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dburton97128

What do you think of this timing chain guide wear?

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Hi,
 
I am wondering what you think of the wear on my chain guides.  Link:

https://flic.kr/s/aHsmrkFZZE

I had a diagnosis of worn chain guides and a recommended replacement quoted at $2300.
 
These all look fine to me though the tensioner pads show more wear than the smaller guides.  Even so it looks like they could go another 200k.  (115k mi on these right now).
 
I don' see any excuse for the chain rattle sound which was heard fully warmed up at idle and went away when the throttle was goosed a bit.  Poor functioning tensioners seems the only explanation though they look totally fine out of the car.  Chains look fine and there are no marks indicating they have contacted anything other than the guides.
 
Don't want to put it all back together and not have it fixed.  Could be low oil pressure, but that seems low probability.  But is there something else I should check while it's open this far?
 
Thanks.
Edited by dburton97128
speeling

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Clapped. And that engine is a varnish pit. Gross. Should have checked oil pressure prior to tearing it down. 

Replace all the guides, the tensioners, the water pump, and hope you make 200k before the head gaskets go or the abused bottom end throws a rod. 

That's disgusting. And if it had been maintained properly with synthetic the guides would show no wear, the oil pressure wouldn't be a problem, and the you wouldn't have it opened up. 

GD

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I just bought this a month or two ago so I don't know the full history.   The motor sounded really good until I changed the oil and had it warmed up good, though I never heard it before changing the oil regardless of temperature. 

I personally run full synthetic in all my vehicles.

Edited by dburton97128
add stuff

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Ah, OK.  The perils of buying used.  I know how that goes.  Do you suppose the previous owner put in oil with a viscosity rating one or two up from recommended?  On my older vehicles (which is nearly all of them) with lots of miles, I sometimes run 10W40 and I've noticed how quiet the motor seems compared to when I use 5W30.

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Read this thread about oil weight.  This oil expert claims lighter weight is better lubrication and increases flow and reduces engine noise and clatter, though one thing I wonder about is the effect on the chain tensioner pressure, which seems could suffer with light weight oil at low rpms.

https://www.subaruoutback.org/forums/61-general-discussions/34372-informative-oil-write-up.html

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They’re fine with conventional oil if changed frequently and never overheat, run low on oil, etc. synthetic is great and there’s no reason not to run it but the first issue is neglect. 

H6 chain noise isn’t typically a big deal.  They can run 300k with the majority of their life having some chain noise. maybe yours was neglected and this isn’t “typical” but I wouldn’t sweat it much, you’re not going to rebuild the block and right all the past wrongs. 

My guess is chain failure will be about number 68 on your list of failure items over the life of this car, ie. you’ll never see it

The only H6 chain noise I tried to mitigate had chain noise under high loads - when you floor it or downshifting up a mountain.  It had done this for years.  I installed new OEM chain guides, water pump and tensioners and the noise didn’t change.  Car was like this for 100,000 miles before I worked on it and is still the same now at like 300k. I presume it was the chains. Luckily the engine/trans was out for other things and chain noise wasn’t a big concern.  

Oil viscosity hardly matters here.  Sure try four different weights, it’s no big deal, not worth reading endless oil diatribes. 

That article is terrible, the useful information per length is near zero. I couldn’t make it far but is there anything substantial in it?

Ferrari and Mercedes, races, and academic pedigree. That’s basically zero qualifications regarding Subaru maintenance.

 

 

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I read the whole thing.  Took about 1/2 hour.  I think there is a lot of eye opening information about temperature performance of various oils vs temperature, if you can make it through.  I think he is spot on about how people misunderstand oil weight ratings and the effect in an engine.

One issue not addressed (since it's not really a lubrication topic) is the viscosity/rpm/pressure issues related to keeping adequate chain tension.  When I hear chain rattle I think that has to be accelerating wear on those parts.

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Just an anecdotal data point on oil pressure and viscosity.

Buddy had a high-miles honda, way over 200k maybe near 300k miles, with the variable valve timing, started throwing an actuation code.

The actuator was being told to whatever and wasn't due to the oil pressure being a bit low, or the oil pressure was supposed to trip a sensor, something like that.

