Fan belt flies off

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Model T Ford Forum: Forum 2016: Fan belt flies off
Top of pagePrevious messageNext messageBottom of page Link to this message  By John Mosher on Monday, September 19, 2016 - 10:05 am:

I have a 27 with a water pump. The problem I'm having is the fan belt comes off at high speeds. I can visually see the fan pulley is pitching downward. I adjusted the pump pulley back some to keep the belt on but nothing lines up properly l can't find a breakdown diagram of the fan pulley and adjustments. Is this repairable, without replacing everything?
Can somebody send me a breakdown diagram


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Monday, September 19, 2016 - 10:32 am:

That's one of the typical problems with water pumps, the belt falls off.

The easiest solution is to remove the water pump. They are not needed or desirable. Get a Ford water inlet from any of the part sellers. You won't have any water pump problems ever again.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Monday, September 19, 2016 - 10:37 am:

John
Couple of things on the "science" side;
1. The shafts need to all be parallel. Check that the water pump shaft is lined up parallel as it is most likely out. Could be up or down or in towards the engine (or perhaps out)
2. The pulleys are all (or should be) crowned. The belt rides towards the crown (or highest diameter). It may seem a bit counter intuitive
Think about these things and examine your installation


Top of pagePrevious messageNext messageBottom of page Link to this message  By Peter Claverie, Memphis TN on Monday, September 19, 2016 - 10:59 am:

The interesting thing about flat belts is that they tend to ride toward the high side of a flat pulley. That's why the pulleys are generally crowned in the middle - so the belt will tend to ride in the center.

If your belt is flying off, it simply is an indicator that the one of the pulleys' shafts is not in alignment. It could be the water pump shaft, or it could be the fan shaft. Occasionally it's the driving pulley, which has gotten loose on the crankshaft because of extreme wear.

I live in the camp, where Royce lives, that believes a water pump is not needed on a Model T that is otherwise reasonably well set up, and you can probably solve your problem by removing it. But it's up to you. Recognize that most Model T water pumps were installed as an attempt to solve an overheating problem. Those problems are caused by one of two things - the easy one to fix is driving with the spark too retarded, and the more likely is rust and/or scale building up in the water passages of the engine or the radiator.

Another "problem" that folks try to solve is that if you over-fill the radiator, the system will 'barf' out the excess until it reaches its optimum level. This 'barfing' tends to continue a while after you stop, and that tends to frighten folks into thinking the car has overheated, and the cooling system can't handle the heat, ergo let's put on a water pump.

If you do remove the pump, remember that when it was installed, it is likely that a thermostat was installed in the upper outlet. Remove it as well.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, September 19, 2016 - 11:46 am:

On a 27 the fan pulley is mounted to the water outlet. Take off the belt and check the bushings. The pulley should not move up and down or side to side, but it should spin freely. If you still have the original bushings, there is an oil hole in the pulley and you need to put in some thick oil such as differential oil or put on a grease fitting and pump in some grease. There are now ball bearing replacements which do not need to be lubricated, but when they get loose must be replaced. Likewise, you have a bushing at the front of the water pump and most water pumps have an adjustment screw which goes from the housing to the side of the block so that your belt does not pull it out of alignment. The crankshaft pulley can as stated above be loose and can lean forward.

Having said all the above, your belt itself might need to be replaced. The leather belts can be stretched if you tighten too tight. It can be stretched in such a way that one edge is larger in diameter than the other. In that case the belt will tend to run off the pulleys. The belt should actually be tightened just enough to keep the pulley from spinning after you slow down the engine. If you tighten too tight you risk either wearing out the bushings or stretching the belt.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Mosher on Monday, September 19, 2016 - 12:14 pm:

I like to say thanks to all for trying to solve my problem. I think the first thing I'm going to do is to remove the water pump. When l purchased (3 months ago) the vehicle it came with the pump installed already. I have no history of the vehicle since the gentlemen has past away who owned it. I haven't tested the radiator yet but it seams to have a good flow. Even when the belt comes off the motor gets hot but it doesn't over heat.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Monday, September 19, 2016 - 12:30 pm:

The car not overheating when the belt comes off (water pump not turning) suggests to me that the pump was installed "just because", and there was no overheating problem to solve by adding it. In that case just removing it is all you need to do. If perchance there really is overheating without the pump, this covers the remedies: http://dauntlessgeezer.com/DG96.html.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Monday, September 19, 2016 - 12:50 pm:

John,

The water pump is not the cause nor solution to your trouble. The problem, as you suspected, is the fan pulley pitching downward. Either the pulley needs to be rebuilt, (new bushings and maybe fan shaft), or maybe the arm is bent. You could also install a ball bearing pulley. Whatever the case, the upper & lower pulleys need to be aligned, with their respective shafts parallel.

Remove the pump or not, as you see fit, or as the car performance dictates.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Monday, September 19, 2016 - 02:25 pm:

I have a '27 without a water pump and the belt occasionally came off despite my attempts to cure the problem so I put a belt guide on it and have had no problem since then. Quick fix and easy to install.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Monday, September 19, 2016 - 03:25 pm:

John,

I'll amend my previous statement a bit. If the water pump shaft/pulley is out of alignment with the other two pulleys then, yes, the water pump itself may be your problem.


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