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If we're just talking about the hairline cracks between the valves, yes absolutely, I would repair them using the valve guide liner repair procedure published by the AERA for these cyl heads (and illustrated in the Member's Area). In fact, I have done this very thing without a problem... :)Quote:
Originally Posted by IUPAC
Jim
No, the heads don't have to be designed for inserts. Yes, metal has to be removed from the seat area to install the insert, but this isn't a problem. The problem is with the induction hardened seat. The valve is running red hot and it is sitting on that relatively narrow seat 75% of the time, pouring heat into it (2/3rd's of a valve's heat is transferred to the coolant through the seat). It is this high, uneven (due to the valve bridge) temperature gradient combined with the valve's incessant pounding on the metal that is the problem.Quote:
Originally Posted by More Power
The exhaust inserts are made of a comparatively ductile high-nickel alloy, so they don't crack. They can tolerate the high temperatures and the pounding of the valves, and they spread the heat and stress over a much larger area in the head.
The ONLY reason induction hardened exhaust seats are used is cost. Inserts use expensive materials, require expensive precision grinding to make, and require time consuming close tolerance machining and careful installation in the head.
What he said ^^^Quote:
Originally Posted by More Power
If you want or need a new head, spend the coin on a set of AMG heads. They will run you $500 each, fully assembled.
Unlike Robyn, I have no qualms about repairing a GM head, but I know the guy doing the repair (cough ME cough).
Shops capable of properly repairing iron heads are hit or miss, with probably more miss than hit :(. Ask how the shop repairs the crack. If they say Lock'n'stitch or pinning, you are probably OK. If they say they weld them, ask what process they use. If they say fusuion welding, and they mention heating the head to 1200 degrees or so, gas welding it with cast iron rod and flux, and letting it cool under sand or other insulation for 24 hours, then they probably know what they are doing. Some shops braze heads, but I would be worried about it's durability on a part that routinely heat cycles since the coefficient of expansion for bronze is much higher than gray iron. Still, I have heard of it being used with success since bronze has good ductility.
If they say they metal spray weld, I would be a bit worried. That process can make excellent, reliable repairs, but it takes a lot of skill to do right. I would probably not risk it.
If they say they arc weld with nickel rod, or any other type of rod, or any other type of electric welding process, walk away. It is possible to make a solid repair with the right filler material, but it takes a lot of knowledge and skill to get it right. Most electric weld repairs fail, and the failure is simply due to improper procedure. There are several procedures to do it right, but you have to strictly play by the rules and you can't be in a hurry. Otherwise you will end up with cracks, or extremely hard areas caused by formation of martensite in the heat-affected zone that will make machining very difficult and be prone to cracking in service.
Anyway, that is my spiel on head repair. FWIW shops that do a lot of (successful) repairs on big diesel heads are going to be the best, but many may not be willing to work on smaller "junk" diesel heads (if the "real" diesels are so reliable and trouble-free, why are they repairing heads, blocks, etc? :rolleyes:).
The last thing to keep in mind about head repairs is that, unless you can do most of the work yourself, it will probably end up costing nearly as much as new AMG heads.
Engine Quest does make a 6.5 head.
http://eqcylinderheads.com/stockreplace.html#stockchevy
its about half way down on the front page. the also sell a 6.5 block
https://parts.aaeq.net/IW_Products.m...EE?company=AAM
if that link doesn't work you have to go to shop online and click new customer.
micky
I think the water passage repair with the bronze liner is a great fix and probably a good idea even if using heads that have no signs of leaks in the area.
Many times fixing problems before they start is a good idea.
***A note here*** I think the hardened seats are a great way to go if the iron is good in thehead. Another addition if they are available would be sodium filled exhaust valves to really get the heat out of the valve head. This practice has been used for many years on heavy service engine. There are some bad points to sodium filled valves but the issues are rare. (Valve heads snap off)
I am still firm in that I would not spend a plug nickel on any welding type repairs on one of these heads.
