Hi everyone,

My fullfat has recently developed an occasional rattle on a cold startup.
At first, it vaguely sounded to me like a starter motor, then did some search and found this video which is exactly what it sounds like. Please note that If i switch it off right away and restart, it all sounds normal.

Unfortunately there's no further usable information on the comments other than chain guides, which is unlikely as the noise is different and had them inspected recently.



It is not the well known and documented Vanos rattle either and I'm not experiencing any other symptoms, none that I am aware of at least, such as loss of power, loss of torque, check engine light or rough idling .

It doesn't sound familiar to my mechanic either. A couple months ago when we did the cam cover gaskers, everything looked normal on the inside. Even had a look down the V with a boroscope; nothing to write home about...

The car otherwise works, sounds and drives great and the consumption is also very good.

I have about 185k on it and I was thinking of doing the chain guides anyway at 220k and above. But if there's something going on I might as well be forced do the Vanos and everything at once on a single (and costly) "sweep" rebuild.
I would hate to fix something which is not actually broken though, should this turns out to be a non issue...

Any ideas and previous experiences pointing me in the right direction would be appreciated.

Thank you

Sounds to me like the oil non return valves are leaking back.. oil has to rise through the engine, on initial start up, and a small amount of engine rattle is heard... then on subsequent starts, it’s not heard, as residual oil remains in the oilways. I’d say it’s normal for your mileage. I have replaced chains and guides, and vanos seals, and at that moment replaced the oil return valves.. which are hidden behind the vanoss solenoids. It’s not a massive job to change them.. and they are only a couple of pounds each.
If you watch your oil light, I bet it takes a second longer to go out on first start, than a subsequent start...
P.s., my chains failed at 140k. Car now on 200k.

Thanks John,

Reading further on the matter, non return check valves, are more and more begining to emerge as a likely candidate. I'll replace them both next week and see if this helps. I'll try to remember to observe the oil light over the weekend, that's an interesting tip

By way of clarification it's 185000 km I have on the clock. If your chain guides failed at 140k miles, then the 220000 km would would be just about right

Hi did this sort your issue ?
I got the exact noise and I can’t find anything online about no return valves.
I might not be searching properly but I can’t find anything.
I’ve had the rattle there for 2 years

Hi, it was a combination of things. First of all the oil filter. Use genuine LR or MAN, the one with paper bottom NOT the ones with plastic. This will make a big difference.
Secondly, the solenoid seals and, finally, the solenoid non-return valves. I still very rarely get rattles but they are short and hardly noticeable.

Thanks will get those ordered and fingers crossed it improves

vs322 wrote:

Hi, it was a combination of things. First of all the oil filter. Use genuine LR or MAN, the one with paper bottom NOT the ones with plastic. This will make a big difference.
Secondly, the solenoid seals and, finally, the solenoid non-return valves. I still very rarely get rattles but they are short and hardly noticeable.

Hi, maybe its too late for giving advices on this issue.

But your rattle on cold start or after long time not running engine is in return valves but not those ones which located behind the vanos solenoids in engine heads. There is another two which are located in engine block under the engine head gasket.

Those two non return valves stops the oil leaking from engine heads to the engine block.
Number 5 on the image.
[/img]

Hi!

Thank you.

This is very good info as I was unaware of this part. I had the timing chains and head gaskets done and all I knew was there is the spacer sleeve. I went through the carton with the parts that were replaced and a non-return valve is not among them. The spacer sleeve is.
When I picked up the car after the job, startup had been quiet. As I was noticing more and more oil leaking over a period of 2-3 months the rattle was getting more frequent and noticeable.
Once a leaking oil return hose was replaced and a small pore on the rocker covers sealed, the rattling has been nearly eliminated, even in warn weather.
I don't know if they missed the non return or left it in place because it wasn't bad. Given the price though, I'm afraid it might be the former...

You are welcome.
99% of situation with rattling noise on cold start is those two non return valves.
Even if they placed them back these valves it is recommended to replace them if you have such issue.

Hope this noise will not come back again but if does you know what to do )

Mine is rattling as well, now I'm hitting my head to the wall) because I took out engine to do some service on it such as replacing timing stuff and etc , and I easily could replace those valves but I didn't)

Sometimes the issue comes from the oil valve inside the oil cup or how do you call it ) But this could be in 1% )

With the amount of work it takes just to access these, It'd better not come back ever again.

My decision is same)
If it makes 1-3 sec noise I don't care) hi volume of music is sorting my issue for now))

Sorting various external leaks seemed to nearly eliminate the problem so that's encouraging. It would be frustrating having to tear down an otherwise
perfectly good engine, messing with heads, headgaskets and blocks just for the sake of replacing a 11 euro part

vs322 wrote:

the oil filter Use genuine LR or MAN, the one with paper bottom NOT the ones with plastic

thanks for reminding me, just about to do an oil change on my old M62

You're welcome