4.6 noise. Video inside

[Niva]

Hey guys,

I have a 1998 HSE (p38a) with a rebuilt engine about 70,000km ago

Recently I noticed a very diesely sounding noise just above idle when cold. Only happens at cold and only betwen idle and say 1800rpm

Madr a video so thought id chuck it up and get some expert opinions :) cheers!

James
https://youtu.be/OFQBHBvlyww

[redandy3575]

Only speculating here.

Possibly incorrect grade of fuel.

Exhaust manifold gasket. As it warms up, the gaskets expands, but when cold it may leak a bit along with some faint un-muffled noise. That s what it sounds like.

[Pedro_The_Swift]

could be a couple of cylinders missing,,,

[prelude]

I don't want to hijack this thread but I believe I have a similar issue with my engine. If I heard it correctly.

I added a video which has the ticking sound more pronounced. The engine only does this when cold and I am not missing any coolant etc. so it does not seem to be the dreaded cylinder liner problem. At first I thought maybe a valve job was needed but I would not expect that to go away when the engine is warm.

A gasket seems a legit option but I can not feel any air leeking and the tick is on the loud side for just escaping air. Any more suggestions?

[Keithy P38]

Sounds like a broken rocker to me...

[banarcus]

After listening to that, yep have to agree with Keithy. Definitely something not right under that rocker cover.

Sent from my SM-N9005 using AULRO mobile app

[Pedro_The_Swift]

If the rocker cover had to come off,,,
whatever else you find wrong--
I'd be retensioning the head bolts,,

why?
because you can.;)

[bee utey]

Cracked exhaust manifolds tend to quieten down after they get hot and the cracks close up.

[prelude]

Thanks for the tips.

Since my wheel bearing is shot and the car has not moved in a while I can see quite a bit of oil that has leaked passed all sort's of gaskets so I think it is just about time to give the V8 a long deserved overhaul soon. Not sure if I am going to invest a a complete rebuild engine, do the work myself as a hobbyist (with all the risk involved) or just do the needed.

Anyone have any thoughts on that?

Cheers!

[Pedro_The_Swift]

Our RV8 is not a technical marvel:angel:
Lots of info on (here) how to replace gaskets properly.

[FANTOM P38]

Could it possibly be a sticking lifter?

[mtb_gary]

Do you have a compression guage or know someone locally that has? A compession test is a good non invasive test. Anothr test would also to hold a strip of paper over the exhaust whilst the car is idling. If the paper doesnt stay steady indicating an evenr exhaust gas flow but rather gets sucked in to the direction of the exhaust then out again you could be looking at a blown head gasket.
The noise sounds very similar to mine when i blew the head gasket between the 2 front cylinders on the lhs bank. I had a rough idle, lacking in power, below 2000 rpm and was drinking fuel like there was a hole in the petrol tank.

[PLR]

G`day ,

i know my hearing is rubbish but for me the duration and clarity of both tell me little .

I`d suggest you both need to localise your individual noise to be able to guess at what it may be .

Generally a stethoscope will be useful , be it screwdriver with your thumb on the handle end to put to your ear or a rod used the same way even a length of hose can work or flash one can be bought from auto parts places .

Once you work out where the noise is coming from and if it is mechanical or not this will help eliminate alot of options .

Cheers

[prelude]

Thanks for the tips! A compression test should be doable, I think a mate of mine has one.

Regarding the exhaust, my car came with an aftermarket cat-back stainless steel exhaust with dual mufflers. One each side of the car. Does the paper strip trick still hold with that configuration?

Also, with a blown head gasket, should the car not use/loose oil or coolant? There are no signs of either, except for leaking oil that is.

Since the latter is getting worse it may be time for that overhaul... :cool:

[mtb_gary]

When i blew my head gasket, it was between cylinders. No coolant loss or exhast gas in the oil. I would imagine the paper test could be done on both exhausts. It should not be sucking air back into the exhast.