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Help needed on manifold issue


jvelde
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Hey, I had a leaking exhaust manifold - got replacement 3 piece gasket kit from O'Reilly. Unhooked fuel line and vacuum from carb, vacuum from manifold to wipers and linkage from carb to throttle. Uncoupled the exhaust manifold to exhaust pipe flange, removed all the manifold nuts (some came out stud and all), cleaned up the faces and installed new gaskets. Torqued manifold nuts/studs to 28 ft./lbs., replaced exhaust flange gasket and reconnected all the previously listed items. Sounds pretty good to here until I tried to start engine to check for leaks!

When I tried to start engine, it made excessive exhaust noise (sounded like no muffler) and would only try to fire up. I tightened up the exhaust flange connections and found the tube coming from the top of the intake manifold to the carb had come loose from the manifold, so I stuck it back into the port. Tried starting again with only minimal improvement - will fire and run very rough then die - still making way too much noise.

So, I have apparently done something wrong in all this - I don't want to do major damage, so any suggestions will be appreciated.

Thanks, John V.

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John'

Is the tube you are talking about the small tube from the manifold to the choke? This tube goes through the exhaust manifold, and should go all the way through the manifold. It should not be moveable. It could allow exhaust noise, but not the rough idle. Sounds like you have a leak in intake. Do you have Intake Manifold Pilot Ring?

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John'

Is the tube you are talking about the small tube from the manifold to the choke? This tube goes through the exhaust manifold, and should go all the way through the manifold. It should not be moveable. It could allow exhaust noise, but not the rough idle. Sounds like you have a leak in intake. Do you have Intake Manifold Pilot Ring?

Thanks m_kent: The tube (about 1/4") goes from the Climatic Control into the center of the exhaust manifold - there is a smaller line coming from the distributor vacuum into the carb as well. There were only two intake manifold pilot rings present when I removed the manifold, so I kept them in place - don't know what became of the other two prior to me getting the car. I will check around the intake again for obvious leaks - since I can't keep the engine running it is difficult to tell too much. Do you think locating two more intake pilot rings is possible?

Thanks again,

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Erik, its so true about the Belleville washers. Isn't there also some type of anti-seize compound that is supposed to be used between the exhaust manifold sections? I think you will end up with leaks without this stuff. Was the gasket you purchased from O'Reilly copper? I have found that the non-copper gaskets tend to blow out rather quickly.

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Isn't there also some type of anti-seize compound that is supposed to be used between the exhaust manifold sections?

Use copper paste and remember that these manifolds were supposed to be leaky when cold and seal up as the engine heated up.

Who ever thought this system up, must have been smoking some great stuff :D

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John

I just mounted a 41 dual carb manifold on a 36. I replaced all studs and gaskets. Same problem you had-wouldn't start unless put gas down carbs . Ran real rough and noisy and then would stall. Found gasket loose on bottom side. Put 3/8 by 4 inch bolts at manifold ends and slid manifold away from head. That manifold is heavy.Then checked all 4 rings and gaskets and slid manifold back in place lifting slightly with a board on fender. Runs quiet now. You definitely need all 4 pilot rings.

Stan

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Okay, current status - called and talked to Bob's (I think it was Bob) who said didn't need rings except to center gaskets. I had already purchased the non-copper set at O'Reilly, so that's what I have used. I had several studs that the nuts were frozen on and one that was completely stripped. I found replacement studs today also at O'Reilly. So, I have removed that heavy beast again and replaced studs, used brass nuts and anti-seize on all studs that I could get out and also on the fine end for the nuts. Carefully replaced manifold and think I have everything in place. I still can't keep it running, but it is way quieter than yesterday. I am thinking I may have messed up the carb adjustment in the removal/replacement process....?! So, after golf tomorrow I will tackle trying to figure that issue out. Just hope I don't have to remove the manifold again - arms are taking a beating getting it off and back on. If you have more input I am open to suggestions.

Thanks,

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John-

You mentioned your "current status - called and talked to Bob's (I think it was Bob) who said didn't need rings except to center gaskets".

By chance, I talked to someone at Bob's today also. My question was about the Belleville washers. Because yesterday, when browsing the new Bob's Catalog, I noticed how they will sell you two-thirds of a new exhaust manifold for just under $900! And the proper copper gaskets and intake rings are also available. But alas- no Belleville washers !!

When I inquired about the washers, I was informed that the '37 Buick does not use Belleville washers.

