Cylinder Head q's...

[jalabert]

Dunno if anyone else has had a peek in the latest issue of volksworld? First time I have picked up a VW mag in years - there is an article in it on servicing cylinder heads: basically covering cleaning all the old crap off, removing the valves and inspecting, reinstalling new valves / springs. The article covered T! heads, but I assume could be easily applicable to T4 heads.

My heads - 1700's - are probably approaching the age when I should consider at least looking at the exhaust valves/seats. Everything I've seen about heads on tinterweb forums usually seems to end in some vague slanging match about sending them to rimco or lem - fine if you live in the states, I suppose... but for those of us out in the boonies (and for those of us with the expense of putting kids through college...) I've never really seen any coverage of anyone tackling anything on the head themselves.

So - drastically bad idea or not? ( I point out rather quickly I have no intention of undertaking any kind of lathe / machine work myself, although I'm sure I can find a competent machinist if the seat needs refacing...)

Any / all opinions gratefully received...

Cheers,

Simon

[RSorak 71Westy]

The reason a machinist is usually involoved is because there's not much one can do to them without the proper guide, valve and seat machining tools.

[Amskeptic]

Dunno if anyone else has had a peek in the latest issue of volksworld? First time I have picked up a VW mag in years - there is an article in it on servicing cylinder heads: basically covering cleaning all the old crap off, removing the valves and inspecting, reinstalling new valves / springs. The article covered T! heads, but I assume could be easily applicable to T4 heads.

My heads - 1700's - are probably approaching the age when I should consider at least looking at the exhaust valves/seats. Everything I've seen about heads on tinterweb forums usually seems to end in some vague slanging match about sending them to rimco or lem - fine if you live in the states, I suppose... but for those of us out in the boonies (and for those of us with the expense of putting kids through college...) I've never really seen any coverage of anyone tackling anything on the head themselves.

So - drastically bad idea or not? ( I point out rather quickly I have no intention of undertaking any kind of lathe / machine work myself, although I'm sure I can find a competent machinist if the seat needs refacing...)

Any / all opinions gratefully received...

Cheers,

Simon

1700 heads are good solid foundations for the home mechanic to Do What He Can Afford.
The original seats are absolutely reliable if the heads pass the crack test. You do want Local Machinist to be smart and knowledgeable about guide replacement. I strongly recommend the "coring" method of removal where you drill out the insides of the guide with successively larger bits until you have a thin wall that will release without galling the bore. The new guides need to be chilled, for real no skimping, and the heads need to be heated and maintained at 300* +, until the metallurgy is fully equally warm throughout. Lubrication of the new guides is called for. We want them to go in smoothly and perfectly piloted to the bore. THIS will help you skate through with a minimal 3-angle valve seat refresh.

I had 515,000 miles on my original heads when they were ruined by a "NASCAR engine rebuilder" who decided quite independently of my work sheet that the guides did not need to be chilled ... his expert opinion included "we don't have a freezer". I had plenty of cracks visible in the exhaust ports and even one leading to the spark plug threads at 435,000 miles. I did not care. Neither did the heads. 1700 heads are strong and stable until you start boring them out and replacing seats "I want bigger valves because . . . because."

[jalabert]

I am probably being very thick here: does one normally not replace a valve without also replacing the guide? I was envisaging something like replacing the valve, lapping it etc, perhaps replacing the valve spring, but using the existing guide.

I thought a new valve only required lapping into the seat - not machining?

[Bleyseng]

replacing the valve guides is a must as they wear a lot in 100k. Once you replace the valves guides you then grind the seats for 3 faces using the new guide as the guide. Then you fit the new valve and lap it to the seats making sure it has the proper seat contact patch.
on 1700 heads maybe you could get away with not replacing the seats but I would replace em with new material.

[Amskeptic]

I am probably being very thick here: does one normally not replace a valve without also replacing the guide? I was envisaging something like replacing the valve, lapping it etc, perhaps replacing the valve spring, but using the existing guide.

I thought a new valve only required lapping into the seat - not machining?

I let the parts tell me what needs to be replaced. Too many times I find that the original parts have more life than replacement parts and too many times I find that disturbing the original manufacturing processes leads to less reliability down the road. Replacement seats that do not have the correct interference fit look no different than those that do, but they release at your first hot engine event. If I hear someone say as a matter of course to replace the seats, they may be suffering from much greater Basic Trust than me. If it is a top-drawer machinist with vast real world experience with my type of engine and my type of driving, well, OK, I have to relent. Otherwise, I have been in the presence of people like my super-spiffy immaculate race engine builder who says all the right things and yet, makes personal decisions at the time of the actual work that makes my blood boil, I have seen the people who staked a seat and missed concentricity, do they care, hell no, ship it out, looks gooooood.

