters would present a faint tick every so often...)

Everything's fine. I get to the end of the block before I head back, and I start to hear a knocking sound. I immediately take it back, park it, and turn it off. Check the oil, level's fine. :mad:

Its a really loud knocking sound, and only is present at low RPMs. When I rev above say 1.5k, it silences itself...

What should I do here? I'm at a loss, and frustrated. I'm more worried that I may have a blown engine, and the XT needs work before I can drive it daily (heads need retorquing, its got a coolant leak I need to trace down).

RAWR!

#2 Manarius

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Posted 10 July 2006 - 06:27 PM

Ummm...driveshaft hitting something? Did you rev it up in neutral to guarantee it was coming from the engine bay?

#3 mikeshoup

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Posted 10 July 2006 - 06:27 PM

Ummm...driveshaft hitting something? Did you rev it up in neutral to guarantee it was coming from the engine bay?

Yes, and it matches engine speed, not car speed.

#4 NorthWet

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Posted 10 July 2006 - 07:11 PM

Aggravated the lifter tick? I have had TOD so bad I thought it was a bad rod bearing. What is the oil pressure like? You might want to change the oil filter just in case the Seafoam broke a lot of sludge loose.

#5 mikeshoup

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Posted 10 July 2006 - 07:48 PM

At the suggestion of subyluvr, I made a recording. It gets a little distorted at parts, but it makes out the sound I'm hearing very clear. This was taken above the engine... its quite loud of a knock.

http://mshoup.us/docs/knock.wav

#6 4x4_Welder

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Posted 10 July 2006 - 08:24 PM

Sounds like the black helicoptors have found you-

Seriously, though, change the oil and filter, maybe twice if you do the first one cold.

#7 DrKrazy

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Posted 10 July 2006 - 08:39 PM

Yep sounds like the TOD, get it warm change out the oil and filter...take it for a high spirted highway drive. Bet ya it will stop, I have seen this car run and it wasn't ticking at all (in fact it was running like a top) so guessing the seafoam just knocked some crap loose and got stuck in one of the lifters/passage ways so that lifter isn't pumping up Mike.

#8 85Sub4WD

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Posted 10 July 2006 - 08:58 PM

I may be the only one - but Im thinking connecting rod bearing - that "tick" was a bit low pitched for me - its a bump, not a tick - wheres your oil pressure? - try some fresh oil, filter and sea foam for starters - ticks as Ive heard them dont always go away with revving either - none of the times Ive had a tick it did at least

actually it sounds almost exactly the same as the bad connecting rod bearings in a mercedes engine I just repaired a couple months ago....

#9 fbh

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Posted 10 July 2006 - 09:08 PM

That sounds pretty bad... I don't think it's a lifter tick, unless your heads are made of wood :burnout:

sounds as if something's impacting the block from the inside...

something with the conrods? worn bearing somewhere....?

Definately from the engine, and not the transmission? (take a broomhandle and firmly press it against various parts of the engine, press your ear to the other end, and figure out what part the sound originates from the loudest)

#10 ()__1337_CRAYOLA__()>

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Posted 10 July 2006 - 10:07 PM

(take a broomhandle and firmly press it against various parts of the engine, press your ear to the other end, and figure out what part the sound originates from the loudest)


Hella Old School lol :burnout:

#11 GeneralDisorder

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Posted 10 July 2006 - 10:24 PM

How many of you have *actually* expereinced a subaru rod knock?

I have, and I'll tell you that it's nothing like that - it's MUCH quieter than lifters till about 30 seconds before it blows through the side of the block. It definately made noise, but it was only under load. At idle with no load you couldn't hear it at all. Ran real pretty - that's why almost without exception rod bearing failure results in the block being destroyed - people don't expect that "little noise" to be so important, and just keep driving till it's too late.

I am with the seafoam knocking some junk in the lifter camp - sounds like just a single lifter is really pissed off.

If this were a GM forum - rod knock all the way.

GD

#12 jeffast

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Posted 10 July 2006 - 10:28 PM

How many of you have *actually* expereinced a subaru rod knock?

I have, and I'll tell you that it's nothing like that - it's MUCH quieter than lifters till about 30 seconds before it blows through the side of the block. It definately made noise, but it was only under load. At idle with no load you couldn't hear it at all. Ran real pretty - that's why almost without exception rod bearing failure results in the block being destroyed - people don't expect that "little noise" to be so important, and just keep driving till it's too late.

I am with the seafoam knocking some junk in the lifter camp - sounds like just a single lifter is really pissed off.

If this were a GM forum - rod knock all the way.

GD

i have and that is a very accurate description of what happens

#13 Mark Humble

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Posted 10 July 2006 - 11:36 PM

Try pulling the plug wires off one at a time, if its a rod knock then the knock will soften quite a bit once you get the right cylinder. If its a lifter the knock will still be there.

#14 fbh

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Posted 11 July 2006 - 12:00 AM

Eh, oldskool works :D:D

#15 baccaruda

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Posted 11 July 2006 - 12:28 AM

maybe you should try the diesel flush that was discussed a few days ago?

#16 fbh

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Posted 11 July 2006 - 12:33 AM

Or if you're crazy, take the timing belt off of the side that's doing it and see if it goes away ;)

#17 mikeshoup

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Posted 11 July 2006 - 08:53 PM

All of you were wrong! Heh.

The right (p/s) timing belt's tensioner was way loose. I'm surprised it didn't jump a tooth. The belt was thwacking against the cover. I ended up breaking the outter cover trying to get it off, so I'm going the whole way and taking all the covers off and running naked.




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