Ongoing Headgasket saga, more questions no answers...

[sle2115]

If the heads were surfaced, wouldn't you leave the precups in, while machining?

NO, that is the cheap way of doing it labor wise. We took them out, cut the heads and then set the pre-cups on a wet diamond tool cutting wheel, a machine that cost about $2000 just to do pre-cups. And yes, we had a machine that would cut them in the head, but that was not the way we did it, or the way it was spec'd to be done. Not to mention if a guy said he was using a belt surfacer, he is about 20 years behind the times. We used a carbon puck broach that would cut about anything. There is another issue with this type of cutter though, they would/could actually lift the pre-cups while cutting, making for a dangerous situation and/or inaccurate cut.

We also used a white compound like a sleeve retainer on all guides and on the pre-cups, worked great.

 

[sle2115]

I had that arguement over an aluminum german diesel head at a machine shop where the idiot put the head on a belt sander and gouged the heck out of it because he was worried about trashing his bit ( but he didn't have any problem with trashing my head Finally found a diesel specialty machine shop ( Hillcrest Camshaft, great folks and the guy didn['t have any trouble milling the heads with the disimilar material cups, it was just like I thought, all he had to do was slow the feed down As long as they ease into it, the bit won't break, but it take a lot longer that way. The man is an artist, he managed to save my head even though the other clown had sanded it down to min spec

-------------Robert

That is not the way we did it, and personally, I would not take my heads to a shop that did. If you want to see artistry, take your time, mill the head, and then set each cup with a depth gauge, the only way we did it. Cost a little more, both to the customer and labor, but the finished product was within spec and done the prescribed manner.

 

[RLDSL]

That is not the way we did it, and personally, I would not take my heads to a shop that did. If you want to see artistry, take your time, mill the head, and then set each cup with a depth gauge, the only way we did it. Cost a little more, both to the customer and labor, but the finished product was within spec and done the prescribed manner.

They guy was trying to salvage a head that had already been ruined. the joker with the belt sander ( supposedly the best machine shop in the state ...20 years behind sounds about right for around here ) had gouged the aluminum so badly thst there were spots way , WAY thinner than min thickness for the head ( critical on those heads ), and the cups were torn up too. The guy at the good shop had me bring him the old gasket and a new gasket and he very carefully , a little at a time,took thin passes until he had a clean mating surface only where it was needed for the gasket, and left the gouges where it didn't matter. The tolerance he was dealing with at that point wasn't even funny. Quite an impressive piece of work. If he hadn't been able to pull that off, I would have been buying a new head casting out of Germany $$$
That shop does all the rebuilds for the international dealer and a few others here as well.
-------Robert

 

[sle2115]

They guy was trying to salvage a head that had already been ruined. the joker with the belt sander ( supposedly the best machine shop in the state ...20 years behind sounds about right for around here ) had gouged the aluminum so badly thst there were spots way , WAY thinner than min thickness for the head ( critical on those heads ), and the cups were torn up too. The guy at the good shop had me bring him the old gasket and a new gasket and he very carefully , a little at a time,took thin passes until he had a clean mating surface only where it was needed for the gasket, and left the gouges where it didn't matter. The tolerance he was dealing with at that point wasn't even funny. Quite an impressive piece of work. If he hadn't been able to pull that off, I would have been buying a new head casting out of Germany $$$
That shop does all the rebuilds for the international dealer and a few others here as well.
-------Robert

Ok, makes sense now, salvage. Honestly though, we removed them. I don't work there anymore, left under good circumstances and was told I had a job there whenever I wanted. My boss spent the money on the pre-cup cutter because it was what IH and Ford specified. Believe me, we all hated it, those cups are very hard and it took some time to chuck each one up, cut it and then verify the depth. We then fixed them in the proper hole with the "white weld" as we called it. At any rate, as we did them, be measured the recess, then cut the pre-cup the required amount, then checked, cut some more if needed, then rechecked etc. It was not the cheap way of doing it as you could easily spend two or three hours getting them all right. We built some pretty cool motors though and my favorite was probably the DT466 that were running on alcohol for pulling tractors. Was often invited over to check them out at the pulls or help diagnose the problem. Always made me feel good that I was considered good enough to touch one of these beasts...then I got to do three all aluminum racing engines for a sprint car, 1300 HP and they were freaking wonderful to work on. I got to flow bench and work the heads over etc. then took much of what I learned there to the pulling tractor heads. Oh the good ole days. I really enjoyed that kind of work, even though it was hard, hot in the summer, cold in the winter and I was always filthy!!! What more could one ask for?

 

[typ4]

quote
I really enjoyed that kind of work, even though it was hard, hot in the summer, cold in the winter and I was always filthy!!! What more could one ask for?

Now you are just braggin!!!

 

[sle2115]

quote
I really enjoyed that kind of work, even though it was hard, hot in the summer, cold in the winter and I was always filthy!!! What more could one ask for?

Now you are just braggin!!!

Yeah maybe so, but I long for the days when I get to do something with my hands...that just don't sound right!!!

