Hi
I have a 2.5TL, 1997, 101000 mi. Running well but has developed a faint fluttering/rattling sound in the engine when either driving or idling. Mech cannot find anything specific but says it is possibly either a torque converter or a "knock low in the engine" and will cost >$1000 even to diagnose b/c of work required to get at the location. Recommends that I wait to see if it gets louder and then either spend the $ to fix or bail and get a new car.

Ideas? It seems to be running fine otherwise, previously had 90K service, O2 sensor, no other surprises.

Thanks!!!

 

Is sound more noticeable on cold running immediately after startup? If yes, it may be a valve clearance is a little too loose. A valve adjustment should fix the problem. Your mechanic should know this, so maybe the sound is not valve noise.

Is the engine running dead smooth, w/ no vibration? If not smooth, you may need a tuneup. Have you had your free emissions tuneup? It's available to 150K miles. I just had one done on my "new to me" 97 2.5TL and it made the engine purr like a new car. You get spark plugs, wires, distributor cap, rotor, and an oil change.

If engine is not unacceptably noisy, I would drive a while. I don't have much faith in your mechanics diagnosis. I've never heard of noise from a torque converter. Any loose parts in a torque converter would mean instant destruction of the torque converter.

Engine knock (pre-ignitiion knock) occurs under load and sounds like marbles in steel bucket. A rattling sound only under throttle pressure, usually w/ a fully warm engine.

A rod knock is a deep distinctive ringing knock, fairly loud, that occurs w/ metronone regularity. If you've ever started your car after an oil change and heard a few knocks until oil pressure is achieved, you've heard engine bearing knock.

Piston slap is a lighter rapping sound that occurs due to loose wrist pins. I don't think the 2.5 engine is known for this sound, but maybe others can comment. It is usually tolerated by an engine, but drives owners crazy.

good luck

 

HI,
The engine is running smooth and it is a little louder when it is warm. It doesn't sound like an engine or rod knock. It's not really a hard metallic sound, more like a scraping/fluttering sound Maybe the pistons as you said.
Anyway per your advice I just left it at the Acura service this morning and they are going to do the free 150K service and diagnose the problem. The service manager could clearly hear the noise so that gives me confidence that they will figure it out.
Appreciate your advice.
M

 

Hopefully, they will locate the noise source.

Some additional possibilities are cooling fan motor failing (loose bearing), or noisy belt tensioner pully bearing. Both should be quickly detected by a competent mechanic.

Let forum know what you find.

good luck

 

Well it took them almost 3 hours of searching but it turns out to be the power steering pump. I will get it back tomorrow.

This was my first experience w/ Acura service and I couldn't be more impressed.

Pleased to have your advice TXHonda as I really did not want to sell this car! Thanks!

 

It sounds like a good dealership for service. Locating sound faults is sometimes very tricky and tedious.

What was problem w/ PS pump, bad bearing, air in pump, bad belt, ...? They are usually very reliable, but occasionally will leak.

regards

 

Apparently both the belt and a bearing in the pump. It was not leaking. They replaced it with a refurbished one from Acura.
Not surprisingly the steering is quite improved, and a very mild shudder that I was getting when driving on the freeway at higher RPM is also gone. Car feels like new.

ALSO, re. this 150K emissions warranty, this car had to have the entire exhaust system replaced at about 65K miles (before I purchased it). Also covered under warranty.

 

Hey guys - could you shed some more light on the 'free 150K service' you refer to above? Who is covered - what is covered etc.

 

It's extensively discussed in various threads on this forum. Emissions warranty is extended to 150K due to a case settlement between Honda and US gov about Honda's interpretation of US emissions rules/policies.

Bottom line is emissions parts are covered to 150K miles and you get a free tuneup at some point,...if you ask. I had the free tuneup and my cracked exhaust manifold fixed under this policy.

good luck

 

They replaced distributor cap, rotor, wires, spark plugs, and an oil change. This did help a lot as the car would often not start after a hard rain when it was parked outside, and this fixed it.

They offered the service at the dealership, I did not have to ask for it. Also the entire exhaust system was covered at an earlier time at a different dealership, but it was having some emissions problems (could not pass CA emissions).

Good luck.