While at the WCN I stopped at the Motul vendor. My car runs hot according to the temp gauge most all of the time. By hot I see the gauge at about 1/3 of the way to hot from mid line. It has always run here since I owned the car. When in traffic or on a hot day it goes to about a little over half the way to hot from midline, maybe a hair more than that.

I have the original two core radiator. I run antifreeze.

The guy at Motul gave me a product named Mo Cool. He said this would help. He advised that I drain the cooling system, use no antifreeze and use enough of the Mo Cool to give the cooling system a 5% solution of this product. He further said that I could just add the Mo Cool without draining the system but that if I did it this way I would only see a 50% improvement over just the solution of antifreeze/water.

Anybody ever use this product? What are your thoughts. My only other solution is to go with a custom built three core unit using my exisiting radiator.

I have used a product called Water Wetter before, designed to do the same thing. I have used it in 1/4 mile V8 drag motors and in my 72Z. I prefer to use antifreeze in my mix to help control corrosion in the system. It did provide some additional cooling effect, perhaps a 5% lowering in temp, so not a lot of help. They are more effective in a straight water system. For my stock cooling system that warms up in the summer traffic and humidity of the St. Louis Metro area, I added an electronic cooling fan to aid in cooling when the stop and go causes the guage to get to warm.

Hi Randy:

For some unknown reason - the L28 I run in one of the 72Z's also ran above normal temps. Everything in the engine was new - everything in the cooling system was new - everything checked out as operating properly {radiator flow rates, water pump, thermostat, fan clutch and fan etc etc}

The engine was broken in - had about 2000 miles - and it still ran warmer than I wanted. Same stop/go traffic overheating fears that you have....

I switched to Mobile 1 - - and that dropped the temp about 10 degrees. Next I added Redline Water Wetter and that dropped the temp. gauge to the middle. In 1995 we had the car at the Z Car Convention in Atlanta - - record high temps there - over 100 degrees during the day. Even then, in stop/go traffic jams on the freeways - the temp. gauge barely got above the center line.

Redline Water Wetter - contains a water pump lubricant, as well as corrosion inhibitors for aluminum heads/cast iron blocks.

You don't need "anti-Freeze"... I'd flush the system and refill with water and Redline Water Wetter.. as well as running synthetic oil {if your not already}....

You can buy Redline Water Wetter at many chain Auto Parts Stores...

FWIW,

Carl B.

Royal Purple has "Purple Ice." It works pretty well, too. I've not used it in my Z because it runs pretty cool as it is, but it's proven itself in diesel motors where overheating was a problem.

Frank

Thanks for the responses guys. Carl, my problem is exactly as you describe. I am not running synthetic oil, but will change that this weekend. I read up on this product last evening and it appears that it also contains lubricant for the water pump and corrosion inhibitors.

I think that I will try it and report back as to what results I get in combination with the Mobil 1.

Randy, late to the thread here, but I thought I'd add that my red car also runs a bit hotter than I'd prefer, assuming we can trust the gauge. (Big assumption). Like yours, it typically runs a bit on the hot side of the middle. That is with a new (factory Nissan) 180 degree thermostat, and a new temperature sender. I still have the original two-row radiator, but have changed to a slightly larger (and lighter) 260Z plastic fan.

My climate is cooler than yours, I typically use some antifreeze, but not 50/50. I'm due to change the coolant this Spring anyway, so I plan to use Water Wetter and a coolant mix of 33/67 or so to try to get the temps down a bit.

Ok, so I drained and flushed the cooling system to rid it of all traces of anti-freeze. Next I drained the old oil and put in Mobil One. After all that I drove to the ZCCIV show in Temecula. It was a warm weekend. I did not notice much of a change on the gauge; maybe slightly, and I mean a slight cooler reading on the gauge. The car did not overheat and I was going 80 most of the way, about 50 miles each leg. It still read about 3/4 hot.

I have a new sender and thermostat as well Arne.

But, as an unexpected and pleasant side effect, my oil pressure gauge now does not read zero at idle. Go figure.

Edited May 28, 200915 yr by rtaylor

Ok, so I drained and flushed the cooling system to rid it of all traces of anti-freeze. Next I drained the old oil and put in Mobil One. After all that I drove to the ZCCIV show in Temecula. It was a warm weekend. I did not notice much of a change on the gauge; maybe slightly, and I mean a slight cooler reading on the gauge. The car did not overheat and I was going 80 most of the way, about 50 miles each leg. It still read about 3/4 hot.

I have a new sender and thermostat as well Arne.

But, as an unexpected and pleasant side effect, my oil pressure gauge now does not read zero at idle. Go figure.

Before adding things into your radiator. Please think why it is running hot.

If the radiator is partially clogged, it will run hot. If the mixture of the coolant is wrong, it will run hot as well. If the thermostat is half way opens when hot, it will run hot. If the cooling fan clutch is no good, it will run hot.

If there is air bubble in the system, it will cause over heat like symptom.

So the list goes on..... But the point is, I would try putting the followings:

1.Radiator shroud $85 at MSA

2. use 8 fin cooling fan as Arnie mentioned. (260Z and 280Z) $65?

3. change thermostat to low temp type. 76C dregrees?

Call me if you have more questions.

I am an ASE Certified Tech.

Esprist

Have any of you stuck a meat thermometer in the water to see what the temperature actually is at a given spot on the gauge? I used to get all excited about where the needle sat on a linear no-marking scale til I checked the actual water temp and found out the temp was right where an L- motor runs best and it was no where near boiling.....

May I step in here?

I am using a SU TBI system with my car. And Have an F54/p90 (-2mm) header, etc.

My needle is always on the 2/3 of the gauge. For my FI system I had t install few sensors. I can monitor them with my laptop... Big difference between my gauge and my screen. I trust my laptop and I will change my gauge, one day

Check your gauge

Bruce. That sounds like a great idea. Rocket science. May I ask a dumb question? I know the cooling system is under pressure when running. Do I bring the parked car up to normal operating temp with the cap off? Will it get to normal operating temp with the cap off? What is a normal temp measured by a thermometor?

I want to keep the metal fan and the 71 did not come stock with the shroud, so that is not an option.

Thanks Esprist. I'll give you a call.

Rocket Science you say? Well certainly it is that..... Bring the temp up with the cap on. shut it off take the cap off take the temp of the water. Maybe take readings 2 or 3 times on the way up to where you think things are getting "hot". That'll give you some intermediate readings on the way up to operating temp. It's hard to tell which direction you are going with only one stake in the ground.....

What should "normal" operating temp be Bruce? Any idea?