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Diagnostic assistance please


James_Douglas

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:confused:Hi All,

I friend called the other day who I sub-contract from now and then. He needed me to step into a company that just fired their CTO (Chief Technical Officer). This will be for about a month or so.

The problem is that it is south of San Francisco. So I have been running the Desoto down there every day.

Yesterday a noise started that sounds like it is in the engine. It could be in the fluid coupling, but I don't think so. It sounds like a few playing cards, clipped onto a bicycle. {With 4.11 gears} It starts at about 30 MPH and gets faster as I go faster. By 50 MPH you can not hear it as the period between the “clacks” is so short that is fades into the louder engine noise.

It seems most pronounced in 4th gear at about 40 MPH. I have disengaged the clutch at this speed and let the engine idle and the sound stops. You can hear the sound stopped if you rev it up, but I have not had time to open the hood and take a listen.

What do you folks think?

Best, James

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Could be the bendix on the starter with a bad return spring! Or the throw-out bearing in the clutch. Take off the dust plate to check the ring gear and see if the teeth look like it has been wacked, better yet look at the bendix gear and see if it is damaged by bouncing off the ring gear after the engine starts.

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James;

Guess I was a weekend or two short of helping to fix your problems. I regret not getting on the ground and having a first hand look under your car. Will do so next trip. Here is my take. First off install your new fluid coupling this weekend. If your diagnosis was and is correct your low end vibration will cease once this is done. I dont completely agree with your diagnosis on that problem but I do not have a better answer at this time. And this new noisy problem sounds related to your current problem. However the instillation of the new parts will prove the point so go for it. Next fix the clutch overcenter spring problem. All of your problems may be related to this overcenter spring adjustment. I know this is a lot of work but once corrected you are done with it. Your engine sounds great and should have no problems pulling an Airstream across the country.

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I'd look around for frayed belt, wiring, loom, plastic grocery bag, or some similar thing that might be rubbing one of the pulleys ( crank, genny, water-pump ), or flapping against the fan blades ?

You might also have some paper or plastic debris trapped against the front of the radiator core that is flapping ?

Frank McMullen

Frank;

Although I did not do a belly up under car inspection on James car I did do a close under hood inspection. James has dotted the T's and crossed the I's:rolleyes: Everything is bundled up good and there is nothing "rubbing" under the hood. He has no water pump fan on his engine but has installed an electric pusher fan in front of the radiator. His electric fan is butted up close to the radiator and silently works well unlike my noisy electric pusher fan that works well but is noisy. I do not believe there is anything rubbing on exposed rotating parts on the under hood top side of his car.

I observed a strange vibration when his car is stopped and the (fluid drive) clutch is "out" such as when stopped at a stoplight. Pushing the clutch pedal to the floor stops this vibration OR accelerating to anything above engine idle speed (after the light turns green) with the clutch out also stops this vibration. James also commented several times of a problem with the clutch pedal requiring under toe assistance to return to the fully "out" position and this problem seemed to worsen.

James, using good sound logic, believes this noise that I (we) heard is an internal bearing in the fluid coupling. I am not as convinced as he is that an internal bearing is the problem but I cannot come up with a better answer. I believe his current problem is related to the problem I observed. He has a freshly rebuilt fluid coupling. I suggest that this fresh coupling be installed and the faulty over center spring adjustments be corrected to see what that does

sf4.jpg

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James, if and when you get this figured out, please post for those of us who may come across the same problem. I've tried to follow your threads on this and the suggestions and am very interested as to what it may be.

At one time I thought it could possibly be that you had the throwout bearing that fits a standard 3 speed and not the thicker one for a fluid drive. Several on the forum said there was no differance in the size of the throwout bearing. According to the ebay supplier I purchased mine from there was a differance, the one he had on ebay was for a 3 speed standard shift yet he said he had one for a fluid drive and of course I purchased it at the same price as the other advertised. With out any spec's to go by and the bearing already being installed all info supplied from the forum and the supplier is "hear say." Your problem has held my attention for a long time and would really think it would help knowing how it works out in the end. Several of your symptoms sound very similer to the same problem i had when my throwout bearng was going out on a 81 Bronco yrs back but that is more "hear say" as to solving your problem.

The valve noise and adjustment will be a much easier fix than your "other" problem for sure but if you even think your going to have to pull the engine again to fix the "other" problem, I would wait, set up the engine on a running stand and then adjust the valve/valves, whichever it may be. As you probably know by now getting to the valves will be much easier adjusting with the engine out. Good luck, Ed

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Hi Don,

I was pretty sure James would have a clean and orderly engine bay; I have had the belt/debris stuff cause the "playing-card" sounds with various vehicles over the years; I have had newspaper/carboard over the radiator in cold weather flap and rattle too, so I thought I'd throw the suggestions out there...

I have heard "scraping noises" from fluid couplings with bad internal bearings

(if the front bearing "runner-hub bearing" is bad, it can allow the guts of the fluid coupling to rub against one another.).

There are also two sets of needle bearings inside the hub of the fluid coupling, that are essentially pilot-bearings for the tranny mainshaft. The "Driving plate" & clutch assembly are supported by a combination of the internal front bearing, and the two sets of needles on the mainshaft, and the front ball-bearing of the tranny. So... if the needle pilot bearings are worn, or the ball bearing in the front of the tranny, or combination of all that are worn, it might allow enough deflection of the interior parts of the Fluid Coupling to cause some scraping... this is a long shot, but a possibility...

I would agree with you that perhaps it is time to install the NOS fluid coupling and see if that makes a difference...

Good luck with it James...

Frank McMullen

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Ok Here is the thing:

Yesterday I took the car out in the AM to eat. I ran it on the boulevard up to 45 MPH and you could hear the sound real good between 30 and 40.

My friend stuck his head down to the floor boards while driving (No SF jokes please) and told me the sound appeared to be coming from the lower drivers side of the engine.

We ate breakfast and headed home. On the trip home the sound lighten up somewhat. The last 2 days have also had a higher ambient temp that the last week when the sound started.

Once home I did 2 things. I changed the oil and the filter. I put in a new set of spark plugs.

I started up the car and let it warm up real good and took it for a run around the block. I did not hear the sound. I parked it.

Today I took the car out and ran it hard around town up to about 45 MPH and I can not hear the sound. Hot or cold.

The sound was very noticeable and now it is gone. The only things done were oil, filter, and plugs.

What was it ?

James

PS, the fluid coupling is still vibrating like heck. I sent George a $500 deposit on a trans and will change the coupling when I get the new trans.

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were any of the old plugs fouled or not working??damp? Have seen brand new plugs out of the box not work the first lick. Some brands are just 'better' than others at working too. What brands were the old plugs,,,and the new plugs???

Only other thing I could even 'think' of is something sucked up to the oil pick up screen, when oil was drained it got 'heavy' and dropped off. maybe will reappear in time. When it comes too close again,,,other than that,,,I cant imagine.

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James,

I've been following this thread but felt the only thing I could offer would be negative so I've kept quiet. I have obviously abandoned that stance.

The fluid coupler is a turbine with many small blades fit close together and set at very close proximity to a mirror image of itself. Add to that the third set of vanes around the perimiter bisecting the other two wheels and an age almost eligible for Social Security and my first best guess is to dismantle it and mic the bearings and visually check the vanes.

Other than shock to the shafts and bearings it probably won't do to much other damage if it goes, like severing your feet, but you've got a good chance of screwing the pooch on your drive train if you let it go. The loss of noise is an indication that something has broken off and is circulating through the tubine at engine rpm.

That's why I haven't written until now; I don't wish you anything other than the best but reality may be setting it.

I hated to park my '48 P-15 for the last time when I did it for the last time, but I can see the light at the end of my tunnel. I hope your light glows soon.

-Randy

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