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what does it mean if your engine is knocking?

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 Post subject: what does it mean if your engine is knocking?
PostPosted: Wed Nov 15, 2006 11:20 am 
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is every case different? is it worth fixing or just put a new motor?


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PostPosted: Wed Nov 15, 2006 12:03 pm 
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Define knocking. Rod knock? Detonation? Lifter tick?

Sam

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PostPosted: Wed Nov 15, 2006 12:03 pm 
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What sort of knocking?

Noisy lifters
vacuum pump noise (10v engines)
piston slap/wrist pin play
etc.

My one 10v NG had a nasty knock at times... I figured it was garbage and i'd drive it till it died. Turns out it was the vacuum pump on the head... pulled out the drive rod, and no more knock.

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PostPosted: Wed Nov 15, 2006 12:31 pm 
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Whoa, I thought this was going to be a "knock, knock" joke...

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PostPosted: Wed Nov 15, 2006 1:03 pm 
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Depends on the knock! If it's a bearing then your looking at grinding a crank and essentially rebuilding the motor.

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PostPosted: Thu Nov 16, 2006 5:45 pm 
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I agree with all. Define the knock.

I have seen 5.0 Mustang v8's with a dead plug knock like a bad crank and rod, change plug and all was well. I have had Harmonic dampers with a bad rubber insert knock badly, especially on diesels. I have also seen Chrysler Slant 6's with #6 piston sitting ontop of the starter and a hole in the side of the block still running after driving it like that for 20 miles (step-sister's 2nd car)

If you have a collapsed lifter it will clatter (Common), in that case, new lifters and you are good. Rod and crank knocks are costly. Piston slap on a cold engine is more of a ringing knock, and is common on cold days on high mileage engines.

Where does the knock appear to be comming from? Valve Cover? Front Cover? down low near oil pan? If you do not have a stethescope, use a long pry-bar, put the handle against your skull just behind your ear and the other end against the engine and find out where the knock is most serious.

However if there are parts of your engine missing and a pool of oil arround them on the ground, you have identified it a little easier.

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PostPosted: Thu Nov 16, 2006 5:53 pm 
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its an engine knock on a 2000 a4 1.8t quattro. i was just told the car has an engine knock but they were saying something about the oil pump being clogged. i havent heard it because i figured running the car would do more damage. thanks for the input guys


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PostPosted: Thu Nov 16, 2006 6:07 pm 
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Are you original owner? it would be the pickup that is clogged vs. the pump itself.

My brother in law's old ranger pickup had an oil pickup that was clogged, caused the cam bearings to seize and break the T-belt. Cause of the clogging was the glop the dealer schmutzed onto the oil pan gasket to get it to seal to stop leaking. Took about 5k miles to show up after he bought the truck.

If it is just the pump, labor content high, parts content low unless you starved a bearing which would mean a rebuild. Then it is cheaper to pick up a low mileage engine from a salvage yard.

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The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me

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PostPosted: Thu Nov 16, 2006 6:10 pm 
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At my work, we had to pull out the oil pan on a 1.8t because SOMEONE didnt change the oil every 3000 miles/3 months.

There was sludge in the motor and the oil pick up tube was clogged.
Best thing to prevent knocking is to change your oil (i think?)

Ive seen/heard evidence that the 1.8ts are fussy about oil starvation.

I hope you dont have to pull the pan. try changing the oil with a new filter
(maybe?)

HTH,
evan

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PostPosted: Thu Nov 16, 2006 7:10 pm 
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is there any way i can tell if the car has a clogged oil pickup or if the bearings were starved. are those the only causes of knocking?thanks again guys


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PostPosted: Thu Nov 16, 2006 7:34 pm 
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Pop the oil pan off to inspect. Getting in there and seeing first hand is really the only way to check those items, AFAIK.

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PostPosted: Fri Nov 17, 2006 8:08 am 
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Yup. And, with the 1.8t, always run full synth, german filters, change both regularly, and always cool the turbo after running it hard.

