Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

VZ Intermittent diesel sound

Razmo99

New Member
Joined
Oct 9, 2017
Messages
2
Reaction score
0
Points
1
Age
24
Location
Sydney
Members Ride
2004 VZ V6
Hi, New to the forum. Been lurking the past few weeks. Couldn't really find an answer to my specific problem. So here I go...

So I pickup this commodore cheap. Had an over heating problem, was a cracked radiator, easy fix. During that time got an oil warning light decided to change oil, noticed it was foul and old. chucked in some Penrite HPR 5 10w-40. No problems.

Got it registered and noticed then when it gets hot it starts to sound like a diesel. If you turn the car off wait 20 sec then turn on again it starts up fine and sound is gone at idle. If you start driving at speed then stop its back. stop and starting of engine will remove again.

So I started to dig deeper in to this, and at idle cold, I get 80psi of pressure Hot is about 20psi. An electric pressure gauge was also installed so I could monitor it look for a pattern etc.
When its noisy pressure drops to 7psi plus or minus a few.

Just last weekend I pulled the sump which was challenging, the instructions posted here where accurate; What a pig of a job. It was full of sludge and pickup was partially blocked, but not to a point that I would say no oil would flow. At this point my theory was that when driving lose sludge was getting sucked up restricting flow then it would settle when engine was turned off.

Also checked Conrods while down there, some side to side but no up and down play; and they where a nice Gold colour not sludge up. Also had cam covers off and checked drain down passages and they seem to be clear. Timing chains are not sloppy and have good tension.

When all re assembled, the problem still persists. I am thinking oil pump now. Just want another opinion on this matter before I go on a tangent and spend time pulling stuff apart that isn't related.

Over all the engine idles fine, minimal vibrations, has decent power(don't have a good reference) this is really the only remaining mechanical issue that I am aware of.

Videos and pictures can be uploaded if they would assist.

I would appreciate any thoughts or opinions

Cheers, Lewis
 

rambunctious

Well-Known Member
Joined
Jun 9, 2011
Messages
1,665
Reaction score
464
Points
83
Location
Mooloolaba
Members Ride
VZ Wagon
Sludge means lack of oil flow=engine damage, which is only showing up above idle.
Isolate the knock if possible.
Top end knock could be injector, but your description of oil pressures indicates engine damage.
Lack of oil to cam bearings have been a problem in the past on older commodores but not necessarily on VZ.
 

Razmo99

New Member
Joined
Oct 9, 2017
Messages
2
Reaction score
0
Points
1
Age
24
Location
Sydney
Members Ride
2004 VZ V6
I need to isolate the knock further; but I think I may have jumped the gun on this. After just re assembling the sump etc, I went for a test drive and the sound was present. Next morning to work(22min away) was fine no sound, pressure didn't go below 20psi. Heading home in the arvo when its hot same thing didn't go below 20psi, and the sound was barley audible. Check oil level and went for a drive again and it was basically gone; just a tiny sound and the tappets occasionally ticking; Going to monitor it.

This is all fine and dandy but I do have some oil leaks now, ones that drip on the exhaust and only do it when in motion, need to sort those out.

I took some pictures when I had the cam covers off just to give you some reference of the level of sludge.
IMG_1348.JPG
IMG_1349.JPG
IMG_1350.JPG
 

Surfwagon

Well-Known Member
Joined
Jun 8, 2006
Messages
1,780
Reaction score
42
Points
48
Location
Sydney/NSW
Members Ride
AMG Mercedes C63 Wagon
Alloytecs should only be ever run with Full Synthetic oil.
That sludge seems to be a common factor with those engines.
Doesn't help that Holden services them with std mineral oil usually unless you specify full synthetic
 

timmanderson

New Member
Joined
Dec 30, 2012
Messages
8
Reaction score
0
Points
1
Location
TARANAKI NEW ZEALAND
Members Ride
Holden Monaro 5.7
I need to isolate the knock further; but I think I may have jumped the gun on this. After just re assembling the sump etc, I went for a test drive and the sound was present. Next morning to work(22min away) was fine no sound, pressure didn't go below 20psi. Heading home in the arvo when its hot same thing didn't go below 20psi, and the sound was barley audible. Check oil level and went for a drive again and it was basically gone; just a tiny sound and the tappets occasionally ticking; Going to monitor it.

This is all fine and dandy but I do have some oil leaks now, ones that drip on the exhaust and only do it when in motion, need to sort those out.

I took some pictures when I had the cam covers off just to give you some reference of the level of sludge.
View attachment 195292 View attachment 195293 View attachment 195294
In the past couple of years i have done a few timing chains on theVZ 3.6 motors and had 1 that started ok and about a couple of minutes later would rattle, What i found was that under the lifter oil gallery it was full of crap that the oil couldnt get back down to the sump, I think it was due to the lack of oil changes, I'd pulled the motor from the car and stripped it and thoroughly cleaned it, I got 1/2 a 2ltr ice cream container of crap.
 

gungazza

Well-Known Member
Joined
Feb 8, 2005
Messages
1,560
Reaction score
114
Points
63
Age
64
Location
west suburbs
Members Ride
executive vt 5.0lt VZ CREWMAN
I would say cam chains ,how many ks
 
Top