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On rebuilding stock heads
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furgo
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PostPosted: Fri Jan 12, 2018 7:30 am    Post subject: On rebuilding stock heads Reply with quote

Lately I've been trying to learn more about parts of the bus I didn't have previous experience with. A while ago, I started with the used vs. new cylinder heads thread, which was very enlightening thanks to everyone's input.

From there I gathered enough knowledge to make an informed decision once I need to replace the heads. For me personally, it will be new, reworked AMC heads. Others might choose other options.

However, I haven't reach the point where heads need to be replaced yet. That's left me wondering about the best course of action to get the maximum life of my current heads. Essentially, I see two options:

a) Leave them alone until the point of failure
b) Take them out now (or in N miles) and get them reworked

And if b), then short of replacing everything (valves, guides, seats, springs...), what would be the best recommendation for a refresh to give an extra bit of life to used stock heads?

• Replacing valves and re-cutting the seats?
• Replacing the valve guides?
• All of the above?
• I'm guessing replacing the valve seats might be not worth doing on used heads and would be an operation that would rather grant getting new heads...

The current head status for more context:

• 130K miles
• Compression values:

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Starbucket
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PostPosted: Fri Jan 12, 2018 9:42 am    Post subject: Re: On rebuilding stock heads Reply with quote

I would leave it alone until you need a rebuild of the whole motor, then new heads, pistons & cyl.s and bearings, clutch, etc.. Do it once right and drive it for another 150K-200K worry free.
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SGKent Premium Member
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PostPosted: Fri Jan 12, 2018 4:08 pm    Post subject: Re: On rebuilding stock heads Reply with quote

Quote:
However, I haven't reach the point where heads need to be replaced yet. That's left me wondering about the best course of action to get the maximum life of my current heads. Essentially, I see two options:


Valve seats use the laws of Chaos to fall out. In layman's terms, somewhere in the world today a valve seat will fall out on a VW bus head or a starter solenoid will stick. The question is when will it be your turn? You can't graph or model that.

You can pull the heads off, have someone rebuild them and stake the old seats to give it a greater margin of safety but the Law of Certainty states that the following morning you will post a thread saying what you have done followed by a statement that you wish you had bought new heads and still plan to.
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Starbucket
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PostPosted: Fri Jan 12, 2018 4:24 pm    Post subject: Re: On rebuilding stock heads Reply with quote

To tell if its your rings or valves, you have to take a reading (as run) then squirt a shot of oil in the plug hole and crank the motor a turn or two and take another reading, if it improves its your rings, if no change , its the valves.
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timvw7476
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PostPosted: Fri Jan 12, 2018 6:49 pm    Post subject: Re: On rebuilding stock heads Reply with quote

The usual reason for head service/rebuild is teardown time, caused by
catastrophic failure, or high oil consumption.
The oil consumption is always rings & bores, stuck oil control rings.
So most type IVs come apart for that reason. The camshaft lobes & lifters
are also finished at that point, exhaust valves & guides too.
I would not worry with numbers well above 100 psi, unless you just have to
tear into your engine for fun & educational purposes.
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airkooledchris
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PostPosted: Fri Jan 12, 2018 9:43 pm    Post subject: Re: On rebuilding stock heads Reply with quote

Go with A
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raygreenwood
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PostPosted: Fri Jan 12, 2018 10:27 pm    Post subject: Re: On rebuilding stock heads Reply with quote

DO NOT leave them alone until failure. In too many cases.....one mght assume that failure of the heads is just a crack....or a seat fallimg out....or receding.....and that the instant it happens....you can safely shut down and tow the bus back home.

It is just as commonly a snapped off valve when the heads fail. That equals a head that ia generally destroyed....a piston and cylinder destroyed.....sometimes a rod.....almost always destroyed bearings and oil cooler from the metal blown into the oil through the hole in the piston.....and if siezure is involved....possibly damage to the case.

It "can" be worth rebuilding the stock heads....by this I mean....if yhey are not cracked and you do not wait for failure.....they can be saved/preserved .....which means new seats, valves, guides, machine the cylinder seats, check for cracks, new exhaust studs.

