Running warm after beating on it at the track the other day

[steveyblack]

So last night I decided to beat on my 2jz mk3 with the stock twins at a local strip. I did 3 back to back hard runs( balls to the walls kind of driving) and I noticed on my last run that I was running warm. When I say warm, I mean that the temp needle was at 3/4 the way up(not into the red and not boiling over) as I was coasting in after my last run. I let it idle for a minute then the temps were back to normal. I have a newer stock mk3 na radiator and the stock clutch fan set up. I was thinking that I might be running a little lean and it was causing it to warm up, I dont have a wideband installed so I cant really know for sure. Maybe its just because I dont have enough air flow through the rad? Ill check for blockages last today. any ideas? The Waterpump, rad cap, radiator, and coolant are about 12-18 months old too. Any ideas on what could be causing me to run warmer after multiple hard runs?

 

[te72]

Do you have the stock shroud that goes under the front lip that bolts to the crossmember? If not, might look into putting one back on there.

Another thing, I would question how old the fan clutch is. When I bought the Mk2, I suspected the fan clutch was bad (was going through the cooling system piece by piece, from least to most expensive. After replacing the fan clutch on mine, it flowed a LOT more air, but it turned out in my case that the radiator was pretty clogged too. Something to consider. Also, has your car ever ran hot? Might look into replacing the rad cap too, I had one that was spitting out coolant even when it wasn't getting particularly hot, and it wasn't particularly old either.

 

[steveyblack]

The rad cap is 2 months old. I dont have the shroud under the car, maybe its time to make one out of some sheet AL i have laying around. Whats your take on making a duct from the front nose( where the air enters the rad/ic)? I was thinking that since im pre 89 and dont have a split nose, I can channel it right to the radiator. and for the bottom grill ill duct it though the IC then have meet with the other duct at the radiator? Its hard to put into words but im working on some drawings so ill post em when Im finished.

As for the clutch fan, I am thinking that it is on its way out since its not as stiff to spin as my old 7mge clutch fan, but would that really effect my temps even when beating on it? Wouldnt there be enough air flow from the speed to cool me down?

as far as the car running hot, yea It ran hot once, I had a radiator hose that tore and I noticed it before pegging the temp gauge though

 

[IJ.]

3/4 on the stock gauge?

 

[Radial]

JZ engines are like ovens, they create huge amounts of heat when taking a beat.
My stock 1JZ would not last more than 2 miles of constant beating (drifting in 3'd gear), before i was at 120c (or 248F) and boiling....
A few friends of mine with 2JZ also share the same problem... We are all doing a BIG radiator conversion this winter with 32x20x4" radiators from Flex-a-Lite.

Most importantly is that the oil gets damn hot as well.... oil cooler is required for beating a JZ-engine, and Larger the better

Good working fans are of course important, but I almost never encounter defective fans.
Just my experience though....

 

[steveyblack]

3/4 on the stock gauge?

yes. it normally sits at a tick over half normally while driving

 

[IJ.]

yes. it normally sits at a tick over half normally while driving

3/4 is bad...

The sender isn't linear, it has a big dead zone in the middle where nothing much happens then 3/4 up is way hot..

 

[IBoughtASupra]

You should get an aftermarket gauge as the stock on is not that accurate. Prosport have some good gauges and they are on my old Supra. I just chose Autometer this time since they can activate certain solenoids if I wanted them to.

 

[steveyblack]

3/4 is bad...

The sender isn't linear, it has a big dead zone in the middle where nothing much happens then 3/4 up is way hot..

How bad? Like I said, it wasnt boiling over nor steaming. ill be picking up a temp gauge and installing that along with my wideband ASAP so I can make sure that im not leaning out. Also, Ill be doing a full coolant flush and re-filling my clutch pack( for the fan) with the new fluid. In time ill also be getting a koyo to replace the stock unit. Thanks for the help guys! Ian, im always grateful when your reply to my threads, thank! you sure do know alot about theses cars!

 

[hvyman]

Do you have a oil cooler installed?

Stock coolant cooled bs cooler sucks. Look into a full flow t stat controlled cooler system.

And a bigger radiator.

 

[te72]

Unfortunately, Ian is right on this one. Our stock gauge doesn't really even move over the halfway point until, if I remember correctly, your temps hit over 230°F (higher even?). That's not good if your system can't keep it below that... that shroud would be a good place to start, as would a new fan clutch if it's not working like it should.

Still, 2 pulls down a drag strip cause you to overheat like that? Seems a bit much.

 

[steveyblack]

Unfortunately, Ian is right on this one. Our stock gauge doesn't really even move over the halfway point until, if I remember correctly, your temps hit over 230°F (higher even?). That's not good if your system can't keep it below that... that shroud would be a good place to start, as would a new fan clutch if it's not working like it should.

Still, 2 pulls down a drag strip cause you to overheat like that? Seems a bit much.

3 runs, its a make shift track at an idustrial complex. You run to one end then turn around and run the other way. Like I said, no steam, no boiling over, just the temp gauge rising.