DonaldSmith Posted August 16, 2020 Report Share Posted August 16, 2020 My 47 DeSoto is very loud, sounding like a blown muffler. But the noise is coming from the engine compartment, more from the manifold side. I could feel no leaks at the exhaust pipe flange, or anywhere else where I could safely put my hand. I'm thinking (dangerous territory), if I could make the engine smoke, I could see where the leak is, at least generally. I have a set of manifold gaskets coming, figuring that I would remove the manifolds. Questions: Has anyone had noisy manifolds, and what was the cause and remedy? Would smoke generation work? Would, SeaFoam be a likely agent to make the smoke? Quote Link to comment Share on other sites More sharing options...
1949 p17 Posted August 16, 2020 Report Share Posted August 16, 2020 you need a stethoscope with a metal tube pushed in the end of the rubber hose. that way it won't burn when you slide it along the manifold listening for the exhaust leak. don't take it apart untill you diagnosis properly. it might be the manifold gasket, or a warped manifold, but use the stethoscope because it will pinpoint the leak and you can use it for other noise diagnosis. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted August 16, 2020 Report Share Posted August 16, 2020 with the engine running spary some WD40 along the area where the gaskets are to see if the nosie quiets down and if the engine runs smoother. If this happens then you have a gasket leak. What about your heat riser is it broken an loose? Rich Hartung Desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 16, 2020 Report Share Posted August 16, 2020 The owner of a 50 Dodge Coronet had a complaint of a kinda raspy exhaust noise up in the front area of the car.... the exhaust manifold had a worn out heat riser shaft and bushings causing exhaust noise coming from around the heat riser shaft and bushings. The heat riser counter weight wobbled....you could feel it being loose in the bushings. Also could see black soot on the back of the counter weight. It's a pretty common cause of exhaust noise coming from the front area of the car. Also a blown out header pipe gasket or cracked manifold. Sometimes to try to find the exhaust manifold leak while the engine is running I rev it a bit and close up the choke plate just enough to make it run really rich to create black smoke and then I can see where the black exhaust smoke is leaking out. Quote Link to comment Share on other sites More sharing options...
Greg51T&CWagon Posted August 16, 2020 Report Share Posted August 16, 2020 To find the leak in my woodstove, i turned out the lights and used a small focusable flashlight. make the beam as narrow as you can. You might pour a little water down the carb at the same time? Quote Link to comment Share on other sites More sharing options...
50mech Posted August 17, 2020 Report Share Posted August 17, 2020 Marvel will make it smoke plenty. Quote Link to comment Share on other sites More sharing options...
Tooljunkie Posted August 17, 2020 Report Share Posted August 17, 2020 A piece of heater hose, 3 feet long. One end to your ear, other end in suspect area. Hose is heat resistant so it will not burn. i see no point to throw parts at it until you identify problem. Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted August 17, 2020 Report Share Posted August 17, 2020 Let's think this through.....there is noise coming from the manifold area.....you have a set of gaskets on the way.....why have you not already started taking off the manifolds? Remove manifolds, replace gaskets and repair as necessary, problem solved. ? 1 Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 17, 2020 Author Report Share Posted August 17, 2020 I did the hose thing, and found the loudest sound over the middle of the manifolds. The car is backed into the garage, with an exhaust vent to the outside, so I can run the engine without fouling the air in the garage. (Of course I'll keep the door open when the engine is running.) I am considering the smoke thing, Marvel Mystery oil or the like. Maybe I can locate the leak before taking everything apart, as some have recommended. The gasket order has been processed, but not yet delivered. So I can putter around in the meantime. The air cleaner is off, for a better view of the manifold. Stay tuned. Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted August 17, 2020 Report Share Posted August 17, 2020 (edited) On 8/16/2020 at 8:05 AM, DonaldSmith said: Questions: Has anyone had noisy manifolds, and what was the cause and remedy? To answer your original question.....Yes, lots of noise due to blown out gasket between exhaust and intake manifolds at the heat riser. Also had some leakage at a couple of exhaust manifold ports. Remedy....remove manifolds and replace gaskets. I installed a blockoff plate between the manifolds since I didn't want to use the heat riser. Once you remove the manifolds you will be able to see soot where the leak(s) is occurring. Edited August 17, 2020 by Sam Buchanan Quote Link to comment Share on other sites More sharing options...
greg g Posted August 17, 2020 Report Share Posted August 17, 2020 The pivot for the heat riser flap is also a common leak. Run around a bit with your choke closed a bit, the rich mix should leave a carbon patch where the leaks are. Quote Link to comment Share on other sites More sharing options...
keithb7 Posted August 17, 2020 Report Share Posted August 17, 2020 (edited) Chirping in to say, a poor performing intake valve, will exhibit the ticking sound of exhaust manifold leak. However the ticking sound is coming back up through the intake manifold. Heard thru the carb venturi body. Yes when I got into the valves I found an intake valve not seating properly. A wet/dry compression test and or an intake manifold vacuum test will reveal intake valve issues. Just something to think about. Edited August 17, 2020 by keithb7 Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 17, 2020 Author Report Share Posted August 17, 2020 The exhaust sound at the engine was a roar. This afternoon I disconnected the battery and removed everything in the way of removing the manifolds (carb, Sisson choke, etc.) I got the twelve manifold nuts loose (9/16" hex head). One fastener to go. The hidden bolt. Any helpful hints? Can I reach and wrench the hidden bolt from topside? Or should I remove the wheel and inner fender panel? Quote Link to comment Share on other sites More sharing options...