Really, riding a desk has it's good points, cool in the summer, warm in the winter etc. but I miss "fixing" things as well as some of the cool toys in the machine shop.

 

[zigg]

I talked at length with DAS yesterday about the pre-cups, and he tells me his "rebuilder" intentionally sets the precups to within .003 to .005 thou protrusion. This is in response to a 6.9 that the precups supposedly came loose apparently, and somehow pounded around and finally damaged heads and/or block on an engine.

I find this intriging, since the max allowable is .0025 from spec's.

I've shaved mine down till they are all less than .002, but now, I'm having second thoughts about putting it back together, and just can't bring myself to start the thing.

Anyway, it's raining again today, so I'm just going to do more cleaning up, and re-check things again...(sigh)

Zigg

 

[dsblack]

Zigg,
Call some other shops that do these heads, and ask them. Something does not make sense here....

 

[yARIC008]

I know mine protruded just a bit. I remember looking at it, infact you could see where a couple pistons just would barley touch the precups. Probably not good but you could see little indentations, I'm guessing they only touched for a little while when the engine was first run then eventually just got pounded back a little.

Didn't travis have a problem with precups bouncing around?

 

[Full Monte]

Zigg,

The factory manual says 80ft-lbs. on the 6.9. It goes in 4 steps. 40, 70, 80 and then 80 again. You have to do it in the order specified, which is different for each step. You might find the instructions on Pete's page on the Drama Stop. I used Felpro gaskets. No probs. so far.

One additional thing that occurs to me....are the threads on the studs you are using the same pitch as the originals? Is the pitch on the threads on the top the same as the pitch on the bottom of the studs? If not, you may not be getting the same clamping force at the same 80 ft. lbs. If the threads on the top of the studs are coarser than at the bottom, you would be losing some of the mechanical advantage given you by the finer threads of the original bolts.

 

[themonkeyoflife]

zigg,

i have been reading over your ordeal and i want to say ive been there. an engine i built had plugged oil galleys and i spent weeks fighting the machine shop to fix. So to your problem -

first - a trick a machinist taught me is when the block is on the stand set a head surface close to level then screw a stud in as far as you want your deepest depth to be then put one on the other edge of the block, same head surface, then set your level across an run all the studs down to its height. this makes the deck distort in the same way for each stud as the same amount of material is being pulled on. but having the studs un even wont cause a head to not seat on a normal engine. a race buildup yes you will see issues but at full throttle not part and the "crush" is achieved in a static state not while running

second - did you have the shop touch your decks ? if so do you know the smoothness that they made the deck. if they did for example 6-12 Ra then standard gaskets wont work you have to have a mls gasket and these require a very smooth finish - 8 Ra or less

third - did you orientate the washers correctly the have a beveled surface and a flat one

fourth - i would highly recommend a MACHINEST straight edge its a totally different beast than most use - a carpenters level or square - the tolerances are much much higher in my experience starrett is top notch then you can check your block, though i think you did already

fifth - is your deck square to the bores for the studs? put a stud in and use a machinists square to check if its right. if the shop mis-loaded your block....

sixth - for holding your precups in use petroleum jelly it vaporizes at about 115 deg fahrenheit

seventh - the arp studs use a special j-type thread that is designed to cut in and provide more surface area to grip onto and arp recommends using there taps that have that thread cut into them

hope all works out

travis

 

[zigg]

A little update

Lots of good info here, Thanks so much guys.

I finally took both heads to the local IH shop that just does diesels. They're shop rate is over $80/hr, but I decided to just bite the bullet and pay what it takes to get this thing fixed.

The head mechanic had already heard about these heads, so he took it on. While I was there, he Mic'd the thickness of the heads, checked the flatness, and warp, and had a look at the pre-cups.

He said it all looked really good. The heads are flat(less than .002 overall), and not warped, and he said the precups look better than he would have bothered with, and they are all nicely seated and very nicely polished and flat, so that's a vote of confidence.

Said that if he had heads that had more than the .0025 protrusion height presented to him, he would not put them on a block and sign his name to it. He added that if one of his junior guys had machined them such that there were some that were .003, and others as high as .007, he would never have allowed that head to be sold to a customer till it was shaved down to within specs, and that it would definately account for leaks if there were that much difference between them. He said that mine were in pristine condition, and that I should just slap 'em on and get on with getting it back together.

I never did have anything done to the block(other than bore and balance) so I've never suspected the block at all. The studs are also not really suspect, especially now since I found all the ridiculous precup heights. The studs actually have a fine thread at the top.


So, I guess that start up will be the final analysis, but for now it looks like the precups were definately the problem.

Again, I want to thank everyone for all the support and problem solving, and lets just cross our fingers and hope it runs like a charm.

I'll put it back together probably this coming weekend, and I'll update on how it goes...

Zigg

 

[Agnem]

Got em' crossed for ya Zigg!

 

[dsblack]

Me too!

 

[gabbyr100rs]

Been following your travail--good wrenching and good luck!