Failing Headgaskets

jacksonchuck

jacksonchuck

Member
Just lost the second headgasket in less than 300 miles on newly rebuild AER touring engine. 6 to one head. Looks like 0.100 oversize. Both gaskets were Snyders B-6051-M premium gaskets. Both gaskets failed between #2 cylinder and block to head coolant passage between #2 and #3. Both were torqued at least three times. First one to 50# and second to 60#. Grade 5 studs Head and Block appear to be dead flat as best as I can tell with a machinists straight edge. Timing right on the button with Nu-Rex scale and timing light. Rich F is at a loss. Has anyone had this same experience and how did they remedy it. When this thing runs it runs great. Can't find a zipper to use to make it easier to take the head off so would like to fix it right.
 
try a copper head gasket
make sure she is running cool and that the rad is full flowing. have seen clogged rads used on new engines ,,,,not good
 
failier between two cylinders next to each other is either a warped block or head, either of them are not flat and causing that problem, composition gaskets are not as reliable as copper ones, i would really check the head for trueness next time off, or even use another head
 
Along with checking the head as ford3 suggests, check the trueness of the block surface also. Be sure to use a precision straight edge, not just a steel rule. Perfectly clean surface should be understandable
 
Checked both head and block with a 12 inch machinists straight edge. Both are flat and true. No light coming in under ruler and cannot get a .001 feeler guage under straightedge anywhere.
 
Did you check the gaskets fire ring alignment to the head? A couple years ago, I had an early 6:1 head that did not properly support/cover the fire ring on the same B-6051-M gasket. As I had never had the problem before, my typical assembly was to... drop the gasket over the bolts and then slide the head on and torque up. I did not notice the combustion chamber of the head was not fully supporting the fire ring. Upon close inspection after failure, I found the problem and sent the head back to the supplier. They sent me a replacement head. I now check for proper support by placing it over the head for a good look prior to slipping it over the bolts. Remember...it matters which side goes up on these gaskets also...look for the marking on the gasket.
Good Day!
 
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I think there were some problems with the 6 to 1 heads as Dave mentioned. Is it a Snyder head ? If so, what did they have to say ? I think they stopped selling them for a while for some reason.
 
I would have the head checked for flatness. I just had mine redone and he had to take alot off. I used a straight edge and didn't really notice any high or low spots but the machinst said other wise.
 

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Will take it to machine shop tomorrow and have it professionally checked. AER said they make a cleanup pass on them anyway. Was a snyders head but recent.
 
No expert here by far, but would suggest planing the head (it's already off),use the copper head gasket with copper spray, torque at least 3 times.
You mention you think it's o.100 oversize. It either is Ose Richo offenR isn't and possibly you're using the WRONG size gasket. I think Larry B had specific head gasket recommendations for his H/C head which would probably also apply to this head. Is it possible the engine if 0.100 oversize not bored on center (no offense Rich)causing the gasket (no matter which one) to not "fit/seal" correctly??
Paul in CT
 
a straightedge can fool you. have it cut regardless. Agree with all that Dave in MN said about checking alignment on head and on block separately before assembly. I had a new head once that had a slight core shift and did not support the fire ring correctly (the raw edge of the fire ring always goes UP
 
Have read all great ideas here of what your problem could be. I agree gasket alignment on both block and head important. Would like to see a glance of what you think head casting thickness may be. It may breath or flex just a bit under compression and allow head to flex a thin casting area in the head and fail the gasket.
 
When did you re-torque the gaskets. I have had bad luck with that type of gasket. I found out the hard way that they have to be re-torqued often and many times. Just keep re-torquing until they hold the torque. On one engine the initial torque was lost after running the engine for only 10 mins. The instructions that come with the gasket say re-torque after 500 miles. If you wait that long you will have a blown gasket.
 
Bob Johnson said:
When did you re-torque the gaskets. I have had bad luck with that type of gasket. I found out the hard way that they have to be re-torqued often and many times. Just keep re-torquing until they hold the torque. On one engine the initial torque was lost after running the engine for only 10 mins. The instructions that come with the gasket say re-torque after 500 miles. If you wait that long you will have a blown gasket.
Click to expand...

Regarding the B-6051-M gasket...
Bob's right on the first warm up...I often see 10-13# loss in torque with the first full warm up. A fast idle is all I do with the first running. I run them about two hours and during...re-torque the head 4 times prior to loading the engine with the Dyno during break-in. I always wait until the engine is cool to re-torque...Just my way of doing things. Once these gaskets seat...they do not leak...from my experience!

Good Day!
 
Bob,

Thanks for sharing your experience. It makes sense and will keep the torque wrench in the car. How much torque did you use? When yours failed was it in the area between the cylinders and center water passage? Seems like a weak place in the gasket. I wonder if using the modern silicone coated composite gasket is worth the hassle or if going with the copper one would be better.
 
True that is what Snyder's will tell you. However, I got tired of messing with those damn silicon seal gaskets and went with a copper sprayed composition Best gasket for the Model B. Haven't had any trouble at all in over 5,000 miles.

But of course you must follow manufacturer's recommendations. I will never use one of those silicon seal gaskets again. Maybe I am doing something wrong, but they sure dont suit me.
 
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