hello, I have a question for the y-block experts. I have been unable to find pressure rating specs for my 239 y. it currently has a 7lb. cap on it. the reason I am not sure this is correct is I also have a 55 merc w/ a 56 312 y in it and it has a 13lb cap? did the pressures of the y-blocks vary over the years? when I run the 239 and it gets hot it does not seem to build pressure, you can remove the cap as if it was cold. I was always told the right lb., cap is critical to the cooling system. any thoughts or opinions? thank you to all that have responded in the past, your input is very helpful, doug.

Questions; Are you loosing fluid noticeably? No pressure? Check the caps gasket. It's likely that your car came with a 13 lb cap, as later Fords did, but not for sure. Some of us have reverted to 7 lb caps due to old rads & possibly to avoid head gasket problems. My 57 is on a 7 lb. but I don't live in a normally hot climate area.

Paul

hello paul, thank you for your input. I am not losing fluid any where. I just put a new 7lb cap on the 239. where I live it does get very hot and humid in the summer. does your 57 tend to run a little on the hot side? my 54 239 does. but as I mentioned I have a 55 merc w/ a 312 and it has a 13lb cap and it never runs hot. I used to drive it parades in the past and even on a hot hot day it would just run a little warmer than normal. maybe the new cap will make a difference, doug.

How many blades on the fan?You can also restrict the bypass hose from the water pump to the intake using a 5/8 pipe plug with a 3/16 hole drilled in it.Just put inside the hose.It cant go anywhere and it will force more coolant through the rad instead of recycling hot coolant back into the motor.This is something Greenbird56 came up with.I have just done this to mine.Seems to make a difference.If you can find a smaller pulley for the waterpump that would help also.Turns water pump a little faster.

  

thanks for the info., oldcarmark. I have already put on a 4-blade fan, it had the original 3-blade. the pipe plug idea is very interesting. I think I am going to try it. when you say it made a difference on your car I assume your gauge is showing that you are running a little cooler. my 239 runs great! and I have never had any problems associated w/ over heating, its just a little cause for concern when the needle on the gauge tends to stay at the 3/4 mark towards hot. I am going to try the plug, thanks, doug.

Where your temp gauge sits is possibly just calibration between the gauge and the sender and nothing to worry about. If it is not boiling then it is probably fine but if you are concerned then you should check with a good temp gauge. Even a 7lb cap should hold pressure, just squeeze the top hose to feel and hear if any air is coming out.

The pressure of the cap allows for the temp to exceed normal boiling point at atmospheric pressure, the higher the pressure then the higher the new boiling point. The cap also counters to a degree the pressure created in the top tank of your radiator when the motor revs increase and the water can not flow through the cores fast enough. You can see what I mean if you take of the cap and rev the engine you will see the water level rise.

I personally have reservations about restricting the bypass hose as it will create extra pressure in your top tank and if it can't escape fast enough through the overflow then it could cause damage. I have a 13lb cap on mine that is holding the correct pressure but still if the revs come up high enough then it will push coolant past the cap, and my bypass isn't restricted. I think that modification would be fine depending on your driving. If your motor only ever sees low revs then it my never reach the pressures in the top tank to push out coolant.

I don't think anyone should get too concerned over the ability of a T-bird motor to overpressure a radiator or cap either one by applying RPM to the primitive pump. That inch spacer hole behind the tiny impeller pretty much kills that theory........

Racers just leave the bypass out completely, even on a 292 that has no spacer - with no ill effects.

The bypass is a "rapid warm-up'" feature pure and simple - the only bad part of that being the fact that it doesn't shut itself off after its no longer needed. Then it becomes a liability to machines like the T-birds that have the goofy pump spacer - and the 3/4 sized radiator.

Sorry can't buy it.......................

 
 Steve Metzger       Tucson, Arizona

I believe you want a 3/8" pipe plug?

"The Master Cylinder"

Enjoying life at the beach in SOCAL

3/8 is correct.I was thinking heater hose ID.

  

OK, I hear you. From the comments made there are no mechanical ill effects from the modification. I did have thoughts of it bursting solder joints or ballooning the top tank. In saying that I still get blow bye when the revs come up, and my cap is good. My car has the standard overflow, so maybe it would not be noticeable if it had an overflow tank that then would allow it to be drawn back. I have noticed that since I let the level drop below half way on the top tank it doesn't seem to be an issue and the coolant level has stabilized. I don't know if any mods have been made to the pump area to increase pressure as I have not worked on it, and it is as I bought the car.