Overheating!!

[Mohuska]

I haven't asked for help often....but I am at a total loss here.

I have had my West Coast Cobra for 8 years. I struggled with overheating for 6 of those years before I shut it in the garage and didn't look at it for a year. Then last year, I decided I would make a huge effort to get it fixed. I took it back to the builder of the engine (for some other upgrades as well including a new cam with bigger balls). We had a whole new Ron Davis radiator (twin fan) and everthing forward of the engine connected with the cooling system replaced.

My builder took it out when completed to a tuner (FAST EFI) and it apparently stayed at 190 deg on the track. I picked it up yesterday and I couldn't get it to stay under 225 deg. I mostly was around 240 deg. I am running a mix of water/antifreeze, there are no visible leaks or sounds of air or water escaping and in cool San Francisco Bay air, it is overheating like crazy. EXACTLY LIKE BEFORE!!!

I made sure it was burped (the best I could), topped the puke tank so I wouldn't suck air, made sure the belts were tight, but NO GO!!. There is a 180 deg Thermostat. The fans are running properly (coming on at 195 deg)......

Could the water pump just not be putting out enough water? It is a Ford 460 bumped out to a 522. It is EFI and not running lean (in fact I think it is running a bit rich) with a 13.7 at idle.........

I don't know if it is a bad gauge, water pump, air in the system.......

SO I ask my fellow motorheads....... got any ideas at all?????

Thanks in advance,

Mike

[Tom Wells]

Mike,

My 521 overheated when I first got it, usually when I stopped for gas which does happen fairly often LOL

Your car's cooling system may or may not be like mine, which has the fill cap below the level of some parts of the hoses.

You say you burped the cooling system, which is how I prevented mine from ever overheating again.

Here's how I burp mine:

When I fill the radiator after draining it, it will take a minimum of five burping and heat cycles to get rid of the air.

With the engine cold, squeeze the upper hose to get all the air bubbles out, adding coolant as needed to get the level back up to the top of the filler, then squeeze some more, add coolant etc.

Make sure the overflow bottle is relatively full and there aren't any leaks in the overflow hose or cap.

Then run the car up to operating temp. After it cools, remove the filler cap and burp more air out - and yes, at first there's more air...

Repeat this process five times! It'll take more than a day to do it, as the car really needs to be cool before the filler is opened again.

If I do this process thoroughly, overheating doesn't happen. I can take the car and idle along in a parade for literally hours without getting above 100C even on a hot day here in Florida. Absent the multiple burping process, the car wouldn't last 15 minutes...

Hope this helps.

If not, how about putting up some specs and photos of your cooling system so we can take another shot at it?

BTW, 460s use two gaskets and a backing plate between the water pump and the front cover. If the backing plate isn't there, the thing will surely overheat.

Let us know,

Tom

[PANAVIA]

The other thing would be to check the tune of the fast efi to see how advanced it is running at idle. Or if there is a table in the fast efi configuration for increasing advance at high temperatures.

Depending on the fast efi setup this is obtainable.

Another question, are you verifying the 200 plus degree temperatures with an in fared thermometer? With their recent size reduction there is no real reason not to have one now.

We could always vacuum bleed. The system too !

Does your thermostat have a pilot hole in it twards the top of the stat ?

We look forward to the details,


Steve

[BT SNAKE]

Mike,
Go get one of these....
http://www.amazon.com/Stant-12270-Co.../dp/B0002SRGWU

One of the best tools I have. Fill the system then place this on where the radiator cap goes and pump
up the pressure forcing the water into the places it usually doesn't reach with grvity. Then take it off, refill and repeat until it wont take another drop.
After that get one of these...
http://www.amazon.com/Raytek-MT4-Non.../dp/B0002198GY

After you go for a spirited drive stop the engine and check the enrty hose temp and the exit hose temp. This will tell you exactly what temp your motor is running at.

Hersh

[vector1]

pulleys correct size? overdrive the waterpump.

[rustyBob]

If you have a 180 t-stat then set the fan to come on at 180 degrees and not 195....
you are probably not running the car as fast as he did at the track and you are not forceing as much air through the radiator as he was....if he was doing 80 at the track and you are sitting still in trafic.....thats part of your problem.

