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FE Power Forums => Non-FE Discussion Forum => Topic started by: AlanCasida on March 18, 2022, 05:27:12 PM

Title: How much water pressure in block ahead of thermostat?
Post by: AlanCasida on March 18, 2022, 05:27:12 PM
OK this is kind of a long story so bear with me. Since I have kind of retired my Galaxie from race duty I decided to hook the heat and a/c back up. While on a drive the heater hose had come off the heater control valve and the motor got really hot. Upon inspection I found trails on the sides of the block where coolant had escaped past the head gasket. So I did a compression check and all the cylinders checked ok but as a precaution I pulled the heads to look at them. Using a straight edge and feeler I saw there was just a minor gap(maybe .005) in the surface but after conferring with a friend I put it back together as is. I got it all back together only this time I had the heater hoses backwards from before and the output hose coming out of the intake went to the heater core first. I went for about a 6 mile drive and on the way back home I stood on it pretty good and all of sudden a bunch of coolant started running into the floorboard. Again I got the car pretty hot getting home. It was a leaking heater core. When I pulled it I found that it was all bulged out and one of the tubes had split. It was not rotted. I had the heat turned off so it was dead headed. I replaced it but before I hooked it up I wanted to see what kind of pressure I was getting inside the motor. So I hooked up an electric oil pressure gauge dead headed in the water port on the intake and a mech water pressure gauge on the extra port on the t-stat. With it fast idling at about 2000 rpm in the shop it had about 25-30 psi in the block with the t-stat closed. When the t-stat finally opened it dropped down to near zero. I went for a short drive and when I ran the motor up to maybe 3500 rpm while driving the psi in the block went to near 50 psi. When I got back home I was revving it up in the shop and the gauge after the t-stat was reading around 10 psi and in the block it would go up to around 30. I guess what I am trying to find out is that normal? I have never checked anything like this before. I think the restriction in the t-stat might cause some pressure differential but I have no idea how much. I think if I put the coolant line coming out of the intake on the heater control valve first would help to keep the core from getting too much pressure too. But I am also wondering if I might have warped the heads when I got it hot and that is causing the extra pressure. The first time I got it REALLY hot.  I just don't want to blow a freeze plug out. Any input on this would be greatly appreciated and sorry for the really long post.   
Title: Re: How much water pressure in block ahead of thermostat?
Post by: pbf777 on March 18, 2022, 08:06:08 PM
............. what I am trying to find out is that normal?

 Yes, this is another function of the variable drive rate mechanical pump; which by the way is not replicated with the substitute electric pumps, and is why these (electric) should not be used in anything but 'short-duration' run engines (e.g. drag cars).   ;)

 Oh, and .005" in the length of warpage, of these heads, is pretty much the limit (still not advisable) to ignore.   :o

 Scott.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: AlanCasida on March 18, 2022, 09:14:02 PM
I think I’ll put my gauge on my 66 f100 and do a comparison. I may be just chasing my tail.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: 2ndgear on March 18, 2022, 10:40:21 PM
Alan I had the same problem that my heater core would leak after replacing it.
What I found my problem was that the fitting coming out of the intake manifold
was the wrong one. The fitting is a special one that has a stand pipe on it. If you
dont have the correct fitting there will be to much water pressure to the heater core
which will cause the core to leak. Hope this helps.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: shady on March 19, 2022, 08:19:18 AM
sounds to me like the heater core was frozen up at one time and reversing the hoses pushed it over the edge.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: My427stang on March 19, 2022, 08:40:42 AM
Although ballooning could of course come from freezing, I have seen the wrong fitting blow a heater core, and now if I install an aftermarket or brass fitting I modify it with a standpipe.

Ford felt they were needed and I believe it's either the creation of steam pockets that can't purge until the heat is run, or the flow amount when the thermostat is closed (which seems less likely)

