Engine Knock (rattle)

[78ScottsdaleK20]

So I drove it over 600 miles with the noise that I had. The noise got progressively worse and louder. I stopped driving it because it was getting worse and the check engine light had come on. I have ordered some top end components such as 2 valves, 2 lifters, and a valve cover.

I will be breaking into the head and checking the valvetrain, and quite possibly as simple as dropping in one or two lifters depending on my findings and hopefully the problem is settled. If not I will do a head job on it.

Anyone have any suggestions on what I should anticipate while inside the head? Tips, tricks or otherwise some wise advice on making the job easier? If I need to replace any valves I will need to yank the head off. That means more parts and since it will be off, I may as well have the whole head gone through, so I wont have to later and all the parts are of the same condition and age.

I will report back with some findings and hopefully it can be of help to others.

Any and all comments and or suggestions are welcomed!

Thanks,

Mike

[PrecisionBoost]

I had some knocking I thought was "top end"

Much to my surprize after opening her up I found that one of the con rods had bent ( probably hydro'd ) and the knocking was the sound of the connecting rod smacking the block!!!!!

It was quite hilarious..... the one piston was about 1/4" down at TDC

So.... I hope your luck is better than mine... after swapping parts between this engine and another engine I ended up with a decent engine installed only to find out the hybrid had a dead oil pump so it's just sitting there in the car.... I don't feel like ripping out the oil pump after putting in all the labor in putting it all together)

I'm going to assume here that you may have a stuck or broken hydraulic lifter.... so that basicly means there is no valve lash adjustment and your cam is slapping the "basicly solid" lifter that has significant play.

This would most likely become worse with thinner viscosity oil and over time the lack of hydraulic action would cause a pretty serious knock ( which may trigger the factory knock sensor )

[78ScottsdaleK20]

So I tore into the head, and didnt really find anything that was obviously wrong, or at least didnt look too wrong until closer and further inspection.

I was looking at the wear patterns on the camshafts for both the intake and exhaust and noticed they were different from cam to cam. The intake cam had wear patterns that were not smooth and even they had what looked like lines, like there wasnt constant pressure on the lobes. The exhaust had signs of smooth and even wear patterns like there was constant pressure on it from the lifters.

When pushing down on most of the lifters, they were solid, (like they are collapsed and or acting like a solid lifter). A few could be pushed down and compressed like the new ones I had just bought. Also on two specifically, (one on the second lifter on #2 cyl and second lifter on #3 cyl) there is significant circular wear on the top of the lifter. Like there was a gap between the lifter and cam lobe.

I took measurements of the cam lobes for both intake and exhaust cams with a micrometer and all seem to be good at 1.860-1.864 inches or 47-47.2 mm. So I dont think any lobes are flat.

Looking at the wear marks on the intake cam lobes that are jagged lines and are not indicating smooth contact I am suspecting that the lifters are acting like solid lifters and are not taking up any of the slack like a hydraulic lifter should be. On another note, there was no sign of excessive wear on the valve stem tips or any sign of failure of valve springs.

I would post pics of the camshafts, but for one, I couldnt get a clear enough pic to show the uneven wear marks and two I tried to upload some pics, and they are too big, and I have a million other things to do than fuss with the computer...

So if any of you are reading this, drop me a line and let me know what you think. I think the overall health of the engine is pretty good looking at what I have seen thus far. I'll drop sixteen new lifters in and see what happens, and I'll report when I get some results.

Until then, any and all suggestions, comments, or otherwise is greatly appreciated.

Thanks for taking the time to read.

Mike

[PrecisionBoost]

The lifters in these engines are not that great.... during various engine swaps/teardowns/build ups I found many lifters that were either completely solid or broken.

So.... I hope your new lifters do the trick.... Really I don't think there is much else on the top end that could be giving you the knocking like you described.... unless of course one of your oil passages are plugged up and your not getting oil into the upper end ( not overly likely )

Chris