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Discussion Starter · #1 ·
Right folks...

Headed into my mechanic today (Mathew as always top guy, really helpful) to get an oil, plugs and air filter change, and also took the chance to check on some annoying noise coming, seems, from the left (far-side) engine bank/side. It sounds clearly as a rotating noise. This is coupled with relatively low engine pressure at service temp on idling; 2 weeks ago @ Joe Macari's service day we hooked-up the SD2 and it was reading 1.7 to 2 bar, which made me a bit concerned.

We (both Mathew and myself) looked around with a stethoscope... no noise coming from the timing chains, no weird noise from the tappets, none from the top of the engine block. The engine, however, has a loud knocking-like noise. Fuel injectors were a bit louder than usual, but that noise was defo not coming from there. BTW saw a 4200 engine dismantled to note the timing chain guidelines/tensioners had snapped... which, seems, is a nasty habit in some late example cars, esp. Gransports. That's why that area of the engine was inspected first, to check if it was one of the chains knocking. But nope.

I'm heading-in next Saturday with more time for a thorough test to find the sucker, but welcome any ideas/suggestions. Interestingly, the oil pressure seems to have gone slightly better after the oil change (used Silkolene Pro S 5W-40) but it's not good enough. I'm guessing it could be the oil pump, but oil pressure goes up to 5 bar immediately with the pedal on the gas, so the car runs well. I must say very well. No problems with acceleration, or response. But that noise...

BTW looking at the oil coming out it showed no nastiness (metal residues, etc.); it looked very clean I must say.

As a sideline, when starting from cold (say, in the morning) you can hear like a metal sheet sligtly knocking, again, from the far-side, noise that dissapears once the engine gets warm. We had a quick look at the steering rack on the lift, but again, it is a rotational noise.

If anyone has an idea/suggestion/faced this, please drop a comment.

Cheers,

Ed
 

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Low oil pressure will cause rod knocking...

Ed,
low oil pressure at idle can cause rods to knock on the crank bearings. Once you get the RPM up enough the oil pressure builds and the knock will go away, that is until after you run for a while with low oil pressure and then the knock will start going away at higher rpm than before, etc... The low oil pressure could be causing a starve condition for oil on one of the rods...
Changing oil will help the low rpm oil condition for a little bit on a weak oil pump as the new oil is not as thick as the old oil at low temperatures and therefore easier to pump. Most people don't think about it but oil actually get's thicker with use, not thinner, with the iron filings and heat....
I would bet you have a weak or clogged oil pump, would take it very easy until after you get it checked out for sure....

Also, one of these up through the drain plug or down from the spark plug hole on the engine will allow you to see all sorts of good stuff...

http://www.griotsgarage.com/product/tools/specialty+tools/video+boroscope.do


Another condition that came to mind is piston slap, which is caused by a forged piston with a worn piston skirt. The slapping noise is a knocking until after the engine warms up and then the noise will go away once the piston has expanded due to heat gain...
 

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Discussion Starter · #3 · (Edited)
Ed,
low oil pressure at idle can cause rods to knock on the crank bearings. Once you get the RPM up enough the oil pressure builds and the knock will go away, that is until after you run for a while with low oil pressure and then the knock will start going away at higher rpm than before, etc... The low oil pressure could be causing a starve condition for oil on one of the rods...
Changing oil will help the low rpm oil condition for a little bit on a weak oil pump as the new oil is not as thick as the old oil at low temperatures and therefore easier to pump. Most people don't think about it but oil actually get's thicker with use, not thinner, with the iron filings and heat....
I would bet you have a weak or clogged oil pump, would take it very easy until after you get it checked out for sure....

Also, one of these up through the drain plug or down from the spark plug hole on the engine will allow you to see all sorts of good stuff...

http://www.griotsgarage.com/product/tools/specialty+tools/video+boroscope.do


Another condition that came to mind is piston slap, which is caused by a forged piston with a worn piston skirt. The slapping noise is a knocking until after the engine warms up and then the noise will go away once the piston has expanded due to heat gain...
Thanks Mark, this is great feedback... luckily I haven't been using the car that much, so have not piled-up mileage on with this condition running. As I said, my bet is the oil pump, which is a sucker to replace (will cut no corners there).