I have never put a gauge on one, but I do agree your numbers sound high.  If you are running an aftermarket fitting, for giggles,  just epoxy a stand pipe with the proper OD right into the fitting and have it almost touch the floor, it won't help the total pressure but can keep it in water, not air, during filling and opening of the stat and cant hurt.  Additionally, you can drill a 1/16 hole in the thermostat to allow it to purge any air at start and reduce that pressure a bit.  I have gone up to 1/8 without any negative thermostat operation, and I have seen much more, but huge holes aren't needed in my experience
Title: Re: How much water pressure in block ahead of thermostat?
Post by: MeanGene on March 19, 2022, 10:02:35 AM
in '77 with my first 427, in my 69 Mach1, first time I nailed it hard, went to 7300 and then the windshield fogged up and the stink from antifreeze, blew the heater core. I have been using a 6" piece of copper tubing as a restrictor in the line to the heater ever since, no more problems
Title: Re: How much water pressure in block ahead of thermostat?
Post by: Rory428 on March 19, 2022, 10:11:59 AM
When I first put my 59 on the road with the fresh 428, the first time I wound it out, the heater core puked all over the floorboards. (Luckily I didn`t have the new carpet in yet!). Having no idea if it was still the original 60+ year old core, or not, I had a new heater core made, and have had no issue since. I have the curved 428CJ reproduction intake manifold heater fitting, which has a crimped standpipe in the bottom.
Alan, do you have the stock type short bypass hose between the water pump and the front of the intake manifold? If so, I always thought that hose would prevent any excess cooling system pressure from building, and that any pressure above the radiator cap rating, would release past the rad cap.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: FrozenMerc on March 19, 2022, 11:32:24 AM
Alan,
    What you are seeing for pressure is normal in my experience.  I built a water pump dyno at my last job for developing water pumps on small engines (generally less than 1200 cc).  The dyno had an electric motor that drove the pump, and then there was a mock cooling system with a throttling valve in place of the thermostat in order to control head pressure at the pump.  With the throttling valve nearly closed, and flow restricted to just a trickle, it was not uncommon to see steady head pressures of 50 to 75 psi, depending on the pump specs.  Add in the water hammer effect from a rapidly closing thermostat due to a rapid cool down (think about splashing through a deep puddle), and it was easy to see coolant pressures spikes exceed a few hundred psi between the pump and thermostat.  I have seen situations were the impeller would actually be knocked off the shaft.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: AlanCasida on March 19, 2022, 11:48:06 AM
I just put my gauge on my '67 F250 w/390 and I got similar readings. At 70 mph around 3000 rpm I was getting around 47 psi. However, when I shut the truck off my gauge maintained about 22 psi. The pressure should have equalized with the radiator by then and been lower than the rating of the cap. What this tells me is using an oil pressure gauge might have been the ideal thing to use. What it also tells me is I got similar readings from a known good source so I am probably good. Much to do about nothing! I do have the intake bypass hose hooked up but the heater hose fitting is not restricted. I am going to either get a restricted fitting or make a restrictor for what I have. Plus I will make sure I have the pressure hose going to the heater control valve first so it doesn't deadhead in the heater core.
Thanks for all the input, I really appreciate it.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: pbf777 on March 19, 2022, 01:42:26 PM
................ so I am probably good. Much to do about nothing!

     Yep!

     But, realize that for yourself and others who may have been unknowing of such, the education, as always, is invaluable.   :)

     Scott.

     


Title: Re: How much water pressure in block ahead of thermostat?
Post by: jayb on March 19, 2022, 04:12:32 PM
Somewhere in the Ford SOHC manual or documentation is a statement that at high RPM, water jacket pressures exceeded 90 psi.  So I don't think what you are seeing is unusual, Alan.

Also, I take exception to the comment that electric water pumps are not suitable for the street.  I've been running them on my race cars at Drag Week, and in my daily summer driver, for years.  In fact, the constant flow provided by the electric pump is a big advantage, in my opinion.  With an electric pump on your engine, Alan, I don't think you would ever have experienced the problem that you did.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: Cyclone03 on March 19, 2022, 07:22:47 PM
Although ballooning could of course come from freezing, I have seen the wrong fitting blow a heater core, and now if I install an aftermarket or brass fitting I modify it with a standpipe.

Ford felt they were needed and I believe it's either the creation of steam pockets that can't purge until the heat is run, or the flow amount when the thermostat is closed (which seems less likely)

I have never put a gauge on one, but I do agree your numbers sound high.  If you are running an aftermarket fitting, for giggles,  just epoxy a stand pipe with the proper OD right into the fitting and have it almost touch the floor, it won't help the total pressure but can keep it in water, not air, during filling and opening of the stat and cant hurt.  Additionally, you can drill a 1/16 hole in the thermostat to allow it to purge any air at start and reduce that pressure a bit.  I have gone up to 1/8 without any negative thermostat operation, and I have seen much more, but huge holes aren't needed in my experience

I thought I was the only one who does this. I use 1/8” pipe nipples cut to length about 1/2” off the intake floor. I just thread the heater hose fitting 3 or 4 full threads.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: CDXXVII on March 20, 2022, 06:12:14 PM
Plus I will make sure I have the pressure hose going to the heater control valve first so it doesn't deadhead in the heater core.
Thanks for all the input, I really appreciate it.

My unmodified Galaxie has no heater control valve in the line going to/from the heater core. The flow is on even with the heater off.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: AlanCasida on March 20, 2022, 07:26:11 PM
Plus I will make sure I have the pressure hose going to the heater control valve first so it doesn't deadhead in the heater core.
Thanks for all the input, I really appreciate it.

My unmodified Galaxie has no heater control valve in the line going to/from the heater core. The flow is on even with the heater off.
What year is your car? My '66 Galaxie factory a/c car came with one. 
Title: Re: How much water pressure in block ahead of thermostat?
Post by: jmlay on March 20, 2022, 07:40:22 PM
Some fox bodies used an inline restrictor. Not sure how the fox heater hose compares to an FE. Should de easy enough to make something similar.:

https://www.npdlink.com/product/restrictor-heater-core-hose-coolant-flow-incl-installation-instructions-repro/185543?backurl=search%2Fproducts%3Fsearch_terms%3Drestrictor%26top_parent%3D150000%26year%3D
Title: Re: How much water pressure in block ahead of thermostat?
Post by: frnkeore on March 21, 2022, 01:43:07 AM
My '60 Galaxie, was ordered new, w/o a heater (or radio). I had to install the heater, when I got it, in 1963.

