coolant in a 12

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    Doug, I noticed in another post on this board that you are running a 1948 Buick muffler on this 12 cylinder car. 8 cylinder Buick for 1948 displaced 248 cu in. Although 6″ round input, it is hard to know what the inside the muffler looks like. Could you be getting an exhaust gas restriction and very modest back pressure condition that elevates while driving and reduces when the car is idling? That may explain the high temps while driving that calms down at idle. Just a thought.




    Buick had two engines in 1948 a 248 CID and a 320 CID. There is info in the Parts and Services Directory on where you can get original spec mufflers. I would suggest purchasing the mufflers only and having a local shop make the pipes.


    Thanks, I will check out the buick muffler and see if there might be a problem. The rather quick drop in temp. at idle was something to think about. When I called Klass Kollection exhaust they said they could make up any lenth of muffler I wanted. The 1933 owners manual shows the car to have a very long muffler and a resonator in front of it. If I find a problem with the buick muffler I can have them make up a longer one the right size etc. Thanks for your help guys. Doug


    Hello Doug, all the above advice is on target, all the mentioned items can and will cause your engine to run hot..

    But the major item in the cooling system has been mentioned, but only in passing: the Radiator.

    These old engines produce a lot of rust flakes from the cooling passageways, these rust flakes are usually too large to go through the radiator’s core/tubes… so they sit in the top tank of the radiator, blocking the free flow of water to the cooling tubes..

    And, the waterpump grease: it gets washed into the cooling system, it’s liquified by the engine heat, but then cools, solidifies and sticks in the cooling tubes of the radiator, clogging the radiator.

    So between sticky waterpump grease in the radiator and the inevitable rust flakes, you most likely have a significant amount of restrictions in your radiator.

    So, I’d recommend reverse flushing your radiator to rid it of the accumulated rust flakes in the top of the radiator, and plan on having the radiator out and cleaned professionally if you continue to have cooling problems.

    The amount of cooling from a brand new radiator is just enough for hot driving, so if you have any other problems, the radiator cannot keep the engine cool.. It just doesn’t have enough capacity unless everything is clean and flowing well.

    Hope this helps..

    Greg Long


    Thanks Greg, Everything was cleaned radiator and engine, both professionally during the rebuild. Paul Johnson called and told me that the Buick muffler was designed to have about 8 psi of back pressure, that along with my discovery that the header pipe is 2 1/4″ and the muffler is only 2″ tells me the engine is having to work harder to get rid of the exhaust, and that may be my problem. Paul is trying to find out how long the 1933 muffler really was. I will have a long one made when I find just how long it was. I think it was in the 5 1/2 to 6 foot range. Here is how it looks so far. Thanks to all you guys for your help. Doug


    Doug, that is a nice looking car. Thanks for sharing the picture.


    Thanks John, and thank you for your help.


    Doug, when John Cislak makes exhaust systems for his or my cars we make them 2 1/4 the whole length. Even the tail pipe. We end up making new hangers as well. As I remember the muffler is 5 1/2 feet on my old 1247. Also, have you put a modern temp gauge in the top of your radiator to check against the PA temp unit…. It may be off. Ed


    Thanks Ed, I am going to town today to get the sidemount mirrors cut at the glass shop. I just got them back from the plater. And will stop by the NAPA store to get the temp parts. Do you think one in the radiator top tank is enough or one in each radiator hose? Also thanks for the lenth on the 2 1/4″ muffler. Doug”


    We just run one in the top of the tank and tape it to the windshield. The top of the tank is the hotest part of the system. Is the radiator pushing water out the overflow? The winterfront should be open all the way. If not disconnect it and hold it wide open till you get the temperature problem fixed.


    I did some homework from the factory information and for 1933 regardless of model (836, 1236, 1247) the exhaust system had a total of 73″ of muffler. The 1st in line from the exhaust manifold was ~14″ long with an OD just >6″, connected to a pipe that curved around the frame followed by a long single muffler. The connecting pipe, as Eddie indicated is all 2 1/4″. The former owner of my 836 Club Brougham used a 4′ long 6″ OD straight through muffler from an International. Since you are not planning to race your car at high RPM, its hard for me to believe that the current system would be that restrictive to influence the engine operating temperature. Thank for sharing your restoration with all of us.


