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How many Subaru owners have/live with piston slap?


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Our '99 outback has Phase I heads, Phase II block. It has ~153k miles on it. Slaps pretty loudly some mornings, quiet other mornings. Slapping started somewhere around 60k-70k miles IIRC. I have found that a good, relatively thick 5w-30 synthetic quiets it down significantly in the winter, as opposed to the pennzoil I used when the car was new. Mobil 1 made it sound like a bucket of bolts and drained looking like water. I am currently contemplating my oil choice for this summer. I love the oil range the manual allows for.

 

The slapping encourages me to warm the engine up fully before moving in the winter. My wife is the primary driver and I can't get her to wait 15 seconds most of the time. The sound to me is like fingernails on a chalkboard. In the summer the slapping seems much less severe. It may be the tensioner, I really have no proof either way. I have read that the tensioner rattle can be engine temperature dependent. At 200k miles I am going to probably pull the engine and do a bunch of stuff, including a new tensioner.

 

EDIT: Regarding BITOG, a great site for sure. Probably more myth and misinformation that any other forum I have frequented, but a lot to be learned if you can stand digging.

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Just did the oil change. Valvoline Maxlife High Mileage, 10W30, plus half a bottle of the Valvoline Engine Protector. The clicking is still there a bit, but much quieter and not at idle. Only at hard revs.

 

Will see how it goes til the next change.

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But I hope this works for you. I also wonder how much of this is valve noise by now.

Subarus must have good cams, but I have found several engines that the cams wore out at 150,000 or so enough to really effect performance.

In my last Mercedes cam and lifter wear was common and I think I had three cams in it in the 17 years I had it.

I have seen a lot of cam wear on V8 Chevys and Fords too.

Followers and lifters are often pretty worn at about this time.

I will pop the vlave covers off my 2.5 around then and see waht I need to do. An OHC engine is so easy to inspect compared to a cam in block.

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I also wonder how much of this is valve noise by now.

Subarus must have good cams, but I have found several engines that the cams wore out at 150,000 or so enough to really effect performance.

What would be the symptoms of said cam wearoutage?

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the valve.

You can usually see that there is a lot of wear on the cam and follower and this is often inconsistant.

There are often cam lift specs in the manual and I have used these and a steel ruler to see if I am still running in specs. When you have a really flat one the valve hardly lifts at all.Hydraulic lifters are a bit tougher to measure as they take up the play a bit.

When you put in a new cam and good followers in an engine that had a badly worn cam you think you now have a rocket.The wear is so subtle over a long period that you don't realize how much power you have lost.

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Thanks for the info. Actually, I've got all the power and zip I could want. It's a "rocket" compared to how it was a year or so ago. Compression seems to be quite good. Good pickup. Cruises at 85mph @ 3800 RPM or so and still has strong passing ability. Just noisy I suppose.

 

Hey ... did I highjack this thread? ;)

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A two part question:

If I can get Subaru to replace some of the pistons under warranty, which I gather is their repair of choice these days for the problem, what is the risk they will do the repair well? In other words how risky a repair is it?

 

Now the second part of the question: this vehicle, a leased vehicle, has been pretty reliable and fun to drive and except for the piston slap, brakes and a front wheel bearing has caused no pain so I am considering buying it at the end of the lease, but I am strongly hesitant because of the piston slap. Would you hesitate as well?

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after all if it is not right you can bring it back and say try again.

I can only judge from my limited 2.5 experience but at a bit over 100,000 it is still using about a pint of oil by the time it is ready to change.

I hope to get a minimum of another 50,000 miles out of mine and it sure seems like it is ready to do it.

I have done major maintence on it from the 80,000 mark when I got it to where it is now and it is a far better car now than when I bought it.

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if the engine in your car has forged aluminum pistons it will make a knocking/tinging type noise until the pistons have warmed up all the way. This is a normal noise for aluminum pistons. I have spoke to subaru techs about this, and read the service bulletins given out to subaru techs. I have also spoke to other non-subaru car owners with the same kind of pistons, and they all note some noise from there engines until warmed up all the way. I live in wisc. and the noise is definetly more present and longer in the winter.

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  • 3 weeks later...

Add me to Suaru owners who's cars have piston slap. Mine is a 2003-Outback Wagon, with about 43,000 miles. We live near Syracuse NY so this winter was cold and snowy.

 

The noise just started this winter. BTW, we use an engine block heater (Subaru installed) and the engine still knocks in the winter when we drive off.

The timing belt tensioner was changed and that didn't help.

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  • 10 months later...

I have 2 Outbacks, a 98 2.5L DOHC (130K) and an 02 2.5L SOHC (19K). Both have piston slap, but the 98 is significantly louder. The 02 has (had) 3 distinct noises that I can identify: (1) piston slap when cold, (2) timing belt tensioner clank when cold, (3) hollow knocking at 2800 RPM only when warm and under light load. I recently had the timing belt tensioner replaced on the 02 and the clanking noise it was making for the first 8 mins of operation was completely cured. I still hear the cold piston slap, but it is minor and I don't care about it. What bothers me the most is the hollow knock. It gradualy comes on as the engine warms up and never goes away. I recorded it and took it to Subaru. I took the Service Manager for a ride to demo it. He said it was normal. I think it is embarrasing. This engine only has 19K miles on it! Who, of my friends/family is ever going to buy a Subaru after taking a ride in mine I asked him? He offered to contact some district representative to have them come and evaluate it. He says only they can authorize an engine teardown. Something is definitely loose in this motor, banging metal against metal as the oil thins out it appears. I was able to get a real good recording of it by placing the mic at the top of the carpet on the passenger floor compartment while driving. Its frequency is half the engine RPM. I'm beginning to suspect that the only cure for Subaru noises may be a good stereo. It's a shame, I'd really like to enjoy the sound of my engine.