As I remember, the water temp control valve, was inside the heater box, in the area of the heater core. Only heater hoses went threw the fire wall.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: 1964Fastback on March 21, 2022, 06:01:14 AM
Yes, on '64 Galaxies, the hoses run directly from the pump/manifold to the heater core at the firewall.  I don't think there is any valving inside.  I think the heater core is hot all the time.  Just with the controls turned off, heat is (somewhat) restricted from inside the car because of the flaps being closed and the fan turned off.  In '65 or '66 they changed that.

Pat
Title: Re: How much water pressure in block ahead of thermostat?
Post by: Falcon67 on March 21, 2022, 09:18:17 AM
[quote author=jayb link=topic=10867.msg121890#msg121890 date=1647724352
Also, I take exception to the comment that electric water pumps are not suitable for the street.  I've been running them on my race cars at Drag Week, and in my daily summer driver, for years.  In fact, the constant flow provided by the electric pump is a big advantage, in my opinion.  With an electric pump on your engine, Alan, I don't think you would ever have experienced the problem that you did.
[/quote]

Echo - no problem running an electric pump on the street and/or race.  The only "problem" I've had with electric water pumps is fabricating a proper alternator mount to route a drive belt past the pump housing. 
Title: Re: How much water pressure in block ahead of thermostat?
Post by: pbf777 on March 21, 2022, 12:22:16 PM

- no problem running an electric pump on the street and/or race.


      Experience is a valuable teacher, always, but be sure to put the lessons into context.

      Example: back in the '70's I had my '72 MACH I with a 351C engine that I just didn't appreciate, but still I was to cheap to just throw it away while it still ran, but couldn't wait for it to fail so as to replace it.  Finally it blew a lower radiator hose, obviously wouldn't hold water, but was still running, Just as a joke I continued to drive that thing to work thru down town and down the Interstate (6-7 miles depending on route chosen) every day to work, to lunch, the store, wherever (O.K. no really long trips but still!) and not 'pussyfooting either, for a month or more!  No one would believe me until I would open the hood where they witnessed that I had removed the radiator hoses top and bottom!  :o  Then one day I was racing this Corvette, on the Interstate on my way home from work, at maybe 120-130 M.P.H. I made it past him pulled across his bow, and wham!  The old gal dropped a valve, blew oil and coolant all over his car; my wish had finally come true!  ::)

      But even though I may have had a good (relatively  ::) ) experience of not having a properly functioning cooling system, perhaps the real lesson was the resiliency of this engine to failure when subjected to such.   :-\

      Scott.

     
Title: Re: How much water pressure in block ahead of thermostat?
Post by: frnkeore on March 21, 2022, 01:17:19 PM
Yes, on '64 Galaxies, the hoses run directly from the pump/manifold to the heater core at the firewall.  I don't think there is any valving inside.  I think the heater core is hot all the time.  Just with the controls turned off, heat is (somewhat) restricted from inside the car because of the flaps being closed and the fan turned off.  In '65 or '66 they changed that.

Pat
I thought I had remembered correctly. Installing a heater, by yourself, isn't easy, at all and I tend to remember thoughts type things.

While Pat is correct on the '62 Ford, the '60 & '61's, are the same and do have a water valve, in the heater box.

I was actually surprised at the pressure generated. Alan, did you test pressure with the thermostat closed and say 3k rpm?
Title: Re: How much water pressure in block ahead of thermostat?
Post by: 1964Fastback on March 21, 2022, 01:29:45 PM
I thought I had remembered correctly. Installing a heater, by yourself, isn't easy, at all and I tend to remember thoughts type things.

While Pat is correct on the '62 Ford, the '60 & '61's, are the same and do have a water valve, in the heater box.

Interesting!  I couldn't tell from the picture but the valve in the heater box is cable operated, to shut off water flow when the heater is turned off?

Pat
Title: Re: How much water pressure in block ahead of thermostat?
Post by: frnkeore on March 21, 2022, 01:52:59 PM
It seems to be a rocker arm that would push and pull a plug.

I never replaced the heater core or the valve, in mine. The thing that always stood out, was how hard it was to get the cable in place and tighten, that's why I remembered it.
Title: Re: How much water pressure in block ahead of thermostat?
Post by: AlanCasida on March 21, 2022, 02:08:50 PM
Yes, on '64 Galaxies, the hoses run directly from the pump/manifold to the heater core at the firewall.  I don't think there is any valving inside.  I think the heater core is hot all the time.  Just with the controls turned off, heat is (somewhat) restricted from inside the car because of the flaps being closed and the fan turned off.  In '65 or '66 they changed that.

Pat
Mine has no blend door. It uses a kind of proportional valve that is also thermostatically operated to control the amount of vacuum going to the heater control valve. Just kind of a mess when it gets 52 years old! I have balked at even hooking it up since it is highly unlikely I'll ever drive it when it's cold enough to need a heater. But, I thought it would be nice to have it all operating again.