This is in regards to the '89 IROC in the sig, the engine (L98) of which has recently been rebuilt.

When I'm on the highway, the temperature is just fine. Going about 70 MPH on a relatively hot day with the A/C on, the temp gague is slightly above the second line at about 200 deg F. I can drive like that all day long with no problems. However, if I'm driving in the city and hit just a couple of long stop lights, the temperature will just climb past 220 and then higher. And I'd better not get into any traffic, because sitting still for longer than a couple of minutes will pull the needle into the redline at 240+ deg F.

I know that both fans are working. In fact, I have had the secondary fan wired to be on all the time, and that didn't do enough to keep the temp from entering the redline--it only made it take a little bit longer before it happened. And I've just recently wired in an adjustable fan switch to control the primary, which I have set to come on at about 150 deg F. So that means that both fans must be running as my gague is climbing towards the redline.

The thing that makes this even more worrisome is that I have all new cooling components on this car...

* New fan motors
* New high-flow water pump
* New high-flow 180 deg F thermostat
* New 3 row copper radiator

I know these cars are heavily dependent on under-car airflow for cooling, but I don't think it should be getting *this* hot with even stock components--much less with my aftermarket stuff. And I don't know if it's a fair comparison, but I could leave my '88 Camaro with the 2.8L V6 engine idling in the driveway all day and it wouldn't pull past 220 deg F--and it's got +130K miles with all original components.

Is it normal for a V8 to be running this hot? It's getting to the poing where I feel like I need to be running red lights and driving in the medians in traffic just to save my engine--and it has yet to even get HOT for the Summer yet.

Thanks

 

Believe it or not we need more information. Is the engine stock? Has the engine always run this hot? No? When was the last time it ran normal?

Since at cruise on the highway you run steady the only thing differant is airflow. You get all the airflow you could ask for at 70 mph. You get nothing sitting still. That means fans. The electric fans stock are not the greatest. I have a 383 stroker and I had the exact same problem. Upgrading my stock dual fans to Spal Dual 11" fans cured my problem instantly. Somewhat expensive they are but much cheaper then a rebuild. Here's the cheapest place on the net for the best fans in the world.
http://www.carshopinc.com/cgi-bin/se...ECHNOLOGIES+11''+DUAL+HI+PERFORMANCE&stpos=0&stype=AND

 

any pics of 'em? will they bolt right in? im lookin to upgrade to better fans also.

 

if you dont drive the car in winter or dont have winter, try running a cooler thermostat, that MIGHT do something

 

Thanks for the replies.

John: One of my goals with the engine rebuild was to rebuild it as close to stock as possible (partially because I was short on cash, but also because I wanted a daily driver and I assumed that GM tuned these cars to be just that off of the showroom floor). Thus, I put the original L98 heads with the same sized valves and a new cam which is *supposed* to be the same as the stock cam for that year. The pistons are hyperkineutics, but I expect that they maintain the same compression ratio (or relatively close to). The block was the original 350 block, and I had it line-bored/honed to 355 ci. Other than that, all of the original sensors, injectors, and the TPI induction went back on.

As far as what the engine used to do... I was only able to drive the car for 20 minutes before we rebuilt the engine, so I couldn't tell you. I will say that the front part of the engine compartment had rust splattering all over it from what looked like a major radiator boilover. But I always just chalked that up to poor maintinence by the previous owner (i.e. putting pure water into the cooling system).

 

somthing you might not have thought of is the condenser.....

yes it's infront of the radiator, but if the air the fans are blowing cannot blow through the condenser freely then i can see where the prob is......

try taking a vaccum cleaner if it's clogged up between and infront of the condensor...... it just might be that simple!

 

yep i had your problem with my old z28..it kept running really really hot so i used a vaccume and sucked up leaves and crap between the condensor and the car ran much cooler. Youd be suprised how much junk gets stuck in there lol

 

That was actually the first thing I thought of!

The thing is, this is still a new radiator, and I only have about a thousand miles on this car after the rebuild. That means that the radiator has had only a thousand miles on the road, and that's a relatively small distance to gather a significant amount of crap.

Also, I intentially put a strip of foam on both sides of the radiator, between the radiator and condenser, to seal that gap that stuff gets in through, so that should minimize the junk that gets in.

Thanks for the replies; keep 'em comming...

