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TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/29/21 2:00 p.m.

My wife's 2011 Jetta S stripped the timing belt the other day.  Hooray!  The semi-competent local shop says it has multiple bent valves.  They want truly ridiculous money to replace the engine with a junkyard unit.  So that's not going to happen.

I have questions.

Any chance I can pull the head and just replace the borked valves?

Besides bent valves what else could be at issue?  Banged up pistons, I suppose.  What about like valve seats getting damaged?  Valve guides and seals?

Alternatively, looks like there are quite a few junkyard engines available locally for $300-500.  Probably will just do that.  With that in mind:

What should be replaced on a JY engine?  I'll do the timing belt, since I don't need to have another failure right away.  What else?  Rear main seal?  Maybe fresh clutch?

Burn the car to the ground?

Dusterbd13-michael
Dusterbd13-michael MegaDork
10/29/21 2:03 p.m.

I generally do all gaskets, belys and hoses in a junkyard engine. Same with pcv valve, new plugs. Use my injectors cause known good, same with slk my sensors. Toss in a new thermostat. 

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
10/29/21 2:13 p.m.

2.0 8v? they do leakdown/compression? Depending on the rpm they can survive. 
 

Toss a jy head on it with hg, head bolts, belt and water pump. I wouldn't fool with a full motor unless there were other issues. 

Tk8398
Tk8398 HalfDork
10/29/21 2:21 p.m.

On the older ones a broken timing belt would sometimes twist the lifters sideways a little and trash the head, but I don't know about the newer VW engines.  If it was mine I would probably pull the head and confirm that valves did hit the pistons, and if there isn't any noticable damage (including making sure the rods are still all the same length) replace the head with another used one.

Mr_Asa
Mr_Asa GRM+ Memberand PowerDork
10/29/21 2:22 p.m.

Not sure how they will do a leakdown test with a bent valve. Other than that, I do agree that I'd probably pull the head before I decide on a full engine.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/29/21 2:29 p.m.

All good info.  Thanks, guys.

I need to call the semi-competent mechanic and find out exactly what they did.  They said some weird nonsense to my wife about how they were going to diagnose it.

That and I need to get the car back.

Would seem there is a pick and pull in town here with a bunch of VW-like objects.  At least one is a similar S model. 

She had a 96 Jetta that did the same thing, but I replaced the timing belt on it and it ran another couple years.  No such luck this time around.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/29/21 3:45 p.m.

Which engine is it?

Exhaust valves for the turbo engines are $80/ea or so.

parker
parker Reader
10/29/21 3:52 p.m.

I had a tensioner pulley seize on a DOHC Neon which led to the same scenario.  Pulled the head, had the bent valves replaced and drove it for another 200,000 miles including multiple track days.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/29/21 4:32 p.m.
Pete. (l33t FS) said:

Which engine is it?

Exhaust valves for the turbo engines are $80/ea or so.

It's the S model, so the engine is the 2.0 8-valve.  The BEV.

1SlowVW
1SlowVW HalfDork
10/29/21 5:56 p.m.

Throw a junk yard head on with a new t belt and head gasket and bolts. No use changing the rest of the motor unless you find a valve lodged in a piston. 

Streetwiseguy
Streetwiseguy MegaDork
10/29/21 7:17 p.m.

Invent a time machine, go back a month, and book it in for a timing belt.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/29/21 7:55 p.m.

In reply to Streetwiseguy :

That's what my wife keeps trying to do.  She's not succeeded in getting to work, so she's settling for wallowing in self-pity.  It's intolerable.

What about a factory service manual?  I see some pdf downloads online.  Does a paper version even exist?  I dug into one of the download sites and they listed the engines covered by the 2011 manual, and the BEV wasn't listed.  Not sure if it's called something else, or just not well supported.

tremm
tremm Reader
10/29/21 9:07 p.m.

List it for sale at a silly price. Maybe you'll be smiled upon & can get something else.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
10/30/21 6:48 a.m.

Mechanically very similar to the aba (mk3) and aeg (mk4) engines. Anything that would be different wiuld be obvious (manifold design, some electrical stuff moves around). About all I would want before diving in is the headbolt torque and sequence and most times the hg kit has that on an instruction sheet.

 

edit: head bolts may have an uncommon drive pattern, may have to order the tool

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/30/21 8:37 a.m.

In reply to Paul_VR6 (Forum Supporter) :

Thanks.  Good to know.  I've already done an ABA timing belt, so maybe the experience will carry over.