Shops wanted a ton of money to mess with it, I just told him to go up a grade or 2, forget if he went 5-30 to 10-40 or to 20-50 (or maybe 15-40), but it bumped the oil pressure enough to keep the car going for a few more years until all the suspension parts failed.

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I believe that is a legitimate point.  The article gives quite a bit of rational for increasing hot viscosity as engines age older.  His point though is that you need to be monitoring oil pressure vs rpm at operating temperature to be able to make that decision correctly.  I'm thinking if there is chain rattle at low rpm or a situation as you described above then increasing weight a bit until it resolves would be a good thing, though at the expense of a bit of fuel economy.  A key point he makes though is to use an oil that retains the proper low viscosity at low temperatures so you get good oil flow when cold.  There are great options today with 0W-30 even up to 5W-50.

I'm sold on good synthetics even more now since seeing all the varnish in my current car.  I've run synthetics in all cars for the last 35 years and never had an engine lubrication related failure.  My truck has over 200k mi and I started it on synthetic after the first oil change with a bypass filter.  I changed oil 3 times in 200k mi, and each time the oil was still good for continued use.  I notice things like my valves never need adjustment.  The gaps remain the same, in my imagination indicating minuscule wear in the engine.  The only exception has been my Toyota Cressida which my daughter ran out of oil and drove until it seized.

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Going up a grade or two in viscosity can increase pressure, but it is a double-edged sword. It flows poorly when cold, and retains more heat due to increased friction. These are both detrimental in their own ways. Subaru engines in particular have extremely tight cold clearances due to the aluminum block design. The clearances are not stable with respect to temperature. If you run an oil like a 40 or a 50 you need to allow longer warmup times to reach thermal stability and maximize thermal growth of the main journal clearances or you will starve the rod bearings. We run Amsoil Dominator 15w50 in a our race engines and they require a 15 minute warm up period prior to driving. We also blueprint all the journal clearances to within a couple tenths and they are specifically set to very near the maximum Subaru clearance specification. 

GD

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How about the Amsoil 5W-50?  That seems it would help alleviate the cold start issue some, though you are probably using the 'racing' oil for other reasons as well.  The 40C viscosity is still higher than the other oils, but I didn't see data for actual cold temperatures.

I thought I saw a graph of real data somewhere that showed Amsoil 5w-30 vs 10W-30 and there was no difference above about 20F.

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just looked at the pics -  those guides don't look terribly degraded to me, look about like the pitting and light edge wear i've seen before.  maybe some of that is from the noise/play in the chain though...

that's some seriously backed on oil. wow. 
 

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12 hours ago, dburton97128 said:

How about the Amsoil 5W-50?  That seems it would help alleviate the cold start issue some, though you are probably using the 'racing' oil for other reasons as well.  The 40C viscosity is still higher than the other oils, but I didn't see data for actual cold temperatures.

I thought I saw a graph of real data somewhere that showed Amsoil 5w-30 vs 10W-30 and there was no difference above about 20F.

You can't really "alleviate" the cold start issues. The engine has half its normal operating temp main journal clearance when cold, but full rod bearing clearance. You can't force enough oil through the mains to get adequate oiling of the rods when cold under load. This is just how Subaru engines work. They should not be heavily loaded when cold.

The 5w50 is a signature series oil and is a GREAT oil worthy of running in high performance engines. Its actually specified for the Ford Focus RS making 350 HP. It is a long life oil, being designed for up to 25,000 miles. 

The Dominator oil withstands higher temperatures and greater shear. It will not lose its viscosity and thin down as quickly. It runs cooler and has the high zinc and phosphorus required by aftermarket turbo and camshaft suppliers. The Dominator is NOT a long life oil and is only good for about 5,000 miles. 

GD

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Makes sense.  But back to the cam chain tension issues:

I'm copying this from another forum post in case anyone over here knows about it. ---

I'm checking my oil pressure relief valve and pump and finding very sparse info about the PRV.

Is there a procedure for checking the relief valve? I can pressurize one port with air until it starts to flow. What should the relief pressure be?

