Rattling sound from gearbox area

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Adam Vinnicombe

Adam Vinnicombe

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I think the jerking is me handing the phone but I will have another look to see if the engine is jerking in a bit.
 
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Adam Vinnicombe

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Right a small update.
Once again I started the engine cold and zero rattling or knocking on start up. Feather the rpm between 2000-2200 rpm rattle is there, I then unplug all the injectors on by one and and the nosie was still there until I unplug number 8 cylinder injector and I couldn't get the noise to come back so that told me that the issue is with nunber 8 cylinder. That pointed to Rod knock I think?
But I replaced the injector connection but by this time the engine was up to operational temperature and no matter what I tried I could not get the rattling noise to come back. Now I'm truly stumped
 

07GtS197

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Hmm it could be rod knock or perhaps the oil is getting thin. My 98 p71 would knock/slap a little when the oil got old and thin. What weight are you running? I would also check the oil pressure with a mechanical gauge just to see where its at especially at cold startup.


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still.doesnt make sense. im still wondering if its a mount/hanger issue or something hitting somewhere. low mileage 4.6's dont have big issues unless they had big nitrous or untuned s/c's through them. if theres no signs of sludge or really poor maintenance, dont overlook the obvious.

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Adam Vinnicombe

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As far as I'm aware it's never had nitrous, turbo or supercharger fitted. It's only got 45,000 on the clock. Going through the paper work the previous owner gave me it had an oil change done at 39,585 miles so around 5,500 miles ago but that was back in 2015 and it had 5w30 in it. I did an oil and filter change the other month and put 5w30 back in it, BUT when I drained the oil it flet like piss water it was very thin but very hot
 

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As far as I'm aware it's never had nitrous, turbo or supercharger fitted. It's only got 45,000 on the clock. Going through the paper work the previous owner gave me it had an oil change done at 39,585 miles so around 5,500 miles ago but that was back in 2015 and it had 5w30 in it. I did an oil and filter change the other month and put 5w30 back in it, BUT when I drained the oil it flet like piss water it was very thin but very hot
Is hot down where you are at , could be oil viscosity breaking down
Mabe put a little bit heavier oil in it
In the winter I run what it calls for .and summer a little more thicker oil
My summers in my area are at 100 to 106
 
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Adam Vinnicombe

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Hi mate I'm in Oxfordshire, Engine and at the moment the day time highs are only 6 degrees C that's about 42F
 

RAU03MACH

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Ok well just curious what type of oil you guys using and how many miles is it changed
Where I'm at in the u.s its 40 to 60 degrees
 

96blak54

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5w-20. The weight of oil is crucial to lasher operation. Any thicker changes how they function as hydraulic actuators. As for main bearings and rod bearings, there are few youtube vids of folks running ketchup or maple syrup as oil and the engine at full tilt!

That rattle sounds like a loose follower/rocker to me. Real thin oil like gasoline/petrol mixeda and the lashers dont operate as they should. Thicker oil and the lashers work overtime....so to speak.

That #8 injector could be stuck wide open causing a phantom problem and loading up the crackcase with fuel. It doesnt take much gas to change oil characteristic.

A simple sparkplug reading comparison should reveal a problem with that cylinder.

I hope you figure out the problem! Its instances like these that make us hate cars!!!
 

RAU03MACH

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5w-20. The weight of oil is crucial to lasher operation. Any thicker changes how they function as hydraulic actuators. As for main bearings and rod bearings, there are few youtube vids of folks running ketchup or maple syrup as oil and the engine at full tilt!

That rattle sounds like a loose follower/rocker to me. Real thin oil like gasoline/petrol mixeda and the lashers dont operate as they should. Thicker oil and the lashers work overtime....so to speak.

That #8 injector could be stuck wide open causing a phantom problem and loading up the crackcase with fuel. It doesnt take much gas to change oil characteristic.

A simple sparkplug reading comparison should reveal a problem with that cylinder.

I hope you figure out the problem! Its instances like these that make us hate cars!!!
That could be
It's hard to tell by video cant tell it's the top end or the bottom end
I hope nothing serious just something simple hopefully
 

Silver95bird

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i prefer the 5w-30 myself, i dont buy into the CAFE inspired thin oil. Those cam journals get whatever's left after the chain tensioner and cam followers leak it all out. IMO, bare aluminum cam journals need all they can get.

5w because of the tight piston to wall clearances is something id definitely stick to though.

I'm sure someone will tell me I'm wrong though, lol. YMMV, to each their own.

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Adam Vinnicombe

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Hi all. Well I took the plugs out today and they look spot on. Put them through a plug cleaner anyway and check they all sparked and they did. I also turned the engine over by hand until the pistons just pasted TDC and inserted a long rod down the spark plug hole and push hard on the pistons to see if they would move and none of them did. So if it is rod knock I'm hearing its not bad enough yet to feel the play. Next I'm going to do an oil drain and filter and see if I can see anything in the oil or filter.
 

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