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rpmdiag, Tech and Instructor
Category: Toyota
Satisfied Customers: 7762
Experience:  Since 1975
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2001 Tacoma 4WD 2.7 liter engine, with slowly increasing

Customer Question

2001 Tacoma 4WD 2.7 liter engine, with slowly increasing loudness of rod like tapping or knocking sound. Began 6 months ago as very intermittent, like noticeable every few days, and lasting 20 minutes or so. In the past month it's present most of the time, but it's not the type that goes away once the piston heats and swells. It actually comes on more often when the engine is all warmed up. Mechanic said is was probably gudgeon pin bearing and that I need a motor swap for $4,000. Question: how to accurately diagnose this knocking?
JA: Where exactly do you think the noise is coming from? And how long has this been going on?
Customer: Front of the engine, near the fan part of the block.
JA: Are you fixing your Tacoma yourself? What have you tried so far?
Customer: Not fixing myself. Need an accurate diagnosis before I'm willing to spend $4k.
JA: Anything else you want the mechanic to know before I connect you?
Customer: How do TM consults work?
Submitted: 9 months ago.
Category: Toyota
Expert:  rpmdiag replied 9 months ago.

Hi, I'm Ron and I will be helping you today.
Stand by for a moment while I prepare your answer.

Expert:  rpmdiag replied 9 months ago.

You need to drop the oil pan and pull off all the rod caps and bearings to find the offending cylinder. This can also be repaired cheaper than a new engine.

Thanks, Ron

Customer: replied 9 months ago.
The gudgeon bearings can be fixed from below?What about other possibilities, like timing chain guides, or other sources of loud tapping/knocking sound?
Expert:  rpmdiag replied 9 months ago.

Doesn't sound like any of that by your description of the noise.

It sounds like rod bearings to me.

Thanks again and please remember to rate me 5 stars and keep this link in case you need me again later on.


Customer: replied 9 months ago.
Can the wrist pin bearings be changed from below?
Expert:  rpmdiag replied 9 months ago.

Yes they can.

Thanks again,


Customer: replied 9 months ago.
If the wrist pin bearing is shot does that usually wear the crankshaft, requiring more bearing replacements? That is what the mechanic told me was the reason for an engine swap.
Customer: replied 9 months ago.
just answer states I can keep asking questions until I'm satisfied with the answers, right Ron?
Customer: replied 9 months ago.
Ron, you gave very brief "answers" to a complex diagnostic problem. My main question was on making a proper diagnosis, which you skipped over and went straight to discussing rod bearings. And you haven't gotten back to my last 2 queries. Therefore I'm rating you a 1 star.
Expert:  rpmdiag replied 9 months ago.
Yep, sure can.
I didn't think there was much else to discuss.
Some work needs to be done now. We also don't abandon you after you have rated either.
Customer: replied 9 months ago.
pulling the oil pan is better at getting a diagnosis than putting it on a general diagnostic machine?
Customer: replied 9 months ago.
Wouldn't it be best to answer my questions, rather than deciding that the discussion is done?
Expert:  rpmdiag replied 9 months ago.

I did FYI

Customer: replied 9 months ago.
Turns out it was a loose power steering pulley making the "connecting rod noise," a common missed diagnosis apparently.