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PostPosted: Fri Nov 17, 2006 10:21 am 
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"From what the car sounds like when it's running, I'm
pretty sure that has rod knock. To me, this means
that because of a low oil pressure situation, the rod
bearings have worn down thin or are gone completely."
that is what the guy who's house the car is at said to me he was interested in buying the car initially.
so does that mean i just have to change the bearing or what do i have to change or fix to get rid of the knock. so does that mean the oil pick up could still be clogged? thanks guys


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PostPosted: Fri Nov 17, 2006 10:31 am 
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If you're lucky you can put in new bearings and it'll be fine. Given the age of the car I'm lead to believe there is a reason the orriginal bearing(s) wore out so quickly. If this problem isn't addressed the new bearings don't stand a chance. If you wait to long, the crank will be damaged and need to be ground (it may already) and you can end up putting a rod through the block. Good that you're not driving it. Where are you located?

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PostPosted: Fri Nov 17, 2006 10:44 am 
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If you're lucky you can put in new bearings and it'll be fine. Given the age of the car I'm lead to believe there is a reason the original bearing(s) wore out so quickly. If this problem isn't addressed the new bearings don't stand a chance. If you wait to long, the crank will be damaged and need to be ground (it may already) and you can end up putting a rod through the block. Good that you're not driving it. Where are you located?

the car has 164k miles if that make a difference. how can i find out if the crank needs to be ground? and I'm located in CT.


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PostPosted: Fri Nov 17, 2006 1:41 pm 
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W/ 164k on the clock, look for a low mileage salvage yard engine to swap. Most likely crank is shot along with at least one rod. Pulling the pan will verify. However if this was caused by oil starvation, the others are not far behind and the piston walls are most likely worn or scuffed since the mains are oiled first followed by cams and pistons.

Figure about $1200 - $2000 for a motor, and an extra $300 for misc stuff to fix (More if you add a new clutch - recommended). also, do not forget the value of labor

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The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me

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PostPosted: Fri Nov 17, 2006 9:48 pm 
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but heres the thing i have a 2.7t s4 motor that i can put in the car. what do you guys think? i know there would be more parts to change rather than if i just put another 1.8t but i already have the motor. or do you think its just better to go the easiest route and just put another atw motor because thats whats in the car. i know the aeb is a more desierable 1.8t but it wont just bolt up like a atw will.


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PostPosted: Sat Nov 18, 2006 1:34 am 
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You better let it in :lol:

...,but seriously! :slap:

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PostPosted: Sat Nov 18, 2006 7:31 pm 
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The easiest is always like for like. The 2.7t is a great motor with crappy stock turbos. However, unlike a v8 swap, there are factory parts available (although some are really pricy) to swap into an A4.

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The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me

2000 A4 Avant
'73 Opel GT with Supercharged Northstar
'48 Chev 3100 5-window - BBO TH400
'53 Chev 3600 3-window - Cummins QSB3.3TAA
'88 Cruisers rogue - VP AQ271C


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PostPosted: Sun Nov 19, 2006 1:38 am 
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but with upgraded turbos(gt28rs) i think the s4 motor would have a greater potential than a 1.8t and still be able to use stock internals. and it would be a sleeper with an s4 motor and 1.8t badges. what would be needed to build the 1.8t? pistons, rods, cams, bearings, valves, what else? is it worth getting a 2.0 aba block over the atw block(would boring it out to a 2.2 be a bad idea?). would an aeb head be a better idea to use over the atw head?(but then i think i would have a cel since mike with the pelican blue a4 sponsored by 034 said it did on his if i use the aeb head). and i would probably need a custom tune because i want to be able to get through emissions. with the 1.8t do you think you can go bigger than a gt35r?


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PostPosted: Sun Nov 19, 2006 11:17 am 
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How much money do you have to spend on this project and are you doing all the work yourself?

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PostPosted: Sun Nov 19, 2006 6:50 pm 
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:stupid: Speed = $, how fast can you afford.

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The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me

2000 A4 Avant
'73 Opel GT with Supercharged Northstar
'48 Chev 3100 5-window - BBO TH400
'53 Chev 3600 3-window - Cummins QSB3.3TAA
'88 Cruisers rogue - VP AQ271C


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