Temp gauge slow to rise

[djunified]

Originally Posted by Lgbpop

Something you need to keep in mind, something I learned when looking for an OEM bypass/heater core assembly when mine had terminal pinholes. The Vulcan engine was designed with cooling jackets in the front and back of the block that are NOT connected internally. This was done to simplify casting the blocks. The bypass part of the OEM bypass/core assembly is the connection, allowing unrestricted flow of coolant throughout the entire block no matter the condition of the heater core.

If your cooling system doesn't include the bypass (in other words, all coolant passes only through the heater core), your engine's operating efficiency and long-term health is being compromised even if the core is perfectly clean.

As you know, my bypass is removed so coolant only passes through the heater core. The core is brand new, so it isnt plugged. And i doubt it will plug because I have installed an inline filter on the heater core inlet hose. This prevents the core from plugging up with rust that is impossible to remove. This filter is easily accessible and cheap to clean/replace.

[behlinla]

Originally Posted by djunified

And i doubt it will plug because I have installed an inline filter on the heater core inlet hose. This prevents the core from plugging up with rust that is impossible to remove. This filter is easily accessible and cheap to clean/replace.

And what happens if the filter clogs? Does it have an automatic pressure bypass? I suppose you'll lose heat, but what if it happens in the summer?

BTW, filter = pressure drop = less flow.

[Lgbpop]

The heater core is not a wide-open hose or pipe - it's a miniature radiator, in which the size if the inlet and outlet are much larger than the passages the coolant passes through to shed heat. In other words, even in new condition the core only allows so much flow through it. By removing the bypass you are cutting down on the coolant flow through the entire system.

[WJC]

I agree with the above posters, re install the bypass.

[Jeff K]

^^^^ +1

On most modern cars, including the Taurus, the heater core is an integral part of the cooling system, not an "extra loop" just for heating the car interior like it was in the old days. On the Vulcan, flow thru the core is important for cooling the bank 1 (firewall side) head. If the filter plugs up, the rear head will overheat. Vulcans do not like to be overheated!!!

[djunified]

Just to let you guys know, my temp gauge still drops periodically from the halfway point to the bottom of "normal". It will then slowly climb back up to the halfway mark. It also seems that when the temp gauge drops, all of the pressure in the cooling system is lost. I wait for it to drop, then i feel the upper rad hose and it is hot but soft. Then i take the cap off the bottle and there is no pressure at all.

I'm pretty sure the Vulcan is the simplest cooling system out of them all. Compare it to the v8 sho, which has the reverse flow design which i don't understand at all.

In the vulcan's simplicity, i still don't understand why the bypass is needed. I think the very early '96s didn't come with a bypass. It was Fords simple idea to throw it in there and solve problems of rust clogging the small passageways in the heater core. I guess they didn't take into consideration that people up north drive these cars, and how important it is to have heat in the winter months.

Think of it this way. Some of you are telling me that the bypass is there to allow more flow for required cooling of the rear bank. Firstly, the size of the hose coming off the lower intake is only 5/8, so it can only carry so much at once. If my heater core is 100%, im pretty sure it can take the flow required for adequate cooling.

I'm really close to giving up on this issue, and just scrapping the car if the engine seizes. I will never again buy a 96+ taurus/sable with the Vulcan engine. Duratec's and sho's from now on.

[Automender12345]

The bypass is really used mostly only used in the beginning of the engine warm up stage until the thermostat opens up. Then the flow is thru the two holes in the the timing cover which has one for each head. Without the bypass there is no water circulation in the engine block because the only outlet is thru the radiator and the thermostat cuts that off when cold.

I left my bypass in place but to get a little more heat in the winter, I put a screw clamp in the bypass hose and tighten it which compresses the hose to force more flow into the heater without totally closing it off. In the spring, I just loosen the clamp.
I believe my 1990 Sable was recalled because of the lack of bypass and overheating. The more flow the more even the temperatures.

[soundu]

Originally Posted by djunified

Just to let you guys know, my temp gauge still drops periodically from the halfway point to the bottom of "normal". It will then slowly climb back up to the halfway mark. It also seems that when the temp gauge drops, all of the pressure in the cooling system is lost. I wait for it to drop, then i feel the upper rad hose and it is hot but soft. Then i take the cap off the bottle and there is no pressure at all.

I'm pretty sure the Vulcan is the simplest cooling system out of them all. Compare it to the v8 sho, which has the reverse flow design which i don't understand at all.

In the vulcan's simplicity, i still don't understand why the bypass is needed. I think the very early '96s didn't come with a bypass. It was Fords simple idea to throw it in there and solve problems of rust clogging the small passageways in the heater core. I guess they didn't take into consideration that people up north drive these cars, and how important it is to have heat in the winter months.

Think of it this way. Some of you are telling me that the bypass is there to allow more flow for required cooling of the rear bank. Firstly, the size of the hose coming off the lower intake is only 5/8, so it can only carry so much at once. If my heater core is 100%, im pretty sure it can take the flow required for adequate cooling.

