TheSamba.com :: View topic

Tue Feb 16, 2010 6:07 pm

First off, it seems like it hasn't been determined that you need a new head. Take it off and get to a expert VW head man. Actually don't take one but take both heads. You want them done identical. One failed, is the other ready to fail? I could go on with a lot more arguments about doing just one side. But it is also interesting to have been following many Samba posts where just one side was repaired and the engine turned out to be a bummer. I think some of the people even ended up bagging the whole bus hobby.

Tue Feb 16, 2010 7:56 pm

Thats what I have been thinking... I mean how do you know the head is bad?

Tue Feb 16, 2010 9:51 pm

The valve either stretched or was pounded in to the point that I didn't have any travel left to adjust it to get it to work. It definitely needs work. It was already starting to go, and needed adjustments too often.

Tue Feb 16, 2010 10:40 pm

cool.. makes sense now... Throw a bandaid on 'er and head on out :)

But, save some $$'s for the rebuild down the road when you can build it like you want it

Wed Feb 17, 2010 12:57 am

First off I am going to repeat that it is better to pull both heads and have them both machined to the same specs. But if you are determined to do only one head you can check your compressed cylinder volume very accurately with a syringe. Just set the cylinder you want to check at TDC compression and fill the cylinder through the spark plug hole with motor oil using a calibrated syringe. The amount of oil it takes will be your compressed volume, from which you can determine your compression ratio. You can also check your squish by using a long thin feeler gauge through the spark plug hole, though carbon deposits will likely throw you results off pretty badly.

Tue Feb 23, 2010 8:46 am

Update: Over the weekend, we got he engine torn down and saw that the old head was missing a piece of the exhaust valve. The cylinders and cylinder walls were still good and we couldn't get the cylinders to wobble, indicating that the rings are probably OK. A couple of my lifters were worn so I ordered new ones. The cam looked "decent"

I get parts in today and should get it the rest of the way put together tonight. My plan is to just slap it together to drive it to work for a couple months. Once I'm up and running, I'm going to fix the head I previously had on it, and then likely swap it back out when I can take my bus back out of service in two months. I think it will get me around until then.

Steve

Tue Feb 23, 2010 1:26 pm

Please elaborate on "couldn't get the cylinders to wobble", any pics of in the combustion chambers and cylinders?

Tue Feb 23, 2010 2:58 pm

Cylinder wobble?? I don't get it either..
Westy Steve wrote: A couple of my lifters were worn so I ordered new ones. The cam looked "decent"

Hmmm.. Sometimes new lifters do not play well with old cams.. I had a new one eat down an entire cam lobe in 50 miles a yr or 2 ago. Maybe it was just a fluke (I've heard of it when all was new too) but it was enough of a PITA that I will always replace the whole team in the future.. Did you pull the other head for a look?? Did you make the chambers the same volume?? Hope it all works out for ya. Enjoy the ride!

Tue Feb 23, 2010 2:59 pm

Sorry. Typing in a hurry when I wrote that. I mean, there was no play in tghe pistons. You can not get them to move side to side within the cylinder and the cylinder wall is not scored. No groove pattern, nothing you can catch a finger nail on, and some discoloration on #3 cylinder. I think I caught the problem early and to limp it home, I took out the pushrod and rocker arms so it couldn't fire.

Unfortunately, no pix because I immediately put the new head on after the inspection. We'll see how it runs next...do a compression test, etc.

Steve

Tue Feb 23, 2010 3:02 pm

So you didn't lap the barrels into the new head? Hmmmm.....this will be interesting.

Tue Feb 23, 2010 3:06 pm

Westy Steve wrote: Sorry. Typing in a hurry when I wrote that. I mean, there was no play in tghe pistons. You can not get them to move side to side within the cylinder and the cylinder wall is not scored. No groove pattern, nothing you can catch a finger nail on, and some discoloration on #3 cylinder. I think I caught the problem early and to limp it home, I took out the pushrod and rocker arms so it couldn't fire.

Unfortunately, no pix because I immediately put the new head on after the inspection. We'll see how it runs next...do a compression test, etc.

Steve

You check piston wear by measuring between the piston and the jug with a feeler gauge, not by trying to move them. You also check the ring clearances with a feeler gauge. Even badly worn P&C's will often LOOK good. You need to properly measure things.

Wed Feb 24, 2010 10:48 am

busdaddy wrote: So you didn't lap the barrels into the new head? Hmmmm.....this will be interesting.

You may be right. I put it all back together and it is giving symptoms like a loose head. Gonna re-check the torque on the heads. Whats interesting is it sounded really great after start up for a few minutes, but after revving it up, it started giving a loose head sound. Gonna have to re-run diagnostics.

Steve

Wed Feb 24, 2010 1:22 pm

Forget diagnostics, get some valve grinding compound.

Wed Feb 24, 2010 2:09 pm

I have a gasket in between the cylinder and the head. Does this eliminate the need to lap the head for the cylinder as long as they are the same diameter?

Also, because I am using a spacer, does that mean that it's very probable that the heads need to be retorqued after it went through the heating and cooling cycle?

The bottom line is that the cam had a little wear but it was fine, the head looked good and had been inspected by the bug shop. The piston and cylinder appeared to be in a good shape and after I started it, it ran like a buttery smooth dream, but then it started making a periodic thumping noise that makes me think my head needs retorqued. If I can get two months of 20 minute commutes out of this thing before I take it all apart I'll be happy, but I need my bus back up and running ASAP. Any constructive criticism is appreciated. I like jokes as much as anyone else, but this is serious to me.

What does it sound like when your head is loose?

What does it sound like if the push rod wasn't aligned properly?

How common place is is to need to retorque a head when you are using a gasket between the cylinder and head?

Is the Bentley manual correct for the torque settings for the 2 liter engine? And is it correct to set valves to 0.006-inch as stated in there? Or have either of these readings been shown to be wrong over the long term?

Thanks,

Steve

Wed Feb 24, 2010 2:39 pm

Could you describe the periodic thumping a little better?

If you used the head gasket then lapping will do less for sealing, It might help a little, I am not sure. I've only heard of lapping without the gasket.

All heads should be retorqued after break in but it often does not get done because its a PITA n the T4.. I would not think running a few minutes would neccesitate retorquing the heads..
If the pushrod isn't in there right, you usually get more of a chatter..
Bentley head torques are the ones to follow and valves are set to 0.006"

Wed Feb 24, 2010 3:37 pm

What kind of gasket(s) are you running? Lapping shouldn't be necessary if you run a gasket.