Need Some Advice...

[James_V35]

Hi guys

I bought a V35 a couple of months ago. Car has been driving OK, but I decided to get the spark plugs changed today and asked the mechanic to have a good look around the engine while in there, including taking off the intake manifold, etc.

Upon inspecting the intake manifold and the areas under it, valve entries, etc, we discovered a massive amount of carbon build up. I am talking heaps, it was layered thick and black as the ace of spades, the mechanic had not seen one that bad before. According to the odometer, the car has done 90,000km but the mechanic said looking at the carbon deposits in the intake manifold, pipes and valve entries, the engine would have done over 200,000km at least. This carbon build up explains the black smoke coming from the exhaust when really accelerating hard as it would have been pushing it through the engine and out the exhaust. The engine oil was also very dirty.

I am going to get the manifold and valve entries cleaned up, new spark plugs installed and an oil change.

Should I be worried? Will the engine last, would you trust it? Any advice or next steps? Is the only option an engine rebuild?

[rs73]

it's probably only been serviced once or twice over its entire life in Japan.

you can get a good mechanic do a carbon clean ( I get mine done at Nissan dealer ) and just change the oil. then see if it still having problems before deciding if you need to go for something serious eg. rebuilding engines.

Mine is 50000km and there were carbon deposit, let alone yours which has done 90000km there will be more deposit if it's never been cleaned before, in which case, very likely never been cleaned.

another option beside engine rebuild is buy a half cut from Japan, other option is sell the car and reimport another one with finger cross in better condition.

[James_V35]

Thanks rs73.

I guess I am also concerned over the fact that the mechanic reckons the engine has done over 200,000km as compared to the clock which says only 90,000km. How much life would the engine have left in it given it's mistreatment.. Would the car be fine if the carbon deposit is cleaned out and the oil changed (I have changed the oil twice already and both times still very dirty).. realistically I can't afford a rebuild and I am guessing a half cut from Japan won't come cheap either..

Edited August 1, 2009 by James_V35

[rs73]

i have no idea. just get it carbon clean. if it still no good then yeah, sell it...

welcome to the import world, where wound back km are as common as a white car in a fleet of courier delivery vans.

[rs73]

but on a brighter note, your mechanic could be wrong...

or over estimating the actual kms...

you never know unless your car comes with full service history from japan...

[James_V35]

Thanks mate.

Anyone else got any ideas or advice.............????

[whtbox]

hmmm i don't know how to say this or this is a right method.

You can keep on using the 98 RON fuel since they have cleaning additive on them.

Then use Mobil1 oil as they have cleaning agent and collect all the carbon build up over time (hence old Mobil 1 oil became darker than normal)

Or use a cleaning additive a LiquiMoly Engine Detox. You can get them at Autobarn or Supercheap auto.

good luck

[Chris Rogers]

to answer your distance question. clocks probably have been swapped,carpet changed and you would be none the wiser. for distance/engine life: its a nissan . it will run for quite a while yet. if it worries you stick the car on ebay and buy another.

fiixing you problem properly , rebuild of the top end.

[rs73]

yeah, I find most Nissans have very smoky engine especially on cold weather start... heaps and heaps of smoke too...

my previous R33 was like that, wasn't the best sounding engine at idle too, but it did went through 5 yrs of ownership and 70,000km of "ab"use with no dramas.

[mosoto]

Thanks rs73.

I guess I am also concerned over the fact that the mechanic reckons the engine has done over 200,000km as compared to the clock which says only 90,000km.

I've said this before and in this case may be quite pertinent.

IIRC Japan cars that are used for daily commuting are subjected to extremes of traffic congestion. They travel relatively short distances (by our standards) but take exceptional amounts of time to do so, hence the odometer reads low but the engine has seen a lot more running hours over it's lifetime.

[Touge Kyousou]

I probably wouldn't be too worried about. Get it cleaned out, change the plugs, filter and get some of those engine treatment additives (some mix with fuel, some mix with oil during change).

The VQ35 does produce alot of blowby and mine was quite dirty too, though it wasn't black at all..just a nice oily coating lol. Maybe the previous owner gave it a bit hence the blowby and black coating inside your plenum.

