head crack repair

[woodwright]

I've got some cracks between the valves, and I've read about the process of reaming out the water port and sleaving it. I'm looking for some more info on it. Thanks

[Robyn]

Yessssss, it can be done, buttttttttttttttttttttt, you end up with cracked heads and a less than stellar end result.

If you are looking for a cheap fix, it's not really there.

With the availability of new aftermarket heads from Clearwater Cyl Head in FL at about $700 for a pair of new heads (to your door) it does not make sense any way you pencil it to fool with old broken iron.

The cost of
New gaskets
New bolts
Little extras during the tear down.
The bronze sleeves
Tools (if you DIYS)
Shop costs (if you farm it out)
Your time and skinned knuckles
Plus, if it fails, the cost of a DO OVER

While down, you will need a valve job as well.
If the heads have any erosion where the fire ring of the gasket sits, the head will need surfacing.

I have personally used the heads from CWCH and they are nice.

Yes, the castings come by boat (China) but I have not heard of any real issues.

Fit and finish were great.

When I sold the rig (94 burb) it had over 50k since the heads were done and was still running great.

At this late date, and with new iron available, it makes little sense to use worn out GM heads, when new stuff with ZERO duty cylcles is available cheap.

The CW heads are ready to bolt on, out of the box, and they send a return ticket to get your old ones back.

Just an FYI CW scavenges the valves and such from the returns, reworks them and installs them in the new castings.

New heads from AMG cost $1000 the last time I heard.

Most GM heads at this point in time have North of 200,000 miles, and many have far more.

If the heads have been off previously and worked on ????? just more worries

If it's a patch up just to get rid of a rig, and you can do all the work yourself, MAYBE ???

Just some thoughts


Missy

[woodwright]

Thanks Robyn, I'll check into those heads. Ive heard from others to not even worry about the cracks between the valves, and that they're cosmetic. These heads look really good besides that.

[a5150nut]

Woodright,

Post some pics of your heads if you would please. Get better answers instead of educated guesses.

[Robyn]

Cracks between the valves is normal on these heads, it's when they reach water that the issues get ugly.

I "assumed" (dangerous) that since you were asking about sleeves for the passages, that you already had issues.

My feelings about the old GM heads is still about the same though, as they are a pit you can toss a lot of $$$$$$ into and end up with nothing.

The best test you can do on these heads if you have a set that are flat, and otherwise ok, is to have them pressure tested after being placed in a tank of very hot water to help open any cracks.

But myself, the new CW heads are a good jump.

I am not hot about the China connection, but these heads have a pretty good track record.

Fritolay was buying them by the pallet load a few years ago to use with all the overhauls on their chip trucks. At the time, the cost was far less and reliability was higher than rebuilding the used ones.

Anyway, good luck

Missy

[woodwright]

Thanks missy. I would love to put new heads on it, I just can't swing that right now. As far as my heads go, I don't know if they're cracked clear through. I've found a liitle more info about the sleaves. You use valve guide sleaves which are $20 for a set. And the reamer is less than $50 but I think a friend has one. Just seems like that would be a good easy fix to make sure they never leak.

[DmaxMaverick]

The "head crack sleeve" isn't, necessarily, a preventative measure. It's a corrective repair. If it isn't broke, don't fix it. If it isn't leaking now, it probably won't. Many of the 6.5 heads crack between the valves, but an actual leak, or any other adverse affect, is quite rare. The heads, as with any engine component of any brand, have other points of failure that are more likely. As Robyn said, have them pressure tested if you're unsure.

[woodwright]

How hard would it be to DIY pressure test? Theres nobody near here that does that.

[DmaxMaverick]

Not hard, if you have fabrication skills and equipment.

If you weren't seeing combustion gasses in the coolant, and/or coolant in the cylinder(s), it's probably not imperative. Generally, they leak or they don't. I don't often pressure test them unless I have a reason. A compression and leak-down test before removal is usually all I need to make that call.

[Robyn]

I agree 100%

One of the most common leak issues on the 6.5 is a failed head gasket at the #1 or #2 cyl (two fronts)

The area in the block that is open in the rear to allow coolant flow is closed in the front, and the head has the port.

This allows coolant to lay right against the deck and the gasket, which due to electrolysis (gasket ring is stainless steel) there is a very real and common issue of erosion of the deck under the gasket fire ring.

Generally, some time around 200,000 miles and NORTH from there, the gasket fabric turns to mush in that area, and along with the eroding deck, the thing blows through into the passage.

The later gaskets have a better metal support that completely reinforces the area.

If the deck has a groove worn into it where the fire ring sits, it needs to be machined and the .010" thicker gasket used.

You can cut the deck up to .015" and be fine.

The last one I did was clean at .012" and I told the machinist NO MORE THAN CLEAN, and make them both the same.

Cut the worst side first, then match them.

Stuffing a new gasket on an eroded deck is a waste of time and $$$$$$

Just an FYI

If you find a #8 cyl with a gray scuffed spot near the top and at the rear of the cyl, the issue can very well be a cracked cyl wall.

The crack developed just below the deck casting (inside, under the deck) and was due to a stress issue.

This was a real concern on later 6.5's (98-99-2000)

Once AMG blocks were fully implemented this issue was eliminated, along with several others.


Missy

[woodwright]

The cracks don't seem to have any sign of coolant. And I think the headgasket was leaking on the passenger side rear.

[scottm]

Robyn, Penninsular sells made-in-usa heads.. Are these amg/gep parts?

http://www.peninsulardiesel.com/WP-P...bly-6-5l-turbo

[scottm]

I don't know about Penninsular heads, but I called this place and they sell real AMG/GEP heads and engines. Here is an amg cyl head. Kinda pricy but no doubt much better than Chinese ebay junk.

https://www.real4wd.com/zedSuite/cat...artNo=05744649

[DmaxMaverick]

The 6.5L engines and heads sold by Peninsular are AMG/GEP. Kennedy also sells the engines (new and reman), but doesn't list heads alone.