We used a stetho + an ultra-sound boro (not a video one; that's some neat gadget...) but now I'm a bit concerned about the rods themselves. If it is a piston that's some major work. Fortunately, the car is under warranty but I'm beginning to get pissed-off, as I've been arguing with the dealer about this and they repeatedly say "it's normal" (even the oil pressure drop, "all Gransports do that" I was told...) against me arguing "that's NOT fu***ng normal..!" :mad:

Thinking of asking for a full engine inspection.

Thanks again Mark..! ;)
 

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One thing to mention, a while ago I had my pressure drop and the red light come up... It was a very hot day and I was driving agressively. anytime I came to a stop, the pressure would drop and the light would come on, as I started driving, the pressure would rise and the light would go away. I talked to the mechs and they said that if one drives VERY aggressively, it happens, and it is nothing to be worried about.

I checked the manual and it says the same thing :]

In regards to a pinging/knocking sound from the engine... What oil are you using? I know that Ferrari Maserati of Orange County told me that when customers complain of that, they use Mobil1 Full Synthetic... and it gets rid of it (thats what I did :D)
 

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Discussion Starter · #5 ·
One thing to mention, a while ago I had my pressure drop and the red light come up... It was a very hot day and I was driving agressively. anytime I came to a stop, the pressure would drop and the light would come on, as I started driving, the pressure would rise and the light would go away. I talked to the mechs and they said that if one drives VERY aggressively, it happens, and it is nothing to be worried about.

I checked the manual and it says the same thing :]

In regards to a pinging/knocking sound from the engine... What oil are you using? I know that Ferrari Maserati of Orange County told me that when customers complain of that, they use Mobil1 Full Synthetic... and it gets rid of it (thats what I did :D)
Hey Ali..!

On the oil, I do use Silkolene Pro S 5W-40, which is the best oil you can get on the European market... it is really a treat to the engine... well, at 200 bucks an oil change supply, it well be..! I could use Mobil 1 but this thing is SO much better... tend to agree with Mark it might be a weak oil pump. Will know next WE.

The oil pressure should be at 2.5 bar on idling... at least here dude, this is not Cali weather-wise :D
 

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Oil pressure should never be low... ever. Driving fast is no exception. It will damage your engine immediately. If you're noticing it, it's already hapenning. If it's happened, it will get much worse, even if you get it to stop knocking now. Once those machined surfaces aren't smooth and protective coatings have been worn the material will begin to fatigue, it's just a matter of time.

Take it to the dealer and tell them to go through the car. Escalate to the manager if needed, tell them you've heard some very bad noises. You should NEVER hear knocking. These guys amaze me... I would not settle for a new pump if you're under warranty. Make them have a look at the rods and inspect the bushings. Piston slap is possible but I would be suprised.

Good Luck
 

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Discussion Starter · #7 ·
Oil pressure should never be low... ever. Driving fast is no exception. It will damage your engine immediately. If you're noticing it, it's already hapenning. If it's happened, it will get much worse, even if you get it to stop knocking now. Once those machined surfaces aren't smooth and protective coatings have been worn the material will begin to fatigue, it's just a matter of time.

Take it to the dealer and tell them to go through the car. Escalate to the manager if needed, tell them you've heard some very bad noises. You should NEVER hear knocking. These guys amaze me... I would not settle for a new pump if you're under warranty. Make them have a look at the rods and inspect the bushings. Piston slap is possible but I would be suprised.

Good Luck
Thanks Jeff, very useful (despite not leaving me in cheering mode) comments as usual.

Car is now booked to go to main dealer on 07/22, but my trusted friend Mathew will have a deep look on Saturday to try to identify the source of the noise.

Will keep everyone posted. If indeed is the oil pump, then I will take it as Jeff suggests and will not settle with just a pump replace, but will expect a comprehensive bill of health.
 
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