Varnish: Is it really harmless?

[martinq]

Originally Posted By: KitaCam
You want varnish? I'll show you varnish...Camry I4 @ 100k miles

Gotta say, that looks like a really clean engine! Is the valve-cover that clean?

 

[OVERKILL]

meep:

But if we assume that most of the BMW engines that HAVE this failure also have varnish, and the overwhelming number of engines running that DON'T have this failure may also have varnish (it is surprising difficult to find a clean BMW engine run on the factory oil and intervals from what I've seen) then is the design itself faulty? Is it the maintenance practice? The choice of lubricant?

I mean even if we consider what you've stated at face-value, that it is the design that is more susceptible to failure in an operating environment where varnish is present, would not keeping the operating environment as varnish-free as possible make sense in ensuring longevity? And in that vein, just because other engines don't have noticeable failings due to varnish build-up doesn't mean it isn't an issue. Coked and varnished up piston rings rob power, pollute your oil with blow-by.... but there are no audible signs that this is an issue. And it happens so gradually that most never notice it. Is varnish harmless there because the end-user is oblivious to it and its effects?

With respect to BMW, yes, they do some pretty weird things at times. I've been lucky not to have to set the cam timing or buy the tool as of yet... fingers crossed

I am enjoying this discussion, I hope others are as well.

 

[OVERKILL]

Originally Posted By: martinq
Originally Posted By: KitaCam
You want varnish? I'll show you varnish...Camry I4 @ 100k miles

Gotta say, that looks like a really clean engine! Is the valve-cover that clean?


Seriously? That's a healthy layer of thin varnish there, that's not clean!

 

[martinq]

Originally Posted By: OVERKILL
Seriously? That's a healthy layer of thin varnish there, that's not clean!

Seriously. I see a slight, and very even, discolouration and very little sign of deposit. If the oil was cleaned off (or take another picture after running with fresh oil) then the colour would be lighter. It looks very clean to me.

 

[OVERKILL]

It would still be bright orange with fresh oil.

Here's my M5 for reference, this oil had some significant mileage on it at this point (M1 0w-40) as you can see from it sitting on the head of the stud and pooled below the nut. Yet the aluminum head is virgin coloured, as is the steel on all the nuts....etc.

 

[KitaCam]

First of all, let me apologize to anyone who thinks a thread jack...I wanted to add to the conversation to help...hope I have...

I had posted the Camry's varinshing because it is clearly varnish at early stages...discoloring of metal parts BEFORE deposits begin to cling to the sticky stuff....
I think identifying/recognizing the early stages of "varnishing", helps to understand how/where/why the deposits build up thereafter is the beginning of understanding how to prevent/cure it.
Enjoy...

Anyway....to address, if not answer, a couple of issues/questions....viewing through the oil filler hole...and viewing the underside of the valve cover

View through the oil filler hole 2.5k miles BEFORE the cover was pulled......it seems that the darker coloration got lighter with PYB after 2.5k miles

Close-up of engine

Underside of valve cover...note the burned hot spots that may be a result of older spark plugs that while firing just fine in terms of MPG efficiency, may have been firing TOO hot...

...again, perhaps a result of a failing PCV valve, or an old-brittle-hard cracking VC gasket that may have been compromised in terms of evacuating AIR if not leaking liquid...as much as the (100k-mile) old plugs.

...also to be noted is the build-up of deposits that don't yet appear on the engine...I think that's interesting...

 

[threeputtpar]

I was going to write a huge dissertaion on this, including my experience with the Ford 4.0 SOHC failure, the current 4.0 SOHC we have now and my experience with the VVT on my Audi A6, but I think I'll be a smart alec and just say this:

A timing belt would cure all of the problems discussed so far. It's worked quite well in the A6, and only needs changing every 75-95k miles. Plus, it gives me an opportunity to obsess over my car every now and then.

I also concur with the statement that there are just too many miles of chains in those engines to be very reliable. And the path they take with that huge u-shaped metal guide is just asking for metal shavings to be spread throughout the engine.

Oh, and the 15k mile OCIs that are factory recommended without UOAs to assure they are safe is rediculous. Not on the BMW 5W-30, anyway.

 

[martinq]

Originally Posted By: KitaCam
Underside of valve cover...note the burned hot spots that may be a result of older spark plugs that while firing just fine in terms of MPG efficiency, may have been firing TOO hot...

Thanks for the extra pics and details KitaCam that's helpful.