If you're worried, just go get a compression test done. That'll give you a decent idea on how the engine really is. Then just do the usual inspection yourself i.e. looking at the drive and ancillary belts (are they cracked, faded, OEM belts ?), look for leaks around hoses and hose joints (like at the power steering pump). How are the brake pad and rotor thickness ? Is the bottom of the car all scuffed/marked etc. How's the steering wheel leather look ? Are there scratches all over the trimming in the boot ? Look at the suspension bushes too (v35's don't tend to be modded much in japan.. are the bushes still ok or are there cracks etc ? Even if the importer tried to hide the true km's i very much doubt they will bother replacing bushes.

Even if it turns out the km's may be wound back..don't despair. For a little bit of money, you can freshen the car up (sussy bushes, shocks, wheel alignment and sussy components retorqued) and it would drive even better than a low km example.. just make sure you get that compression test done first so you know if it will last or if it's on it's last legs.

GL

[James_V35]

Thanks for the help guys, much appreciated. It took the mechanic the best part of a whole day to get it cleaned up to a reasonable level.

Just a question about compression - I am going to get a compression test done. Can anyone please tell me what psi each cylinder should be running? At what psi would you say it is running too low and what does a lower psi mean?

[James_V35]

OK well the compression test results are in. The manifold and intake cleanout took 2 days of solid work..... it was caked black.

1 - 170psi

2 - 170psi

3 - 150psi

4 - 170psi

5 - 150psi

6 - 170psi

I have been told the standard is 175psi. Two have come in at 150psi. Should I be worried about this? Will the engine last long? I have had the carbon deposits and build up cleaned out with a new air filter installed.. the exhaust actually hits a somewhat deeper note now like the car is actually breathing.. it never had that before.

Thoughts?

Edited August 5, 2009 by James_V35

[Touge Kyousou]

There's really no standard in compression as different engines vary and even different units of the same engine can vary a little bit.

To me.. the results are decent ? 170 is good! I think 150 is still kind of acceptable. The engine should last for a fair while yet and i'd daresay with compression like that, i don't think it would have traveled 200,000kms. The exhaust note going deeper is a good sign

If you keep up good servicing, warm up/down car and use good oil..

Did your mech determine with the 150 cylinders, is the leak seals or valves ? How are the two cylinders position in relation to each other.

Might wanna look at getting an oil catch tank fitted btw ? Will prevent alot of that buildup in the intake and plenum (so the blowby hose doesn't feed straight into intake, it goes into a can with a filter that catches all the vapourised oil and muck.. and they're cheap).

You should give a performance workshop a call (that inspects jap cars a bit) and ask them about the comp. results to be sure as i'm no qualified mechanic (just flick through some import magazine and see what names keep popping up).

Btw, did you check the stuff i mentioned above ?

[GoldV35]

OK well the compression test results are in. The manifold and intake cleanout took 2 days of solid work..... it was caked black.

1 - 170psi

2 - 170psi

3 - 150psi

4 - 170psi

5 - 150psi

6 - 170psi

I have been told the standard is 175psi. Two have come in at 150psi. Should I be worried about this? Will the engine last long? I have had the carbon deposits and build up cleaned out with a new air filter installed.. the exhaust actually hits a somewhat deeper note now like the car is actually breathing.. it never had that before.

Thoughts?

Possible causes:

1. Lack of oil causing the rings to be overworked.

2. Old (worn) and weak rings.

3. Crack or opening in the head - but that doesn't necessarily mean water in the oil or oil in the water.

4. Cracked cylinder

5. Burned, warped or cracked valve(s).

6. Burned or cracked piston.

7. Cylinder worn or out of round.

8. Blown or leaky head gasket.

9. Sticky valve(s).

10. Broken or worn valve spring(s).

11. Bent/worn pushrod(s)

12. Worn camshaft, or a broken lobe on the cam.

13. Worn or bent rocker arm(s).

14. Collapsed lifter(s).

The main suspects would probably be 2, 7 and 8.

[James_V35]

There's really no standard in compression as different engines vary and even different units of the same engine can vary a little bit.

