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post #1 of (permalink) Old 09-10-2003, 04:01 PM Thread Starter
 
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Intake leak on 250 I-6

HELP!!! I have a new rebuilt '74 250 I-6 that I cannot get to quite leaking at the intake. I've tried two new gaskets, with and without silicone, stacking two gaskets together with and without silicone. Still leaks!!! There are no evident cracks or anything wrong with the head and/or intake. Any ideas? I am stumped!!! Any ideas or tricks offered will be MUCH appreciated. (other than should've gone with a v-8) Thanks [img]images/graemlins/thud.gif[/img]
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post #2 of (permalink) Old 09-10-2003, 04:39 PM
ratlover
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Re: Intake leak on 250 I-6

Do you know its an intake leak? And or were the leak is? Between the carb and the intake or head and intake?

is it the funky manifold that is a combo intake /exhaust bolted together combo thingy? Possible crack?

Does it only go fubar when it warms up? I had a 62 straight six that did that. Very fun, not really


gotta leave work.....later
post #3 of (permalink) Old 09-10-2003, 05:18 PM Thread Starter
 
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Re: Intake leak on 250 I-6

Yeah it is the combo intake/exhaust bolted together. I am sure it is leaking around the intake gasket. I start the engine and, while it's running, spray starting fluid around the intake. The engine revs when I hit the part where the intake mates with the gasket with the head. There doesn't appear to be any leak on the front section, possibly a VERY small one on the middle and a health one on the rear. I have taken the whole unit completely off and scrubbed the hell out of it and there doesn't appear to be any cracks. The carb seems to be fine, when starting fluid is sprayed around it, nothing hapens.
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post #4 of (permalink) Old 09-11-2003, 08:44 AM
ratlover
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Re: Intake leak on 250 I-6

you lay a straight edge across the head/mani and is it reasonably straight?

I would attempt gorrila snot or superblack rtv. Lay a bead and let it get a skim over it then put it on the head but dont tighten it all the way and squish out the rtv. let it cure a few more hours then squish her down some more. let it cure the full 24 then see what you got. really sounds like you have some sorta mechanical problem with the manifold/head if you are pretty sure you know were its coming from and you cant get her to seal with a gasket. With a gasket I would torque to its proper spec(cant be much) then run her for a bit of warm up cool down cycles then retorque. overtightening can cause leaks too.

On second thought.....I have never used black rtv on a I6....it might require copper. I dont know if a I6 mani gets too hot for the super black?
post #5 of (permalink) Old 09-11-2003, 11:11 AM Thread Starter
 
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Re: Intake leak on 250 I-6

Hmmm, I'll check it out with the straight edge. A friend of mine suggested unbolting the intake/exhaust assembly so it is just a little loose and then bolt it to the head, in case the two weren't lined up properly. The manifold does get VERY warm, no idea of temp, but I had used orange hi temp RTV (650 deg.), copper is a good idea though, when i go to pick up a new gasket I'll check it out. I may have been tightening the stuff down too far as well. After the first couple failures, I pretty much gave her all I had with the wrench. I suppose it could be just a large combination of small things?!! I REALLY appreciate the advice. I am headed to the inlaws for a VERY long weekend, so I may not get to the engine till early next week, but I'll let you know what happens. Thanks again!!
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post #6 of (permalink) Old 09-11-2003, 01:43 PM
ratlover
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Re: Intake leak on 250 I-6

your friends suggestion is a good one.....good luck [img]images/graemlins/smile.gif[/img]
post #7 of (permalink) Old 09-14-2003, 05:39 PM
RolngThun
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Re: Intake leak on 250 I-6

I think you will probally have to take the intake, exhaust manifold still bolted together to your machine shop. They will resurface it for you. They will machine it bolted together to amke sure they are flat with each other.
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