You replace guides that are leaning towards the wear limit, but it is your decision! Do you want a head that is reset to "0" for another 120,000 miles, or are you trying to get running for another 35,000 miles? Do you *have* to replace intake valves? I keep the oem VW valves if they measure out. I kept my oil pump in the Road Warrior for over 300,000 miles because the thing worked. I do not listen to categorical claims to the contrary. Your decision. It is not black and white. Just be informed and work with people you can trust. And be aware that black and white does not exist as far as the results. I have seen $uper-$piff land on its ass, and I have lived with junkyard saves that keep on giving. The reality of what works and what doesn't is in the details, hidden or otherwise.
Colin

[vdubyah73]

I am probably being very thick here: does one normally not replace a valve without also replacing the guide? I was envisaging something like replacing the valve, lapping it etc, perhaps replacing the valve spring, but using the existing guide.

I thought a new valve only required lapping into the seat - not machining?

replacing valve guides, could be argued, is one of the reasons we have this huge acvw thing all over th globe. can't give details but empi started from a dealership making their own and repairing heads. vw didn't want that. vw wanted heads discarded and replaced with new. if i'm remembering right it kinda started the race part of it as well. i wanna say names like the vittones, the bergs and others were all working together, developing aftermarket stuff for our cars. all because this guy wanted to repair instead replace. this was back in the early to mid 60's

[jalabert]

When the time comes then, I will look, see, measure, then decide. I'm approaching this by way of something like a midlife service - I was really thinking of worrying about the exhaust valves only, but checking out the inlets too. Len Hoffman put something on the samba that got me thinking, - about valve springs wearing out resulting in the crap being beaten out of the seat, hence my mentioning the springs too.

Mileage wise I suppose these things are still babies - a mere 60,000 on them since new - the opinions I've picked up are that exhaust valves at least should be replaced at 70-80k. I just want to keep what I know is good, good - without screwing it up trying to do so...

Thank you for the discussion...

Simon

[Amskeptic]

When the time comes then, I will look, see, measure, then decide. I'm approaching this by way of something like a midlife service - I was really thinking of worrying about the exhaust valves only, but checking out the inlets too. Len Hoffman put something on the samba that got me thinking, - about valve springs wearing out resulting in the crap being beaten out of the seat, hence my mentioning the springs too.

Mileage wise I suppose these things are still babies - a mere 60,000 on them since new - the opinions I've picked up are that exhaust valves at least should be replaced at 70-80k. I just want to keep what I know is good, good - without screwing it up trying to do so...

Thank you for the discussion...

Simon

60,000 original miles? By all means then, be very conservative with what you decide to do. Yes, replace any part that is past the wear limit , but good lord your seats? The originals are the most reliable installation you have IF the heads have not been run chronically hot.

Valve springs? VW original are good springs! (check them of course) Who on Earth would tell you to tear that head up and put in new crap?

I have a factory built 2.0 that had 36,000 miles on it when I bought it in 2008. It now has 85,000 miles.
Because it is original, I am not touching that engine until at least 125,000 miles. My valve adjustments are telling me that everything is nice and happy, it has never run hot hot (maybe a few 430* CHTS here and there) and I trust the factory build to give me a solid 150,000 + on the lower end.
Colin

[jalabert]

When the time comes then, I will look, see, measure, then decide. I'm approaching this by way of something like a midlife service - I was really thinking of worrying about the exhaust valves only, but checking out the inlets too. Len Hoffman put something on the samba that got me thinking, - about valve springs wearing out resulting in the crap being beaten out of the seat, hence my mentioning the springs too.

Mileage wise I suppose these things are still babies - a mere 60,000 on them since new - the opinions I've picked up are that exhaust valves at least should be replaced at 70-80k. I just want to keep what I know is good, good - without screwing it up trying to do so...

Thank you for the discussion...

Simon

60,000 original miles? By all means then, be very conservative with what you decide to do. Yes, replace any part that is past the wear limit , but good lord your seats? The originals are the most reliable installation you have IF the heads have not been run chronically hot.