It's much more likely that the dark spots you see are the colder areas. If I recall, varnish tends to become visible in cold, low-flow areas first and get darker first. It's interesting that the varnish has created a shadow of the sparkplug tubes. Hmmm.

Which way does the cam rotate? Do the top of the lobes throw to the front or the back?

 

[OVERKILL]

Originally Posted By: threeputtpar
I was going to write a huge dissertaion on this, including my experience with the Ford 4.0 SOHC failure, the current 4.0 SOHC we have now and my experience with the VVT on my Audi A6, but I think I'll be a smart alec and just say this:

A timing belt would cure all of the problems discussed so far. It's worked quite well in the A6, and only needs changing every 75-95k miles. Plus, it gives me an opportunity to obsess over my car every now and then.

I also concur with the statement that there are just too many miles of chains in those engines to be very reliable. And the path they take with that huge u-shaped metal guide is just asking for metal shavings to be spread throughout the engine.

Oh, and the 15k mile OCIs that are factory recommended without UOAs to assure they are safe is rediculous. Not on the BMW 5W-30, anyway.


I think the U-shaped guide is ridiculous too. They should have used a routing similar to that of the Modular IMHO. However, I'm banking on reasonable OCI's on good oil keeping mine intact

 

[KitaCam]

re. Martinq:

I don't have any knowledge to answer your question about the direction of rotating cam lobes...I can ask at Toyonation if that would help ya...

As for the "shadow" areas...they're pretty regular and defined so they aren't going to be the result of arbitrary areas of a failing gasket...
...the colder "shadows" are at the rear of the engine, so heat from the exhaust manifold on the other side may be hot enough to prevent them... maybe...

 

[OVERKILL]

For those wondering what that giant U-shaped guide looks like, here:

 

[morris]

are chains really better than push rods? i think not.

 

[OVERKILL]

Originally Posted By: morris
are chains really better than push rods? i think not.


Push-rod motors have chains too.........

 

[Clevy]

Originally Posted By: OVERKILL
Originally Posted By: Donald
The problem is the absurd path of the timing chain. Way different than one on my old 289 Mustang.


But not all that far off from the path of the Ford Modular engines

Now Ford had guide failures for a few years, but it was because of the quality of the guides. Earlier years didn't have the problem, and neither did later ones.


Believe it or not some of the chains themselves were more abrasive than others. It all depends on how dull the die was that was stamping out the links. When the die is sharp and new the chain edges are perfectly smooth,as the die dulls the chain edge becomes more abrasive because the link is less cut and more ripped from the stock.

Originally Posted By: LeakySeals
Take a look at any engine pic on here going through a de-sludge/deposit cleanup. Whats underneath the sludge? A heavy layer of varnish. Its no coincidence. Varnish is telling us something about the oil and surface temperatures of the engine. Varnish always mattered, it can glaze cylinder walls, coke rings, make lifters stick. Matters more today. Tighter clearances, smaller oil gallies everywhere. Any sticky buildup in the tiny gallies of the variable valve timing system will cause issues eventually. So while you may be able to live with it, it cannot be ignored as "normal" anymore.


Very well said.

Originally Posted By: Donald
The problem is the absurd path of the timing chain. Way different than one on my old 289 Mustang.


Completely different animals. My 4.6 4V is very similar to the dohc pictured above except iirc the longer chain from the crank turns the exhaust cam first,then a shorter chain runs from a gear on the exhaust cam to the intake cam,so opposite than the m62 pictured above.
Back to topic. I believe varnish could very well pose problems in today's extremely complex running motors. Vvt operation is just a single possible issue.
I was on the fence about varnish being harmless but the more I read,the farther I lean to the varnish bad side of that fence.
I completely understand why pennzoil is pushing those sequence (4 or 5?Test results we have been reading about lately.
I think leaky seals has said it very well.

 

[Clevy]

Originally Posted By: Hokiefyd
Originally Posted By: OVERKILL
But that's just it. Many (most?) of the cars will never have this problem. But the ones that DO have the problem, appear to suffer from varnish build-up and I'm curious as to the correlation. This is a huge double roller chain that spans both banks too, so slap and whip may be of far greater detriment in this application than in others.


Do the Modulars use double row timing chains? Something from my memory tells me they are single row. If that is correct, that may play a part here, too. A double row chain would have more inertia and more mass for a tensioner to control; there may be some unique requirements of a tensioner in this situation compared with others. Even this last set of pictures doesn't look that bad to me; about typical for an engine using long OCIs. If the various components are too sensitive to this type of deposit formation, then perhaps the oil change interval is too long as specified. It certainly wouldn't be the first time that's happened in the history of the automobile.
Originally Posted By: KrisZ
I'm having a hard time believing that the engine in the last set of pictures saw exclusively 3k mile ocis. This is internet after all and all sorts of things are posted just to mess with everybody.