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My 01 OBW has it, been living with it since we bought it... (Jan 01) It goes away when warm. Not too concerned yet... We just baby it until it warms up... Nice slow take off's, etc.. Not worth the hassle of haveing to deal with the dealer, especially if it won't do any damage...

 

I lived with an 88 Dodge Dakota that had a 2.2L 4 banger in it with bad wrist pins... Same kinda sound... I saw several Omni's, Horizons, Turismos and let's not forget the good ole' K Car with over 100k and knocking wrist pins... Scaravan's and Voyager's too. Boy Chrysler really overused that motor didn't they...

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My 97 Impreza Outback had classic piston slap for the three weeks that I had the car. Went away after 5-10 minutes of driving and never really bothered me a whole lot. I was going to try a different oil in it when it came time for a change to see if that would make a difference.

 

Urban Coyote

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In 96? every time I hear piston slap I think 2.5, but now that I think of the late 2.2s had some of the same problems didn't they?

 

My '00 2.2 with 81k miles is quiet as a mouse. My 2.5 on the other hand... :rolleyes:

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(3) hollow knocking at 2800 RPM only when warm and under light load.

SNIP

What bothers me the most is the hollow knock. It gradualy comes on as the engine warms up and never goes away. I recorded it and took it to Subaru. I took the Service Manager for a ride to demo it. He said it was normal. I think it is embarrasing.

 

This really sounds like a rod bearing. A slightly deeper-sounding hollow knock at 1500-2000 rpm, under load (brake-torque), would be indicative of a main bearing.

 

Stepping up a grade of oil thickness might prevent damage in the event you need to keep the car and can't get satisfaction from Subaru.

 

Curious, what kind of oil do you use now? I previously could hear a rod noise with Mobil 1 10W-30. I switched to a slightly thicker oil and it's gone.

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Cold piston slap is nothing serious, but a rod noise is another matter altogether. There's no way a rod can knock without premature failure in it's future.

 

IMO, it would be a good idea to plumb-in a temporary oil pressure gauge and drive around with it for couple days. If the pressure doesn't meet spec, then have your dealer document it, and that's your ace-in-the-hole for getting the problem dealt with under warranty.

 

If the pressure looks good and stepping up to a 40 weight oil (0W-40 or 5W-40 for winter) cures the noise, you might have no worries.

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  • 11 months later...

I have an '05 Baja that has had this problem since it got 9,000 miles on it. It's so bad on bitter cold mornings that I'm almost afraid to drive it. It's been to the dealer 3 times for it. They replaced the timing belt tensioner, and it's not as bad, but they say it's "normal". I find it amazing that any manufacturer would sell a car nowadays that sounds like this. If this is a "normal" vehicle for them, it's definitely my LAST Subaru.

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I eventually got my two left pistons replaced under waranty. I brought a recording of the noise to the dealer and this made it clear exactly what I was talking about. Two days after that he called me and explained that he found an internal memo suggesting they replace the two pistons on the driver side with a special countermeasure design that has a tighter clearance. If you ask for this you will eventually get it if you want. Just be patient and document every failed attempt at the dealer. The contermeasure pistons are out there. I saw them with my own eyes and held them in my hands. Good luck. Unfortunately this had no effect on the noise in my case because it was apparently not piston slap. I sold the car after this because I could not stand an engine sounding like that. I think it was more evident because I had a manual trans. While I was at the dealer I tested a 6 cylinder outback. There is one word for this engine. SMOOTH. Such wonderful relief! No lumpy exhaust. No embarrasing knocking. Just smoth as silk. Like a "normal" engine. I love the 6. What a pleasure to drive.

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Neither my 99 obw 2.5l or my 95 2.2l suffers from pistion slap, however my fathers 01 obw with 65,000 on it does. It sounds like a diesel when cold, but runs smooth when warm- no other problems thus far. Question- Does pistion slap progressively get worse? Also, Does it rob the engine of horsepower? I agree that it can/ is annoying, but piston slap or not- these engines are damn good.......................most of the time, you always find a lemon somewhere.

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It does not seem to hurt a lot. I just got back an analisis from Blackstone that says no problem and it is a common issue. Many other manufacturers are having the sme issue including Honda and GM. The new EPA standards seem to require short skirts which does not hurt some engine designs like inline sixes, but does not seem to be easy for V engines and our fabled flat four.

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You know, I'm really getting sick of hearing people complain about this "problem". Every car makes noise when it runs. Every car has a warm up period. Stop worrying about this "problem" and drive the car. Because it's not a problem at all. It won't affect the life of the engine and it gives you better gas mileage.

 

I've seen 2.5L engines with 140K on them, that still had the cylinder honing scuffs on the cylinder wall. Subaru's are built to last for as long as the customer wants to maintain the car.

 

(Sorry had to rant a little.)

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