running temperature

[capnjoe]

It's summer and I'm driving my Scorpion more (with the new seats and upholstery, great new stereo and the comfort of a new water pump, timing belt and tensioner bearing - for those who have been following my exploits in this forum)

I think the engine is running hotter than it used to- It's mid on the gauge at about 190. I am concerned about the thermostat sticking. The aux fan is coming on fine (replaced that relay last year).

What's normal and proper?

Cheers, Joe

[A1.6HPE]

Hello capnjoe,
Mine normally runs about 3mm/0.8inch below the midpoint. In continuous high speed cruisng it sits just below the midpoint. I believe that sitting on 190 is the norm, I suspect that my thermostat is stuck open.

Leo

[capnjoe]

Hi Leo, thanks as always for your interest. I've decided that my Scorp is running significantly more hot than before. Something has changed. I put another post in with "thermostat" as the title because that's what I'm tending to blame (since it happened sudddenly). Still, the thermostat cost $100 at least from Chris Obert, so I'd like to somehow check this before ordering one. I'd be happy to hear from anyone with a good idea in this regard. Unlike Scotland, it gets really hot in Annapolis this time of year! Joe

[Will]

The most common reason for runing hot is an imperfect bleed, which the Scorpion is notorious for. You need to avail yourself of the bleeder on the radiator, or run the back end up on ramps so the upper hose can be disconnected asnd be the high point of the system- see the tech FAQ on this on IAP's website.

Additionally, if you replaced the Scorpion water pump with a Beta model, your flow through the radiator is likely at a slower rate due to the Beta pump's thinner impeller. The Scorpion uses the deeper impeller common to the volumex cars

That said, 190 is a good temp. Remember, the hotter it is, the more power it makes. 190 is safely sahy of the boiling point, IMO you are at an ideal temp.

Double check to make sure that your system hold pressure, and 190 should be fine. If your system does not hold pressure, the symptom is a boil-over a minute or two after stopping the car. BTDT.

If you want to pay $100 plus for a thermostat, I guess it's your prerogative, but I have a bunch here and you can take your pick for $50. Guaranteed to be operational.

[capnjoe]

Hello Will, It was great to see a reply from you. I guess I'd prefer that my Scorpion run where it always has (a long way from overheating) as opposed to on the verge, even though efficiency is better. I don't like change in this regard. Since I recently changed the water pump, the need for bleed is a really plausible theory. I looked for the FAQ on the IAP site and ended up with a few relevant Fiat pages but nothing that I was sure applied to the Scorpion- perhaps you could give me a more precise reference.

Today I ran the car and opened the radiator drain (?) screw in the boot a few times. The screw is a #7 allen on top of the radiator, and when it is opened coolant will run onto the pavement from somewhere under the car. The tech manual refers to this as a drain screw but it's on top of the radiator some I'm not sure whether or not it's a vent as well. This did not seem to change anything. The car heated up until the aux fan came on. Seems that it used to be that when the aux fan came on the temp came right down, but it does not seem to.

If my problem is not bleed (not sure) then is it perhaps the radiator? I did put some stop-leak in last year and it stopped leaking, but maybe it stopped working... I have the radiator overhaul procedure in the Lancia manual and will try that if it's indicated.

If you can further enlighten me on bleeding using the drain screw I'd appreciate it as always. Writing you next on the wheel bearing.

Thanks to all- Joe

[Will]

Joe:
Two things for you to try:

a) disconnect the small hose between the head tee and the overflow bottle from the tee in the head. Suck on the hose and see if it draws coolant up from the overflow bottle. Tastes nasty, eh? ;) At least now you know the tube didn't fdall out of the coolant bottle fitting. I'm referring to the tube inside which I call the re-uptake tube because , well, I don't know the proper nomenclature.

If that part is disconnected, when your coolant is cooling down (and thus contracting in volume) then your motor draws air instead of coolant into the system. What this means, is it is impossible to bleed!

b) Assuming you can indeed draw air up the hose and it does not run back down, reconnect the hose to the tee on the head and disconnect it from the coolant bottle. bring this hose stragt up and support it vertically (cord to engine lid works). Then stick a small funnel in the end of the hose and fill it. Pinch it shut and attach it to the coolant bottle (vise grips help).

If the car is stil running hot, my bet is your radiator is sludged up or you have some other preoblem that I can't help you with. See when the fan cycles. If the fan doesn't come on unil late, the switch for it may be buried in crud, or just plan not working.

Post more info and I'll try to help, but 190 is a pretty good temp. Seroiusly. It's not "almost overheating". First, you have the coolant itself, which boils at a higher temperasture than water, and secondly, you have the system pressure, which raises the boiling point.

Did you hygro the coolant before and after your pump change? If you had mostly water in there before, it would tend to run a little cooler.

[Shane Taylor]

Hi,

I think Will hit the mark in his last comment. There are possibly 3 factors that can contribute to overheating from my experience with Beta's :-

1. Leaking water
2. Sludged Radiator
3. Water pump

Since you have replaced the pump and are still experiencing high temps, my question would be - when was the last time you had the radiator cleaned out or the core replaced ?

Since I replaced the core in my Beta Coupe, the running temp sits around 1/4 mark and goes up a little when I am idoling.

regards, Shane

[Bali]

Hi,

Will, you have written this: "Double check to make sure that your system hold pressure, and 190 should be fine. If your system does not hold pressure, the symptom is a boil-over a minute or two after stopping the car"

My car (which is a Coupe) behaves like this. After stopping the car it is usually boils over some water even it wasn't too hot!
So maybe it cannot hold pressure? I have a brand new extension tank cap but it doesn't help...
Where should I check?
I have used mixed coolant: antifreeze + destilled water.

(Before this I had a cooling system flush and used stop leak additive because the heating was ineffective.)


Thanks,

Bali

[capnjoe]

Hi Will and all, Thanks again. I will try the coolant sucking experiment but if it's OK with you I'll use my "topsider" vacuum pump instead. I'm not sure I understand what part B accomlishes or tests. You seem to be substituting the hose/funnel arrangement for the expansion tank. Is this to provide a temporary alternate expansion tank in case of failing your "part a"? The level seems to change in the tank so I think this is a long shot, but I'll follow it anyway.

I am starting to suspect the radiator more. Again, there is a procedure in the manual for overhauling it on the bench. It looks straightforward to get it out of the car. I suppose I could also flush it in the car first and see what comes out. In answer to Shane, I'm am forced to admit that "never" is the answer to when the radiator was last flushed- since it was replaced in 1983 after freezing up (when I moved from Florida to OK, the winters were a lot colder).
Best, Joe

[Will]

Joe:
Part (b) is how you do a complete bleed, that hose is the HIGH POINT in the system. By filling through it, filling the volume of it, and then plugging it into the coolant tank, you make sure the water outlet doesn't have air in it. Air in the water outlet is bad. everything from the water outlet forward goes down to the radiator, so air in the water outlet creates a blockage or "air lock" in the hose.

Bali:
I don't remember what my Beta water bottle looked like, or if it had any fittings in the top, but it was the glued fitting in the top of my scorpion bottle that was the culprit. I would suggest you run the car to temp and shut it off and look for bubbling, listen for hissing. A spray bottle with a 50/50 mix of dish detergent and water is a good cheap DIY substitute for commercial leak finder, spray around all the hoses, clamps, and seams in the coolant bottle, etc.

I'm not saying this will cure your problem, just trying to help you diagnose it. Could be something else entirely, I'm just saying that's what happened to me.

Remember, the coolant still circulates after the motor is turned off, but it is circulating by convection, so it is moving slower and absorbs more heat per its volume. Because of this, it is a good idea if you have been running the car hard, to let it idle for 5 minutes to cool down. If you change to an electric pump (or any pump that has a tight-fitting impeller) then this is MANDATORY. The stock FIAT pumps have loose flow-through impellers that allow sufficient convection that it *usually* will keep a *near stock* motor from overheating via convection. The volumexes use a pump with a deeper impeller (ditto for a scorpion) which you may want to fit if you've made significant output increases to the motor.

[capnjoe]

Sorry for being so slow, but I think I'm getting this. You say to hook up the funnel to make it the high point. Then I suppose I must start the car and get it up to temp to open the thermostat, with the heater on- to make sure that all trapped air has a way to get out. Then the last step is to disconnect the funnel and without admitting air put the hose back on the exp. tank.

Thus the radiator drain/bleed screw is not involved at all.

Do I have this right?

Thanks, again- Joe

[Will]

I actually put the hose back on the coolant bottle first, then run the car.
I guess you could try the other way but don't be surprised if coolant gushes up the tube- I think there is positive pressure at that point in the sytstem with the motor running. I guess it wouldn't hurt to try, but I'd clamp the tube shut before starting the car, THEN loosen the clamp and see if coolant is getting sucked in or pushed out.

[capnjoe]

Will, but even if you've made the funnel the high point, is not there still air trapped in the radiator unless it too is vented?

I ran the car on the highway the other night, and found that it controlled at a different temp in the evening. From that I conclude that the thermostat is probably doing fine, and that the change I've observed is still likely related to the radiator being either clogged or not vented, or both. I think the next step is to backflush the radiator, and then do your bleeding procedure.

J

[Will]

The hard lines under the car tend to establish a water lock, allowing you to replace the water pump, or even disconnect everything in the back up to the hard lines, without draining or pulling air into the radiator.

however, if you messed with the radiator of the radiator hoses at the front of the car, or (as is often the case) changed the fan switch, Then you almost always need to BLEED the radiator!


I say almost always because the tubes in the back hold a little volume, and it's possible to change an item like that fan switch in a manner that us pipe monkeys call "on the fly", losing just a small dribble of fluid (ounce or two).