Cold start kock, oil starved? OIl filter?

Messages
97
Location
Long Island, NY
VW Passat 1.8t When the car is cold, as soon as i turn the key and for only like a fraction of a second the motor has a slight knock. Im talking half a second to 1 second. I guess it takes a that much time for the oil pressure to kick up? Its this normal or could it be a slightly clogged pick up tube? It seems like its starved for oil for a second then the noise is gone. Its sounds like a rod knock. The car has to sit for a few hours to have this happen again. 140K miles on the car, new oil Shell Rotella T6 and a big oil filter. It was doing this before but not as bad. IM using a Mobil 1 Oil filter.
 

Why_Anything

Thread starter
Messages
97
Location
Long Island, NY
Please dont feel sorry for me as it does NOTHING to help me understand this issue. Im going to try and OEM filter from VW tomorrow and what ever oil they would use.
 
Messages
7,485
Location
S California
You might have an oil 'sludge' condition. VW/Audi has given an unlimited mileage engine warranty on 1997-2004 model year vehicles using the 1.8t engine in the US. Look for intermittent oil light indication and/or a noisy engine. The oil pick up tube gauze filter becomes blocked with sludge causing reduced oil flow to the engine. The oil pump is located inside the sump and can be changed without engine removal.
 
Messages
26,449
Location
MA, Mittelfranken.de
You might have sludge or hard carbon particles in the pan partially restricting the pick up. IIRC these engines use a tapered cone pick up that doesn't have a lot of surface area. Nothing you add to the oil or brand and cleaning ability of the oil will clear it if it is. I would drop the pan on this one before something blows. Whatever bearing (if it is a bearing) is making noise its probably getting close to toasted and should be replaced before the crank takes a hit. This can possibly be done in the car if your careful.
 
Messages
8,311
Location
Grand Rapids, MI
I doubt a split second knock is anything to worry about. My Acura has a start-up rattle that sometimes lasts a second or two before the oil reaches the head, even with a working filter ADBV. I'm not worried about it at all. However, the 1.8T in your VW is a sludge prone motor, IIRC, so maybe your galleries are a bit clogged?
 
Messages
2,232
Location
socal
My s10 has the same cold start up knock. No check engine light. When I replaced the valve cover gaskets recently, I did notice caked on sludge under the covers. I may do a engine flush or mmo on the next oil change.
 
Messages
26,449
Location
MA, Mittelfranken.de
Originally Posted By: ThirdeYe
I doubt a split second knock is anything to worry about. My Acura has a start-up rattle that sometimes lasts a second or two before the oil reaches the head, even with a working filter ADBV. I'm not worried about it at all. However, the 1.8T in your VW is a sludge prone motor, IIRC, so maybe your galleries are a bit clogged?
Start up rattle is one thing, knock is another. This engine is well known for oil related problems the effect the rod and main bearings. A momentary knock from the bottom end after sitting a couple of hours is a good sign something is not right.
 
Messages
2,107
Location
Appleton, WI
The cam chain tensioners are a known failure part in VAG vehicles. Your symptoms sound like this is worth pursuing. Can you determine if the sound you're hearing is coming from the back side of the engine at the top of the head? You'll be looking for this part: http://www.ecstuning.com/Volkswagen-Passat_B5-FWD-1.8T/Engine/Timing/Chain_Tensioner/ES2622537/ Half of it will be hidden under the valve cover and you should be able to see the part with the 3 bolt holes with bolts in them. The adjuster is hydraulically controlled via engine oil, and there's a small screen that the oil passes through to get into the solenoid that can get clogged. This would momentarily throw the timing of the valves off until the solenoid is pressured up. Or the plastic pads the chain rides on could be worn down and the chain is contacting the metal housing at startup. That happens often in the Audi 4.2 V8.
 
Messages
5,133
Location
chicago, Illinois
I'm surprised that one of the low oil pressure warning sensors hasn't tripped yet. If they are working properly even just at start up they should trigger if there is a problem. Do you even notice that the low oil pressure warning lamp stays on for more than just a second (for the bulb test) ?
 
Messages
26,449
Location
MA, Mittelfranken.de
Originally Posted By: Why_Anything
Well i have an update, after a long drive and the car is nice and hot. I'm at 15-17 psi and [email protected] around 2000-2100 rpm. That 15-17psi number scares me. For now im going to pretend its just lower because of the $19 sunpro gauge im using.
With the engine cold is there a lag in the gauge? There is always a slight amount of lag but as bearings worn to the point of cold knock it can get more noticeable. I have seen them sit on zero for a full second or two then jump up when a bearing is going south. Get the car on ramps and leave it overnight, chock the wheels and whatever you need to do to secure the car and go under it while someone else starts it. You should hear the knock clearly from the pan if there is one.
 
Messages
468
Location
new Jersey
That noise is the tensioner for the cams .... located at the back of the head . Not a problem if it only goes on for a second or two .
 
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