Mobil makes a synthetic oil suitable for use in turbo diesels called Delvac 1 in 5W-40.

I used this oil exclusively in a 1992 Maxima 3.0L for just under 300,000 miles and it never burned oil. It contains a very high detergent additive package.

Mobil technical support can provide detailed information on their lubricants and can be reached at 800-MOBIL-25 Option 3.

 

Gurgen,

15W/50 could starve some tight areas pretty quickly. I remember putting 20/50 Castrol GTX in my '88 vette. I thought it was OK since it was summer. Had 5/30 in it from new until about 9000 miles, then I decided to go 20/50. About a minute after startup it started to rattle and didnt stop. Never did this before. I drained it immediately and went back to 5/30. Quieted right down and never did it again. Thick oil is for older engines, not a newer VQ. Stay thin.

Karl

 

OK

I will go back to 10w30 or 10w40. You think this is ok?

Gurgen

 

Under normal circumstances, 10W/30 should be the right choice. But if some mechanical wear has already taken place, it may actually create more consumption now. It certainly wont hurt to go back to 10/30, but until the root cause is addressed, be prepared to see a bit more blue out the back.

Once your new motor is built, breakin with the 5/30 and switch to 10/30 after 1500 miles. No reason to go any thicker until its about worn out (you wont have the car at that point anyway).

 

"Guys... I got a problem... Car Smoking... "

see Gurg, you;'re a bad influence! Your car saw you doing it and thought it was okay!

2 G or not 2 G, there's no question!

 

Randy

LMAO!!!!!!!

 

Most turbo seals are going to want to see a max of about 25 psi. Otherwise oil will tend to leak passed the seals. In most cases sizing a turbo feed line small tends to act as a restrictor itself. You can also check the oil return line from the turbo to make sure it is not clogged or kinked. If the turbo bearings see pressure from oil backing up then it can cause excess pressure to build at the seals as well. Turbo seals are a rather simple device. Nothing more than a ring. Actual failure of a seal is rare without some other kind of failure as well. Putting too much oil pressure causes oil to leak past the seal, but once you lower pressure to within the seals limits the seal should work fine again.

I can't confirm if bb turbos need less oil, but with bearings too much oil is not the problem. If there is no shaft play, then the bearing is probably getting enough oil. The seal is where the problem seems to be at this point.

As for comments on valve stem seals, I would highly doubt it on such a new motor. I replaced a set of them in my 240sx and the new ones appeared to be made of Viton. I would be surprised if they used something different in the VQ. Viton can withstand high temperatures well and has good flexibility. And considering the oil found in the intake pipes, I would suspect the problem is likely in the turbo system.

 

CKwik

Thanks for the info. I'll be getting some first hand opinions soon, but at this point i am leanign toward the turbos seal, ifit were not for the fact that it will NOT smoke anymore! I don't know what is going on! It will not smoke after I rev the engine. However, after a hard accel for about 1 sec in 3rd gear on the fwy, i did notice a pretty big cloud of smoke just shoot out from the back of my car (2 days ago). Bottom line... I could not really replicat the problem (i think out of several tries, there might have been a tiny fraction of the prev. amount of smoke after an off-idle rev, but that as only once and lasted for about 1 seconds (a puff of sorts).

However... there is bigger fish to fry. It seems like the left manifold has CRACKED YET AGAIN. I am not sure what is keeping me from a complete flip out.... but something is... I guess it just gets better with age... This is the 3rd crack on the stainless steel turbo manifolds in ~4000 miles! I do not know if these are connected... but the follwoing happened today. I was driving on the fw at about 8pm when I just hit the gas in D. The car downshifted to about 4000-4500 rpm and almost instantly the car puffed (like a rev limit/fuel cut off) and would barely rev (as if a spark plug or two is/are out. I am thinking "there goes the tranny. But, the "limp mode" cae to mind right after. I pulled over, did the gas pedal method ecu rest, and hte car is back to normal, normal revving, etc. Or is it? 10 minutes later as I arrive to my destination, as it is far quieter in an empty parking lot, I rev the car to about 2000 rpm and, lo and behold, the characteristic "tractor/diesel" puffing sound is there - a leaking manifold! Darn it...

BUt, and what's worse IMO, there is a constant and rpm-dependent (i.e. frequency varies with rpm) there is an audible "tapping" sound. I do not think that this is exhaust related, as the smooth increase in frequency with rpms is obsered, whereas the exhaust leak sound goes away at higher rpms. What can this be. The car does not seem to have lost any power at all, idles very smoothly (BTW, at idle the tapping is not audible), no smoke from the exhaust!

I am going to the nut house real soon.

BTW... the return line on the turbos is not kinked and is of a very wide OD (almost 1"). I am still thinking that it may be the oil getting into the intake via the pcv system... or the test pipes having had some oil in them that is burning off....

G

 

Oh man, I feel your pain!! Do you ever feel as though it's time to just sell the car and buy a Toyota Camry? Some days I do.

I don't know what PSI you're at but what you described does indeed sound like the proverbial limp mode caused by MAF voltage reaching 5 volts prior to 4700 rpms.

