#4 exhaust valve on fritz

[DanHoug]

frustrating.... a little over 10k miles on my rebuild with new AMC heads from GoWesty with the upgraged exhaust valve.

symptoms:
- #4 dead on start up with strong miss, pull plug wire and no change in cadence. once warm, engine runs smoothly.

with both valve lash adjusters backed off at TDC:
- 80% leak down test failure on that cylinder cold, not tested warm yet. can hear and feel air coming out of exhaust during leak down test.

- cold compression 85#s on that cylinder, haven't tested warm.

i was really hoping it was going to be a valve adjustment issue but it is not looking that way. rented an inspection camera and can't really see the valves thru the plug hole. the mirror attachment is too large to enter spark plug hole. looks like i'm pulling the engine, i hate pulling the head with the engine in the van.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Igeo]

Unfortunate for sure.
Burned seat? Valve hanging up? What's the compression like on the other 3?
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1987 Westfalia 2.1 WBX Manual

[11BC2]

Have you removed the valve cover yet?

[DanHoug]

compression and leak down is fine on the other 3. i know intakes can get gummy from a leaky injector but i don't hear of exhausts getting sticky-- just burned on seat or valve.

what bugs me is i don't really have anything else to do to this engine while it is down, did it all 10k miles ago. only thing would be put speedy sleeves on output flange seal surfaces to eliminate a weep. but at least the engine will come down nicely, antiseize on everything.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[DanHoug]

[Igeo]

I'm new to these engines, so forgive the questions.
I knlow that older air-cooled, mechanical lifter VW's were sensitive to too tight valves (burned valve seats). I know these atre hydrauliic, but they are adjustable- could that have played a factor? Also, a high ratio rocker might keep the valve off the seat a little longer (?) which makes 'em run hot. You running those?
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1987 Westfalia 2.1 WBX Manual

[DanHoug]

no high ratio rockers. valve lash mis-adjustment is possible tho i was pretty darn careful to set at 1.5 turns past contact when i rebuilt the engine.

i suppose i need a hot leak down test before i pull everything. might show a different result.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[tencentlife]

You don't have a bad leakdown until you've removed the valve gear and whapped the suspect valve with a mallet while under pressure. The air pressure and movement forces the valve to center up and close more like it does when running. It's the closest you can come to simulating running conditions without interference by valve gear, and you'll often see a valve that leaks a little seal right up. Then you know that valve and seat are actually OK and can look for other causes of the problem.

With all valve gear removed, you can also test with pistons at various heights, to be sure they're not just sealing at TDC. Another trick to see how rings actually seal when running is to put a bar on the crankshaft and turn it to raise the piston while watching ring leakdown, slight ring leakage will also often seal right up because the rings never seal statically while running, they are always in motion.

Leakdown is to test containment, not valve actuation, so get valve actuation out of the way and test containment in isolation. You haven't done a really comprehensive containment test until you've done these extra steps, but they're worth it vs. tearing down a top end that actually has good rings, cyls, valves and seats.
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[DanHoug]

thanks, Chris. i'll absolutely do whack-a-mole prior to condemnation/teardown. it'll be interesting to see if it changes.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[DanHoug]

Forensics today.

removed the valve train and whacked the exhaust valve top with a rubber mallet to seat the valve. still at 85% leak down with air felt in the exhaust pipe.

here's some interesting photos. first, the spark plugs, arranged as per the engine. #4 on bottom left. notice it has not been burning as cleanly.

now the adjusters. #4 hammered. the valve was NOT clacking, the lifter was doing its job of maintaining clearance to the point of normal sounds.

and the valve top. mushroomed and some deposits suggesting it has been running hot.

i'm going to pull the engine, replace all 4 exhaust valves with TRW because i don't know why this one has failed. i am not confident of the quality of the valves in the head. maybe i screwed up on the preload on my rebuild but i was careful. it'll be interesting to see the condition of the seat once i tear it apart.

Questions:
- any GOOD adjusters out there? i can rob one from an engine i have that i know is OEM.

- i'm putting lash caps on and the rocker tower spacers. any gotchyas on doing that? not really inclined to high ratio rockers but maybe this is the time.

- why why why did this happen? 10K miles on a GW AMC head.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Igeo]

Could have been hanging up in the guide. Might explain the damage to the tip of the stem. And if the valve doesn't close properly on the seat, heat can't transfer and the valve burns.
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1987 Westfalia 2.1 WBX Manual

[DanHoug]

more info... pulled the engine and trans. removed head. took out #4 exhaust valve. it is marked "103 49S" and i can't get any Google hits on that part number. the seat width is worn crazy wide.. 4mm

aaaaand there's a bit of stem to guide clearance

Link


this valve has a stem of 8mm. OEM VW is 9mm on exhaust so i've ordered a set of TRW 9mm exhausts plus the guides. should be better heat transfer for the future but i'm puzzled as to why this one valve wore so quickly.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Igeo]

Wow, that's a lot of clearance Clarence (sorry, couldn't resist!).
I think the result of such big stem clearance under operating conditions is the valve will tend to roll about the seat before actually making a seal if it even has time to make a seal. The result is the wear you are seeing. At least you found your problem. Merry Christmas!
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1987 Westfalia 2.1 WBX Manual

[Wildthings]

Is the guide largely missing, just broken apart? I have heard bad things about the quality of the guides the AMC uses.

[DanHoug]

merely ovalled...

does anyone know if the AMC heads, equipped with 8mm stem exhaust valves can be rebuilt with the standard OEM 9mm guides? in other words, is the OD of the 8mm guide they used the same OD as the OEM 9mm guide?
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[borninabus]

[DanHoug]

GW says they are closed thru 1/1/19 but my plan is to call them and verify once i pull the guide.

yeah, that whole warranty thing... this is over a year old because it took me a while to do my engine and trans rebuild plus get a new knee. i so hate to be THAT guy that expects compensation for something beyond warranty. i can envision at least 3 'excuses' they could throw at me for the failure that are beyond their control. i'll just suck this one up to keep my blood pressure down but i'd like to talk to them on their thoughts of rebuilding this.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Abscate]

If you are nominally over a year but can document 10,000 miles, I bet they will step up for you. Those guides are horrible
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.ssS!

[DanHoug]

hmmmm.... maybe i should wait until they open to pull the guides. was going to do it over the weekend/holiday. darn it. i need my single car garage back for winter!!
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Zeitgeist 13]

Personally, I would document your repair procedures, but just keep moving forward. Once you tie yourself to GW's response timeline the insult to injury is multiplied. At best you might get some store credit as compensation
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Casey--

'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik?