Dropped the old girl off at the mechanic this a.m.

geekdaddy

X1/9 Learner's Permit...
So I took my X to a local mechanic that I trust -- as much as I trust ANYONE to work on my car. I've never hired anyone to work on her previously.

For those following at home, this mechanic helped me diagnose a problem where I'm getting air intrustion in my radiator. We now believe the allison's header is too close and wrapped around my water pump pipe and causing the coolant to boil just before it hits the pump. He will remove the header and water pump pipe, and modify the pipe so it is closer to the block and further from the header. He will also build and tack-weld a small heat shield to it.

Anyhow, it felt very weird to drop her off with him. I gave him instructions, shop guides, and some spare parts which he may not have even needed. Kinda reminded me of dropping off one of my kids at day-care for the very first time...
 
I know how you feel Greg...

You've got a lotta time invested in that car. Don't want anyone screwing it up! :eek:
 
This will be a very interesting "fix"...

Sort of a "vapor-lock" issue that useta haunt older vehicles at the fuel pump.

Do keep us posted.
 
I had a similar problem wit Allison's header and solved it by wrapping the header with heat tape near the vulnerable areas. No more over heating.:)
 
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Got her back on Thursday and mechanic thought all is good but after driving for a few days it's better but not resolved. Temps are lower but too high and still producing air in the system.

See photos below of the water pipe which is modified and closer to the engine block. 2nd and 3rd photos show the air gap (now) between the pipe and header. Was previously 0.2 inches from the header. Now with header wrap on the tube and on the header there is 0.8 inch gap. The 4th photo is annotated with the Temps I measured while idling in my driveway after a drive. I expect these Temps are higher immediately after a spirited drive or a highway run and subsequent stop.

The header was previously over 550 degrees and now 500 on the surface of the wrap.
The water pipe was previously 280 degrees and is now 250 on the surface of the wrap and 235 degrees at the bare end of the pipe near the water pump.
I had not previously measured the surface of the water pump facing the header tube but checked this time and it was nearly 350 degrees!

I'm going to replace the water pipe wrap with a more reflective thin insulator and will fabricate a heat shield for the water pump. If that doesn't work I'm out of ideas. The good news is that even with these engine bay temps the X does not overheat but the temps will rise over normal (up to ~210 sometimes) and the radiator slowly fills with air so IMO I am running the coolant, water pump, and other components over spec which must be resolved...


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Dang. 235ºF is over the boiling point of 50/50 AF/water mix, and that was the outside of the pipe....

That pipe clearance is decent though. The air gap should be sufficient. The header wrap is a dubious fix as it will absolutley promote rapid corrison of the steel pipe, unless he made it of SS?

Have you considered also switching to Evans Waterless? That is what I use. no worries about boiling the coolant, and the system can be pressureless, since water is not a required component.

Bit of a PITA to convert, as all water/AF mix MUST be entirely flushed with their prep mix, otherwise the Evans will gel.
 
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Cooling system will not function (maintain correct engine running temp) until the air source is found and properly stopped from introducing air into the cooling system.

Engine operating temps much over 212F makes me nervous under all conditions due to the heat stress on engine internals.

In the case or Mazda rotaries, either coolant or oil operating temperatures over 200F means rotary engine failure in short time. Mazda Miata NA-NB have designed in cooling system problem with cylinders 3 & 4 which results in cylinder head gasket failures (these are multi layer steel) at to above 230F coolant temp measured near cylinders 3 & 4.


Insulation alone is often not the ideal fix as the heat needs to go some where, trying to contain it without consideration for other items that are a heat source can result in other problems. Creating ways to allow the heat to escape helps.

As for heat loading, the stock exxe does not have cooling problems. Even in upped power output version of the stock 1500cc engine, the cooling system designed and built in the exxe works good enough. We proved with endurance road racing.



Bernice


Temps are lower but too high and still producing air in the system.
 
Understood Bernice and thanks for the fdbk. My system ran cool with the prior IAP header installed 2+ years ago and problems began when I installed the new one.
My temp guage reads 190 most of the time except when there is both air in the radiator and I've slowed the vehicle speed after a hard run. But agree it's got to be resolved.
Also agree that insulation and reflection can only do so much and the heat must go elsewhere. Hoping that I can insulate and reflect enough header heat away from critical components like the water pump/pipe so they can stay cool while the heat dissapates elsewhere.

My present theory is that air is introduced into the system by excessive header heat causing some coolant boil in these areas and settling in the radiator where they cool and rise to the surface -- slowly displacing coolant there. Not 100 pct certain but the measured temps certainly support this hypothesis. Improved shielding and insulation under development :hammer:
 
If you go the shield route, use stainless steel as it reflects heat well and is a relatively poor conductor. I would attach the sheild to the header so more heat isn't transferred to the engine or other components
 
Are you sure that you are chasing the right problem?
Air in the system will send you temp high when slowing down. Typical X1/9 behavior.
Air can find its way into the system in multiple ways. Unfortunately, a very small hole somewhere is enough to suck air into the system when the car cools. No water will ever exit this leak, so it is very hard to find.
Mark Plaia for instance chased a problem like this for years. Turned out to be a super small rust pinhole at the flange of one of the coolant pipes where the hose goes on.

