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Vq25Det Major Repairs

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Equilibrise Community Regular

Equilibrise

Posted
Posted

Where to start....

Had an engine knock a couple of months back. It was recommended to replace the engine (which I probably should have looking back on it now) as several diagnosis' suggested that the noise was due to a worn bearing, although every diagnosis said that it was a different bearing. So I decided to do the rebuild myself, as the cost of doing all the work myself and the cost of replacement parts was assumed to be cheaper than the cost of another second hand engine and having a wife and kids to support, money can be tight at times.

I removed the engine from the sad looking Stagea, dismantled and found the cuplrit causing all of the dramas. It was a heavily worn main bearing (bearing for holding the crankshaft in place). Now it gets heavier. As the bearing had been wearing down it released metal shavings (which just sank to the bottom of the sump) and a fine metal dust which in turn was pumped throughout the engine. Because of this dust and crankshaft movement, other bearings were damaged. I installed new bearings and checked clearances with a flexiguage. It showed damage had been done to the crankshaft and block, so now they go off to the machinist. St George crankshafts took the job on and were very professional and friendly. The crankshaft required machining and polishing and the block and crankshaft journals required machining and a tunnel bore. Once completed it all looked brand new and the even saved me a few dollars supplying new bearings at they're cost price.

Once the block was home again, I performed a light crossed hatched cylinder hone and a very thorough clean out several times. I dismantled the heads completely. Cleaned every component and every bolt to a point where they looked almost brand new. Installed new valve stem seals and began reassembly with a coating of fresh oil on every bolt and component. It began looking like a motor again and when it came time to fit the rear timing case back on I couldn't find the new oil rings. After searching everywhere and concluding that they must have fallen out of the parts box somewhere I decided to order some more, yet being a Saturday morning Nissan parts were closed. This gave me a chance to have a look at the highflowed turbo and see if I could work out why Stagea turbos make so much noise.

Just when I thought my stomach couldn't sink any lower, I found excessive shaft play in the turbine. The turbo had not changed its whine or any characteristics since the day I bought it almost 2 years ago. I'm not sure if it was fine metal from this which caused excessive where on the main bearings or the other way around. I took the turbo to GCG, who did the original highflow (previous owner) and after assesing they informed a complete rebuild was necessary. I decided to upgrade at this point. The stock turbo housings are being machined and fitted with a Garrett GT3076 turbine. I have a new set of braided oil and coolant lines to go in with it.

Now all that is left is a fuel pump, injectors, fuel reg and ecu on my power upgrade list, and yet I may have to do those now anyway, just to support the new turbine.

Any body want to see dismantle and assembly pics?

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scotty nm35 Grand Master

scotty nm35

Posted
Posted

It's a big job isn't it Adam. What oil rings were you missing, the orings for the case to block around the oil gallery?

Why did you decide on a laggy GT3076? Are you planning to run an Emanage?

Post up some pics mate. :)

Jetwreck Grand Master

Jetwreck

Posted
Posted

Yes please for pic's.

The 30/76 may be a bit big for our engine unless you are playing around with compression, looking at putting a piggy back on it and running bigger injectors. I'm running a 30/71 and when I was on the standard ECU I pretty much maxed everything at 14-15PSI.....not to mention the lag. Please also not that if you are going this way you will more than likely need a 17-18mm spacer for the intake pipe and also need to modify the pipe going to the FMIC by 17-18mm. A new 80mm suction pipe matched to your turbo would be a great idea as well as the stock one is a POS.

P.S. I'll might also mention that that turbo on your car was a noisy POS from Day 1....how it's lasted as long as it has I have no idea. I don't know what your paying but I would be talking to Precision or Hypergear over GCG as they are the main suppliers....I have only ever seen 2 GCG turbo's on our cars and they were both noisy and rated very low is HP.

P.S.S You have my number so feel free to call if needed.

Duncan Grand Master

Duncan

Posted
Posted

Well that is painful luck, but turbo failure regularly follows engine failure....the turbo bearings have even tighter clearances than the engine ones so they very commonly fail at the same time due to either the falling oil pressure when the engine bearing fails, or due to the metal that gets everywhere.

