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Knocking Sound On SD33T

Tech Talk for Nissan owners.

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Knocking Sound On SD33T

Post by coxy321 »

Hi all. After the trip (Seymour to Sydney - and back again), the old MK is making this knocking sound when you start it up. It sounded like a broken engine mount, or the exhaust hitting something, but I can't see anything happening under there!

It seems to be happening at low revs, like when you start it in the morning and it idles really low, or when its warm and the motor is winding over on normal startup. The car runs fine at normal revs and temp. so I'm guessing that it can't be too serious - but I could be wrong ($$$$$$$$$) :cry:

Any suggestions before i take it to the diesel mechanic?

Coxy
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Post by Screwy »

knocking.......

in engine?

if its not the engine mount rubber worn and the metal knocking on metal.....

could well be a Big end bearing.... common problem when the k's start getting on....

without hearing its hard to tell, if ya take it down ur mechanic he will probably be able to pick it straight away...

screwy
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Post by coxy321 »

Thanks mate. The trucks only ticked over 296kms when we got back from sydney, so I'm really hoping its nothing major. We're going up to the cape next year so I hope its not going to hurt the wallet, or cause me hassles later down the track.

Hows your rig going anyway screwy? I didn't have enough time to hang around on saturday cause one of my mates had a bit of a family emergency back in geelong, and we had to get back asap.

Coxy
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Post by bazzle »

"May" be leaking injector (injector knock)
Crack each one open if you know how and see if noise changes.

bazzle
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Post by berazafi »

bazzles guess would be mine guess had the same thing happen
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Post by coxy321 »

Was it a fairly prominent knocking sound?
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eng knock

Post by BACON »

Tri checkin your timing, i had the same prob.
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Post by coxy321 »

Okay. I had a job on out on the road wednesday, and I checked the oil after i finished. It had about 3/4, so i topped it up. This morning before work, I thought i'd crank it over with the bonnet open, so that i could see if the engine mounts were loose, and to see if i could spot the problem. After trying this theory, and not finding anything, I then noticed the splash-back of sump oil around the front of the motor, on the fan, and basically a little bit of black oil everywhere. It looks as though it has all come from the crank pulley. And i'm guessing that this it the answer to my knocking sound.

I'm taking the car into a workshop next week, but roughly how much is this going to cost? My old man suggested to start looking at V8 conversions in the mean time. I hate V8's.

Coxy
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Post by jtraf »

Front oil seal on the motor is weeping.........Mine did that as well and they are all supposed to do the same thing. I was quoted $500 dollars to strip down repair and replace........I just never did it cause it was never a very heavy leak.

I don't believe this would be the cause of your issue. Just in case check the main bolt on the front pulley to ensure it has not come loose.....

You could always try the old piece of garden hose trick. Start it up and put a short length of garden hose to your ear and move the other end around the motor. The knocking sound can be pinpointed like this.

HTH
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Post by Screwy »

your crank would have to be loose for the knocking sound to have anything to so with the oil leaking from the crank.

if the mains bearing bolts have come a little loose thenthe crank will move causing a knock and u will leak oil.

BUT i very very much doubt ur crank is loose, i think that oil leaking is a seperate problem.


screwy
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Post by coxy321 »

I'll see what the guys say during the week, and i'll post the results. Just curious, has anybody done a conversion from an SD33/T or L28 to a 4.2TDi out of a GU? I dont think i've come across one yet.
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Post by ozy1 »

with the conversion to td42 you will need to run the GU gearbox too, and this makes the conversion harder, as that box has a centre rear output, where your MQ has an ofset out put, so your rear shaft will be on all sorts of anglesa, maybe creating a vibe issue,

also, i think the GQ/GU box and transfer is a longer combo, so your rear tail shaft will be even shorter,
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Post by coxy321 »

Bummer. I know someone that might've parted with theirs. Doesn't matter.
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Post by Screwy »

ozy1 wrote:with the conversion to td42 you will need to run the GU gearbox too, and this makes the conversion harder, as that box has a centre rear output, where your MQ has an ofset out put, so your rear shaft will be on all sorts of anglesa, maybe creating a vibe issue,

also, i think the GQ/GU box and transfer is a longer combo, so your rear tail shaft will be even shorter,
the gearbox is more than likely wider as well, so all floor pan mods not to mention new gear shifter holes for transfer etc....

and because of the design, as shawn said the rear shaft will be short.... and it will be very short ;)
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Post by coxy321 »

Okay. We're not 100% sure of the verdict yet (as to how serious the problem is), but it seems that the harmonic balancer has sh@t itself. This explains the leaking oil from the crank pulley, and apparently it only makes the knocking sound on startup cause thats when the most load is placed on it. It doesn't knock while running cause it sort of runs itself true.

I'm heading back down to the workshop tomorrow to see whether its just a repair job, or worst case, its flogged all the seals and front main bearing and needs major heart surgery. :cry:

Poor old girl. And so young too....
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Post by coxy321 »

Alright. Turns out that somehow the nut on the harmonic balancer has worked its way loose enough to allow the balancer, balancer sleeve, and key/keyway to get just about completely flogged out. The key looked like a banana that'd been stepped on, and the keyway was basically rounded off on one side.

Its got me stuffed though, cause as far as me and dad know (and what the service receipts say), the balancer hasn't actually been touched since we owned it, yet my mechanic found silicone around the seal stopping the oil from seeping out. :? ???

The verdict is basically that for the cost of replacing the crank, i can get a second hand motor and have it "done over", as the crank is now irrepairable.
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Post by Adsman »

Why not replace the seal and get a new key, then liquid metal them together. There's some really good metal bonding products on the market. It maybe worth a try. Cheaper than a motor and sht loads easier. Maybe post a close up pic of the damage? Then someone might have another suggestion? ;)
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Post by Screwy »

Adsman wrote:Why not replace the seal and get a new key, then liquid metal them together. There's some really good metal bonding products on the market. It maybe worth a try. Cheaper than a motor and sht loads easier. Maybe post a close up pic of the damage? Then someone might have another suggestion? ;)
i think by this coxy means that there is damage on the crank also and therefor maybe the ballancer is unbalancable anymore....

cheers
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Post by coxy321 »

Personally IMHO, its screwed. I'll see if i can get some pics up. Patroldude tells me that the SD33 and SD33T cranks are exactly the same.....true???
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Post by berazafi »

If you want a bottom end Pm me I am in melbourne and it will be cheap enough to be worth your while, it could probably do with a spruce up but was drivable when it was pulled out, btw its a sd33T block

Dave
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