Help with Engine knock - rod bearing/hydaulic lifter/fuel injector, which one?

[abhusa]

I think you are barking up the wrong tree with the lifter additive. Defective lifters usually get lose, not tighter. A slightly burned valve will cause your symptoms. You need a compression and preferably a leak down test to rule out mechanical issues.

I'm not super familiar with the Barra engines except that they have a very good reputation in general. Is 2007 one of the years where some of them had valve spring breakage?

Hi, I agree it most likely is a valve issue. But like I mentioned d earlier manually cranking the engine seems impossible for now until I figure out how , for the leak test. I have the 190 Barra 4l, they are considered bullet proof. Car will likely break apart before the engine. Another engine would probably have conked off or puttered if it were a burnt valve. This one drives like it doesn't care. I have a boroscope , wondering if I can glean any info thru the spark well with it. Not high resolution, but should be good enough. There are plenty of anecdotes online that state their lifter noise went away with an additive. I added it to see if it might be a stuck lifter, not thinking it to be a permanent solution. I will give it a couple hundred KMs and let you know. If it does quieten a fair bit, then about 8 months down the line I will add rislone which claims to clean the valves and lifters. By then I should have figured out how to do the leak down. In any case my fuel trims have sorted themselves out and are balancing to +-10, combined. Only a problem at idle which reads -12.5 LTFt, which I think is livable.

 

[abhusa]

I think you are barking up the wrong tree with the lifter additive. Defective lifters usually get lose, not tighter. A slightly burned valve will cause your symptoms. You need a compression and preferably a leak down test to rule out mechanical issues.

I'm not super familiar with the Barra engines except that they have a very good reputation in general. Is 2007 one of the years where some of them had valve spring breakage?

Hi,
one thing puzzling me is if it were a burnt valve, I would imagine the rough idle would not go away when engine is hot. But am absolutely sure the rough idling often times reduces quite a bit to being of not much concern, when engine temp is past the quarter mark. If it were a burnt valve, i can only imagine the valve face is expanding due to thermal expansion to close the tiny hole/trimmed edge that might exist to reduce the rough idle.

 

[kschachn]

How’s the leak down test coming?

 

[abhusa]

How’s the leak down test coming?

I cant get to the crankbolt to get the cylinder head to TDC. Its placed inline towards the front, and between it and the radiator fan, there is no place to barely fit my hand leave aside a wrench. I am going to see if can get my hands on a vacuum gauge. Should give me the same overall end result i am after, which is to see if i have a sticky or burnt valve and much easier.

 

[kschachn]

I cant get to the crankbolt to get the cylinder head to TDC. Its placed inline towards the front, and between it and the radiator fan, there is no place to barely fit my hand leave aside a wrench. I am going to see if can get my hands on a vacuum gauge. Should give me the same overall end result i am after, which is to see if i have a sticky or burnt valve and much easier.

A vacuum gauge is not a substitute for a properly performed leak down test.

You're continuing to shoot at everything but the target.

 

[abhusa]

Incase anyone is interested I have figured out what happened. Leak test is a long wayz away as not in the mood to remove any parts for something I am pretty sure off. Will post results of a vacuum test when I do it and it is a valid test to know if one has a burnt valve somewhere in the engine. I got the car cheap (so I thought) and it was shuddering at idle, but i just thought it would need new plugs and coils at most. Subsequently, when I did the smoke test, discovered the oring leak in injector 1, head side, and changed O-rings, then changed the injector , issue continued. Nothing seemed to fix the issue and it didnt feel like a lifter tick or rod bearing, hence came on this site. What I believe has happened is the previous owner neglected the bad oring which was causing a super lean STFT LTFT ~~16%. Probably more in actuality. After fixing the Oring the shudder didnt go away, by then damage had occured and a valve had burnt off (before I bought the car). A super lean mixture can burn off valves. And am pretty sure that is the case. Now the car is old and I am cheap, so I am gonna let it run till it dies and just do the usual maintenance on it. If I can get 30k kms out of it, got my money's worth. Let us see.

 

[Barkleymut]

Any chance it is an exhaust manifold leak? Does the noise go away after the engine is hot?

 

[abhusa]

Any chance it is an exhaust manifold leak? Does the noise go away after the engine is hot?

Not likely, I don't hear any hissing sounds or see any visible cracks. The O2 sensor reads correctly . Also, an exhaust leak would cause a lean condition not rich.

 

[kschachn]

How's that vacuum test coming along?