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-   -   attention machinists...need opinions on cyl head repair (http://www.hotrodders.com/forum/attention-machinists-need-opinions-cyl-head-repair-87157.html)

ratlover 04-17-2006 03:14 PM

attention machinists...need opinions on cyl head repair
 
Hi guys,
it's been a while... been busy finishing my boat project. This aint't your typical sbc chev question. I have a turbocharged,aftercooled diesel 6 cyl (volvo)... okay it aint no hotrod, but its a pretty hot engine. everything was great up until it broke a valve spring and swallowed an exhaust valve . got the engine shut down pretty quick... a new piston and valves in that hole will clean it up, but after subsequent inspection it revealed cracks between the intake and exhaust seats in adjacent cylinders($$$). a replacement head new is $9000 and a reman is $5000. I have found a place that does the lock-nstitch repair which eliminates the welding process. just wondering if the repair with this process is a good fix for 21:1 compression. I understand this is a common problem in diesels. should I do the remaining two cylinders to eliminate future occurances (4/6 are cracked). cannot find a core. any thoughts or wisdom appreciated. Thanks. hope you don't mind straying outside the boundaries a little on the "hotrod" in question.

cliff tate 04-17-2006 04:20 PM

volvo head
 
do not stich the head it will fail ther is a co in the vancouver aria that hot welds heads edc i beleve, call the service dpt at any finning store they will tell you who is doing hotweld on heads, it was at 1 time quite comon on cat engines and a very good repair. cliff

machine shop tom 04-17-2006 04:39 PM

Is it an aluminum or cast iron head? If it is aluminum, any high-end race or cylinder head specialist should be able to repair it. If it is cast iron, there is a guy in mid-Michigan that may be able to repair it by welding. He guarantees his work and has a good rep.

tom

ratlover 04-17-2006 07:48 PM

It is a cast iron head. As a welder I am always a little leary of welding cast iron. The heat control is so essential to a successful repair with no future stress or cracks showing up. These days hard to find anyone who can make a living at it. Just wondering if you have any experience with these pins.

machine shop tom 04-17-2006 08:21 PM

Quote:

Originally Posted by ratlover
It is a cast iron head. As a welder I am always a little leary of welding cast iron. The heat control is so essential to a successful repair with no future stress or cracks showing up. These days hard to find anyone who can make a living at it. Just wondering if you have any experience with these pins.

I am also a little leery of welding cast iron. I don't crack repair castings but I have seen quite a few that have been pinned or stitched. Properly done, it works quite well.

tom

topfuel 04-17-2006 08:38 PM

ratlover, the shop I used to work at did mostly diesel and industrial engines. I have used tapered pins to repair cracks on dozens of gas and diesel heads including Volvo/White heads. I had a customer who, like you, couldn't swallow the cost of a replacement or exchange head, he had a 1693 Caterpillar engine. By the time I was done, there were over 80 pins in the head. The head was pressure tested after the work was completed and showed no leakage. When I left the shop 7 years later, it was still running strong. Done properly the repair will last. Find a good shop and good luck. I hope this helps.

Barry

cliff tate 04-17-2006 09:43 PM

welding heads
 
Quote:

Originally Posted by ratlover
It is a cast iron head. As a welder I am always a little leary of welding cast iron. The heat control is so essential to a successful repair with no future stress or cracks showing up. These days hard to find anyone who can make a living at it. Just wondering if you have any experience with these pins.

the type of welding i refered to theygrind the cracks out toatly heat the head red hot then gas weldthe cracks cool the head for at least 24 hrs re machine inst new inserts and guides. this proses has been around for many years for heavey duty diesel engines and worked very well. the cat dealer i worked for used thes headsextensively with good reults. head hunters was 1 co edc anothercliff

ratlover 04-17-2006 10:19 PM

thanks to all for your replies. I would have gone with the welding, but could not find anybody locally that gave me a sense of confidence that they do this with any frequency. I did a little reading on the net and the new technology utilizes straight pins with an under cut face which acts to wedge the material together instead of apart when driven in as a taper would. They also are designed with a break-away head that snaps off at the designed torque they will seat at ( and to ensure all pins are seated with the same pressure.). I was mostly wondering about first hand experience in the long haul. These guys seem reputable and assure me that they only weld as a last resort if the shapes involved will not work with the pins. I'll let you know how it works out. it seems like if it survives in a diesel application, it may be able to with stand hi-po applications as well. The down side is 3-4 hours at $67/hr per cylinder. still cheaper than the reman though....just barely.

ratlover 06-01-2006 06:34 PM

1 Attachment(s)
I said I would follow up so....
seems to work great. total bill for machining and generic seats,($7 vs $70 per seat for volvo!) $1950 CDN. pinned all six between the int and exhaust. Including 3 new valves, a piston and liner total cost $3500. No charge for my re and re time though! Have 30 hours on it now, so I think it will be ok. Thanks for the assistance.


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