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Tapping when first starts. What is it? Ways to remedy?


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1999 Legacy Wagon 2.2 L 172K AT

 

Did a valve job and car runs fine except when I first start it... especially on cold mornings. Then there is a tapping sound that resolves after a couple of minutes when engine warms up. It's louder the colder it is (air temperature). Also, it's louder under load then when idling or when I come off the gas.

 

I added MotorKote and it quieted considerably. I just added some Rislone too and it may have helped a little too but not a lot.

 

Once warm, it runs quietly and when restarting at the end of the day to go home.. it's much quieter than in the AM when it's sat longer and is much colder. When it's under freezing, it's most prominent when first started.

 

Any ideas what this might be and if there is a way to remedy it?  Trying to figure out if it's something stuck cause it's gunked up inside (just got the car a couple of months ago).. or if something needs adjusting or what.

 

Thanks for your opinions and suggestions. 

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Hydraulic lash adjusters.(HLAs) Most of the time they quiet down with a fresh oil change and get progressively louder when the oil thins or especially if it gets low. Marvel mystery oil can help.

 

Very normal for these motors as they get into their golden years.

 

If they get bad/stay bad they can be pulled, replaced or re primed. Usually though some clatter on a cold start up or after sitting for a few days is par for the course for these motors and not indicating anything wrong.

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Have you guys tried while doing the fresh oil change, you can use some Dura-lube for one quart of the oil and see how that quiets things down. Now in this case they may need to be adjusted.

 

My father worked as Crane Superintendent for several years for the government. They had an oil expert come in and he had a machine that had a bearing that spun from a motor.  From the bearing was a breaker bar that when you pulled down on it would read lbs of pressure. 

So the expert ran different brands of oil that would shoot around this bearing and you could see how much pressure it would take to stop the bearing. 

 

Do you know what the worse oil was that tested????      Penzoil. And it was funny cause my Dad swore by it. Not anymore. 

 

Some of the highest readings came from Mobil 1 and Castrol. I am sure that didn't test ever brand. 

But when the oil expert put in the Dura-lube with the Castrol, he was hanging on the breaker bar with all his weight and couldn't stop the bearing.

It made my Dad a believer in Castrol from then on. I liked Castrol anyways myself and ever once in a while I will do Royal Purple but I don't race my either. 

Edited by Naked Buell
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My wife's Forester has the same symptoms you describe and her 2.5l has piston slap.

 

Was this noise present before your valve work?

 

 

As for oil additives, not a good idea.  I work for a vehicle manufacturer and we don't recommend using any sort of additive in the engine oil.

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Thanks everyone for the responses. I am a bit confused by them however... if it was improper adjustment of the valves why would it only do it when cold and how would throttle position change the loudness? 

 

Piston slap is an interesting idea. Still, if it was piston slap, why did the MotorKote really lessen the noise? I wouldn't have thought it would do that.

 

Naked Bull, I have always chosen MotorKote over Dura-Lub but am open to changing my mind if you can convince me why it's better.  I am wondering if it would be due to wear or gummed up rings. I am trying to do what i can to clean up the internal workings. I bought the car with 162K on it and immediately did the valve job since it had a miss when I bought it. I don't know but I am thinking the car may have sat for a while in more recent times prior to my buying it. I switched to full synthetic oil and plan on changing the oil more frequently than I might normally.. like every 5k or so for a while and wanted something that might help free up things like rings and lifters etc by cleaning out the gunk.  After reading what I could on the subject, I went with Rislone. Always open to other ideas. 

 

I really appreciate all the input. I am trying to learn all I can about this cause I really love Subarus and have since the mid and late 70's. I used to sell them back then and loved showing people under the hood how much more robust the construction was than the Toyotas and Datsuns. They were also way ahead of the industry back then with the SEEC-T engine.

 

Anyway.. enough nostalgia. Please keep giving my your opinion on my tapping issue and ideas as to how to correct if possible.  I want to drive this car until the wheels fall off or the body completely rusts away and a healthy/happy engine is the key to getting there. 

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That engine is notorious for oil consumption due to oil control ring clogging. It's probably got one or more scuffed piston skirts from this as well and needs the pistons knurled and the rings replaced. Very typical. What you hear is most likely piston slap that diminishes as the piston expands to fill the bore.

 

GD

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  • 2 weeks later...

Ok... sounds good. Will just change the full synthetic oil in it every 6000 miles adding MotorKote for good measure and run it till the wheels fall off.... then buy another. 

Thanks for all the input. 

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It's piston slap.  Period. 

Remedy - knurl the existing pistons or install new ones. 

 

Or a rod bearing.

 

Replacing pistons is a lot of work only to hear it knock again.

Edited by uniberp
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