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bmacf · Post by **bmacf** » Sun Aug 13, 2006 6:41 am

Hey everyone, I need help with an overheating in my '88 Milano 3.0. Here are the symptoms: I drive it for 15 minutes and the temp gauge progresses up towards 250 deg. F and doesn't stop. Although it's summer here, I have the problem regardless of temperature outside (it was 70 deg F this AM).

Here's what I've done so far: remove the Tom Zat thermostat, run the richest mixture I can (I have Megasquirt), bled the system of air (nose up in the air, opened bleed screw). I even shielded the heater hose by the passenger side header.

Diagnosis-wise, I've done a compression test (185+/-5 all around). I looked at the temperature (infrared temp gun) of the thermostat and it was 235 deg F. The upper rad hose was 205. The "lower" rad hose was 215. The driver side upper part of the radiator was 200-ish. The passenger side was 215-ish. There are no signs of coolant dripping cold or hot. There are no signs of coolant in the oil or oil in the coolant. The spark plugs are slightly carboned over - but I've been running a rich mixture.

The water pump is an IAP unit - 1 year old - no sign of leaking at the bearing. The radiator is a 3.0 radiator, 2 years old. The thermostat was a lower temp Zat unit, but I've pulled it out since having the problem.

The only thing I can think of that I haven't checked is the flow of the waterpump. Any idea how to do that? I'd also like to pressurize the coolant system, but haven't been able to successfully rig up a coolant bottle cap that I can pressurize.

Any suggestions would be most welcomed. The fall track season is just around the corner!

Thanks,
Bill in Maryland, USA

bmacf · Post by **bmacf** » Sun Aug 13, 2006 6:46 am

Forgot to add that my fan is running. In fact I have an auxiliary fan (permacool?) with an adjustable thermostat set to the lowest setting. The OEM fan is connected to the same adjustable thermostat and appears to be flowing very well when it is on.

Thanks,
Bill

sh0rtlife · Post by **sh0rtlife** » Sun Aug 13, 2006 10:09 am

you do have a t-stat in place tho right?...no t-stat will cause an overheat since the water isnt restricted it rushes by so fast that it doesnt soak up much heat

what it sounds like tho is a few things...1 your block probably has a whole ton of sediment in it (the only way to get it out is to remove freze plugs and dredge it out with something..i like metal coathangers and a water hose running water thru the block the whole time)and your radiator is partaily pluged(only 1 real test for this...is to drain it and plug the upper and lower hose outlets and fill with water and then see how fast it drains...it should drain quickly).....or the impeler blade on the water pump has fallen off(gotta remove the pump to find out)...iv seen it in just about all engines at least once...it does happen and lastly...are your fans spinning in the right direction?

Mats · Post by **Mats** » Sun Aug 13, 2006 11:34 am

You need a thermostat do redirect 100% of the flow to the radiator.

What kind of ignition advance are you running?

ar4me · Post by **ar4me** » Sun Aug 13, 2006 4:57 pm

You need a thermostat in place on the V6 to avoid overheating - hmm...
I have run both 12v and 24v V6 without thermostats. The 12v with an empty housing, on both street and track - ran as cool as any other 12v V6 I have had on the street and track.
Jes

bmacf · Post by **bmacf** » Sun Aug 13, 2006 5:11 pm

Hey everyone, thanks for the tips. I did indeed pull the thermostat out when the overheating problem first occurred. Since then I've richened up the mixture and shielded one of the hoses from the passenger side header. So maybe I ought to put the thermostat in and see if the other two fixes have corrected the problem.

I'm running up to 26 degrees of advance, but that's at WOT, which I haven't been heavy on the gas. I can look at my logs, but I would guess up to 17 deg advanced at the most.

I'll try putting the thermostat back, and if that doesn't work I guess the water pump comes off.

Thanks,
Bill in Maryland

Mats · Post by **Mats** » Sun Aug 13, 2006 11:12 pm

I don't get it, you run 27 at WOT but 17 at most?

At low loads you should be able to run MUCH more advance, 40ish maybe (Barry? Z? JK?) and 17 sounds extremely low, even 27 at WOT sounds weird, fixed advance?
If you run low advance you will have heat problems.

Edit: By the way, have you verified the ignition advance with a timing light or are those numbers just straight from the map?

Murray · Post by **Murray** » Mon Aug 14, 2006 1:26 am

Bill given the information you have provided my money is on poor flow through the radiator.I'd try shortlife's suggestion of running some water through it to see if it drains rapidly.It's relatively easy to pull the rad and get it professionaly cleaned out.

bmacf · Post by **bmacf** » Sun Aug 20, 2006 9:05 am

Problem solved: auxiliary and main fan flowing against eachother.

Yes I know, I told you the fans were flowing in the right direction. But I only checked this by putting my hand in the engine bay to make sure there was flow. It's just one fan was stronger than the other (interestingly, the newer auxiliary fan was winning). I think this explains the way the temperature was going up: slow and steady. I was getting some cooling but not a lot (for future readers). A quick rewiring of the main fan and voila, problem solved...I think.

To an old country music tune...
Momma, don't let your electrical engineers work on their Alfas....

Thanks for all the help.

Bill in Maryland

x-rad · Post by **x-rad** » Sun Aug 20, 2006 10:04 am

I had a similar problem when I first bought my car, except both fans were wired to run in reverse! I noticed it the first time I stood in front of the car and felt hot air blowing on my knees!

Post by **Zamani** » Sun Aug 20, 2006 12:07 pm

Hehehe

Murray · Post by **Murray** » Sun Aug 20, 2006 3:27 pm

Reverse thrusters

That's got to seriously reduce braking distances.

Overheating mystery