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Noisy 4.8 engine

Posted: 27 Aug 2013 08:21
by pdasilva
When starting up my Patrol this morning it sounded like a tractor for the first 10 seconds. This is the first time that this has happened. While riding to work the tappets sounded a bit noisy or I think it was tappet noise. The Patrol is on 112000km and last service at 100 000km with previous owner at Nissan.

Any idea what would cause this ? I will be changing the engine oil with Magnetec as well as filter tonight to see if this resolves the problem.

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 08:32
by ricster
I like the Delo 400 oil more than the Magnatec.... just a personal opinion. I use it in my SANI 3.0 V6, and made it sound a lot better than when I used other oils..... and then works great on my 4.2 turbo diesel

sounds like hydraulic lifters aren't getting well oiled on start up. Do a good engine flush to get the old oil that may be gummed up inside and flush with a cheap oil, then new filters and oil and all should be well

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 11:29
by Stefaansie
Hi,

Just yesterday I thought about it again when I heard a LC diesel, oldish but as quiet as you can get. My 4,2 diesel(140K km) is extremely noisy aswell. The book says to adjust or check the valve clearance every 20K km. This has been done by SAC Boksburg, but its still noisy. Only thing that I can now replace is the push rods, at R280 a pop, I need 12.
I dont know the 4,8 petrol, but at that mileage It doesn't sound right.

For my petrol vehicles, I use Castrol Edge 5W40. Fully synthetic. I was even contemplating to use it in the Diesel Trol. Maybe even the Edge Sport 10W60. IMHO that might be the very best oil money can buy.

Some other oil that might do the trick is this ultimate stuff from shell Helix, they used it in that Patrol Extreme challenge of some sorts. Google is your friend.

If I might add. Never cut back on oil costs. Give your Patrol the best.

Regards,

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 13:19
by Wheels
If it sounds like tappets , it could be. The 4.8 motor uses shims with a overhead cam. No push rods etc. I have heard about a case where the shim got dislocated.
Also make sure you have enough oil pressure. Make sure your oil light in the dash is working.

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 13:21
by Grant
Andre,


Push rods at the mileage you have is very early. Mine have never been changed at 395k km. Suggest you visit SAC Centurion . Gerhard has never had to set the tappets as they are quiet and troll is running very well.

:mytwocents: :mytwocents: :mytwocents:

PS Agree with Cedric. Delo 400 is the only oil I will use int he Troll. Engines is not made for the full synthetic stuff. Delo does wonders as the troll runs better and also oil pressure does not drop down as much on low rpm.

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 13:33
by Stefaansie
Thanx Grant,

Yeah I've spoken to someone else about the push rods, and he also recons its might rather be the tappets. I'll speak to Graham about the valve clearances and see what we can do.

In the meantime i'll stick to the Delo 400 then.

Sorry for the Thead-jacking.

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 13:47
by PathMaker
Hi Paulo
I have spoken to Graham husband & mechanic) about your problem and his comments are as follows :
1. 4.8 Patrol is a skim head motor so no tappets to adjust or set.
2. You problem is most probably low oil pressure and he agrees with the engine flush (use the actual engine flush product here to loosen gunk/sludge), run the car hot, drain oil (up to you if you want to reflush with cheap oil) and replace with new oil filter & good quality, relative viscosity oil.
3. Graham also recommends a 15W40 oil. (AGIP truck or truck plus also a good oil with similar properties to Caltex Delo 400).\
Hope this helps.
Chow for now
Vanessa :salute:

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 13:56
by ricster
Just following on the hijacking.... :redface: ..... it might be that the rocker arm where the valve stem (Valve stem clearance) connects has a slight indentation. The gap between the rocker and valve stem should be 0,34mm ( if I'm not mistaken) on a 4.2 diesel. I have personally set mine and still have a slight tick tick from one or two rockers. So I'm assuming that the gap is about 0.38- 0.4mm even when I fit a feeler gauge in there at 0.34mm. This can be cured by either refacing the rocker arm, or reducing the gap to 0.30 - 0.32mm.

I think the problem becomes bigger as the bigger the gap is the more it bangs the top of the rocker arm and the more it deforms the rocker arm face, and so the problem gets worse..... just my theory anyway

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 14:15
by Wheels
If it sounds like tappets , it could be. The 4.8 motor uses shims with a overhead cam. No push rods etc. I have heard about a case where the shim got dislocated.
Also make sure you have enough oil pressure. Make sure your oil light in the dash is working.

Re: Noisy 4.8 engine

Posted: 27 Aug 2013 16:59
by Peter Connan
While I am not discounting any of the above, I have heard of several 4.8's and at least one 4.5 where the exhaust manifold or the bolting thereof has failed. This can make a very similar noise in the early stages, and particularly the cracked manifold sometimes seals when temperature has been reached...