Timing chain slap/rattle BAMBOOZLED

[jakeb]

Would it seize up or down in the bore?

[jakeb]

I had checked that gasket multiple times when I put it in. 99.9% I have the correct one. If I remember correctly the other one didn't match at all.

I am also using the newer plastic style pressure release valve. I JUST pulled the lower oil pan to pull that valve out. When I pulled the spring out the valve didn't just drop down and out of the bore. I had to pull it out..... What would it do it is was sticking all the way up? Does that valve route out up to the top of the head as well?

This is a new engine but MANY of the prior starts there was no noise.....

[bmwman91]

Oil to the tensioner is provided by the long groove in the back of the timing case, not via the head as far as I recall. If you use the later timing case, you MUST also use the later steel case-to-block gasket associated with it. The groove that supplies the tensioner is in a different location on the two cases, and the gasket is also slotted differently. It could be that if there is a gasket mismatch, it is has plugged up the passage. The oil should come up to pressure within a second or less, so if it is taking longer than that, your issue may also be there. The original oil bypass plunger in the timing case was metal and prone to seizing open. A newer design was released that was plastic, so you may want to consider replacing the plunger/spring/etc (check RealOEM) if it is original...maybe it seized?

[jakeb]

It has the early (metal) oil filter housing.
Later front timing chain cover without the idler gear.
The oil pressure check is in the head replaced it.

Checked multiple times I had the right gasket for the front part....

I wouldn't think the tensioner could go loose either. It's pretty stiff with the spring and once oil is in it. But every cold start it has a lot of chain slop and noise....

Not sure how the tensioner could go loose every cold start. I've built other m42s and never had this issue...

[varg]

The M42 oil pump suction side is the square hole on the bottom of the timing case, and the discharge is the top of the two stacked square holes visible when the oil filter housing is off. The pressure relief valve is visible through these ports, the lower of the two is completely blocked when the relief valve is in the normal position. When the relief valve opens the bottom port which is connected through to pump suction is opened and pressurized oil is allowed to recirculate through the pump.

Are you using an early or late style oil filter housing? The late style has a removable anti-drainback valve which goes into the round port in the timing case, the early style has an integral anti-drainback valve in the round discharge port of the housing.

The tensioner is fed oil through an oil gallery in the head. There is a check valve in the block-to-head interface on some late M42s, which probably has something to do with a change to the head casting.

If this M42 you've built is a frankenstein of older and newer parts, it's possible one of the valves isn't there, or that the wrong timing case gasket was used which can interfere with some of the passages in the case. If not, I'd check the rail and make sure there are no defects and then the dowel it pivots on. The tensioner should not go loose even if oil pressure is lost, it has a fairly strong spring in it.

[jakeb]

but it goes away once pressure comes up....

Does anyone know just how the pressure relief valve works?

[MrBurgundy]

Maybe you blocked an oil passage when putting on new the new seals and gaskets.

[MrBurgundy]

something to do with the oil pressure.

[jakeb]

Have an m42 that I built for a turbo 2002. EVERYTHING inside the engine is new other than cams, lifters, crank, and rods. I recently started having an issue where when the engine is cold the timing chain slaps and the rail hits the inside of the timing chain case. Ran the car with the valve cover off and could see the rail moving. Once the oil pressure comes up the sound goes away after about 15 seconds.

I replaced the timing chain tensioner with a different one...came from other car with zero noise. I had actually swapped the tensioner that was in this car to the other car and no noise there either but...

I had squeezed all the oil out of the tensioner multiple times and thought the sound was gone but...nope.

I have built a couple of these engines and swap A LOT of them into 2002s.

I am somewhat at a loss as to what is going on now....
I am now wondering if there is something wrong with the oil control valve in the oil filter housing or a check valve somewhere.
If anyone has any ideas PLEASE post. I am trying to get this car done for Vintage in NC which is quickly approaching.