Former VWDieselParts.com Forum

I picked up a hydraulic head the other day off a parts car and got it checked out by the machine shop. Main issue is that it shows a .014" warp on the surface of the head. I called a shop in Indy about baking the head back into shape - they're the only shop in the region that has the proper equipment - but the machinist that he could mill it instead.I was sure that there's no milling tolerance for these heads, but he said he'd done it plenty of times, and could mill if it's under .015".

Am I getting snaked? Every shop I talk to says I should mill it, even the shop with the oven.

What they're forgetting is that this is an overhead cam motor. The warp extends into the cam journals. You can mill the head for a good fit and HG seal, but the camshaft will wear against the cam caps, unless you line-bore the journals. Then, you'll lose oil pressure because the bores will be too big.

.014 is a LOT. I'm no machinist, but I tell people to heat the head with .009 or greater warp. I base that on a 1.6TD head that was run warped with a blown HG for over a year. The car came from a warm-weather climate, so they just kept adding water to the radiator. When I pulled the head, there was about .010 warp. I could clearly see where the cam had started to eat away at the aluminum on the #1 and # 5 caps, so much so that there was a ridge on the inside of the caps.

Put it this way. Pull all the lifters out, and bring the head and a camshaft to the shop. Set the camshaft in the saddles and see how much it rocks. I'm sure it will rock noticeably. Ask them if they think that will pass inspection. If they tell you that it's fine, take it to another shop.

What Quantum TD said... plus, if done properly, ie. clamped-heated-cooled, then milled down just a thou or two to flat, that head should pull back to within specs. The cam towers can then be align-bored & then fitted with bearing shells for good fit and good lubrication. Just match up the oil holes. OTOH (as mentioned in the PM I sent you) it doesn't look too promising for finding good-but-low priced 1.6 hydro heads right now, but all you need is one; it could just suddenly appear!

Topline supposedly has good new units @ decent prices , $500-600, when they have them. The p----- source on ebay... ummm, haven't heard a lot of cheering about his stuff, but YMMV. Many will pull the handle; few will really win!

I'd get them to bake that head; IMHO 0.014" is way too much to mill off, even if the cam's alignment wasn't thrown off. The thinner the head, the easier it will be to warp it out in the future.

J.R.
SoCal

While I've never personally used TOPLINE, I know people who have, and have had good-great results. Just steer clear of the AMC heads. They have weak valve seats and use shoddy valve-train parts on complete heads. I've seen it on both watercooled and aircooled heads.

My old winter Jetta that I ran for 4-5 winters has a topline head on it. I've never done anything with the head or anything, and never had a problem with it.

So, what I left out of this thread is that I still have a good mechanical head. Flat as can be and with good valves in them. The reason I'm pulling for a hydro head is because the good block I picked up has the second smaller oil drain hole off the front. I've heard that even with that second hole tapped and plugged, the head gasket could still end up leaking and blowing.

So, for the hyrdaulic head... should I even bother with it? Stripping it free of everything and rebuilding it sounds like more than I care to bite off with a good mech head on my bench. The guy I talked to didn't even quote me a price for baking it, just milling it. That alone is $75.

Well, I AM a Machinist....and an engineer/ mechanic / VW Diesel enthuisiast.

I just don't understand all the hype when it comes to warped aluminum heads.
The structure of the head itself is flimsy compared to the block, which is a substantial
and rigid structure.

Now, this flimsy aluminum 'box' gets bolted to the larger 'box' (block) with TEN
bolts that are torqued to the point where they (EACH ONE) are providing several
hundred pounds of clamping force to the entire surface of head itself.

My question is: How can the head NOT PULL DOWN FLAT against the block if it does
not lie flat when you squeeze it down with 700+ pounds of clamp force?
The gasket is there to take up any irregularities.
I am not sure about the possibilities of the head being 'humped' (high or low in the middle).
But 'rocking' so as to not be flat on one end....?

Spray two light coats of Permatex copper coat on the gasket (both sides),
CLAMP it down to the block with the head bolts (I use the ARP Stud Kit), re-torque after one thermal cycle (outta luck re-torquing if you're using the sucky stretch bolts) and give it hell...

Interesting take on this.

I've often wondered the same thing.

I'm pretty much out of available credit ($$) for this project, so now I'm at the point where I need to scale back and reprioritize as much as possible if I want to have a working engine within the next 3 months.

I'm considering taking the head back to where I got it and getting money back, then just throwing my mechanical head on my block. Otherwise, I'd need to invest a lot more time and money into a head that is not at 100%... I'd need to replace valves (bad vacuum pressure on valves for cylinders 2 and 3), skim some thousands off the head, and say some prayers in hopes that all the other variables don't leave me with a busted head. If I did just replace valves and spend money on resurfacing, what's the worst that could happen, and how long would it take for it to happen?

All I was worried about with my mechanical head was the possibility that the head gasket will leak because the hydro block and head don't match 100%. And the fact that running a turbo with a hydro head could be better in the long run.

I appreciate all the tips and suggestions, but what I thought would be a simple head swap is turning into a huge head ache.

dkmc wrote:My question is: How can the head NOT PULL DOWN FLAT against the block if it does
not lie flat when you squeeze it down with 700+ pounds of clamp force?
The gasket is there to take up any irregularities.

Spray two light coats of Permatex copper coat on the gasket (both sides),

Tried it: new head gasket blew the first time the engine came up to full temperature. Dunno if the head was just too warped for the gasket to deal with, or if the Permatex copper actually caused the gasket to blow.

As I recall, it had 11mm non-stretch bolts though. ARP studs might make the difference, but I'm still a little leery of head gasket sealant.

Good to know. Is the Permatex Copper a good idea to put on head gaskets in general? If I'm clamping a mech head to a hydro block with 12 mm bolts I'd like to make sure everything is good and sealed. But if the sealant could potentially cause a gasket to blow, then NO WAY!

Have used the Permatex copper spray with OK results, but IMO the K & W copper spray goes on more evenly, so that's what I use (on non-VW stuff too). As dkmc noted: 2 light coats. I try to give each coat 15-30 minutes to tack up, before next step;even an hour would probably be OK if you can keep dust, animals & humanoids away from hanging gaskets for that long.

Cheap guide pins for locating the gasket & then the head at the proper position on the block without sliding>>> a pair of old headbolts with heads cut off and a screwdriver slot hacksawed into the top of each shank. Just unscrew, lift out with a magnet, replace with new bolts After you have the other 8 bolts finger-tight.

Studs preferred, of course, but if you're stuck using bolts, lube 'em up good. Make sure the washer-to-bolt head interface is well lubed also. Tension on the bolts/studs holds it together; friction just tells lies to your torque wrench.

I always wondered if head bolts necessitated thread locking fluid. But lube makes sense, at least for potentially eliminating those nasty creaking sounds. Is it lubro moly assembly lube that you'd need or simple motor oil?

Seems to me.....stretch bolts are supposed to be installed DRY....

But now that I've used the ARP studs, I will NEVER go back to the stretchy ones

I have 2 engines that have each gone over 250,000 miles with copper-coat coated head gaskets.