Any crack that goes through to water other than as mentioned above would see the head on the bone pile for Sandford and Son around here.
Too much good iron out there to risk the time $$$ and heartache if and when it fails.
I am not a glutton for punishment but would still opt for a fresh head (even the aftermarket ones) over a welded or otherwise repaired head)
******Except for the bronze sleave fix****** :D:):D Good stuff
One failure and slosh a load of glycol into the crankcase and make a mess and OH Sh** Frank, I dont think so.
***If I were faced with what MAX found on his new castings I would replace the precups with a good set (new or used) originals and lightly touch the decks with the surface grinder or the mill and get the puppies put together.****
I personally would feel very good about these and would not lose even one minutes sleep and I am very anal about how I build engines.
Just my 2 cents worth.
Been building engines since I was in High school and had very few failures.
I dont count the race engines that we scattered in the drag boats.
BBC chevies can and do come apart when you take them into the 8-10 grand RPM arena :eek: The last oops was a cam that I did not degree in and the gear was not indexed properly and the engine ran like crap. (My fault for not checking it)
This decision is one that the individual bankrolling the project has to feel warm and fuzzy with.
I will say this, I will never post to anyone that welding on the 6.2/6.5 heads is a good idea.
If you or your fav shop can do a repair and make it stick, Great, I am happy that you got it to fly. :)
I dont trust this stuff simply because I have seen too many failures and I know I am not capable of doing it.
Most mechanics (even those who make their living at it) are not even close to being skilled at doing such repairs.
I dont really think I can add any more pertinent info to this, but am still interested in any sucess or failure of the aftermarket heads/ blocks or any other parts that are being made for these engines.
Good luck to all
I will agree that, in general, welding up a head is a bad idea. Not because it can't be done right, but because it is VERY LIKELY to be done wrong. OTOH, I think a Lock'n'Stitch repair is a good way to go if you must repair the heads.
The only problem I see with the bronze sleeve repair is that, while it may keep water from leaking into the chamber it does not repair the seat. You don't dare put an insert in there for fear that the crack will spread and let the insert come loose, so that leaves you with keeping the integral cracked induction-hardened seat. :( This repair if fine if, say, you notice the crack while replacing a head gasket and you don't plan on doing a valve job. In that case, sleeve 'em and keep on running them ;)
I have considered putting my old cups in the Chinese heads, surfacing them, and running 'em. I'm just so PO''ed with these heads that I have a hard time convincing myself to do it :mad:
Yup
I have seen heads run with cracks in the seats for many K miles with no aparent effect.
I have seen a couple heads that the cracks had widened out and resulted in a burned Valve/seat.
I agree that if the crack allows the head to move then the retention of the hardened seat may me compromised.
These are all very reasonable situations that do and will present them selves to the techincian trying to repair the little beast.
These very situations are one my big reasons for looking at the replacement heads from the aftermarket.
As I have posted, when I needed a set of heads, GM did not have any available that I could find. The open market saw things on ebay but I was not willing to buy "NEW" castings that I could not prove were new or possibly just cleaned and fluffed up.
I have bought off ebay and had very good luck.
Only had one guy try to scam me but caught it in time and used paypal to pay for it and got my $$$ back.
MAX
I dont blame you for being a bit giddy about things. With the cost of a build and all the work, one hates to find out after the fact that the parts were junk or worse yet have it grenade on you.
After seeing the piles of Military stuff that had been removed from HMMWV's and being sold I really cant say much about any of the stuff thats used out there.
I went through a huge warehouse of blocks heads and cranks that had come from the military and after an hour of looking stuff over for usable parts I got tired and went home. Too much scrap iron to look through.
This was the largest amount of 6.2/6.5 parts I have ever seen in one place.
The private sector is even worse as the bone yards always sell the stuff as being good. Then just try to get them to adjust things if its junk.
