Author Topic: 1956 dual four intake leaking at the heads UPDATE 10/17  (Read 319 times)

Offline cadman56

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Re: 1956 dual four intake leaking at the heads
« Reply #10 on: October 09, 2017, 07:29:30 AM »
Thanks for the warning.  Guess getting stupid in old age.
Anyway, I used BEST gaskets which are composition.  The manifold seemed to sit flat and solid before bolting it down.
Tearing it down again today.  Will post again after problem found and fixed.
Larry Blanchard CLC#5820
1956 Cadillac Coupe deVille (sold)
1956 Cadillac convertible (sold)
1956 Cadillac Eldorado Seville
1967 Cadillac Eldorado (sold)
1968 Cadillac convertible
1991 Cadillac Fleetwood Brougham dElegance

Offline rare eldorado

Re: 1956 dual four intake leaking at the heads
« Reply #11 on: October 09, 2017, 10:46:19 AM »
Hello Cadman56  A safe way to check for a manifold leak would be too put some trans/ fluid in a oiler can or plastic bottle .When sucked into the manifold it will burn white out the exhaust. Or use carbuator cleaner with tube extension supplied with can ,, ,motor will rev up .Make sure it is not sucking any in top of carb//.Also check your p/b valve if it is bad it will cause the same problem ...even though the brakes work .Is your car equipped with a pcv? it can also cause the same problem .Another way to check for a leak is too unplug all vacume lines  and plug  ports .If car runs fine then connect them 1 at a time to find the leak.

Offline PHIL WHYTE CLC 14192

Re: 1956 dual four intake leaking at the heads
« Reply #12 on: October 09, 2017, 10:59:21 AM »
I used the Best Gasket ones on my 54 but was thinking of fitting the Olsen ones that blank off the heat riser [if your manifold is cracked in that area, this might solve it?]. I saw that you said that the vacuum advance is working correctly, so maybe this is pointless as you have already checked this, but have you checked the vacuum line from the manifold to the carb and the power brake vacuum hose and all the other vacuum hoses/fittings? If any of these are leaking it will knock the timing out and run really badly. Sorry if I am telling you something you already know. Phil

Offline cadman56

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Re: 1956 dual four intake leaking at the heads UPDATE
« Reply #13 on: October 10, 2017, 11:53:09 AM »
UPDATE:
I had to pry the manifold loose, those BEST gaskets really sealed.  They separated at the perforated steel between the masket material, now I have to scrape.  Bummer.  Great news is manifold is OK.  Yay!
I will now start checking deeper with a compression test.  I am afraid the timing chain may have slipped.  With my failing eyesight I may have not seen the timing marks correctly.
I will let you all know.
My wife was just learning to drive this car so we could enjoy it.  Oh well, I bet we have all been here at some time.
Larry
Larry Blanchard CLC#5820
1956 Cadillac Coupe deVille (sold)
1956 Cadillac convertible (sold)
1956 Cadillac Eldorado Seville
1967 Cadillac Eldorado (sold)
1968 Cadillac convertible
1991 Cadillac Fleetwood Brougham dElegance