Turbo / engine pull question

[Corvidae]

I bought a '93 TT (100% stock) with about 77K miles on it a month or two ago. Since just after I bought it (it was fine doing test drives and such), I started to notice strange things with the turbos (stock boost gauge showing a max boost of 2-3 psi and strong vacuum almost all the time and a noticeable vibration at 3.5-4K RPM). This past weekend, I took the car out for a spin and started to notice white smoke out of the passenger side exhaust. Drove back home and did some investigating over the last couple of days. There's a veritable smokescreen coming out of the passenger side and a little smoke out of the driver's side, both smelling like coolant. ECU is showing a knock sensor failure (not the problem) and one EGR fault (40+ starts ago). After some research, it seems like the turbo seals have / are failing. Does this sound right, or is there something else I can check?

If it is the turbo seals, I'm going to have to pull the engine. Obviously, I'd need a kit to replace them; I was thinking about this:

http://www.z1motorsports.com/product_in ... ts_id=1547

I'm also planning on doing an EGR delete and potentially replacing the knock sensor while the engine is out. The belts have been replaced in the last 10K miles, so I probably don't need to do those, but should I do a 60K kit while it's out? Also, is there anything else you would suggest while it's out of the car?

[marty1mc]

The real question is "How much do you want to spend?"

Yes, I would do the 120K kit instead of the 60k and get the pulleys as part of it as well as Ramey studs for the idler pulleys. As for the gasket kit, I would get the engine gasket kit from concept Z performance for $288. It has every gasket on the engine. It would allow you to pull the plenum and reseal the valve covers. I would also add the half moons to the kit if you intend to pull the exhaust covers. This kit doesn't have the copper oil supply hoses that are in the kit you listed, but you can buy those if needed.

Things to consider:

New knock sensor and cable - $180
New Silicone hoses for IAV, PCV, Water, vacuum - don't get silicone for any oil or power steering - $400
New PCV Valves
Replace the steering rack bushings - easier while the motor is out - $35
New EFI harness - $350
New Alternator Harness - $245
New Battery harness - $75

[Corvidae]

Answer: "As little as I can get away with, within reason." I obviously don't want to have to do this again if I don't need to, but I can't just go whole-hog and replace everything.

Here's my cart at CoZ. I can't really afford to do all of this, but it'll still beat having to take it into the shop and pay twice as much for half the work. Is there anything here that wouldn't be classified "strongly recommended" while I have the engine out?

CZP 300ZX EGR Bypass Kit 1 $32.00 $32.00
Part#: 300-14719-VP100

Nissan OEM 300ZX Engine Gasket Kit (90-94) Plus Missing Gaskets 1 $288.00 $288.00
Part#: NIS300-10101P
Twin Turbo1993

Nissan OEM 300ZX Z32 Detonation Knock Sensor 1 $95.00 $95.00
Part#: NIS300-22060-30P00

Nissan OEM 300ZX Z32 Detonation Knock Sensor Harness 1 $32.34 $32.34
Part#: 300-24078-30P00

Nissan OEM 300ZX 120,000 Mile Timing Belt - Complete Kit w/ Drive Belts 1 $574.00 $574.00
Part#: NIS300-TBKIT120K
StockTwin Turbo1990-1993


Also, does my turbo seal diagnosis seem accurate? Don't want to have to do this twice. :P

[marty1mc]

What you described sounds right. You won't know for sure until you pull it down. Also, call Kyle at ImportPartsPro.com and see if he can knock anything off the prices. You may save a few bucks.

Take a good look at the hoses around the plenum. If they are hard as a rock, then you either don't pull the plenum or you will need to buy all of those. If you do buy them, go silicone. Silicone doesn't cost any additional over OEM and lasts forever. The air and pcv hoses tend to break while you are getting them off, so look before you leap or you will be spending more money.

Make sure your harness is in good shape. You can get by without the Alt or Battery, but the EFI is very brittle after 18 yrs. Word for the wise: The alternator harnesses have been discontinued by Nissan. So if you ever want one, get it now or very soon...

I would find $35 for Energy Suspension steering rack bushings and replace them (if you haven't) while the motor is out.

Good luck,

Marty

[Corvidae]

The plenum hoses seem okay and several were replaced less than 4 months ago due to vandalism (before I purchased the car). The timing belt, idle pulley (left) and tensioner (right) were replaced at the same time, as well as all the injectors (with gaskets), 4 coil packs, plenum gasket, upper and lower O-rings, and pigtails. Should I still worry about the 120K kit, given this info?

The plenum hoses are still fairly soft, and they look to be just fine. Some misc. hoses were replaced with the servicve, I just don't know which ones.

I will definitely add the steering rack bushings. At 1K for parts alone, $35 isn't going to break the bank.

[marty1mc]

When you have the motor out, look it over and then decide. Do you have documentation when the stuff was replaced and that it WAS replaced? if so, then no, I wouldn't put the expense for a 120k kit. However, you didn't mention water pump or thermostat?

Look at where the leaks on the engine are occurring, then decide what you need to do. I would rather wait a week for parts than spend $1k for parts I don't need. Besides, you have turbos to buy if your diagnosis is correct.

[Corvidae]

All of the parts listed above were replaced between 3/30/11 and 4/19/11. There's been maybe 2500 miles on it since then. I have no records on the water pump or thermostat, although getting replacements for those would be far cheaper than the kits if that's the only thing left.

What would be the odds that it would be the turbos themselves and not just the seals? Would REALLY like to keep the stock turbos, if only to save the insane money it'll cost to replace them (I know there are ones that cost far more, but I don't have that kind of cash).

Thanks for the advice; I really appreciate it. This is the first time I've done something anywhere near this major, but I have a friend helping who's done a lot of engine pulls (just not on a Z). It'll be a learning experience for both of us; just going to take it slowly and carefully.

[marty1mc]

The seals I suspect would be bad are inside the turbo. Look at this drawing: http://htturbo.com/gp.html

If you look at it, you will see 1,2,3,21 are all a type of seal. When these go, oil/water can get inside the turbo. But, there is also a journal bearing #4 in the drawing that may be bad as well. When you pull the motor, look for oil in the output of the compressor side. That is a clear indication a seal is going or gone. When you pull the turbo, feel for axial play (in and out) all journal turbos will have some up and down play since there is a bearing journal and the oil pressure inside the journal provides the bearing action. But, axial play is bad.

You can either rebuild the turbo (have it done so it is balanced as well) or replace the CHRA. Rebuilding the turbo is possible if the turbine and compressor blades are not damaged. If the turbo blades are damaged, you need to look closely at the housing as well.

Rebuilds are in the neighborhood of $250/300 a turbo. New CHRA is around $400 per turbo.

Here is a link to a new CHRA for your turbo.

http://www.z1motorsports.com/product_in ... ts_id=2574

Here are the instructions on how to install it (so you can see the task isn't horrible)

http://upload.z1motorsports.com/Turbo%2 ... 20CHRA.pdf

[Corvidae]

Thanks for the info. I'll look into that when I get the motor out.

Thanks again!