For my dollars the new ready to bolt on head sure seemed and still does seem like a pretty good bang for the $$$$$
GM only offers 1 year on their replacement parts.
As I said, whoever is bankrolling the particular job has to make the decision and be happy with it.
If asked right here and right now, I would recommend as set of CCH heads over any of the remans out there.
One exception would be a set of heads that I had owned and had magged them myself and then done the machine work to do the valves and seats and decked them.
There is just too much junk iron out there that has been warmed over and sold to unsuspecting buyers.
Most folks would not spot any issues until the engine was fired up and then ultimately failed.
At this point I think we have aired almost all good arguements pro and con on the different ways to proceed.
Robyn
I bought a pair of DSG's new heads last june as my existing had a couple cracks in between the valves.
I splurged on the fully assembled units and they looked fantastic! Nice, clean castings, that now have 30k. So far so good! I am not sure if they cast them or if they farm out the foundry work, but the price was'nt bad, 400 a piece. Cant recall what kind of warranty though.
i have an engine quest heads on the 318 i have they are an excllent casting
Quote:
Originally Posted by MaxPF
Well, my current plan is to stuff my slightly cracked 3-dot precups in the CCH heads, deck them, touch up the seats, and put them together.
I think I have been fair about my assessment of these heads. The cup material is inferior IMO, and the cups weren't machined for a proper fit. The casting is a bit rough as well. OTOH, there are no gross flaws in the casting, and the seat machining appears to be quite good. I threw an intake gasket on them today, and the ports actually match up as good as the GM heads. Also, closer inspection revealed that there IS more metal in the deck area. I still need to measure the guide clearance, but judging by the fit of the valve stems I think they are fine.
Make no mistake, I am still p****d off that I have to spend another couple hundred dollars to make these right, but I think they should give good service. We shall see...
One other thing. I had bead blasted my 3-dot cups and I was inspecting them when I noticed a cast-in circle on the side that had "N 80" cast into it. One material commonly used to make precombustion chambers is an alloy called "Nimonic 80", which is an alloy that is approx. 80% nickel, 20% chromium, with a small amount of titanium and aluminum. I wonder if the "N 80" means it is made from Nimonic 80... :confused:
I have not heard of the N80 but I did cruise through the heads that I have in the shop and all but one had none magnetic precups.
I am not sure of the origin of the one head that has magnetic precups but it came off of a running engine and it has GM cast into it in the top??????????????
Kepp us posted on the project
Robyn
Just wanted to voice my opinion and then I'm out of here.
If you buy the cheap Chinese knockoffs you deserve the consequences and yes I am quite certain that there will be...
I perused some of the GM technical books we have at work, and I found something interesting. According to the GM book I read the J-code 6.2's and all 6.5's have precups made from "super alloy", which is of course what the high-nickel, high-temp alloys are called. However, it said that C-code 6.2's used precups made from gray iron... I wonder if that is what the aftermarket cups are made of...Quote:
Originally Posted by Robyn
Do tell... what consequences would you be speaking of?Quote:
Originally Posted by Kennedy
I hate to disagree here but there does not HAVE to be consequences.
The stuff that came from GM had consequences by the metric buttload.
One of our members bought a block from the Fritolay garage and there head mechanic has been using the CCH heads on the little delivery vans for a long time. To date he says they have had zero failures.
**** I earlier quoted this as Fedex,, Nope Fritolay ******
According to him the least time on any set of heads they have is 3 years and you know those little trucks get the crap run out of them and its all tough town stop and go driving with all sorts of different drivers running them.
If Frito will gamble on these then its a good bet that its cost effective.
Large fleet operators generally dont fool around. They cant afford to have trucks down all the time and if they are seeing failure after failure they will be doing something different and soon.
I hate seeing the Chinese stuff as much as the rest of you but I am not going to subscribe to a broad statement that because its made there that there will be consequences.
Just my 2 cents worth, Again :)
Nothing personal John, just how I see it.
