Tap, tap, taparoo...

[capecove]

Good morning all...

 

I have a quick question for you regarding the proper care and feeding of my 1992 Loyale Wagon.

 

We bought it last Thursday and have since put almost 900 miles on the vehicle. We love it and it has been a great vehicle thus far. A little underpowered, but that has been good for a lead footer like my wife...

 

Regardless, it seems to have no strange issues save one really, and it may be perfectly normal. In the morning, after a full 12-16 hours off, the car starts right up and after a short period of time idling, say around 20-30 seconds, it begins a small tapping sound that increases in volume over the period of, say, 60 seconds, then completely stops. We can no longer hear the sound at that point. Then, a few minutes later the cycle beings anew. After driving down the road, for the rest of the day the sound is not noticeable, we do not hear any strange sounds. I know there is an automatic hydraulic lifter adjustment and wonder if that is what is taking place.

 

Anyhow, I just want to make sure there is no significant damage being done to the engine while it warms up and idles with it's tapping stuff.

 

Thanks folks!

Edited April 2, 2009 by capecove
Poor grammar...

[bheinen74]

It's a Subaru, they sometimes tap.

[capecove]

Sounds good, we can easily live with it as long as it is normal.

[88RxTuner]

It's one of your Hydraulic Lifter Assemblies, or Hydraulic Lash Adjusters, or simply HLAs. They use oil pressure to adjust valve lash automatically. When one of them is 'bad' ( I use this term loosely, cause you'll probably retire before it actually fails..) it will bleed off oil pressure inside it, which creates more valve lash, and it will start tapping. It's a Subaru thing.

 

The reason the cycle repeats itself? They spin. The head has an oil pressure galley that goes into the bore. The HLAs have an oil port on one side with an oil groove that goes all the way around, supposedly ensuring no matter where in it's spinning it is, oil can get into that hole. Well, that's not always the case. When it spins around to where the holes line up, it gets full oil pressure and pumps up the HLA, making the tapping noise stop. When it rotates away from the pressure hole, depending on how much carbon and crap is in the oil groove, it may not get enough pressure to pump up, and will start to bleed down. This results in excessive valve lash, and the tapping noise. When it spins round to where it lines up the holes again, it pumps back up and the noise stops again... Thus repeats the cycle.

 

Another possibility is that the O-ring on the oil pump is sucking air, but this will lead to fairly consistent tapping across the board, and it wont stop or cycle.

 

It's pretty normal. I havent heard many older Subarus that dont have lifter noise. My advice is to ignore it... You could throw some QUALITY oil treatment like Sea-foam or Lucas in there, and if it doesnt fix it, dont worry about it unless it becomes dramatically more pronounced.

 

Hope this answers your question!

88RxTuner

[capecove]

Thanks Tuner... I appreciate the insight.

 

After purchasing the vehicle I made sure the rear diff fluid and transaxle fluid were good, which they were. I believe that it is possible the previous owners just had the fluids drained and refilled less than a month or two ago, both fluids were so clean that I was shocked. When I did my oil change, I did put in a pint bottle of Seafoam, like you folks had suggested. It hasn't made any difference thus far, a least it is not noticeable. But, we will see what happens over the next couple thousand miles.

 

Thank you again, a great description and it makes perfect sense. I was a bit horrified at the thought that it could be rocker arm noise, like in my old Volvo PRV V-6 engines (http://en.wikipedia.org/wiki/PRV_engine), spelling a short simple end to the engine. I am really interested in seeing this Subaru last to double its mileage. Here's to hoping!

 

Jason

 

It's one of your Hydraulic Lifter Assemblies, or Hydraulic Lash Adjusters, or simply HLAs. They use oil pressure to adjust valve lash automatically. When one of them is 'bad' ( I use this term loosely, cause you'll probably retire before it actually fails..) it will bleed off oil pressure inside it, which creates more valve lash, and it will start tapping. It's a Subaru thing.

 

The reason the cycle repeats itself? They spin. The head has an oil pressure galley that goes into the bore. The HLAs have an oil port on one side with an oil groove that goes all the way around, supposedly ensuring no matter where in it's spinning it is, oil can get into that hole. Well, that's not always the case. When it spins around to where the holes line up, it gets full oil pressure and pumps up the HLA, making the tapping noise stop. When it rotates away from the pressure hole, depending on how much carbon and crap is in the oil groove, it may not get enough pressure to pump up, and will start to bleed down. This results in excessive valve lash, and the tapping noise. When it spins round to where it lines up the holes again, it pumps back up and the noise stops again... Thus repeats the cycle.

 

Another possibility is that the O-ring on the oil pump is sucking air, but this will lead to fairly consistent tapping across the board, and it wont stop or cycle.

 

It's pretty normal. I havent heard many older Subarus that dont have lifter noise. My advice is to ignore it... You could throw some QUALITY oil treatment like Sea-foam or Lucas in there, and if it doesnt fix it, dont worry about it unless it becomes dramatically more pronounced.

 

Hope this answers your question!

88RxTuner