Cracked heads

[ttpost]

still working on truck # 1 tdc learn problems, in the mean time truck #2 also 6.5 94 diesel blew a headgasket. while i had it apart i decided to do a valve job, so i hot tanked the heads and upon clean up i noticed i have cracks between the intake and exhaust valves on all cylinders, the truck ran well until the head gasket blew, due to finances right now i cant afford new heads. i have no choice to run what i have for now, i assume these were cracked for along time before the head gasket blew, i never have over heated it and i have owned for most of its life. does anyone have any suggestions, or ideas on what kind of problems i will be dealing with running the heads as is for now. has anyone else done this and if so what kind of results did you have. thanks rob

[More Power]

We have a tech page in the subscriber section that details how to economically repair these sort of cylinder head cracks.

Jim

[ttpost]

Jim, thanks so much. I was able to locate the bushings and i had the reamer, so i have made the repairs and it only cost me 22$, i cant thank you enough. I had thought about something similiar, but i wasnt sure of the dimensions or even if it would work. Once again jim thanks alot rob

[Flatlander6.2]

Jim,
Would the repair that is shown in the members section be suitable if there are cracks that extend into the valve seat?

[ttpost]

flat lander , i assume you found cracks? several of my seats were cracked, i have no choice but to run it as is right now, i did do a valve job since i have all of the equipment. i will be putting the motor in tomorrow, i will let you know how it does. i do have good compression on all of my cylinders so far. i will post updates. i do plan on replacing my heads at a later date. rob

[Flatlander6.2]

I do have cracks, have lapped the valves and will be puting heads on hopefully today. I did compression about 6 weeks ago and was 420 to 435. I too have no choice at the moment than to run as is, but plan on a proper fix at a later date.

[More Power]

Jim,
Would the repair that is shown in the members section be suitable if there are cracks that extend into the valve seat?

Many of these hairline cracks between the valves do extend into the valve seat area. The repair procedure works for them too. The hairline cracks fill with carbon and don't appear to leak or be a problem over the long haul.

However, if the crack is wider than a hairline, I'd probably look for a new head. If replacing a head, be sure to replace it with one having the same seven-digit casting number (ensures the same valve diameters) and pre-cup design.

As a side note, most of these hairline cracks don't extend far enough into the head to reach the machined cooling passage. That's why most people only notice them when taking the engine apart for some other reason.

I don't hear of it so often now, but there was a time when different shops around the country would attempt to weld the cracks. I don't have any long-term information regarding how effective that sort of repair is. I do know that welding cast-iron engine components can be tricky. The valve guide liner type repair is, in my opinion, more effective long-term.

If any cracks radiate out in some other area of the valve seat, I'd probably replace the head. Some have tried valve seat inserts, and that might be a good solution, but I don't know enough about it.

Jim

[ttpost]

flatlander hows your project coming along, i am up and running. my truck is running alot better than it was and getting better fuel mileage. no overheating problems the trick from jim has been a great help, and the valve job was just the ticket. i bet i gained 40 or 50 hp. i am really pleased thanks again jim. rob