My (mis) understanding was that if you fail to use those washers and the anti-seize, that soon you will be ordering yet another exhaust manifold. But what do I know, they are the experts.

Anyway-I digress. Back to the problem at hand...

I hope that the new O'Reilly composite gaskets are up to the task at hand. Especially now, after they have been reinstalled again. Sorry to harp about gaskets, but these manifolds were a poor design in the 30's. You need all the help from your gaskets that you can get. (Ask me how I know!).

John, as other posters have mentioned, you seem to be describing a bad vacuum leak. Did you use any kind of sealer on the intake gasket? And how about the carb gasket? Was this replaced as well? Carb bolts all snug? The fact that she is running better the second time around could suggest that you have done some good, in the process, of eliminating some vacuum leaks.

If you can get the engine to run long enough to get it up to operating temperature, you might try hooking a vacuum gauge up to the intake manifold. Don't use the ported vacuum at the base of the carb. You should see 18-21" steady vacuum. You can then try slowly closing the choke. A well sealed engine should start coughing with even a little choke. On the other hand, if you have vacuum leaks, your application of choke may actually improve the engine's idle. (This idea only works when the engine is fully warmed up). You can also do the usual tests for seeking out vacuum leaks (propane enrichment or oil, for example-But don't use starting fluid or carb cleaner).

It is also possible (but probably less likely) that the old gaskets that you replaced were leaking and the carburetor and ignition timing was set to account for it. Now, perhaps, the new gaskets have improved the vacuum leak situation. Now the engine needs to be re-tuned for the present situation. The trusty vacuum gauge should provide some answers. Let us know what your vacuum gauge says. Hope this helps, Joe

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Joe, thanks for the information - I am going to go through the shop manual and try to adjust the carb per the procedure outlined. I have never done any carb work, so this could get interesting...! If I can get the carb adjusted to the point I can run a vacuum test I'll let you know what the outcome is. I did not remove the carb when i took the manifold off, so have done nothing with those gaskets. And no, I didn't use gasket sealer, which I hope not to regret.

Thanks again, all advice appreciated.

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John, most of the time you will be fine without any sealer on the intake. It all depends on the condition of the mating surfaces. If surfaces were a bit rough, I might use some of the copper spray on the intake gasket surfaces to guard against those blasted intake leaks and lean misfires. I rarely use any spray on the exhaust gaskets and never on the carb gasket.

Also, I would recommend making carb adjustments as a last resort, especially if you are unfamiliar with it. I'll assume it ran OK before the new gaskets, so chances are your carb is OK. You really never want to touch the carb without good cause and especially never before the engine is fully up to temperature.

Are you familiar with vacuum leak testing? This should be your main priority. Then try to get it running long enough for the vacuum gauge.

The big question now is: Even though the engine is not running very well, why won't it stay running? It needs just three things: fuel, compression and spark. Any one of the three not present in sufficient quantity and she won't run. You'll need to find out what you have and what you are missing. I always play detective retracing each one of my steps- what changed between when it last ran well and now.

Good Luck and let us know about the vacuum gauge results. This will really help with the diagnosis. Joe

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idrjoe_: Well it is running and I drove it around the neighborhood last evening to warm it up and then did the vacuum test. Only about 13 ft/lbs vs. the 19 when tested several months ago, so there are obviously some intake leaks. I will be working on it more today - need to get it going by tomorrow for cruize in on Saturday evening and trip to Granbury and Weatherford on Sunday. Hate to show up in my daily driver 2000 Mazda, but may have to!

Keep those tip and ideas coming, and Thanks.

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John,

I suggest you contact Olsen's gaskets for the pilot rings and gasket materials as well as great advice from experts. I am not familiar with the three piece manifolds as all my Buicks all have one piece manifolds.

I suggest you can check to see if there is a recess in the head for the pilot rings. Not only do they help locate the manifold, they also help prevent gasket failures.

I have had good luck using WD40 to locate vacuum leaks. Just spray it around all the intake seals and when the engine speeds up, you have located the area of the leak.

Good luck,

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Final entry (I hope)...everything is back together and functioning well - yeah!! I did a test drive of about 15 miles at a variety of speeds up to about 55 and all seems to be working. The engine is much quieter, so I suspect I have had the exhaust leak for some time (maybe since purchasing the car). I really appreciate the advice and good suggestions I have received.

Thanks to you all.

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