[flipscobra]

The best thing to do is put a manual switch on your dash, where you can cut it on when you come to a stop or in heavy traffic. I don't want mine getting nowhere near 100 celcius, it will stay cooler if you cut the fans on every time you come to a stop or your just idling along

[jetsbaby]

Originally Posted by rusty Bob

If you have a 180 t-stat then set the fan to come on at 180 degrees and not 195....
you are probably not running the car as fast as he did at the track and you are not forcing as much air through the radiator as he was....if he was doing 80 at the track and you are sitting still in traffic.....that's part of your problem.

Sorry that is bad info..If he does that his electric fans will never shut off..Stay with the termostat you have..

[flipscobra]

Jets all you have to do is flip a switch an your fan will go off, so how you get your fans will run all the time. The only way they will run all the time is if its running hot, If I wait for the stupid themstat to cut on mine would be running hotter than I want it to get, an run a 160 thermasat, an drill a few extra holes in the face

[vettestr]

I hate hot engines !!!

Verify you have at least 30* ignition timing at 2700 RPM.. this is a min. not a target

verify your crank pulley is larger than water pump pulley by a min of 15 %

V you have a working 180* T-stat and it is not being bypassed (rad cool until t-stat opens on start up)

I place fan sensor in rad to turn on fans if temp above 180* (this allows fans to cycle)

I have a manual fans on - dash switch so can turn on in traffic .... period

air / fuel ratio a little fat helps cool engine. lean mix runs hotter check what you have

you never specified when or how it was overheating... IE. only in traffic but cools at freeway speed or only when on the freeway or stop n go starts overheating and won't recover once she starts to get hot or ??????? GOOD LUCK be patient

[rustyBob]

10 years of working in a radiator shop and a lifetime of lead poisoning......bad info!!!!

i didnt say to change the t-stat....i said to lower the temp on the fan swithch to 180
if you set the switch to come on and off at 195 then your coolent will always be hotter
than the t-stat and it will never "cycle" the coolent the way it's designed to...

my car runs at 180 on 100 degree days in slow traffic....i never have overheating problems....

but then i worked in a radiator shop for 10 years........

[Mohuska]

First, thanks for all the advice. This one of the things I really like about this forum is that there are so many with experience on such things. While I have been working on cars for many years, it is good to get feedback and new ideas.

To add a little more detail, my Cobra will get up to 180 deg within a couple of minutes of starting. The fuel/air ratio is 13.7 at idle (14.7 would be stoicimetric), so it does run a bit rich. In fact, even cruisin down the road I smell overrich fumes (not to mention that my clothes smell like unburned gas when I stop).

My engine is a 460 that was punched out to a 522 with TWM stacks and a FAST ECU controlling everything. As far as running, it is a beast! Seems to have incredible response and more than enough grunt in all 5 gears.

Regarding overheating, it will go up to 225+ shortly after I get on the road and will vary between 200 and 240. If I come to a stop with it idling (after running hard) the temp will drop very quickly to 190-200. As I said before, the fans come on at 195. If I cruise about 35 down the street, it will go down to 200 and mostly stay there. If I hit it hard off the line, it will jump to 200-230 and then come down when I stop again.

I think that getting a coolant bleed valve will be the first step and then I will pressure test the system (thanks Hersh). I will run it several times and bleed, burp and refill (thanks Tom).

I don't think I need to change the fan settings. Most BB motors like mine generally run at 190+ (even my Jeep GC runs typically at 190+)

Thanks again to everyone. I will post on this after I try some fixes. In the meanwhile, I still appreciate any ideas.

Cheers,

Mike

[Tom Wells]

Mike,

One more thought after your further description: it sounds like you have been reading a voltmeter instead of a temp gauge

Is the temp gauge electrical? If so, could it be responding to alternator voltage? When you spin the engine faster, the voltage may rise, and the gauge may indicate higher temp which may or may not be the case.

Maybe Hersh's suggestion of using an infrared non-contact temp gauge on it would be a good diagnostic?

Just another bit of confusion for the pile...

If it's mechanical, please ignore the preceding!

Tom

[Mohuska]

Tom,

Thanks for the insight. Is there a way to determine that the gauge could be fluxuating based on voltage?

