Rod knock or lifter tap?

[Deathmug]

Hey guys, here's the problem I'm having. I did a few pulls the other day, and all the sudden I start getting a knocking from cyl #4 at about 2500 RPM, and continuing through the RPM range. At first I thought maybe it was just lifter tapping, but it does not do it at idle. I pulled the plugs while it was revved up enough to start knocking, and it completely stopped when I pulled the #4.

Is that an indication of a spun rod bearing perhaps? Does anyone have a suggestion as to what I should look for next?

Thanks.

 

[92AWDHX40]

I spun a rod bearing my car just stopped nothing moved. Lifter tick mine was noticeable while at idle,no harm just annoying. This sounds like something else maybe in cylinder 4, spin a rod bearing and it wont be a ticking sound, can you hear something, my tick was just that a tick.

 

[Deathmug]

I would call it more of a knocking sound than a tapping sound. I'll try to get a video posed up later.

I planned on checking the gap between the lifters and rockers with a feeling gauge. Does anyone know what the correct gap there is supposed to be?

 

[BogusSVO]

there is no gap between the HLA and the follower, there is no gap between the cam and the roller on the follower.

Hydrolic Lash Adjuster = HLA

the HLA pumps up to remove all lash between the parts... if you have a gap, the HLA has collapsed and is not pumping up.

 

[Deathmug]

Update:

I pulled the lifter to inspect them. They look fine, and it turns out they are G3 lifters as well. After restall they did clack for a few minutes until they filled with oil. The noise it's making is definitely not the lifters, because for awhile there it would make both distinct noises at the same time.

I was thinking about checking the rod bearings next. Is there an easy way to do that?

 

[ILLiCliPSE]

Update:

I pulled the lifter to inspect them. They look fine, and it turns out they are G3 lifters as well. After restall they did clack for a few minutes until they filled with oil. The noise it's making is definitely not the lifters, because for awhile there it would make both distinct noises at the same time.

I was thinking about checking the rod bearings next. Is there an easy way to do that?

Drain your oil and see if there's any metal/ bearing material in it. You could also just crack open the oil pan and take off the rod caps, but you'd have to drain the oil first anyway. It's not too bad to pull the pan with the motor in the car, especially on a FWD.

 

[Deathmug]

Update:
I pulled the oil pan and it did have Some copper looking flakes in it. As predicted, the number 4 cyl rod bearing was torn up, and was the culprit for the flakes.
The crank did not seam to have any serious scoring on it. What are the odds that a simple bearing swap will be a lasting fix?
Also, what would metal in the oil cause besides a possible turbo blow-up?
Thanks guys

 

[lil corb]

Update:
I pulled the oil pan and it did have Some copper looking flakes in it. As predicted, the number 4 cyl rod bearing was torn up, and was the culprit for the flakes.
The crank did not seam to have any serious scoring on it. What are the odds that a simple bearing swap will be a lasting fix?
Also, what would metal in the oil cause besides a possible turbo blow-up?
Thanks guys

I would replace the OFH assembly as the metal flakes can cause issues in the future.

 

[BogusSVO]

well if the bearing is tore up and flaking, sounds like you need more than just a bearing swap.

1) bearings do not spin for no reason.
2) the tolerances on high/low spec on the big end of a con rod is so close (.0007) that I would be concerned that the big end is out of round, causing the new bearing to spin also.
3) metal flake is in the entire oiling system now and has to be cleaned out.

 

[g4ebguy90]

Crank needs to be pulled out and very most likely machined. The rod will also need to be machined. Since you have a 7 bolt, the rod also will need new rod bolts, as yours have stretched.

Honestly. A block swap will be cheapest, and your best bet.

Btw, the reason the knock stopped when you pulled the plug wire, is because you no longer were putting load on that cyl. It's actually a very good way to tell that now that I think about it, and will use that to my advantage.

Btw once you take that crank out, your going to need new bolts for that, all the other rods. It's a big mess. I found all this out while rebuilding my 7 bolt. I thought you could just reuse everything.