Equilibrise Community Regular

Equilibrise

Posted
  • Author
Posted

Yes Scotty, massive job. Yea they were the missing o-rings. I have got more now and timing case is on. I was originally going for a GT3071R, but for some reason was recommended the 3076. I will speak to the guy in the morning anyway. I will have to go for an emanage, injectors, etc. Do you guys know of any decent tuners in Sydney who are at least a little familiar with our cars?

Craig, It's just the turbine that is being replaced and stock housings kept, so from my understanding all attachments should be the same (except for oil and coolant lines), yet I have been wanting to change the poorly designed suction pipe for some time anyway. I'll give you a bell when I get 5 mins spare.


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More pics tomorrow.

  • Like 1
Jetwreck Grand Master

Jetwreck

Posted
Posted (edited)

Yes Scotty, massive job. Yea they were the missing o-rings. I have got more now and timing case is on. I was originally going for a GT3071R, but for some reason was recommended the 3076. I will speak to the guy in the morning anyway. I will have to go for an emanage, injectors, etc. Do you guys know of any decent tuners in Sydney who are at least a little familiar with our cars?

Craig, It's just the turbine that is being replaced and stock housings kept, so from my understanding all attachments should be the same (except for oil and coolant lines), yet I have been wanting to change the poorly designed suction pipe for some time anyway. I'll give you a bell when I get 5 mins spare.

More pics tomorrow.

I hope GCG didn't tell you that the install wont need anything changed other than the turbo lines as I'm pretty sure that with the Garret core your turbo will be 17-18 mm shorter. This may not make a difference when working on a C34 but the difference is quite substantial with the M35 if you want it done properly. Talking from a lot of experience there are slight changes as I have mentioned. I also recommend you update you suction pipe.

I do E-Manage(I have base maps to get you to the tuner as well) and injectors(I have a set of Deca 610cc atm for sale at a good price). I use JEZ to do the tune as he is the only one in Sydney that I trust and his done enough of them now.

Talk soon. Don't go for the 30/76!!!....you'll be sorry.

P.S. You will also need to upgrade your fuel pump and hard wire it, Actuator and BOV to get the most out of it.

Edited by Jetwreck
Daleo Grand Master

Daleo

Posted
Posted

GCG sound like they have no clue. :/

I didn't have a very good experience dealing with GCG, I thought it was just me being a low dollar value customer; but a mate had a very poor experience, and he was looking at spending tens of thousands on his $300k show car.

Others speak highly of them; but I'm not convinced, and the OP's turbo was incredibly noisy, right from the start, just as Jetwreck said.

Equilibrise Community Regular

Equilibrise

Posted
  • Author
Posted

Thanks heaps for all of your input everyone!

The cause could have been either or a combination of:

- putting 0-40W full syn oil in and already worn engine (not knowing it was that worn)

- turbo bearing granules being pumped through the oil

To update, the engine is back together - timing chains, case and sump back on and sump banjo's drilled out to 2.5mm (after reading Scotty's post regarding this).

I have a very new looking stock turbo with GT3071 internals, a better bov, new oil lines and an emanage ultimate.

More pics with next post.

MrStabby Grand Master

MrStabby

Posted
Posted

Thanks heaps for all of your input everyone!

The cause could have been either or a combination of:

- putting 0-40W full syn oil in and already worn engine (not knowing it was that worn)

Sounds like a sensible oil choice to me, worn or not, there's no reason to think that would contribute to the problem. (Am I missing something?)

Jetwreck Grand Master

Jetwreck

Posted
Posted

Yup....you missing something.....they gerarate a lot of heat and have big oil pressure.

Sowing machine oil specs are not good for it. I ran 5w 30 once and dumped it after 1000k because the motor was not liking it at all.

MrStabby Grand Master

MrStabby

Posted
Posted

Yup....you missing something.....they gerarate a lot of heat and have big oil pressure.

Sowing machine oil specs are not good for it. I ran 5w 30 once and dumped it after 1000k because the motor was not liking it at all.

Nissan would have been aware of the heat and pressure when they came up with the oil spec.

What was wrong with the 5w-30 you ran? Did you get a UOA?

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