Rebuilding a 2.0 TSI after timing failure at 173k *ON A BUDGET* (less than $1k spent) - And Then Balance Shafts 2 Years Later

[brat_burner]

Absolutely, although checking the guides is typically included in the scope of a valve job (or at least it was for me when I was a machinist). If I found they worn, then I would inform the customer that they needed to be replaced.

True true, my bad.

 

[zrickety]

Ok, so I'm making progress. Half the bent valves are out. Because they are partially open, it's difficult to get the keepers off. Some ports have more build up than others...they will be cleaned. Exhaust side looks really good, which is to be expected.

 

[zrickety]

I kept trucking, and got all the bent valves out. I cleaned the ports to a degree. I was putting in the new valves and found at least 2 of the valve guides are shot. I don't think they were actually worn, as the seats looked good, but probably stretched out when the valves crashed. So I'm trying to find a reputable machine shop to do the guides. It sounds like this will add about $300 to the cost of the rebuild. I'm in a rural area, so all the machinists are an hour away in 3 directions.

 

[zrickety]

 

[zrickety]

Absolutely, although checking the guides is typically included in the scope of a valve job (or at least it was for me when I was a machinist).

I missed your post earlier. Since you are a machinist, I would love your input. The book spec on guide wear is .8mm as I posted. 6 of the 8 intake valves are within spec. There are 2 (cylinder 2) which appear to be ~1.0mm. I know this is outside spec, but the new valves still seat very well. Angles match stock. Do you think it would last another 4-5 years as is or do I risk breaking a valve?

 

[Roadrunner_GTI]

I missed your post earlier. Since you are a machinist, I would love your input. The book spec on guide wear is .8mm as I posted. 6 of the 8 intake valves are within spec. There are 2 (cylinder 2) which appear to be ~1.0mm. I know this is outside spec, but the new valves still seat very well. Angles match stock. Do you think it would last another 4-5 years as is or do I risk breaking a valve?

How are you checking wear on the guides? Typically we would insert the valve in the guide, pull it out about 1" above the valve seat, and wiggle (or rock) the valve back and forth. Using this method, .8mm (.032") of movement indicates .016" of wear on each side of the guide. Going up to 1mm (.040") now we're talking .020" of wear on each side of the guide. That's a substantial amount of wear and most reputable machine shops would not be comfortable sending that out the door due to liability concerns. Will it cause the valve to break? Possible, probably a fairly low chance. Will it cause oil consumption? More than likely. It's a gamble honestly. Sorry, wish I had better news.

 

[zrickety]

How are you checking wear on the guides? Typically we would insert the valve in the guide, pull it out about 1" above the valve seat, and wiggle (or rock) the valve back and forth.

Yes, that is exactly how I am checking the wear. Wouldn't new seals mitigate oil consumption? I find it interesting that the 2 shops I talked to are saying new guides are not concentric and require machining the seats...why wouldn't they be centered?
The one shop said January. There is also a tech school near me that's back in session in January. If they want the experience and it saves me money, I'll give them the job.

 

[Roadrunner_GTI]

Yes, that is exactly how I am checking the wear. Wouldn't new seals mitigate oil consumption? I find it interesting that the 2 shops I talked to are saying new guides are not concentric and require machining the seats...why wouldn't they be centered?
The one shop said January. There is also a tech school near me that's back in session in January. If they want the experience and it saves me money, I'll give them the job.

Even with new seals, the worn out guides will allow the valves to move laterally and cause oil to leak past the seal. The seals and guides work together. In addition, the play in the valve will cause a poor seal at the valve seat, leading to potential valve failure.

I was under the impression you were already having a valve job performed, meaning machining the valve seats and grinding the valves you're reusing. This is especially the case for a head that has new valves and an absolute must for a head that has new guides. The process to replace guides is to drive the old guides out with a pneumatic hammer, drive new undersized guides in, ream the new guides to the proper size of the valve stems, machine seats centered on the new guides. Then lastly would be to resurface the head. Not doing these steps is essentially wasting your time on this type of job, because you'll be pulling the head again to do it right in the near future.

 

[GeorgiaBII]

Please listen to Ronnie, I've gone behind more than one novice/hobby mechanic and had to completely redo the job they did because they didn't have a machine shop do the necessary operations when the head was off.

0.8mm is a max spec that you would expect to find a 150 to 200k engine. Since you are already apart you want to put it back together at minimum spec not maximum.


*note* I'm doing this exact same job as we speak and my head is going into the machine shop for a complete rebuild. No point in not doing it.

Old saying "penny wise pound foolish" comes to mind.

 

[zrickety]

*note* I'm doing this exact same job as we speak and my head is going into the machine shop for a complete rebuild. No point in not doing it.

Bill, thanks for the reply. I'm curious where you brought yours and how much they're charging??
I hear you guys. I'm familiar with CNC/Bridgeport machines...which is why I say the new guides should be centered to the existing seats. I understand valve grinding/lapping. I've done similar head work to a hydro-locked Honda B16 engine, by myself. It ran strong, sold it years later still running. Head was still flat, found another block that had gouges in the surface. Local machine shop said they couldn't do anything with the block (lame), I used JB weld in the low spots and fine sanding to make it flat. I honed, installed new pistons, rings, that engine never gave a single problem.
All that said, I will hand off this valve guide work after New Year's. Preferably the tech school, but whoever is capable. One shop said they weren't sure they could get new guides, but I know IE sells them. All Ford and Chevy guys around here.
Merry Christmas everybody!!

 

[GeorgiaBII]

Bill, thanks for the reply. I'm curious where you brought yours and how much they're charging??

I'm dropping down to Macon with it and going to use a buddies machine shop to do the work so other than parts $9 a valve and however many valve guides I need it won't cost me anything but lunch since I'll be doing the work myself.

 

[zrickety]

I'm dropping down to Macon with it and going to use a buddies machine shop to do the work...

Awesome. Where are you sourcing the guides? If your buddy is reasonable, I would toss him the work.

 

[Roadrunner_GTI]

Bill, thanks for the reply. I'm curious where you brought yours and how much they're charging??
I hear you guys. I'm familiar with CNC/Bridgeport machines...which is why I say the new guides should be centered to the existing seats. I understand valve grinding/lapping. I've done similar head work to a hydro-locked Honda B16 engine, by myself. It ran strong, sold it years later still running. Head was still flat, found another block that had gouges in the surface. Local machine shop said they couldn't do anything with the block (lame), I used JB weld in the low spots and fine sanding to make it flat. I honed, installed new pistons, rings, that engine never gave a single problem.
All that said, I will hand off this valve guide work after New Year's. Preferably the tech school, but whoever is capable. One shop said they weren't sure they could get new guides, but I know IE sells them. All Ford and Chevy guys around here.
Merry Christmas everybody!!

The Ford / Chevy machine shops are a dime a dozen, tough to find good machinists that can work on a variety of things. Here's another supplier for valve guides, slightly cheaper than IE. Good luck and keep us updated!

 

[zrickety]

Ronnie, thanks for the link. Apparently these guys have been around awhile on the west coast but I never knew.

 

[zrickety]

I found a machine shop in Columbus, GA with great reviews. Dropped the head off today, looks like they've been there a long time and do lots of business. I bought the IE guides for their 'proprietary material' and good air flow. I wanted them to have all the pieces on hand.
Only having them do the intake side, which includes the valve job. He told me it should be ready Friday.