Mkos1980

iTrader: (8)

Car is an 89 Camaro 355. Fresh rebuild. Has about 5K on it. New (rebuilt) waterpump, 200/180 fan switch, new radiator, and duel fans. At idle all day long it'll kick on at 200 off at 180. 5 minutes later kick back on then off like normal. But after about 2 hours on the interstate it'll start to get hot, but wont go over 210ish. Air dam is present, but the plastic panel from the lower spoiler up behind the front clip is missing. Is that needed for coolness?

Sonix

iTrader: (1)

I can't think of any panel down there that isn't the air dam... Or do you mean a panel that goes parallel with the ground? that would be necessary, otherwise air would just go towards the rad, then straight down, instead of through the rad.
wait, this your blown 355? Stock rad still? I'd guess it needs more than stock cooling..?

ttypecamaro

iTrader: (2)

mine does that from running too many RPMs at cruise (2700-3000), and really rich, same when it was too lean, and same when it was just right. I see you have a 4 speed. There are 4 solutions that I can think of: run it hot, get overdrive, slow down, try to increase cooling. I don't have that thing that goes to the front spoiler either, just the lower air dam. I also have 3.23s and a 4 speed, only cause I broke 5th! It seems it didn't matter how many R's when it was in overdrive, probably because I was moving pretty fast (increased cooling). hope this helps.

Also lower loads (more vacuum) seems to make it run hotter. when youre in 5th there is a little more load on the engine than 4th.

Mkos1980

iTrader: (8)

Did this without blower. 4 Speed is overdrive. Its a 700* Cant go no slower then 60 on the highway.

I was reading that somebody had a rebuilt waterpump and the clearances were way off inside the pump causing a lot of bypass at more then idle rpms causing insufficiant cooling at highway speeds.

GarageToys

iTrader: (6)

I had the exact same problem- only worse- mine heated up after a few minutes of expressway driving, not 2 hours worth. It would cycle between 180-200 in traffic and climb up to 225 during 10 miles of expressway driving. When I got back in stop-and-go, it went back down.

My problem was the air dam. I had trimmed down a stock IROC air dam and it wasn't getting enough air. When I installed the correct 91 Formula air dam - it cools like a champ.

ttypecamaro

iTrader: (2)

I was looking at the wrong person's info, I saw a T10. I also had a 700r4about 9 months ago. I had heat problems on the highway with that too, probably because I wasn't using TC lock-up. I changed the transmission (and bigger turbos) and the problem went away. So my problem could have been from torque converter inefficiency or exhaust back-pressure. I agree, its probably more dangerous to go too slow on the highway. Mine would heat up in just a couple minutes as well.

Temperature creeping up over a long period of time is definitely a symptom of a bad water pump.

What is your cruise rpm? probably around 2400? stall converter? Dual electric fans? Stock chip?

On a more technical note: There is a highway speed threshold in the stock PROM chip where the fan is disabled, I'm not sure the exact speed but its around 50mph. Also, my JET fan switch (200/185) actually turns the fan on at 215F as measured by my Holley Commander 950 PRO. I put both sensors next to each other on the front of the intake.