Valve springs? VW original are good springs! (check them of course) Who on Earth would tell you to tear that head up and put in new crap?

I have a factory built 2.0 that had 36,000 miles on it when I bought it in 2008. It now has 85,000 miles.
Because it is original, I am not touching that engine until at least 125,000 miles. My valve adjustments are telling me that everything is nice and happy, it has never run hot hot (maybe a few 430* CHTS here and there) and I trust the factory build to give me a solid 150,000 + on the lower end.
Colin

Yep, 60,000 original miles, VW factory engine (fitted in France, of all places) Likewise, my valve adjustments are telling me it's happy, everything else looks good. I think the thread I was referring to re: the valve springs was one on the samba that started out talking about AMC heads, Len Hoffman was talking about the valve springs he puts in vs the AMC ones and was explaining the cycle whereby worn-out valve springs multiply the likelihood of seat failure. Like you say, the factory seats are always going to be the best, so how to be kind to them and avoid the perils of the machine shop?

My Dad has an Austin Seven and lapping new valves in is literally a service item on them, something like every 5,000 miles. As a history question, what changed for us to have to stop doing that?

After reading what you plan to do...maybe I'll just leave well enough alone for another 60k...

Cheers,

Simon

[Amskeptic]

60,000 original miles, VW factory engine
Like you say, the factory seats are always going to be the best,
so how to be kind to them and avoid the perils of the machine shop?

My Dad has an Austin Seven and lapping new valves in is literally a service item on them,
what changed for us to have to stop doing that?

After reading what you plan to do...maybe I'll just leave well enough alone for another 60k...

The best way to be kind to a VW engine is to keep it clean and well-maintained. Really. That's it.
The 1700 heads are excellent heavy dense aluminum, dremel the flashing off the fins where you can reach, especially in the exhaust fin area . . .




This are pictures of how I check airflow (new Autolinea heads from Brazil, flashing had closed off EVERY space at the exhaust ports!! would not have lasted a week) I like original German heads!!!! Take care of them!!




My uncle had a number of the early British cars, an Austin 7, a Jaguar XK 120 and an original MG TC (both bought new) and a Crosley. We had to lap valves before the advent of hardened seats . . . now we have to ask fancy machine shops to cut through those things.
Colin

[Bleyseng]

Len uses a different valve seat material than what VW did originally. VW used a sintered metal for the valve seats and Len uses a metal that has better expansion characteristics to match the aluminum so they won't ever fall out.

[Amskeptic]

Len uses a different valve seat material than what VW did originally. VW used a sintered metal for the valve seats and Len uses a metal that has better expansion characteristics to match the aluminum so they won't ever fall out.

Len is one of the people I trust. But I will pick apart any advertising claims. "Len uses a metal" oh really? that has "better expansion characteristics"? really now? that "matches" ? aluminum, matches? Hardened steel that matches . . . . aluminum?? cough cough.

Stop already. If Len manages to stick decent hardened tungsten titanium chrome molybdenum high carbon cold forged steel steel seats with eye of newt in better than anyone else, I will leave it at that.

The whole paragraph above puts the blame on VW for being so damn stupid that they couldn't come up with the right "metal" to prevent the seats from falling out. Seats fall out due to operator error PERIOD when it comes to oem VW heads. After that, it is up to all number of variables of installation prowess, materials used, condition of the reconditioned head, you name it.

But this whole thread here is an example of good German VW heads almost getting gutted in an atmosphere of scorn towards the original engineering when the scorn needs to be placed closer to the source. Us. Driving with vacuum hose flapping. Driving with oily filth packed into the fins. Driving with a lean mixture, bitching about low power, not stopping to check, you know, Geoff, you are one of the people who do care.
Colin

[vdubyah73]

vwoa considered heads as wear items back in the day. empi got it's start by making and replacing valve guides at a vw dealership. vwoa was not happy.

[Amskeptic]

vwoa considered heads as wear items back in the day. empi got it's start by making and replacing valve guides at a vw dealership. vwoa was not happy.

Now that I have had my coffee . . . Bill, do you remember any cylinder head issues that required any sort of corrective action in the '60s and '70s? I remember only that the valve adjustment clearances were opened up to overcome the dealer mechanics who did not adjust properly cold engines.
Nothing about seats. The TSB for 2.0 engines I think was the first VW engineering boo-boo, the 94mm pistons were just that one millimeter too big and were scuffing cylinder walls.
Colin