Very confused #8..
#12
Hey guys thanks for the help, did a leak down test at 90PSI going in it will only hold about 28% and we could hear air rushing out of the throttle body, didn't hear any out of exhaust. Hoping the plenum repair will fix all my problems! Thanks again will be back if I have an further issues! Also I'm thinking I should re run the wires to Mopar spec.
Good luck !
Last edited by fj5gtx; 04-02-2019 at 09:20 PM.
#14
I've been doing this kind of thing for more than 40 years, the number 8 intake valve, or valve seat, has issues. Nothing you do with the intake manifold is going to fix that. You need to pull the valve cover, and check the valve springs, and whatever else you can see there. (like, how the valve moves, etc.) If everything there looks ok, time to pull the head.
#16
Need to see what the problem actually is. We already know it involves the number 8 intake valve, from stuff previously done. You can peek in there with a bore scope, and see if anything obvious presents itself..... but, I would bet real money that the head is going to need to come off.
#17
Its not the intakes job to seal the combustion chamber. So correct, there is no way the plenum is going to cause a combustion chamber leak. Its job is to mix fuel/air and deliver it to the intake valves. Watch some videos on youtube to gain perspective, I'm sure there is someone making a cool movie on combustion chamber dynamics.
#19
#20
From what I'm reading here, have you reperformed a leakdown test with positive results? As mentioned by others, any problem with a leakdown test or a compression test involves the combustion chamber which makes the plenum totally irrelevant. Unless the leakdown test was performed incorrectly with the #8 cylinder in a postion other than TDC on the compression stroke. If you performed the leakdown test at TDC at the beginning of the intake stroke, you might actually hear air coming out of the throttle body which is not a valid leakdown test. Something is getting lost in this post. A failed properly performed leakdown test, if you hear air coming out in any quantity, means that at a minimum the heads need to come off. There is some wiggle room in a properly performed leakdown test but actually hearing air escaping means that the engine is not going to run properly no matter what you do.