But.....why go through that unless there were no new or low mile castings available. Such heroic efforts are only worth it anymore on an engine that has no NEW parts available.

And....thats not dirt cheap and as SGKent is pointing out.....you now have rebuilt heads whose aluminum still has a zillion heat cycles and has lost the elasticity to REALLY hold valve seats in for a full lifespan.
In a bus.....these rebuilt heads may last 10k...20k....maybe 30k....maybe much less.

Yes....that elasticity can be re-annealed by a full service head shop....but its expensive. All ferrous metal comes out.....the head is heated in an oven.....and seat bores redone, new seats, new everything. If you can find a shop that does that......the costs can exceed starting from new castings.

I would get new castings from AMC....have new seats with proper interference fit installed, hood wuality valves and guides.
Ray
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PostPosted: Sat Jan 13, 2018 12:44 am    Post subject: Re: On rebuilding stock heads Reply with quote

Quote:
hood wuality valves and guides.
Ray


The Wabbit has spoken - best to listen to him. Smile

Just kidding with you Ray, my typing is worse Smile
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* VW Buses and VW cars share many of the same systems but if you haven't owned a bus and maintained it for awhile, you really don't know how different it is.
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raygreenwood
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PostPosted: Sat Jan 13, 2018 2:51 am    Post subject: Re: On rebuilding stock heads Reply with quote

SGKent wrote:
Quote:
hood wuality valves and guides.
Ray


The Wabbit has spoken - best to listen to him. Smile

Just kidding with you Ray, my typing is worse Smile


I'm lucky it came out that good.....I was standing on an airport bus....it was vewy, vewy cwowded.....Wink

Ray
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furgo
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PostPosted: Sat Jan 13, 2018 5:19 am    Post subject: Re: On rebuilding stock heads Reply with quote

Thanks everyone for the feedback.

So it seems it's unanymous:

a) Leave them alone until the point of failure (or rebuild)

I guess the big question here is how to best estimate the point in time for an engine rebuild and head replacement.

Some commented on the compression numbers: note I only added them to give more context as to the current state of the heads. I'm not worried about the actual figures, as they still are within specs.
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Starbucket
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PostPosted: Sat Jan 13, 2018 8:23 am    Post subject: Re: On rebuilding stock heads Reply with quote

When the motor starts to feel tired, lacking the old get up and go, smoking, and using oil it will be time to start gathering parts. Another thought is keep your eye out for a wrecked bus that you can buy the motor from and use it while you rebuild yours at your leisure.
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Wildthings
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PostPosted: Sat Jan 13, 2018 8:31 am    Post subject: Re: On rebuilding stock heads Reply with quote

Adding something like Marvel Mystery Oil to the engine oil and gas will clean the engine up a bit and then running synthetic oil will keep it cleaner. Doing such may bring you compression up.
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Manfred58sc
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PostPosted: Sat Jan 13, 2018 8:33 am    Post subject: Re: On rebuilding stock heads Reply with quote

"Go till you blow" is a very poor way to operate machinery. Much wiser to service the unit after normal wear cycles ( 120K on T-4 would be about right ). Save the parts,lower cost, more reliable. The disposable mindset is a by product of today's throwaway cars.
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PostPosted: Sat Jan 13, 2018 9:02 am    Post subject: Re: On rebuilding stock heads Reply with quote

Getting 120k service out of stock heads is pretty good. Usually the valve seat have loosen up from the heat cycleing and valve pounding. Dump the heads
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PostPosted: Sat Jan 13, 2018 9:38 am    Post subject: Re: On rebuilding stock heads Reply with quote

I got 250K miles out of a set of used 1800 heads that had no work done to them but to have the guides replaced when I first bought them and have known others who have gotten 250K out of Vanagon AC heads and one that got 350K out of factory heads on a late Bay. Keeping an engine well tuned and the cooling system operating in factory condition will alleviate a whole lot of head problems.
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furgo
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PostPosted: Sat Jan 13, 2018 9:51 am    Post subject: Re: On rebuilding stock heads Reply with quote

Manfred58sc wrote:
"Go till you blow" is a very poor way to operate machinery. Much wiser to service the unit after normal wear cycles ( 120K on T-4 would be about right ). Save the parts,lower cost, more reliable. The disposable mindset is a by product of today's throwaway cars.


