• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Cracked head. What do you think about it?

Will L. said:
After welding, it has to be machined. Get price on that also before welding it. You might be cheaper to get a new head.
Click to expand...
Oh sure. After welding, it must be machined. It's not expensive in Moscow. I can buy a new head only in the US or China. But the shipping cost is very expensive. So I can to bay only the used head or I can to try the head repairs
 
Tell me pls, is between valves the cooling jacket in this engine? One of my friend argues that such a crack is not a problem. But I disassembled the engine and saw the dirty oil emulsion. Gaskets were not damage. I think it's because of the crack.
 
The majority of 6.5 heads are cracked there, and most don't leak. Several have run heads with easily visible cracks there with no problems, but a few have had them crack and say thats the only place they could find with a problem to cause a combustion leak. The sleeves are because it is such a widespread problem just to be safe.
 
Zombie

I looked into this more. One company that made a kit for this was Goodson part #DCR-62-KIT titled as GM 62 liter crack repair kit. Unfortunately they quit making the kits back in 2013 from low sales.

I spoke to several reputable machine shops, they all have done it with perfect sucess. One machine shop that I had previously been to where the owner knew I did 6.2/6.5 was amazed I didn’t know of this.

I am seriously thinking of doing it preventively.
Comments?
 
If you have the old production heads, I could possibly see doing this, possibly (keeping in mind the old Army adage, "If it ain't broke, don't fix it") but with the labor involved, plus the machining costs, is it really worth it vs. waiting to do it if one (or both) does finally fail and if so, where (on the 15 in Vegas or out in the middle of ****ing nowhere in the dessert bombing around). If you have newer, better heads, why bother?
 
The link no longer works, so jic the posts on the YouTube video dies-
Brass tube diameter is 10mm, length is 73mm, drill bit is 9.7mm.

Optimizer heads crack also. I haven’t cleaned either head yet, hopefully ok, but I can’t remember a 200,000 mile head that didn’t have a crack in it. I see it as inevitable.
I am not going back into this engine once done.

This isn’t a technical task. Remove plug, drill to depth, cut brass to length and drive in, and plug.

I can’t see how fitting the brass tube would have any negative affect, and the local machine shops say the same from experience doing it. So other than cost and that is 8 new 3/8” screw in plugs-$25 & 2’ of brass tube $8. The brass at an interference fit will be a time delay in heat transfer, but will still tranfer all the heat. Brass is almost exactly twice the thermal conductivity as cast iron-with that and the related emissivity it actually should improve removing heat from between the valves.
 
This is good stuff. Just I didn't find any visible cracks in the heads that came off 254k motor. I'm thinking it might be a good thing to do on my rebuild even if it doesn't have cracks or am I missing something?
 
@Rodd my pojnt exactly. There are other things we do at the machine shop like balance the crank assembly that costs some money as insurance. This is so cheap. Worst case would be someone needing to buy a drillbit, drill it stop, and a 3/8 npt tap. Pretty sure I have those.

I have time to wait for response of someone having negative input, and if ANYONE has a thought “it’s bad because X”, please speak up.

Husker6.5 mentioned costs- but $100 for anyone diy, and under $35 (I looked at amazon) for me diy-worth it.

ak diesel driver mentioned keeping cool more important- yes I fully agree. With my replacement radiator lowest price @ 800 BEFORE coating- and the entire stack will get coated, doing best waterpump, crossover, fanclutch option- and still pursing adapting hmmwv 100% lockup clutch to the spin on pump, water wetter, etc. and will fill the system using vacuum to hopefully pull liquid to he farthest reaches...Thinking I am covering that aspect as good as I can.
This is just one more small safety net.

@Twisted Steel Performance - the heads you cut up, did this passage flow through, or isn’t it a dead end possible air pocket? I mentioned to you before when I did coolant flow testing, I never touched these plugs.

Anybody have close up pics of cutaways they could post here or post link to? Time to log on with my tv to examine closer-

As overkill as it sounds- should the plugs be a bleeder to ensure venting any trapped air? If they are a coolant dead end, I could see how trapped air by chance allows some to crack and others to not crack.
 
SmithvilleD said:
Yep, seals (or ensures it remains sealed against future cracks) the water jacket. It's not uncommon for cylinder head shops that do a lot of 6.5 heads, to, pro-actively, drill all those passages & punch in the valve guide inserts - to eliminate comebacks/future problems.

A well respected, local cylinder head shop here in Kansas City did that process to my truck's heads. They had long-term 6.5 experience with the Frito-Lay 6.5 powered stepvan fleet. The shop would stand behind their work & the stock GM head's pressure/integrity reliability if this process was done. Can't recall the cost as it was over 9 years ago, but it wasn't enough additional $ to be pushing the process for additional shop profit margin.

I didn't see the cost-effective aftermarket or GEP head options available now, in 2007, so I went this route - can't complain as it's still running trouble free.
Click to expand...
My 94 cc srw also had that fix about 100,000 miles ago. No issues yet
 
I will half to look for the pics, they are gone from a couple sites I posted them on... the stock passage did not flow between the valves it was a plug of cast iron for strength I think.. the p400 heads has more material and a passage between the valves..
 
I just took a look at my heads and didn't see any cracks between the valves or piston areas. From the video above I looks like the pipe is inserted between the 2 cylinder areas but I did see the plugs and holes that line up and run between the valves. Not sure where the pipe is inserted. I made a video of it. Tell me if you see cracks or anything out of the ordinary.

 
In between the intake and exhaust valve of each cylinder.
Use brake cleaner and scrub the tiny area btween the valves. Sometimes you cant see the crack through the carbon from burned fuel.

It is where the tiny “freeze plug” is. Ya pop the plug, drill the hole, tap for threads, drive in pipe, screw in plug. Go back and watch video at beginning on thread with that description.
He points out a tiny crack- they can be hard to see when they start.
 
You must log in or register to reply here.
Back
Top