I'm really close to giving up on this issue, and just scrapping the car if the engine seizes. I will never again buy a 96+ taurus/sable with the Vulcan engine. Duratec's and sho's from now on.

Nothing is perfect. If you followed a few recent duratec threads, there has
been a hole in the oil pan with catastrophic results, and burnt valves and
low compression.

Now, the SHO's are notorious for cam issues if they have not been welded
with also catastrophic results.

The bypass was an add on after early gen3's had cooling issues.
If the heater core plugged up, the coolant flow would be impaired causing
heating issues in the heads.

Your a brave guy if you took the degass cap off with the motor hot
and running. Hope you took precautions. If you found NO pressure there,
you have issues. You just need to find them. Maybe you need to get the
motor hot and stop and turn off the car. Open the hood and listen closely
for pissing or hissing sounds. Look for anything damp or wet.

Your losing pressure somewhere.

you need to step back and retrace your steps.

YOU might want to build one of my ghetto coolant pressure gages and
leave it inserted in the degass lines and try to keep an eye on the pressures.

and you are 100% sure the thermostat is a motorcraft with the jiggle
valve clocked at 12:00, and NOT in backwards?

[Automender12345]

[QUOTE]Just to let you guys know, my temp gauge still drops periodically from the halfway point to the bottom of "normal". It will then slowly climb back up to the halfway mark. It also seems that when the temp gauge drops, all of the pressure in the cooling system is lost. I wait for it to drop, then i feel the upper rad hose and it is hot but soft. Then i take the cap off the bottle and there is no pressure at all.

I'm pretty sure the Vulcan is the simplest cooling system out of them all. Compare it to the v8 sho, which has the reverse flow design which i don't understand at all.
[QUOTE]

That makes sense, since the temperature is related to the pressure. Just like a pressure cooker the higher the pressure the higher the temperature. At atmospheric temperature your coolant will boiler just a bit over 212F and can't get any hotter. If you go to the top of a mountain and try to heat food by boiling it doesnt get hot because the pressure is a lot lower. Raise the pressure by 14 to 16 psi which is regulated by the cap the coolant will not boil until over 260F. I might be off on the numbers a little. The trick is not to let it boil since the metal to coolant heat transfer drops significantly and you will overheat.

It works the other way around, a hot coolant system is still functioning but take that cap off and suddenly you have water that is not supposed to be liquid anymore by the laws of physics and flashes to superheated steam. It will burn the hell out of your face and hands.

Get a new Ford cap or have yours tested. It may be venting early or not sealing at higher pressures.

[Lgbpop]

Originally Posted by djunified

Just to let you guys know, my temp gauge still drops periodically from the halfway point to the bottom of "normal". It will then slowly climb back up to the halfway mark. It also seems that when the temp gauge drops, all of the pressure in the cooling system is lost. I wait for it to drop, then i feel the upper rad hose and it is hot but soft. Then i take the cap off the bottle and there is no pressure at all.

I'm pretty sure the Vulcan is the simplest cooling system out of them all. Compare it to the v8 sho, which has the reverse flow design which i don't understand at all.

In the vulcan's simplicity, i still don't understand why the bypass is needed. I think the very early '96s didn't come with a bypass. It was Fords simple idea to throw it in there and solve problems of rust clogging the small passageways in the heater core. I guess they didn't take into consideration that people up north drive these cars, and how important it is to have heat in the winter months.

Think of it this way. Some of you are telling me that the bypass is there to allow more flow for required cooling of the rear bank. Firstly, the size of the hose coming off the lower intake is only 5/8, so it can only carry so much at once. If my heater core is 100%, im pretty sure it can take the flow required for adequate cooling.

I'm really close to giving up on this issue, and just scrapping the car if the engine seizes. I will never again buy a 96+ taurus/sable with the Vulcan engine. Duratec's and sho's from now on.

I'm not gonna bother reading your posts on this subject anymore. You have changed the design of your vehicle such that it no longer can do what it was designed to do, complain because it no longer does what it's supposed to do, and can't understand why. I will explain it, once. I will not explain it further, and I will not argue about your rationale for changing the design of the engine.

The bypass hose, as you call it, really is a coolant flow hose and has been there in one form or another doing what it does since the Vulcan was designed. In its day, the Vulcan was a daring departure from the normal engine block cast with all cooling passages en bloc. In the Vulcan, to save complexity of casting the front and back ends of the block are connected by an external hose-&-pipe assembly, from which a line is detoured to accommodate the heater core. Note well - that assembly's main purpose is NOT to accommodate a heater, but to connect the front and back halves of the engine block for proper cooling. The heater is a coincident piece of equipment. The Vulcan design would be the same without the heater core. That hose has to be there for the cooling system to operate as designed. I am not saying your particular engine will cool properly if you restore the missing coolant passage, but I am saying it cannot cool properly without it.

Just trying to help you out here. This is how a recent acquaintance of mine - a design engineer at FoMoCo - explained the design to me. F&AM is a wonderful organization for meeting people from all walks of life. Happy to share what I learned, hope you make use of it.