I am just saying, because the heat transfer at the crossing of the exhaust pipe and the water pipe seems to me to be negligable in the grand scheme of things.
When I was still in college, I could have probably calculated this. Isn't the an ME student here on the forum? :)
 
It would be interesting to see what the temperature readings are for a stock exhaust just as a comparison. I have a header on my X, otherwise I'd be happy to take temp readings in the same areas you did.
 
Several thoughts on this....

1. You must have a leak in the system. Here's why: your cooling system is under pressure. That pressure is defined by the rating of your radiator cap. For every pound of pressure, the boiling point of a 50/50 mix will increase roughly 3 degrees. SInce 50/50 at no pressure boils at 235 degrees, a 10lb cap should make the boiling point around 265 degrees - well above the temperature you are measuring on the pipe. The only explanations are that your temp readings on the pipe at incorrect (i.e. low) OR - your system is not sealed and not holding pressure.

2. Increasing the cap pressure and/or the antifreeze to water mix to 60/40 or 70/30 will both serve to raise the boiling point considerably.

BUT - neither will be of value IF your system has a leak that is allowing pressure to escape.

3. Have you performed a pressure "leak down" test on your cooling system? If not, this is the first place I would start. Its quick, cheap (many auto parts stores "loan" the equipment to do this for free). You must find and fix the leak before anything else. If you do, likely you won't need anything else!

4. As mentioned by lookforjoe, waterless Antifreeze is a great alternative - its a pain to flush the system but once down, you can drive on Mercury and not overheat. But again -- ONLY once you've found your leak.

It sounds like you've already invested some $$$ in having a professional reroute pipes, reweld flanges, etc. None of that may have been necessary, but at least, it won't hurt and will probably help overall.

Summary: Find that leak!

Ed
 
I have to agree with Ed

Summary: Find that leak!

I am no physicist but I am struggling to understand how a hotspot in your closed cooling system would cause air to be introduced.

If it is TRULY a closed system, then you might get a hotspot to boil the coolant in one location. But when the steam pocket (or whatever you want to call the gasses that boiled out of the liquid coolant) flow to a cooler area, they will revert to the liquid state and there will be no net change in the ratio of liquid to gas in your coolant system.

The only way this could be happening that I can see is that air is being introduced. And I can only see two possible explanations for that:

1. You have a one-way valve somewhere in your system. For example, a "speed-bleeder" type air bleeder somewhere high up in your coolant system. These valves are designed to help you bleed the air out of your radiator by pushing a small button that allows the air out. Normally these are held shut by a spring, and of course the pressure in your coolant system. But on cooldown I have heard that the system can develop negative pressure great enough to overcome the spring in the valve and allow air in. Thus, the symptom you describe - no apparent leak, but air getting in.

2. You have a two-way valve somewhere in your system. By this I mean a leak that is both letting coolant out and air in. You are not seeing the coolant leaking because it is somewhere hard to access and it is evaporating before it can drip on the ground. Or it only squirts when the pressure is high, not when the car is sitting at idle. Or some other explanation like that.

I would say that if your radiator is filling with air, then the coolant is being displaced and has to be going somewhere, which lends more credence to explanation 2.

Again I'm no physicist but that's what makes sense to me.

Pete
 
If you are NOT seeing ANY liquid leakage, there are only two possibilities I can think of:

Its possible (but unlikely) that you have a hole through which, air can come in but no liquid can leave - sort of like GoreTex! Again, not likely.

Or, there's plenty of places where air could be coming in and going out without fluid as well. Since the cooling system is never completely "full" of liquid, think of all the places higher up in the cooling system where air can congregate with liquid. Likely culprits are places like the neck of the overflow tank, air bleeder on top of radiator (heck, that could be leaking liquid only when you are running and you'd never know it unless you stuffed a paper towel around it and checked after a hard run).

Leakdown test is the way to go.

Ed
 
Greg... I don't know how you caught Bob Brownitis...

but it appears that you did. What is it with youse guys?

So look, let's try what I said one more time... Let's start again with Vapor Lock.

When the fuel lines overheated in those old cars of yesteryear... the gas in the line would BOIL off and turn into a GASEOUS state... which the fuel pump could not pump... so the engine starved and died. Cooling the lines down (with clothes pins clipped on the fuel lines acting as a radiator of sorts...) would convert the fuel back from a gas into a liquid, and further cooling would freeze the fuel into a solid. (I understand that's no gud either, but have no personal experience...)

So now letza go back to the coolant issue. Usually I say "If air gets in, then coolant must be going out..." In this case though... I think the coolant is just being converted (boiling off) into a gas (air) and you are bleeding it off.