While I agree with the first statement, and I see that I should have probably worded option a) differently... with the amount of work I've already put rebuilding NLA parts for the bus, I feel this can hardly be described as disposable mindset Smile

In fact, to me personally it would be the last thing that comes to mind when thinking of a bus.

Wildthings wrote:
I got 250K miles out of a set of used 1800 heads that had no work done to them but to have the guides replaced when I first bought them


Thanks, it's great to have some actual, first-hand figures from someone as a reference –although I'm aware these will vary depending on each engine and how anal the owner was with servicing it.

Out of interest, what made you replace the valve guides? Was there obvious wear when you got the used heads?
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asiab3
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PostPosted: Sat Jan 13, 2018 11:10 am    Post subject: Re: On rebuilding stock heads Reply with quote

After dealing with a few pairs of Len's HAM heads this year, I can attest that they are the cheapest option out there if you can do math.

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Wasted youth
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PostPosted: Sat Jan 13, 2018 11:43 am    Post subject: Re: On rebuilding stock heads Reply with quote

Just keep in mind that HAM no longer rebuilds used Type 4 Bus heads.

https://newsite.hamheads.com/2017/01/16/vw-2-0-transporter-cylinderheads/
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Wildthings
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PostPosted: Sun Jan 14, 2018 3:52 pm    Post subject: Re: On rebuilding stock heads Reply with quote

furgo wrote:
Manfred58sc wrote:
"Go till you blow" is a very poor way to operate machinery. Much wiser to service the unit after normal wear cycles ( 120K on T-4 would be about right ). Save the parts,lower cost, more reliable. The disposable mindset is a by product of today's throwaway cars.


While I agree with the first statement, and I see that I should have probably worded option a) differently... with the amount of work I've already put rebuilding NLA parts for the bus, I feel this can hardly be described as disposable mindset Smile

In fact, to me personally it would be the last thing that comes to mind when thinking of a bus.

Wildthings wrote:
I got 250K miles out of a set of used 1800 heads that had no work done to them but to have the guides replaced when I first bought them


Thanks, it's great to have some actual, first-hand figures from someone as a reference –although I'm aware these will vary depending on each engine and how anal the owner was with servicing it.

Out of interest, what made you replace the valve guides? Was there obvious wear when you got the used heads?


I had the heads off to do other engine work and sent them in and told the guy to fix what was needed and he felt that doing the guides was sufficient, I am sure he touched up the valve seating surface and the seats, but don't remember exactly because that was 27+ years ago. IIRC he charged me either $60 or $80, which would probably equate to maybe $200 or $250 today. The heads came off of a '74 412 which had either 100 or 150K miles on the clock and I had put ~20K miles on them before sending them in, which gives a total mileage between 370 & 420K miles. I need to pop the timing gear off the cam so I can see what it was, I was surely a great combo giving good power, good gas mileage, and a nice long life. At the time I just asked the shop to supply an RV grind that they liked, and didn't pay any more mind to it than that.
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furgo
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PostPosted: Mon Jan 15, 2018 4:50 am    Post subject: Re: On rebuilding stock heads Reply with quote

Wildthings wrote:


I had the heads off to do other engine work and sent them in and told the guy to fix what was needed and he felt that doing the guides was sufficient, I am sure he touched up the valve seating surface and the seats, but don't remember exactly because that was 27+ years ago. IIRC he charged me either $60 or $80, which would probably equate to maybe $200 or $250 today. The heads came off of a '74 412 which had either 100 or 150K miles on the clock and I had put ~20K miles on them before sending them in, which gives a total mileage between 370 & 420K miles. I need to pop the timing gear off the cam so I can see what it was, I was surely a great combo giving good power, good gas mileage, and a nice long life. At the time I just asked the shop to supply an RV grind that they liked, and didn't pay any more mind to it than that.


Thanks, that seems to further confirm that if they need to be reworked better do it while the motor is out for other work. And unrelated, nice to learn about an "RV grind", which I had no idea what it was before I looked it up Smile
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