I doubt very much overkill would post any info he believed to be incorrect. It is very troubling though that an interval that short still led to varnish of any kind.
Overkill,don't you use M1 0w-40 in yours. How is it performing as far as cleanliness and have you seen the insides of it lately.
5000km intervals and still it looks like that. Is this perhaps evidence of something bigger being wrong and can we imagine if the owner just blindly decided to extend the oci because he is using a synthetic oil?
Makes me think twice about extending an interval without data for sure.

Great thread topic overkill. Very interesting.

 

[Clevy]

Originally Posted By: KitaCam
First of all, let me apologize to anyone who thinks a thread jack...I wanted to add to the conversation to help...hope I have...

I had posted the Camry's varinshing because it is clearly varnish at early stages...discoloring of metal parts BEFORE deposits begin to cling to the sticky stuff....
I think identifying/recognizing the early stages of "varnishing", helps to understand how/where/why the deposits build up thereafter is the beginning of understanding how to prevent/cure it.
Enjoy...

Anyway....to address, if not answer, a couple of issues/questions....viewing through the oil filler hole...and viewing the underside of the valve cover

View through the oil filler hole 2.5k miles BEFORE the cover was pulled......it seems that the darker coloration got lighter with PYB after 2.5k miles

Close-up of engine

Underside of valve cover...note the burned hot spots that may be a result of older spark plugs that while firing just fine in terms of MPG efficiency, may have been firing TOO hot...

...again, perhaps a result of a failing PCV valve, or an old-brittle-hard cracking VC gasket that may have been compromised in terms of evacuating AIR if not leaking liquid...as much as the (100k-mile) old plugs.

...also to be noted is the build-up of deposits that don't yet appear on the engine...I think that's interesting...

Well since you have the cover off I would cut that metal baffle off so you can actually see the head with the oil fill cap removed.
Just a thought

 

[KitaCam]

Great idea...but the cover is already back on the head...still...

I can see the coloration on and below the baffle, and as the color there has already gotten lighter, I think it fair to assume what I see there will be a reasonable indication of what it's like elsewhere...though I could pull the cover again after a couple of OCs with PP

 

[Clevy]

Originally Posted By: morris
are chains really better than push rods? i think not.


Great question. It took me a long time to accept Fords decision to basically eliminate pushrods from their gasoline engine line up. I don't think there is a single pushrod engine left is there?
Most Japanese engines have eliminated pushrods from their engines as well. I'm sure there must be some exceptions however the oem's seem to be trending away from pushrod motors,with the exception being Chev and Dodge who are still using cam in block V-8s.
There was a thread on ohc vs ohv a few months ago. I asked if anyone could figure out which platform would offer less resistance. Someone figured out that the difference was 15% or less in favour of the ohc engines.
Cam in block is old news however soon we aren't going to need cams at all and the valves will be gas or electrically actuated.
Ohc offer more tuning potential as well as a far broader useable powerband. Variable valve timing is limited in what it can do with an ohv engine and really isn't revolutionary in that platform however if you had a cam phaser in a dohc engine and you can adjust both the intake and exhaust event independent of each other then that is really something special,albeit much more complicated.
Cams being able to be adjusted like that could possibly help a V-8 spin to 8000rpm from the factory and have a straight flat torque curve and the same flat curve in the hp department.
Vvt and dohc is the future of engines in my opinion. All oem's have some form of ohc engine in their line up.

 

[Clevy]

Originally Posted By: KitaCam
Great idea...but the cover is already back on the head...still...

I can see the coloration on and below the baffle, and as the color there has already gotten lighter, I think it fair to assume what I see there will be a reasonable indication of what it's like elsewhere...though I could pull the cover again after a couple of OCs with PP


Please do. I'd be very interested to see what if anything the pp did. Are you using any additive or just oil. Maybe start a thread with pics. It would be informative for sure. Thanks
Sorry to go off topic overkill

 

[KitaCam]

No additives...PP only...the engine runs smoothly and quietly, moreso with PP (and new plugs, TB cleaning, and new PCV valve), than with PYB...

If I see no change in 10k (two OCs with PP), additives may be considered...

Seey'all in 10k/12months...