I mean, YOU GREG, have ME convinced there is NO leak and there is NO head gasket issue either.

With that all said... I have NOT seen your Engine Cover and I have NOT seen your Side Vents either. What I type next just MIGHT be the cure for what ails you.

I suggest you remove BOTH side vents and CUT off the grid-work on the back side, and with a file just clean them up a bit... repaint with (what else) Duplicolor Trim Black (opt.) and now you will have about 25% - 33% more airflow into the engine bay.

Next, open the latch so the Engine Cover raises (or remove it) and take it for a spin. See if NOW your temps drop significantly.

If so, time to ditch the rain tray and if you wish, make it re-install-able for those good times on the ice and snow!

HTHs Greg, I can identify with your frustration.
 
If you are NOT seeing ANY liquid leakage, there are only two possibilities I can think of:



Its possible (but unlikely) that you have a hole through which, air can come in but no liquid can leave - sort of like GoreTex! Again, not likely.



That is exactly what does happen in reality, even though it doesn't seem to make sense.
On the cases I have seen, not even the pressure tester showed a leak.
 
Could it be bad head gasket?

I don't think anyone has mentioned this yet... and it happened to me! I had a head gasket go bad and air was being forced into the cooling system from the combustion of a cylinder. When we pulled the head off, you could see the fault!
 
Success?!

I made two adjustments and have now driven the X about 75 miles. I can't confirm the problem is COMPLETELY resolved but it may be. At a minimum it is substantially improved. Here's what I did: (1) shielded the water pump and water pump pipe from header heat. I purchases some thin reflective high temp insulation and faced the top of the water pump and wrapped the pipe with it. I also fabricated aluminum shields for each area of concern. Photos below. (2) I noticed the coolant return line in the overflow tank pretty much pees into the tank from the very top of the tank. So when the engine is reving and the coolant flow is high the fast stream is churning air into the coolant in the tank. I topped off the tank much higher than normal. Coolant is a 1/2 inch from the top of the tank and even with the bottom of the return line. Now there is less "churn" in the tank.

The result? The shielding is working! difficult to get behind the shielding with my IR thermometer but the water pump housing is ~180 degrees. The outside of the insulation of the water pipe (under the shield) is approximately 210 degrees. Probably cooler under the insulation. It also takes my car much longer to warm-up now. Prior to the shields I could easily begin opening the thermostat after idling in the driveway for a few mins and then driving for a few miles. Now? I can drive several miles (5-6?) before the thermostat opens. At road speeds the guage is locked on the midpoint. At an extended stop or a stop at the exit ramp after a highway run, the guage blips up a notch or so (see pic below) and then hits the midpoint as soon as I drive again. I can let the X sit in the driveway for 20-30 mins idling after a drive and the cooling fans kick-in when the guage hits about the same point as shown (maybe a little higher) and then the X cools itself down.

I'm not yet claiming victory because I need to run more miles. But this is a substantial improvement. I can assure you that prior to adding the shields and topping off the coolant, if I had driven 75 miles the radiator fans in the front would come on too late and the X would have difficulty cooling itself down if idling for 20-30 minutes in the driveway after a run -- which only happens when a significant amt of air has displaced coolant in the radiator.

What does this mean??? Not sure. The air problem may have had nothing to do with the header heat or coolant boiling. Not sure. It could have been the height of the return line relative to the coolant level in my overflow tank. But one thing's for sure -- this header is HOT and it heats-up the cooling system. The shields are doing a lot to minimize that. I'll drive another 50-100 miles, keep checking the cooling system performance, and then burp the radiator to find out how much air is in there (if any).
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Quick response to other comments/questions

I've pressure tested the coolant system up to 20 psi. No leaks. I've tried adding dye to help. Still no leaks detected.
I've pressure tested the cylinders. All good.
I've leak-down tested the cylinders. All good.
I've exhaust gas tested the overflow tank. All good.

So not likely a head gasket but I replaced it anyhow and re-ran the tests. Same result. Asked a mechanic to perform the same tests in case I screwed them up. He found no problems in these areas either.

This is why I've been more focused recently on the header heat and (late last week) on the coolant reservoir return line.
 
Nice work!

Water pump shielding looks great!

Nit-picking - I'd say the coolant pipe shield ideally should have a little more air gap between it and the pipe - the air gap makes the difference. Probably if you just doubled the thickness of the doubled-sided tape it would be perfect. The clamped end also allows heat transfer back to the pipe, I can understand why you added it though.

Clearly, it is doing a good job as it is.

With the coolant reservoir, I noticed the SS tank introduced much more 'churn' from the returning coolant than the plastic tank version due to the internal height of that return spout - so I switched back to the plastic version. I was comparing it to Volvo tanks, that have baffles between the return & main cavity to prevent en masse aeration of the coolant in the tank...
 
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