t4 oil consumption

[SGKent]

We just took a trip to Yosemite - typical 2nd and 3rd gear climbs into the Sierra Mountains from sea level to 6500 feet and back down to 4,000 then return. There is one grade called Priest Grade on Hwy 120 that is 2nd gear with switchbacks for about 1200 feet of climb. Coming down we take the Old Priest Grade which is steeper but shorter . Letting it compression brake in 1st is too low and 2nd requires constant braking which is enough to result in brake fade near the bottom. Usually we have a SUV or pick-up on our tail near the top and by the bottom of the grade they are way behind us - buses do so well on winding roads and a big SUV with an auto-trans can't keep up.

I suspect that during this compression braking and the long hard climbs are the moments when our engine is consuming the most oil. I read some old threads and the VW owner's manual to see what VW considered normal for oil consumption. My 1971 1600 DP used to burn a quart about every 1200 - 3000 miles. As I recall, I would add a quart and by the time an oil change was due it was 1/2 quart low again. Sometimes I might take a long slow trip and it would only burn a quart over an oil change. So on average that would be 1.5 quarts per 3000 miles - which is about 2000 miles per quart - sometimes more sometimes less.

This 1977 T4 2.0 seems to vary oil use. I have gone 1000 miles with no change on the dipstick but hard climbs and descents seem to make it worse. On this trip we used about 1/3 qt over 500- 600 miles so that makes consumption about 1500 - 1800 miles per quart - just a little more than my 1600 DP. Of course the bore is bigger so there is more surface area. Also the engine only has 3000 miles on it so it is still breaking in a little.

VW shows in the 1977 manual that oil consumption is considered Ok between .17 US qt per 1000 miles (1 qt per 5,800 miles) to 2.38 quarts per 1000 miles. Wow what a spread that is. So it got me wondering - what are other 2.0 buses with good solid motors getting on oil consumption?
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[RatCamper]

You are absolutely right about engine braking causing more oil burning.

It's been a while so unfortunately I can't really chip in on amount of oil loss. Anyway mine used to lose most of its oil through leaks.
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Vehicle: 1975 Special order delivery walkthrough panel based pop-top camper (LCA / Sunliner). Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.

[blue77bay]

i dont add any oil between changes,at 3000 miles when i am due ,the dipstick shows between full and the add mark however ,we dont have much in the way of hills here and mine generally just runs up n down highways at 55mph ,i understand your donk is newish but how tight are the valve guides? ,with lots of switchbacks and on overrun the suction past the guides will be extreme and with lots of oil flooding the heads from the cornering sideloads it would be real easy to see elevated oil consumption
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I like hammers. Lots of hammers. Hammers and me go way back.
A large hammer collection is like an instant problem solver
Mark tucker wrote:,wack off as needed

[airkooledchris]

Ive never gotten one of my 2.0's to NOT leak at least a little oil, so I can't say what the consumption is. Certainly when ive taken the busses into the serious hills and gotten the oil really hot, a lot more will either leak or be otherwise consumed, usually in the neighborhood of reaching the bottom of the fill mark on the dip stick. (for trips equal to climbing up into Yosemite)

[merlinj79]

I usually change at 6 months, without reaching 3000 maybe 1000-2000. Usually don't need to add between changes (I do have hills).

A road trip into the mountains (any road trip out of San Diego) might result in adding 1/2 qt. somewhere along the line.

9 year old engine, 20K miles.
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Rick
"Pumpkin II"
Stock 2L FI '77 Westy
CA Smog Stuff

[TGOT]

This page of my 79 owners manual says up to 2.4 US quarts per 1000 miles is ok.

I on my 79 with no leaks I expected to use one quart between oil changes so 3000 miles. All my others were an ecological disaster so its fair to say I had no idea how much consumption vs leaking was going on.

[SGKent]

[raygreenwood]

I have never owned a bus or a 2.0L type 4. I have driven more than a few. But I have owned many type 4 vehicles (411,412). I have driven them heavily loaded and empty oevr virtually every terrain immaginable and for many very long trips. My 411 and 412's leaked nothing and used typically about 1/3 of a quart or less in the 3000 mile interval between oil changes.

