I've recently replaced the engine in a 2004 Focus. Before putting the new engine in I checked the con rod bearings and the bores. There was no marking at all. The whole engine looked pretty clean inside. I gave it a new cam belt and tensioner. Now I have it running it's making a rhythmic rattling/squeaking noise.

Any ideas what's wrong?

I've tried running it without the aux belt and it still makes the noise. As far as I can tell, the noise is coming from the middle of the engine. There's no smoke from the exhaust. The noise is still there but faster at higher revs, and still there when it's warmed up. The engine revs up fine without hesitation.

Here's a video, although it's a lot squeakier in reality.

Sounds like cam followers or a small end bearing.

Try pulling off one plug lead at a time , with the plug not firing it may be possible to at least identify which cylinder is causing the problem . May be worth doing a cylinder leakage test as well? Difficult to diagnose noises when using a video or as one of my previous employers asked me to do ,over a mobile phone

When my Blacktop made noises like that it turned out to be piston slap from a very badly worn piston [it still went well and dind't smoke though!]

Having said that my guess on a silvertop would be htdraulic tappets.

Stu

From previous experience with bike engines, it could actually be a big end. It's amazing how sound 'travels' up the engine to make it sound top end.

Try a stethoscope if possible, or use a very long screwdriver with one end on the engine and the other to your ear, you will soon track down exactly where the tapping/knocking originates.

Looks like I'll have to get the sump off again. :/ Good job this car isn't costing me anything.

It's actually piddling oil out from somewhere around the front crank/oil pump. Maybe it's not getting oil to a main bearing and it's worn down. Looks like there's plenty on the cams though. I'll check the front oil seal and the main bearings when I can and report back.

I whipped the sump off and checked the con-rod bearings.

Not my photo (it was getting dark) but they look similar to this, although not as worn as the top one here:





I couldn't sort the oil leak without getting the crank pulley off so I'll try that another time.

quote:

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Originally posted by SJ
When my Blacktop made noises like that it turned out to be piston slap from a very badly worn piston [it still went well and dind't smoke though!]


Stu

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Interesting. Mine was the same - one worn piston on an otherwise decent engine.