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My vg30et has a bad knock


Zchef85

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ok so i have a 85 300zxt with a few bolt ons. I was driving pretty aggressively in the middle of nowhere the other night and after burning a little rubber i heard a really loud knock coming from the engine, it went away after a minute but then when i started driving it got worse(sounds pretty bad) so i parked it. I am not sure how it happened, maybe boost spike or I had boosting for too long (no I/C). anyways I need to do something,I think the machine work would be too much $$$ so I think I am going juts bolt all my accesories to a rebuilt short block. I am considering a vg33 block, will all my acessories bolt up?( alternator, turbo oil feed oil pan etc..) and will my CR be the same. I am also open to any suggestions to my current predicament. thank guys.

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are you SURE it's a knock?

 

I thought the same thing. would you believe it was the flippin' cruise control cable not being tightened down to the actuator on the passenger of the engine bay! It has a jam nut that was loose and it was jumping up and down on a piece of hollow plastic (the housing) and it sound like the knock of all engine knocks.

 

GAHT DANG. it only happened when i hammered it or when I gave the throttle or brake a quick jab. It did sure have me scared though.

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No i am sure it is a internal mechanical knock, it occurs when I start engine and load it, starts to knock bad above 2k, by the way cruise control unit is removed. oh and about my new short block options I would like to go vg33 what are the best years and If not vg33 then is one vg30 block better than other and I am looking to keep the stock CR (7.8:1)

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I'm willing to bet your oil pump has worn passed the acceptable tolerance for clearance between the housing/inner/outer pump gears. Maybe an oil pump R&R and a new sump pickup tube would clear the issue? At least if it does not, you can take the turbo oil pump off and use it with your VG30 crank and VG33 block (someone correct me on this if I'm wrong).

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The pistons make the difference in the CR. That is it. Yes, one block is better than the others. The W series engine are better, they have enlarged coolant passages in the heads and block. Also the wrist pins are full floating and the crank is different by having the "long snout".

 

You cant just bolt all of your stuff onto a vg33. There are a lot of differences that will need to be changed to make it work.

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I have located an 84t short block will everything bolt up? I know the turbo on the 84 is not water cooled, just oil cooled.

Yes, answered in the other thread.

what years did they make the W blocks, and is there any difference between the cylinder heads?

They made the W series engines from 4/87 and on. Yes, answered here...

The W series engine are better, they have enlarged coolant passages in the heads and block.
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Yes, answered in the other thread.

 

They made the W series engines from 4/87 and on. Yes, answered here...

 

Hey J,

 

I'm not sure if the Canadian 05/87's got the later heads, as nissan seemed to give everything to us at about 08/87 instead cause we're "cooler" :emo:

 

Do you have pics, or know of any designation on the head which indicates later or earlier heads of the split year?

 

I'm trying to buy a headgasket kit this weekend, and I'm putting it all back together next week, hopefully =)

 

And if you got some sites with some mild VG30ET head porting tips ;)

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Hey J,

 

I'm not sure if the Canadian 05/87's got the later heads, as nissan seemed to give everything to us at about 08/87 instead cause we're "cooler" :emo:

 

Do you have pics, or know of any designation on the head which indicates later or earlier heads of the split year?

 

I'm trying to buy a headgasket kit this weekend, and I'm putting it all back together next week, hopefully =)

 

And if you got some sites with some mild VG30ET head porting tips ;)

 

Nissan did some funny stuff right about that time for the Z31's... Some of the Z31's got all of the goodies where as some still received the a/b engine. The 4/87 date for the W series engines is fuzzy. Some cars got them some did not. I know that in 9/87 (my black car) got the W series. The easiest way to find out is to look at the block by where the head mates up to the deck on the passenger back side and there will be a a/b/w stamping there. I am uploading some pics right now of one of my A engines...

DSC00524.jpg

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Ok, I am not too sure if I answered your question completely Raff... If you are looking at the head, the coolant passages near the front and rear of the head will be about 1cm long and 5mm wide in an egg shape (on a W series). On an A/B series engine the coolant passages will be a circle and will be about 5mm diameter.

 

Does this answer your question a little better?

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THANKS JAY :D

 

I'll take a pic and report back when I go in there tonight to clean up the oily banzai tree nissan planted under my lower intake.

LOL!!!

 

And what's with that stupid bolt on the back and front of the heads that is like 8 x 1.25 and about 2 cm in height. What the hell is that there for? LOL.

 

That bolt is there so that you break the head because you know "you have all the bolts out" :icon55:... I think it is just there to seal the water/oil passage right by there. BTW I am glad you asked these questions, now I need to install that bolt.

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