I got my car back nearly four weeks ago after having the engine rebuilt with a new direct from Subaru short motor. Ever since it has knocked on start up, only for about half a second then it stops and doesn't return. If I stop the engine and start it within a couple of minutes the knocking doesn't happen, but if I leave it for a while it knocks.

I tried starting while watching the oil pressure light and the knock coincides exactly with the light being on. The car runs fine and is smooth and pulls really well. It does make a very slight scarping noise at idle from around the turbo area.

I am approaching the end of the 1000 mile running in period (kept to less than 3500rpm and no laboring the motor as recommended by a reputable tuner). I will change the oil and begin to incrementally increase the revs.

Surely this knocking can't be right, I have done everything I was told religiously. Has anyone experienced the same think?

Stevo

 

If its still on "run in" oil, it may take longer to pressurise the lifters.

I would wait and see what it's like after the oil change before worrying too much.

 

The knocking is a crank/main/big end type noise, It is not a tapping a lifter would make.

 

It should not knock at all on a new short engine; did they replace the oil pump? You will need to get the oil pressure checked, or give it back to the person who re-built it to get it tested, even with running in oil there should be no unusual noises.

 

Knocks are serious. Get it looked at ASAP and don't run the car.

 

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Yes a new oil pump was fitted.

I have spoken to the firm who fitted the new short motor, they have agreed to take the car back. I have no reason to doubt their word as i have dealt with them before and I've always had the impression they are honest and have the customers interest at heart.