I need to get the car back today and dig into it a bit.  See what I have to fix before going much further.  Hopefully I know more by this afternoon.

1SlowVW
1SlowVW HalfDork
10/30/21 10:43 a.m.

In reply to TVR Scott :

If you have done an aba t belt already the only big obstacles you are going to face are getting exhaust manifold bolts off and a sore back from being hunched over for a few hours. 8v vw motors are not complex. Does yours have some sort of vvt? 

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/30/21 12:06 p.m.

In reply to 1SlowVW :

I feel a bit ignorant on this one.  I've not really worked on this car much before.  Rock Auto lists some VVT stuff.  It's due on the tow truck in maybe a half hour or so.  I'll see more then.

Talked with the guy at the shop and they just swapped in a new belt and tried to fire it.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/30/21 12:17 p.m.

Adding a modest amount of confusion, the O'Reilly website calls this engine the CBPA.  Looks like it might just be another revision of the BEV.  I'll have to wait and see what the VIN tag says.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/30/21 6:14 p.m.

Got everything torn down this afternoon.  It actually came apart really easily.  Didn't need to use any giant cheater-bars or anything.

Found the culprit:

The #4 exhaust valve is definitely bent over.  Kind of hard to photograph but obvious by eye.

Here's the matching piston.  I don't see much of any damage:

Thoughts from those wise in the ways of valve replacement?  Should I set up something to block off the combustion chamber and then pressure test the other valves?

It's been a few decades since I've had a head apart.  What do I need for replacing that bent valve?  Do I just lap-in the new one or is there a more elaborate process?

Streetwiseguy
Streetwiseguy MegaDork
10/30/21 6:42 p.m.

If the belt stripped and you bent one valve, odds are the other three exhausts are super suspect.  I would spend the money on a machine shop, because it really sucks to take it apart again.  The guides can be damaged a bit, too, so they should be checked.

I'd say the pistons will be fine.  That's not a very big hit.

Confirm hydraulic or solid lifters, too. That changes your reassembly process.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/30/21 6:49 p.m.

I have pulled many valve-hit pistons out and I have never found one that had pinched rings.

I did have a 4.0 Chrysler that developed righteous piston slap.  But that one actually had a valve head break off while we were rolling the engine over with a ratchet and checking timing.  (Belt jumped time because an idler pulley bearing seal fell off and got wedged between the crank sprocket and belt)  Engine ran fine for years afterwards, it just sounded a little hellish.

 

+1 on replacing ALL exhaust valves.  Check the carbon on the piston tops for contact evidence.  OTOH I am biased because on turbo Audi 10v engines, the sodium filled exhaust valves tend to lose their heads, so replacing them with superalloy/Inconel valves is a reliability update.  Cheaper, too, I think I paid $250 for five.

TVR Scott
TVR Scott GRM+ Memberand SuperDork
10/31/21 8:48 a.m.

In reply to Pete. (l33t FS) :

Looking at the pistons, I don't really see any marks that would indicate contact on the other exhaust valves.  Are there other ways to inspect the valves?

What's the procedure look like to just replace valves?  Is it a huge process with a bunch of special tools, or no big deal?

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/31/21 9:07 a.m.

If you can't even see any marks in the carbon, the pistons are fine.  That 4.0 I mentioned required picking the valve out of the piston with a screwdriver.

Best way to inspect the valves is to remove them, chuck them in a drill, and spin them in front of a CRT type television or monitor.  The strobe effect from the CRT will make any bending immediately obvious.

If the valve is only slightly bent, it might actually pass a leakage test (kerosene or gasoline in the ports and check for seepage) because the valve spring will bend the valve straight.

 

Special tools... You need a valvespring compressor with a deep adaptor to get down into the lifter hole.   A pocket magnet to deal with the valve keepers.  And a driver mandrel to install the new valve stem seal, but you can often make do with a 12 point socket.

 

I have all the tools, but I prefer to just hand it off to a machine shop.  They'll check the valves and cut the valves and seats if they're okay.

MrFancypants
MrFancypants Reader
10/31/21 10:32 a.m.

How much is a remanufactured head after core?  In the past I've done this as it had been the easiest somewhat cost effective option.

JoeTR6
JoeTR6 Dork
10/31/21 10:48 a.m.

Having the head checked by a competent machine shop would be good insurance.  I've taken valves out of a TR6 head before and have a tool, but it might not work with a modern VW head.  If you don't get the valve keepers fully seated, they can pop out and you drop a valve leading to another level of problems. Unless you are really time constrained, use a pro.

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