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VW MKIII-A3/B4 TDIs This is a discussion about MKIII-A3/MkIII Jetta/Golf (<99.5) and B4 Passats (96,97) TDI's. Non TDI related postings will be moved or removed.

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Old October 27th, 2006, 05:57   #1
all2go
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Join Date: Jun 2005
Default Hammering valve guides in ??

I took the valve train parts to the machine shop yesterday. The "machinist" started on my head while I was there and used a large ballpeen hammer and what looked like a punch that fit through the center of the guide to hammer it into place. He complained that he did not have the correct diameter tool to fit the guides "but this one should work". It should have fit the hole exactly but it was a little too small. He seemed to have the correct diameter for all American cars and a few Jap cars, but not a 7mm. After some trouble getting the first guide in he said "I will have to freeze them first". He then put them in the refrigerator freezer and told me the head would be ready tomorrow. I looked at the one guide he did while he walked to the freezer and the top looked a little flattened where he had beat on it. I pushed one of the valves in and although it did still go in there was some initial resistance. I am also worried the seal will not fit properly now.

I am concerned that the brass guides will be deformed installing them in this manner. SHOULD THEY NOT BE PRESSED IN ?? Is it standard practice to install them this way IF one has the right tools?

He also said he did not have the right tool to surface the valve seats and that he would lap them in. That does not concern me as much as hand lapping probably does a better job if done correctly.

If the guides should be pressed in I would really like to know so I can say something before I pay.

Finding people to respect a VW is hard.
Andrew.

Last edited by all2go; October 27th, 2006 at 16:18.
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Old October 27th, 2006, 08:03   #2
Herm TDI
 
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Befor you decided to replace valve guides did you check the valve guide run-out (using new valves)?

The only time you should consider replacing the valve guides is if they are actually worn. There is a lot of wear tolerance on the TDI valve guides.

Measured with a new valve (intake and exhaust) 1.3 MM or 0.051" Beleave me .051" is a whole lot for permisable tolerance.

I would not consider replacing the valve guides untill I was closer to 0.40" or 1 MM. At that point I would indeed replace the guides.

Last edited by Herm TDI; October 27th, 2006 at 09:00.
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Old October 27th, 2006, 08:09   #3
Herm TDI
 
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What the Bentley manual says:
Note:
Do not replace the valve guides in cylinder heads where the valve seats can no longer be reworked, or cylinder heads which have already been machined to the minimum dimension.
- Press out worn valve guides using 3121 from camshaft side (valve guides with shoulder - service version - from combustion chamber side).
Installing
- Press new guides in up to shoulder (lubricated with oil) from camshaft side in cold cylinder head using 3121 drift. Note:
When the valve guide shoulder makes contact, do NOT allow the pressure to exceed 2000 psi or the shoulder could break off.
- Ream out guides with 3120 hand reamer and plenty of cutting fluid.
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Old October 27th, 2006, 09:06   #4
Chris Bell
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Driving in the guides is the correct procedure but guide OD should be measured and compared against the old guides. The head should be oven-heated and/or the guides chilled to minimize head guide boss spalling.

Valve stem to guide clearance should be measured with a dial bore gauge...rocking the valve and measuring lateral movement is OK for a rough indication of clearance, but a dial bore gauge reveals the degree of taper, which is the true measure of guide wear. Reaming the guide ID is old tech and doesn't give as round and straight a hole as conventional mandrel honing or Sunnen diamond honing.
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Old October 27th, 2006, 16:28   #5
all2go
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Thanks for the correct info. I picked it up just now and I will install it tomorrow. I will have to operate on trust at this point as it is done now.

The valve stems did move laterally in the old guides, they are bought and installed so it is a fait accompli.

It was a rebuilt head from VW in 2000 and it just got another valve job, oh well.

Could Bentley owners post the correct torque values please? Head, intake, exhaust etc...1Z engine, '96 Passat. I used jetta torque values in 2000 and they worked but it would be nice to know if they are the same. Should be.

Thanks,
Andrew.
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