    A typical symptom of a restrictive or plugged exhaust system is smooth rpm limiting loss of power. We are seeing this a lot with cat. converters plugging up in modern cars..

    Unless you are feeling like the car is pushing against ferocious head wind, or constantly climbing a hill when actually on level ground.. I doubt that a marginally undersize exhaust system is causing overheating.. it’s possible, but a remote chance..

    Is the muffler a straight through design or a bypass design ?? It’s pretty hard to clog up or restrict a straight through muffler. If it’s a bypass design I’d replace it anyway.

    Greg Long


    The service manager at the Buick agency where we had our Buicks serviced explained that Buick the straight eight mufflers (circa 1940’s) were designed to provide a slight back pressure of about 8 psi. When this back pressure dropped so did the performance of the engine. On our 1948 Roadmaster with Dyna-Flow, when the muffler got loud and the back prssure was lost engine performance was degraded. When an new muffler was installed, the problem went away. I don’t know if the current after market mufflers incorporate this deisgn feature, however, it is something to take into consideration in using a Buick muffler on a Pierce-Arrow.


    Thanks again for all your input, I really need everyones help. The exhaust systen is worth putting in right and seeing if it helps. As far as I can tell from what everone has said the long muffler was between 5 and 5 1/2 feet long and 6 ” in Diam. I will order one today. The next thing to try is to back flush the radiator. When I was rebuilding the engine I cleaned out half a large coffee can of rust from the water passages and then sent the block to the machine shop where they put it in the cleaner (rotating sprayer) for three or four days. At some point I will find the problem. Doug”


    I had heating issues at the Rochester meet a month ago. My car gets a flush every spring and fall, so the cooling system should stay fairly clean. And at the last several meets, the car ran without using any water, or getting hot on on any of the tours.

    But this year, while on the second tour to the Mississippi River and back to Rochester, I developed an overheat situation that did not go away, even with slow, 35mph driving into a 10+ mph headwind. Normally driving like this would give me 140* water temps.. I had 210* temps.. The fan is a 6 blade fan, the belts are not slipping, I’m running pure water, and the waterpump has modern seals.

    I just reverse flushed the radiator, and flushed out about a half cup of loose rust flakes, all about pea-sized. After a test drive, this may have been my problem, but I\’m not totally satisfied yet, the top tank of the radiator still has a coating of oily grease, so I may try some form of flushing agent or solvent.. Or I may break down and pull the radiator and have it cleaned or re-cored. I don\’t think this radiator has ever been opened up, or professionally cleaned. I’m sure the accumulated waterpump grease and small rust flakes have a significant number of the radiator’s tubes clogged.

    Anyone know the best source for blank cores for the ’33 radiator? I hate paying 3xRetail when a radiator shop hears \’Pierce Arrow\’.

    Greg Long


    Greg: Two things. 1) To clean out the grease and light hardness deposits from a radiator, fill it with freswh water and a cup of dishwahser detergent like Cascade. Drive the car for an hour or so and then drain and flush the system until the odor of the detergent can no longer be smelled. 2) Keep a filter in the upper radiator hose. This could be a Gano filter or as simple as a section of panty hose inserted in the inlet to the radiator, lapped over the outside of the inlet and secured by the upper radiator hose and clamp. This way if something does come loose in the block in won’t get into the radiator.


    Hi Paul, I flush with cascade every spring when I remove the antifreeze and put in clean water. But Cascade just doesn’t cut the grease. I’m thinking of filling the system with some kind of solvent that will dissolve the grease.

    I used to have a piece of panty hose in the upper radiator hose, but a few years back the piece of panty hose shredded and I didn’t replace it. I’ll put one in next spring.


    Gentlemen, I am about to run some of this through my cooling system. It worked great on the rusty gas tank. It should be fine for the cooling system.

    It works like it says it does on the web site.


    Greg, A few years back I used a solvent by por-15 that you mix with water at about one part solution to 10 parts water. I liked it better than regular solvent, I think it was bio-degradable also. Don’t know how it would do in a cooling system, but it might be worth looking into. Doug


    Ed, Let us know how it goes and how much it took to do the cooling system, do you have to use it straight or mixed with water ? Thanks

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