Blowing Gaskets

cranked_dodge

cranked_dodge

Diesel Pro
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Jul 31, 2007
Messages
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We did some work for a customer. We fire ringed the block decked the block and head so everything is straight and flat.

He is running twins and running high boost, over 100psi and he keeps blowing out the front and the rear of the gasket.

We are running Scheid marine gasket and Scheid rings.

He has blown 2 gaskets out now and the rings are looking fine. He has about 10 thou crush on the rings.

I am not real familiar with the 12V so I was hoping that some of you 12V guys out there can give me a direction to head and to look at.

Thanks
 
who is doing the install? are the studs getting torqued correct with a calibrated wrench?
 
It does not have a coolant bypass kit on it at all. I just talked to him about that.
He is doing the install and he is a High Performance Snowmobile engine builder so all of his wreches are calibrated correctly, he is running the ARP 625 studs and he has torqued them to ARP specs and this second time he did 6 cycles on the torque and the last two pulls the nut did not move.

Possibly he is pressuring up the coolant too much.
 
So that added 1/2 point of compression to the mix. Does it blow the gasket out the front or is it just pushing water out. Is he still running the factory cap on the radiator? Was the head checked for cracks that may lead to the water jacket that doesnt leak except under high boost?
 
we recut the pistons 5 thou to keep the compression the same. The head is brand new and when we got it it was sent to get oversize valves put in so I had them check it just to make sure there was nothing wrong with it.
It is blowing the gasket out the front and back and he is getting oil into the water.

I am not sure if he is running the factory cap or not.
 
I just talked to my customer and he put a 5lb rad cap on after he blew the gasket the first time.
It is pushing water out the back of the gasket. He hasnt gotten any oil out this time but possibly because the gasket isn't blown as much as the first time.

On the street testing it was fine. It wasnt untill he went to the track and did a long pull with the truck that the gasket blew.

He is running a water pump that has had the fins clipped on it.
 
Re-check the head and block for flatness, you said a new head and that started the wheels rolling. 100 psi is not that much, I ran 80-85 with a single .051 O-Ring in the head for years with zero issues.

Jim
 
he has checked them both again for flatness and they are perfect. He is running upwards around 120psi for boost.
 
What are you torquing the 625's to and they have never been over torqued have they? If they have they are probably junk studs. 12mm studs have been known to stretch under extreme conditions that why alot go with 14mm in performance engines also.
 
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He has torqued them to 150ft/lbs in three steps increasing the torque each time and the final times were to 150ft/lbs.
As far as he is telling me he never over torqued them.
I know we went with 14mm in our CR race engine but he wanted to stick to the 12mm

Thanks for all the insight on this
 
I would check the depths of the fire rings. Sometimes when you cut them with bolt on fixture it is hard to keep them consistent. The trucks I have seen that had problems that was it. When I cut them I surface the head and cut them in the CNC in one set up .
 
Toolman said:
I would check the depths of the fire rings. Sometimes when you cut them with bolt on fixture it is hard to keep them consistent. The trucks I have seen that had problems that was it. When I cut them I surface the head and cut them in the CNC in one set up .
Click to expand...

This ^^^^
 
I blew a headgasket out of my 12v this summer. I have Haisley .105 fire rings, ARP studs and stock water pump. After teardown, the gasket was blown out at each end. Did some research and ended up installing an electric water pump and a bypass kit from Enterprise Engine. I was told the bypass is not needed with the electric pump. I have made at least 8 hooks since and haven't had any problems. If this is a street driven truck, you may have to clip impeller fins some more and install a bypass kit. It is the rpms that were the root of my problem.
 
Toolman said:
I would check the depths of the fire rings. Sometimes when you cut them with bolt on fixture it is hard to keep them consistent. The trucks I have seen that had problems that was it. When I cut them I surface the head and cut them in the CNC in one set up .
Click to expand...

Like the new avitar Bruce and X3 on this ^^^ procedure. If he has kept the old rings marked for each hole he can mic the rings in 6 or more spots going around the rings looking for even crush. Mine blew on the #6 hole but my ring did not have even crush even with 625's cranked to 165ft lbs and doing the 10lb per pull all the way up. Later finding out the cut depth did vary a little but my crush was the big blame.

Whats his drive pressure's at full tilt?
 
I will have to find out what his drive pressures are at.
I know the fire rings are all evenly cut.
We measured them all once they were cut and then when he took the head off I had him measure the crush around the rings and they all were perfect.

I am thinking that it could be the coolant pressure issue.

I will get him to check out a few more things.
 
Have him run a carbon test on the coolant to see if its compression that is filling the coolant system or something else causing it to pressurize with that in mind the thermostat isnt sticking partially shut is it? if it has one.
 
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