To me.. the results are decent ? 170 is good! I think 150 is still kind of acceptable. The engine should last for a fair while yet and i'd daresay with compression like that, i don't think it would have traveled 200,000kms. The exhaust note going deeper is a good sign

If you keep up good servicing, warm up/down car and use good oil..

Did your mech determine with the 150 cylinders, is the leak seals or valves ? How are the two cylinders position in relation to each other.

Might wanna look at getting an oil catch tank fitted btw ? Will prevent alot of that buildup in the intake and plenum (so the blowby hose doesn't feed straight into intake, it goes into a can with a filter that catches all the vapourised oil and muck.. and they're cheap).

You should give a performance workshop a call (that inspects jap cars a bit) and ask them about the comp. results to be sure as i'm no qualified mechanic (just flick through some import magazine and see what names keep popping up).

Btw, did you check the stuff i mentioned above ?

Thanks Jon. I didn't check any of the bushings, etc but the car looks in A1 condition.. paint is perfect, body looks straight, interior is in virtually perfect condition aside from a small amount of wear on the interior driver's door handle, the steering wheel is immaculate, auto shifter knob in same knick as the steering wheel, carpets are good and has the original Skyline mats which are also in great knick, and not a mark in the boot area looks pristine. Drive belts were all ok except for the air-con belt which was OEM and was severley cracked up, so I had that replaced. So all in all, if you took the engine out of the equation, the car looks basically mint. Just the standard clouding of the headlight covers but everyone experiences that. Physically the car looks better than 90,000km as opposed to 200,000km.

If not for the engine, I would never consider selling it. The engine has an occasional rough idle but when driving, is perfect. I think I saw a couple of other people on this forum a while ago that had this problem. So I am really at a loss as to what to do.. do I take a chance and hang on to it because I love it (go with my heart) or do I sell it to someone that wants to do it up and get something else (go with my head). If the engine craps itself I am stuffed and won't be able to fix something that major.

Edited August 5, 2009 by James_V35

[rs73]

it'll be fine,

if u can't live with the thought of 2 cylinders are running 20psi lower than the other 4, get a brand new car is the other choice, even if it means a 4 cylinder Toyota Yaris.

[180 wanabe]

If the engine craps itself I am stuffed and won't be able to fix something that major.

Mate i would not worry too much about the 20psi difference, at the end of the day I doubt its going to make your car any more likley to break than any other V35 getting around

Nissan make good engines after all the SR20 in my old 180sx was running 105-100 psi in the cyls before i had it rebuilt and it still threw out 180wrkw @ 1.3 bar LOL

[rs73]

Just to keep in mind, Japan economy was booming in the 80s early 90s with most engines come out of the Nissan factory are believed to be over engineered, that is they're built bullet proof with thicker blocks than necessary... it does take its toll on its company financial though... they could have saved money if they didn't build the engine block as thick, e.g. using less material, etc.

When Renault ex-boss takeover, it's all about new/refreshed horizons, design & financial, etc as the company need ways to cost cutting and at the same time refresh its image to get back on its feet... so the new VQ might not be engineered to be as tough as the old engine, as they're mostly NA there was no need for Nissan to build them to withstand force induction (Except VQ25DET). Although they're still good engine, but there's been report in modified 350z/G35 in USA that VQ engine have what they call 'glass' bottom end.

So I wouldn't say the new VQ engines are as tough as the old RB and SR engines. All the big numbers out of Japan on modified/turbocharged VQ have their engine rebuilt with Top Secret/Jun parts.

But again. even stock, they are still good engine.s

treat it well and respect it, it won't crap out on you unexpectedly.

[scathing]

but there's been report in modified 350z/G35 in USA that VQ engine have what they call 'glass' bottom end.

'Glass' is relative. The stock NA bottom end will only take around half a bar of boost before it dies. That's a pretty low amount of boost, which is probably what gives it the reputation. There are a lot of people out there chasing numbers, and 7-8psi isn't something you can brag about to some 2JZ-GTE driving mate.

But when you consider that most of the twin turbo kits pushing that kind of boost make 280rwkW (which is about all the bottom end will take as well) then it doesn't seem that glassy. That's a usable amount of power in most people's books.

There aren't many stock NA motors that will let you go FI and make that much power reliably, regardless of when it was made.