I don't believe in the philosphy that keeping the oil level somewhere between the two marks is satisfactory. There is so little oil in these engines that I keep it exactly full...always...and carefully check it at every fill up on level ground after its drained down.

You are on the right track. Valve guide condition is of prime importance for oil usage. This is why I never rebuild an engine at any level without 100% replacing the guides and making sure they are spot on. If its over 70K miles and the heads come off...its poor economy NOT to get a general valve job that includes guides at the very least.

The issue with valve guide wear and oil usage...especially on heavy deceleration...is that heavy deceleration increases crankcase pressure...and since rpm is still up...so is oil pressure....whcih keeps the oil level in the rocker boxes high. This along with case pressure can push more oil past worn guides....and can tax even good valve guides

One other thing related tro crankcase pressures that is noticably different and has been noted to definately cause more oil usage...is the one time when I had a crimp in the intake side of my 412's flow through crankcase ventilation system....which very quickly proved that crankcase pressure will cause oil pypass at the valve stems. Went through a quart in 1500 miles and though I would lose my mind until I found the crimp at the air intake feeder line at the air cleaner.

This is also why the L-jet injected 1.8 in the 412 and the 2.0l in the bus will probably use a slight bit more oil than the injected 411 or 412. The 411/412 has a vastly superior flow through PCV system.....intake air from the air cleaner, through a flame trap splitter, through each rocker box, through the pushrod tubes, exiting at the oil baffel box through the PCV valve....so its a pull through system using live vacuum from the center manifold. It creates quite a bit more vacuum and flow through air volume in the case than the later diaphram differential breather valve system used on L-jet.

Aside from the problems above...the only time my oil consumption ever increased was when the milage on an otherwise un serviced engine approached high miles...like 100K miles or over. Upon pulling the heads....and checking careefully....I have always found that the valve guides were beginning to wear or valve stem wear was becoming noticable.
Ray

[Wildthings]

My aging 1800 (~250K miles) uses a quart at between 1000-2000 miles running at 65-75 mph. A hundred thousand miles ago, it used maybe half of that. Seldom go down the kind of long descents you have in California though.

[El_Güero]

[nathansnathan]

[RatCamper]

[nathansnathan]

[notchboy]

When I drove my 77 2 liter out from San Antone to Seattle, I had to keep an eye on the consuption. So I thought it just was old and ate oil. Here in Seattle I do drive it considerably less and have noticed little to no consuption. Until yesterday.

Yesterday I had to drive from Covington out the 18, some mild hills in 3rd then out the 90 up the pass tword Snoqualmi. The lifters started ticking on the way home. Today I check the level and it was low-almost a quart.

It may of been leaning tword low, but this is the first noticable level change in awile.

Whats changed? 3rd gear climbs at duration.
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[Wildthings]

There is a reason that ACVW engines don't have valve stem seals, they just don't have that much need in them. The valve stems slope slightly uphill verses heavily downhill as in most other automotive engines. You can probably suck a little bit of oil in through the intake valve guide during low manifold vacuum operation, but it would be hard to suck any through the exhaust valve guide.

If an engine is sucking oil on decel, I would think it more likely to be doing it past the rings.

[nathansnathan]

[SGKent]

on some engines a seal will only cause the valve guides to wear more. The only car I have ever owned with seals that didn't wear guides was a Fiat 124 DOHC cam engine where the cam pushed straight down on the liftercup which sat on top of the valve. On a VW there is a wiping action from the rocker arm which spins and rocks the valve. Over time that wears the guides especially if they have no oil to lubricate. Also a VW head gets much hotter than a water cooled head. Some seals are like little umbrellas that just keep the splash off. Those still let a little oil through. That said, I tried seals back in the 1970's on my 1600 DP to see what the effect would be and all it did was wear the guides quicker.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Wildthings]

[nathansnathan]

The seal is like a squared off o-ring around the valve stem. Actually, it's hard to see how it would do much as when the valve opens it gets pushed by the valve guide toward the end of the stem, and there is nothing to move it back down. Seems like it would work only at full lift because of that. The fiche calls it "oil ring". I'm pretty sure this engine is untouched from the factory having these seals, not to say they didn't contribute to the wear at the guides.

[Wildthings]