Do I dare take the end cap off to clean and inspect it? Those are NLA so a good check and restore of this one is in order.

*** There is a protrusion with an orifice that spays oil on the chain. The oriface was not plugged, but there is a small plastic piece behind it with a tiny screen. That screen is no more. A remaining fragment proved to be basically decomposed and turned to dust at the slightest touch. This part does not appear in the parts guides. Must be a part of the NLA PRV assembly. I can't imagine them making you buy a $200 part to replace a $3 screen though.

Any info on that screen?

Thanks.

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Any screens in that engine are plugged or blown out. Generally you don't need such things if you run good oil and filters. Like the turbo banjo bolt screens - we always remove them and throw them away. 

The pressure relief valve is going to be around 90 psi. Yes absolutely dissasemble, clean, and inspect it. 

Though honestly with the condition of that lump I would buy a new oil pump, or a JDM replacement engine. 

GD

Edited by GeneralDisorder

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It looks like I don't get to check (or replace) the oil pump. Those bolts are ridiculously tight. Supposed to be put on with 4.7FP, but even with 30-40 FP they aren't coming loose. One began to cam out so that ends that. No room for an impact driver in there, if that would even work.

I see older year H6 motors from JDM on ebay, but my security says they have malware and won't let me go to their web page.  No warranty on those motors unless I am a certified mechanic doing the install.  Maybe I'll just do what I can on this one and go for a replacement later if it doesn't hold up.

image.png.4e8eecb545eac235c76d1964f6151335.png

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i've bought numerous Subaru and Subaru H6 JDM engines/trans from various ebay and other suppliers.  

they probably all have the same sources so i doubt the product or success rates vary much, probably just comes down to customer service. 

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I did find several suppliers ranging from $700 for a more stripped engine to $1300-1700 for a complete engine.  I decided I don't really want to swap an engine so I'll replace everything in this one that looks like it would be iffy to go another  100k miles and hope for the best.

While I have the tensioners and pressure relief plate off I'll back flush whatever passages I can to make sure they are clear and see if any residue comes out.  Is there anything I need to be careful about while doing that?  I'll use 0W-20 oil for that.

After re-assembly I'll run it a day then do an engine flush and then a fresh oil change.  I'll check the pan with a bore scope camera and if it looks like there is any build up in the pan I'll drop that and clean it up as well.

Here's to hoping for the best.

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In replacing the center small guide a spacing of 8.4-8.6 mm is specified.  From the dwg in the manual it's not totally clear to me the reference planes for that measurement.  It looks like the back of the bushing on the right side, and I'm not quite sure on the left, though it looks like the front face of the guide (if that's a small gap between the face of the bushing and the chain in the diag.

image.thumb.png.1955726244a62d8602e848333dbd620f.png

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I notice a slight misalignment in my timing marks on the Passenger side when the Drive side cams are lined up. Is this a normal or does this indicate stretching of the P side chain?

Alignment is off by about 1/4 tooth between the upper and lower sprockets.

P side:                                                                                                                                      D side:

image.png.4cd8331a9a672461022ea58cb82db626.png

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The chain guide clearance is the clearance between the two guides just as it says - the path the chain travels between the two guides. 

The alignment pictures I don't recall where I have seen them before while assembling .  while I dislike any bit off, if the tensioners aren't under full pressure then a small amount of slack, and a commensurate few degrees off on the pulley alignments, would be expected. 

I would carefully go over it again, make sure all the pulleys and guides are properly installed, bolts are tight.  Go over every mechanical part which locates and rotates the chain and make sure it's secure.  If that's all in place then i'd assume you're looking at tensioner slack that goes away once they're apply full pressure. 

you can probably "mimic" this by visualizing the direction of rotation/slack being taken up and how will impact the sprockets/alignment marks, and on 4 cylinders I have put it under a momentarily increased tension via a sprocket bolt to see what happens, i imagine you may be able to do that with the H6 as well. 

Edited by idosubaru

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I carefully re-checked this multiple times.  Chains are under tension and cranked in the driving direction.  Either this is normal or it could be the P side chain is stretched.  I ordered new chains and will report if it makes any difference.

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