 

i noticed you metioned you used a copper 3 core? i've made a comparison on my hot running 86'. with the oem aluminum single 1 core it ran 15-12* cooler than with the 3 core copper/brass one i had bought. both were new. anyways hmm....do you have a new rad cap? what % mixture of a/f to water are you running? how about you cat convertor? how old/new is it? have you tried to connect a manual gauge to it to verify the temps? man how i hate overheating problems.

 

Mystikkal: That stuff about the 3 core radiator is a little bit of a let down.

The radiator cap is new, and I think it's a 13Lb cap (not sure--I'd have to check). I tried to do a 50/50 mixture of antifreeze/water. The only thing strange about the coolant is that it has gone from a normal bright (almost neon) translucent green to a dark, opaque, almost hunter green type color. I have been told that it's because of the crap left over in the block after being tanked/magnafluxed/etc. I've been wanting to take care of that (and plan to), but I don't see how that would affect cooling.

The catalytic converter looks like it might have been changed by the previous owner (there's an area of obvious welding on the A.I.R. tube), so I can't say how old it is.

I haven't used a manual gague on it.

 

Sancho,

That new "high-flow" water pump - was it a straight or reverse-rotation design?

 

ah yes with the serpentine reverse rotation this is a cause for concern as well.

 

I'm not sure about the flow direction on it. I do know that it looks identitical to the original pump from the outside. I took the plate with 5 or 6 screws off of the old pump just to see what they looked like inside, and my guess is that the only difference between the stocker in this one is the number of fins on the impeller--just a guess though. I just remember it saying that it was a bolt-on replacement for SBCs--and unless SBC includes the LT1, they all flow the same direction, correct?

Plus, I can remember that, when I was filling the coolant system for the first time (with the engine running), I could see the coolant gushing out from the radiator fins when looking down the fill cap. This would have to mean that the coolant was entering the radiator at the upper hose and exiting at the lower.

Is that the correct direction?

 

well there are two different types of water pumps when it comes to thirdgens....

standard rotation - found on non serpentine setups pre 86
reverse rotation - found on 87+ and up serpetine setups

they visually look the same. i'd double check on the pump to be sure.

 

Gotcha...

Well, I can always go back to the place where I got the pump and look at the box. I'll do that if it makes things easier...

But, isn't it sufficient just to see that the coolant is comming in at the top of the radiator (i.e. comming from the intake manifold) and exiting the radiator at the bottom (i.e. entering the engine back at the pump)?

 

I'm wondering something about the condenser...

Was the intention of the placement of the condenser in front of the radiator such that ALL of the air that goes through the radiator must go through the condenser first? If so, two things come to mind...

1. Like I mentioned earlier, I put some foam strips on both sides of the radiator, in the gap between the tanks and the condenser. The idea was to lessen the amount of crap that enters that area. However, I'm wondering if those gaps were intentionally left there to allow more air to enter the front of the radiator.

2. I can remember when the engine and radiator were out of this car, I was in the engine compartment cleaning things up with oven cleaner and a garden hose. I was getting a little bit "water happy" and ended up blasting the condenser from the side with relatively high pressure water (DOH!). Obviously, that completely bent over a large amount of the fins on the condenser. I tried for more than an hour to straighten those fins out but, for those of you who have been there, you know that you can never get those things looking like they used to before you screwed it up. I'm wondering if I just permanently damaged the condenser.

 

Sancho,

Kind of a longshot, but I just had a similar problem. When I ever I was driving slowly or stopped at a light, my car would hover around 240 degrees, even when it was 55 degrees outside. I had a few other problems as well. I found out from a member here (Mike55TPI) that some of my problems were related to my TCC not releasing due to a bad lockup solenoid. I had the solenoid replaced, and my car stopped stalling at lights, and now runs around 195 degrees, even stopped for 15 minutes in 85 degree weather. The TCC being locked up at a stop put to much strain on the engine I think. Like a I said, it may be a longshot, but it may be something to look into, especially after all the cooling mods you have done.

One thing to try is to drive around in DRIVE. If the issue gets better, then it may be related to your TCC or tranny.

Hope this helps.

Andy

 

The specs for the Spal Dual 11" fans are here:
http://www.dewitts.com/download/fans_11.pdf

And here's a picture of them. they will suck your pant leg in through the front bumper if you walk in front of the car. They also sound like a jet engine taking off when you start them.