I do have an infrared temp sensor already. I will check out entry and exit temps no matter what.

Mike

[Z-linkCobra]

Someone mentioned pulley sizes. If your moving the water too fast through the radiator it doesnt have a chance to cool down before it goes back into the motor. You said when your just cruising it seems to be fine. If you push it a little harder..(higher rpms) it climbs up. BB fords are notorious for running a little hot anyway...then you throw a high volume water pump on it from an engine builder looking to sell parts and you have enhanced the problem...slow the water flow down.


Just my thoughts

[Tom Wells]

Mike,

The back of the gauge is likely not easily accessible being behind the dash panel so the sending unit is where I'd begin.

The temp sender is toward the front of the intake manifold, if it's similar to mine - I have an Edelbrock Torker II - yours may be different.

Anyway, mine is just behind the thermostat housing, a little bit to the passenger side rear of the distributor.

Put a lead from the voltmeter there, ground the other one and watch it and the gauge while you increase the engine speed if the cables are long enough. Get a volunteer to watch one or the other if need be. I don't think the car needs to move, just the engine speed would need to be increased to say 2500 rpm.

If the voltmeter and the gauge are both steady from idle to 2500, then that would seem to rule out the sender and the gauge.

Caution: I haven't actually tried this - it does seem logical...

Tom

PS: The infrared temp measurement does sound like the way to go.

[HighPlainsDrifter]

Hi,
I had a 460 for 12 years so I know how hot they get.

1- take a small 4" x 4" piece of paper and put it infront of rad while fans are ON. if it sticks to the rad you have them correct, if it doesn't then the fans are blowing the wrong way ! rewire them.

2- You can NEVER burp the rad properly. The only way to do it is to put a T fitting (from a prestone rad backflush kit) in the TOP line of the heater line from the intake manifold.Open it and fill the water until it runs out, now all the air is out.

Good luck,
Perry.

[kitcarbp]

OK the info you provide here if accurate is important. you stated:

Regarding overheating, it will go up to 225+ shortly after I get on the road and will vary between 200 and 240. If I come to a stop with it idling (after running hard) the temp will drop very quickly to 190-200. As I said before, the fans come on at 195. If I cruise about 35 down the street, it will go down to 200 and mostly stay there. If I hit it hard off the line, it will jump to 200-230 and then come down when I stop again.

I would first install another gauge and sender (mechanical one is cheap and quick) to verify it behaves the same way and that you dont have a fault with gauge, sender or the wiring. The fact that your temp drops when your engine speed and road speed (less air flow) drops is opposite as to what should happen (until the fans kick-on).
If the new gauge confirms temps are still erratic, air in the system is likely for this fluctuation. I sent you the changes I made to my WCC 460 system to make it easier for air to exit during system fill. The changes I made eliminates the "ritualistic and repeated burping" you will need to do over and over as others have experienced.

BTW assuming the fans are wired correctly to pull, is your alternator and wiring for your new twin fans up to the task ? you did not share any info on this. Twin fans will use alot of current. Make sure they are operating with the required current to get the proper cfms. You will need dedicated heavy duty relays to run the fans when the FAST system triggers these relays.

[Mohuska]

Bill,

Checked out the plumbing today after talking to you. The hose that comes out of the bottom of the surge tank actually goes to a fitting in the top of the radiator on the low pressure side.

I am going to remove the hose that now goes from the T-stat to the surge tank and plug the fitting in the surge tank. I should then have only ONE hose from the bottom of the surge tank to the top of the radiator and the radiator cap overflow hose to the bottom of the overflow tank.

We ordered the GM bleeder valve and it will be here next Monday. We'll then bleed the air and hopefully all will be much better. I will check temps with my infrared and see then what the gauge reads. If in doubt, I will replace the gauge and we'll go from there.

I will keep you posted. Thanks for all your help.

Mike

[mdross1]

Assuming you have enough cooling capacity,you have some great advice to work with.My 460 high effeciency radiator made of copper was sized by a 30 yr veteran in the radiator business.At first made me nervous until system was completely burped of air.It goes to 190 degrees quite fast then stays there.On hot days and in traffic the fan runs contantly,only shuts off when cruising for a while no load.