When I hear you say RPM independent tapping sound my immediate thought is always "oh no, engine damage" but obviously there are other things it could be.

Do you have a BOV yet?

--Steve

 

So the problem has become less noticable? Check that drain line and make sure there are no obstructions. The problem may only show itself during higher RPM's then where oil pressure is higher and there is more flow. If oil is coming out of the PCV then chances are that line will have some oil in it. It should be easy to check.

As far as the manifold, where is it cracking? The manifold is stainless steel. Stainless steel has a high rate of expansion compared to most other materials. This makes it particularly sucseptible to cracking if proper provisions aren't used. Looking at some pictures of the kit, the flange that attaches to the head is a single piece. Cut it so that there is a flange for each port. This will relieve a lot of stress on the joints. The flange to the head generally stays much cooler than the rest of the manifold as the heads absorbs heat from it and there is less of it in direct contact with the hot exhaust gasses. The flange will expand at a different rate as a result and the tubing will expand faster to a greater extent than the flange. The result is that the tubes will want to pull the center of the flange away from the head. But since it's bolted down, it can't. With enough heat, the expansion and the fact that metal gets weaker with heat, the manifold will crack at the weakest stress point.

I'm not sure if the PE kit was the one I saw, but someone posted a picture of a TT kit got the VQ on one of the forums a while back. It showed the turbo being bolted to the tranny with a bracket. If this is the PE kit, then get rid of that bracket. The entire exhaust system is designed to allow for expansion. Bolting the turbo to the motor or any part of the exhaust to the car without provisions to allow for expansion is bad news. OEM uses rubber exhaust hangers for a reason.

Not sure about the tapping noise. It's a bit hard to diagnose tapping noises over the internet unfortunately.

 

seems like the bases are covered in the smoking section. in regards to your cracking manifold problem, are you using flex piping along you exhaust system?

04 DG/G/6MT/Premium/Nav/Clear Bra
Bone Stock...to be continued...
"You kill mah brodah, now I kill you!" - some old kung-fu flick

 

OK... now the tapping is gone.........AAAAAAAAAAAAAAAAAAA! I am going crazy!!!!!!!!!!!!!!!!!!!!!!!! I guess it's a good thing though.

I had brunch with David Inall of APS this morning, and after looking at the car he pointed out/explained why the way the PE guys have designed the PCV system (my original suspect) IS the problem, in his opinion. So, I am getting a catch can, reconnecting the PCV system correctly, and seeing what happens. He says that if the valve seals have not been damaged yet, then the smoking will go away by the time I drive up to S.F. (the residual left in the piping). We'll see. This is good news... as good as it can be imo.

No BOV yet (I did already buy it though)... will try to install it tomorrow! You don;t realy need it now... as the surge line cannot be reached until you boost far higher than 7-8 psi. Of coursr, it's good practice.

G



<P ID="edit"><FONT class="small"><EM>Edited by gurgenpb on 09/12/04 10:33 PM.</EM></FONT></P>

 

CKwik...

This morning, to demo the smoke to David, the car did in fact exhibit the symtom, but to a much lesser degree than before. Given the new theory outlined above, I am optimistic (and oil catch can is a good idea - period!).

As far as RPMs, that's the darn thing with this... there is NO SMOKE WHATSOEVER at high rpms, only under these specific circumstances (revving from idle while the car is at rest, and observing the smoke a few seconds later, not even DURING this no load rev). The explanation as I understand it is that, given that hte PCV system is now NOT connected to the intake manifold and hence the crankcase sees no sufficient vacuum at idle (and the pcv valve may not even open at that low of a vacuum - around -5 to 0) as you come off idle, the increased vacuum in the crankcase (due to the greater vacuum in the intake tube) now clears the built up pressure that is fuller with oil vapors than if you were actually driving the car (which could have kept the pcv valve open due to greater load and allow for normal/near-normal PCV system function). Hence, coming off-idle, more oil is present in the intake charge than before, hene smoke. How does this sound to you?

David did not think that it is the turbos leaking, we'll see.

Gurgen

 

Forgot....

As far as the mounting is concerned..... no, the turbos are not attached by any bracket to the engien. The only point which is fastened to the drivetrain is the u-shaped bracket holding hte downpipes to the tranny, via rubber "washers".

This is what baffles me... I took extreme care mounting hte downpipes this time around. Installed thicker rubber "washers", so there is slightly more give yet good support. The mounts that attach the downpipes to the bracket had snapped off when they were uninstalled (right before I bought the pipes). Perfect I thought. We first installed the resonated test pipes, followed by the "enhanced" U-bracket, tightened the mounts onto the bracket, and only then welded the mounts onto the downpipe. This is as meticulous and careful as you can get. There is support upwards this way and zero stress when the manifolds are warm (so more or less back to their normal shape). As they heat up and travel down a bit, the give on the rubber spacers will allow for that expansion. There is no allowance for an expansion "aft" however, and that would not be possible without fabricating a very specialised, possibly full rubber mount.

After all.... PE does not recommend doing away with the bracket at all to allow for any kind of expansion. This just sucks

Gurgen

 

Profile...

I DO have flex joints... 6" long once at that (I was paranoid after the first pair of cracks).

G