GM has done us no favors so there is no love lost there.
Robyn
Do those vendors selling Chinese heads say they are not AMG heads in their ads, or would the average buyer assume they are AMG heads based on the wording in those ads? :rolleyes:
As long as the ads include all relavent info, then it is really about what the consumer wants. Do the Chinese heads or blocks contain a Navistar logo?
Jim
My experience with CCH has been a good one.
They were honest about the fact that the castings are from overseas.
There is no reference to GM/AMG/GEP anywhere in their ads.
The heads and blocks do NOT have any references to GM/GEP/AMG or Navistar on them.
The heads have a casrting number but no other logos or markings.
I can honestly say that when I bought these that I was totally aware of what I was buying, BUTTTTTTTT I ask questions and plenty of them.
The CCH sales page just lists the 6.5 heads with a number and what it fits.
They offer a reman head and then the other ones (new)
There is absolutely nothing to suggest either way as to what it is.
When one orders a 6.5 head from them you basically have to ask the service rep about the 6.5 heads and then it goes from there.
When I oirdered my set, I sked them to tell me about the new castings and the pacakge deal.
The rep explained that the castings were from off shore and that many of the other parts were reconditioned items or new depending on what they had at the time.
My heads had all new exhaust valves and the intakes were some of each.
The keepers apeared to be all new.
There was never a hit at trying to cover up anything. When I asked a question I got an answer right up front and no Hum Hawing.
They said who what where when and why.
Now I will agree that in due time when the market place is full of these there is going to be only one way to tell these from GM heads and that is going to be the fact that these heads do not have a GM cast into the head under the rocker shaft stands.
To settle a point, there seemed to be no effort to pass these off as GM/GEP or AMG stuff, none at all.
Just what I know from dealing with the outfit.
They are also very upfront with their warranty policy too.
Buy a complete head and it gets a 3 year unlimited mileage warranty for materials and workmanship.
My set cost me $670 to the door with a sticker to place on the boxes to ship my old units back at no cost to me.
They were boxed well with plenty of padding and sprayed with a no rust compound too.
I am still of the opinion that this is not a bad way to go.
I have asked for and do encourage anyone who has RUN a set of these on their 6.5 to chime in, with Pro or con comments.
If someone has an honest bitch about this product (as in it failed) please let us know here.
Speculation as to what MIGHT happen does not count. If they work and last thats great. If someone can say, Hey I bought a set and they failed at 50K miles in 2 years, then we need to know this.
With the Frito trucks using these I am betting they are not a bad jump for the BUCK
Best
Robyn
Would someone who doesn't read the forums assume CCH's 6.5 heads are aftermarket by what their online ads say? If not, their ads should say what they are so anyone buying their "6.5 heads" can make an informed decision. ;)
I just received a new Summit catalog a few days ago. Inside, is a big selection of aftermarket cylinder heads for all manner of gas engines. All of the individual listings are clearly worded to let the buyer know exactly who manufacturers them. That's how it should be done.
Jim
Just as an item to promote thought.
This afternoon I spoke with sales rep from the local Cummins outlet.
I asked him where the blocks for the different Cummins engines were cast.
The answer was "Cummins has plants world wide including China and Brazil that may supply materials for various engine assembly plants here in the States"
Take this however you like. I will bet that some of the Dodge pickups are running around with blocks that are cast in China.
I am not offering this as any excuse or justification of anything.
There are far too many outfits that have spent big $$$ setting up plants overseas so there does exist the possibility that many of these foundaries can handle far more work than they have to do and very well may be the source of the 6.5 blocks that are showing up.
Under the circumstances anyone with the $$$ could contract to have almost anything cast over there and shipped to the States to be machined in their own facility.
Just some speculation. If cummins has a plant there bet me that a whole lot of companies do too.
later
Robyn
If AMG/GEP had a plant in China that produced 6.5 heads/blocks, I doubt you'd be hearing the negative about the parts...... :)
Jim