Top end rattle

[phil2.016v]

Hi everyone,

I have a 94 S2 Avant with rattly followers. The oil pressure seems to be ok–1.5 bar on tickover, rising to 4.5 when driving. The cam followers were replaced 10k miles ago and the oil pick-up was cleaned at the same time. The rattle gets worse as the engine warms up because of the thinning oil but sometimes dissapears and it sound fine!!

Any ideas would be appreciated!

[iain1067]

Might not be the new lifters, could be cam chain

Iain

[BRY]

Shouldn't have those issues at your mileage.
How often do you check the oil level?

[Jamo]

What oil are you using?
i had this with Castrol 10W40 when i went to 10W50 and 10W60 the rattling went.

[S2 Ant]

I would say that simply putting in thicker oil is not the solution, it simply hides the problem. Its doing it for a reason and shouldnt be, 10w40 is more than adequate.

[mcandmar]

Could it be your PAS pump? The piston part of mine is worn and rattles, sounds just like a noisy lifter.

[phil2.016v]

Top end rattle

Car has covered 110k miles and has been fully serviced at every schedule, oil was changed again yesterday to oe spec and the rattling has remained the same. Could it be a partially blocked oil pickup? The pas pump was changed 2 weeks ago because of a leak which turned out to be a knacked rack hose!! Fun eh!

While we are at it, what boost should a standard car produce 7-10 psi or more?

Cheers

[phil2.016v]

I suppose that's what you get for 2600 notes!!

[A1QSHIP]

When I purchased my coupe with 52,000 miles showing, I had a "rattle" in the top end of my 7a motor. I was told it was most likely a distributor gear so I ordered one. While waiting for it to arrive I made a trip of about 100 miles at a "spirited" hi-speed pace. During the trip the oil warning lamp came on. Stopping to investigate I discovered that I was two quarts low on oil. Since the oil level had been checked prior to the trip, this meant that the engine had consumed the oil during the drive. Added to this was that now there was an ominous knocking noise in the engine. There were no external oil leaks evident. Disassembly of the engine revealed #3 rod bearing had spun and the top of an exhaust valve guide had been worn away by a broken inner valve spring. The oil had simply gone past the valve guide and been burned up in the catalytic convertors. It turned out OK for me as I got a "basket of snakes" with the replacement engine.

[Greg_S]

Could it be a partially blocked oil pickup? The pas pump was changed 2 weeks ago because of a leak which turned out to be a knacked rack hose!! Fun eh!

While we are at it, what boost should a standard car produce 7-10 psi or more?

Cheers

yeah it could be the oil pick up, the strainer might have got gunked up

[mcandmar]

"top of an exhaust valve guide had been worn away by a broken inner valve spring"

Funny that as i had a similar problem on my 7A, when i first got the car it didn’t make any noise but would cut out at 6300rpms very suddenly. Turned out it had a broken inner valve spring and a bent valve. I assume the bent valve was the metallic sounding rev limiter at 6300rpms Since sorting that it runs sweet as a nut to 7400rpms.

I'd never heard of broken valve springs on these engines but it’s a possibility if your getting a noise in the head?

[phil2.016v]

Still rattles, and I've noticed that the oil pressure drops to 1.1-1.2 bar on warm idle. I think I'll change the oil pump just in case.

Anyone know how much they are?

[phil2.016v]

The Avant's on the ramp again today with part of the sump removed, the pickup looks fine and I noticed in the history that it was cleaned around 9 thousand miles ago when the new lifters were put in, might have to change to thicker oil for now and then maybe check the big ends and mains for wear which might cause a drop in pressure up the top.?

[Greenm3]

Have a look at this thread if i recall there is a valve which controls the oil level in the head mayb this could be a cause?

http://www.s2forum.com/forum/showthread.php?t=3458&page=1

[phil2.016v]

Good info, cheers for that. Problem is, mine rattles when it's warm. I've looked at the oil pick up today and it's clear as I suspected, so I got the lads to put some 5-50 synthetic in it for now.