Would this be a blown head gasket? Strange test results

[speed1972]

I can't figure this one out......
My buddy put a cobra intake on his motor and started having overheating issues and it was pushing water out the radiator. We figured that it blew a head gasket so he took it to a local mechanic and had it chemical tested. Of course the liquid changed color indicating a blown head gasket. It wasn't a big deal because he was building a new motor to take its place in a few months.

Ok so heres where the problem starts, we put the new motor in this past weekend, fire it up and same thing, it overheats and pushes water out the radiator. He took it back to a local shop and again had it chemical tested, same result, blown head gasket. At that point, he ran a compression test on all cylinders and they ranged from 147 to 152. Common sense tells me to go back to the initial change which was the intake but I don't see how this could cause the problem. Exhaust gases in the cooling system and pushing water out the radiator indicate a blown head gasket completely.....but the compression results don't agree........

Does anyone have any clue what is going on here?

thanks, Larry

 

[EMW150]

I've had issues in the past similar to what you're seeing. In my case it was the cylinder head dowels were too long for the receivers in the Canfield heads. Instead of the bolts clamping the gasket, it was just putting stress on the dowels. You couldn't visibly see this until I mocked it up without a head gasket. When tightening down the intake it would push the heads downward on the block and slightly lift at the top. Overtorquing the intake will cause that type of problem even if you don't have issues with the dowels. I never torque the intake more than 15 ft-lbs.

 

[EMW150]

Forgot to mention, head gasket can be leaking and not show on a compression test. Depends on the severity of the leak.

 

[speed1972]

I guess that would make sense... I just never heard that an intake could offset the clamping force of the heads though..... Any other input?

 

[EMW150]

I guess that would make sense... I just never heard that an intake could offset the clamping force of the heads though..... Any other input?

Do you know the part # of the head gaskets used?

 

[speed1972]

I will have to find out. I know its a standard felpro gasket, just don't know part # right off hand

 

[PurpleStripes]

Sounds like a crack. Compression may not sure a crack unless it's hot. Does sound odd. I have diagnosed 100s of blown head gaskets and never quite heard of anything like this. Is it possible that when installing the new lower intake, that an intake bolt caused a crack in the head? Anything odd in the oil? Could the head gaskets be upside down? I would use a pressure tester to pressure up the cooling system and look for tell-tale signs of coolant in the cylinder(wet plugs, excessive smoke, missing with cooling system pressured up, coolant smell in exhaust gas). Also, if you get your hands on a pressure tester, place it on the radiator neck like normal. Then start the car....if the pressure starts to come up instantly or does so while powerbraking, then blown gasket it be. Try this with car cold. Hopes this helps.

 

[fastimes69]

Did you put in a new thermostat when you put in the new intake.Did it already have a t-stat. Make sure you did not put it in backwards. My buddy with a Cobra had similar problems, just a thought......

 

[speed1972]

thanks for the thoughts guys.. tried it with a new t-stat and without one at all, thought maybe there was an air pocket. Also, it pushes water whether it is cold or hot. All signs point to a head gasket but why would 2 different motors have the exact same problem? It doesn't make sense to me. Anyway, he will do some more testing this week....

 

[speed1972]

any other ideas guys?

 

[EMW150]

any other ideas guys?

All you can do is pull it apart and inspect the gaskets and see if you can see where they were leaking. If you can't find evidence of a leak, inspect the heads for cracks and have pressure tested. If the head gaskets are leaking, straightedge the heads and make sure they're not warped. Other than that, clean it up and put it back together. Try Felpro #8548 PT-2 gaskets or 9333 PT-1s. Also check those dowels.

 

[StockLX]

my head gasket blew real bad, filled the crank with about 2l of coolant. when i pulled the heads i found that the dowel was sucked up into the head all the way. where do you get the proper dowel? and can the dowel be reused? i reused mine 3 head swaps.

 

[EMW150]

my head gasket blew real bad, filled the crank with about 2l of coolant. when i pulled the heads i found that the dowel was sucked up into the head all the way. where do you get the proper dowel? and can the dowel be reused? i reused mine 3 head swaps.

I use Trick Flow dowels. They're a hardened steel. You should replace the stock Ford type anytime you change head gaskets.

 

[tunedin302]

Did you cut out the coolant passages in the "lower intake to head" gaskets?

 

[StockLX]

should the dowel even be able to fit all the way up inside of the head?

 

[EMW150]

should the dowel even be able to fit all the way up inside of the head?

It can. As long as they're tapped into the block tight they'll get the job done. That's why I recommend replacing them every time because they get distorted after use and don't fit as tight.