50mech Posted August 17, 2020 Report Share Posted August 17, 2020 Is it that close? As I recall on mine I simply used sockets on extensions. The hidden bolt was so badly corroded it was just round and I ended up using a 1/2" Irwin extractor that I had to grind shorter a couple times to make grab. That bolt is still stuck in the extractor. Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 17, 2020 Author Report Share Posted August 17, 2020 I think I will have to remove the wheel and inner fender access panel, to reach the hidden bolt. It's hiding behind the heat riser. (Visible at the bottom of the exhaust manifold is the counterweight and four bolt heads at the heat riser that hold the manifolds together.) Also, removing the access panel will help access the exhaust pipe flange. I found an old photo. The last time I tried to adjust the valves, I had to quit, because of the painful contortions to my back. Maybe one bolt is something I can handle. Could I reach the bolt from directly under the car, rather than going through the access panel? I would have to be extra careful with blocks and jacks, of course. Keep the wheel on. A face shield would help keep the falling crap off my face. Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted August 17, 2020 Report Share Posted August 17, 2020 (edited) Donald, I think you can reach the bolt from either direction, whichever is less painful. ? I put a nut on the stud from the bottom one time (it was missing) but I went through the fender this last time when I replaced the gaskets. It's fiddly but can be done. I suggest you go ahead and remove the wheel and liner, it just gives you a lot more options. Edited August 17, 2020 by Sam Buchanan Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 17, 2020 Author Report Share Posted August 17, 2020 Sam Buchanan says: " I suggest you go ahead and remove the wheel and liner, it just gives you a lot more options."" Thanks, Sam. Better to lean into machinery than to look up at it. Thanks guys for sharing your thoughts. Stay tuned. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted August 17, 2020 Report Share Posted August 17, 2020 Hey Don Smith. Looking at the front wheel being held up by a jack stand and from what I can it looks to be from Harbor Freight. There was recall on several of their units. You might want to check the HF webpage to verify that you do not have a recalled jack stand. The recalled one have an issue that you can hit the adjusting arm the whole unit will colapse. This is not good when working on a car or even underneath a car. Word of caution. Rich Hartung NDC Desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 17, 2020 Author Report Share Posted August 17, 2020 Point well taken. The photo does not show that the floor jack is still in position. Always more than one means to hold the car up. It's an old photo, before the jack stand problem came to light. And usually, the jack stand is at at near its lowest position, so the ratchet does not come into play . Also, if I remove a wheel, I'll put the wheel under the car. as an additional safeguard. 1 Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 18, 2020 Report Share Posted August 18, 2020 Looks like a lot of black soot at the header pipe blowing back to the tappet cover. Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 18, 2020 Author Report Share Posted August 18, 2020 Doddggeb4ya said: "Looks like a lot of black soot at the header pipe blowing back to the tappet cover." It's a real old photo, but I will check it out. But lately I couldn't feel or hear any leakage at that gasket. The sound seems to be coming from the middle of the manifold. Steady sound, not pulsed. (Maybe the bushing on the heat riser shaft?) Lots of fun ahead. Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 18, 2020 Author Report Share Posted August 18, 2020 Jacked up the car, left the jack in place, placed a jackstand under the frame, took the wheel off, and slid it under the frame by the jack. Took the inner fender panel off. Reached the hidden nut from the wheel well, and removed the nut (and washer). At the exhaust pipe flange, one stubborn bolt and nut remain . Heat? Wax? PB Blaster? Take a long break? The manifold nuts on the topside are loose. Started to remove one of the two bolts on the under side, one each side of the heat riser. Question: Do these bolts go into a water passage? Will I have to drain out the coolant? Photo looking up at the hidden nut and the two long bolts. (I don't know why the underside of the manifold is so red - rust?) Quote Link to comment Share on other sites More sharing options...
Sam Buchanan Posted August 18, 2020 Report Share Posted August 18, 2020 (edited) 52 minutes ago, DonaldSmith said: At the exhaust pipe flange, one stubborn bolt and nut remain . Heat? Wax? PB Blaster? Take a long break? The manifold nuts on the topside are loose. Started to remove one of the two bolts on the under side, one each side of the heat riser. Question: Do these bolts go into a water passage? Will I have to drain out the coolant? Answer to first question; Sawzall (the bolt, not the pipe). You want new bolts with anti-seize in the flange when you put it back together. Second question; Yes, unless you want to mop up the shop floor. Edited August 18, 2020 by Sam Buchanan 1 Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted August 21, 2020 Author Report Share Posted August 21, 2020 I got the exhaust flange bolts off. (Soot on one side of the gasket! Was this the leak?) I should have replaced that gasket first. But now I might as well keep going, to remove the manifolds and inspect them for exhaust leaks. The two underside "bolts" are studs. The nuts didn't come off; the studs came out. Yes, they went into a water passage. I had drained the radiator, but not the block. I quickly put a pan under the two stud locations. How heavy are the manifolds? I guess they are too heavy for me at my age. I devised a lifter, as shown, attached to the carburetor bolts, so that two people could lift the ends. Now I'm thinking that the pole that I would use is two frail. Maybe a 2 x 2 would be better. Quote Link to comment Share on other sites More sharing options...
keithb7 Posted August 22, 2020 Report Share Posted August 22, 2020 I just weighed my spare set for you. 1 Quote Link to comment Share on other sites More sharing options...
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