Unseen24-7

Why does my engine overheat if i downshift to 1st gear during autox whereas if i stay in 2nd for the whole run my temps are barely above normal. Would an electric fan make a noticeble difference? suggestions please

finky

iTrader: (2)

There is no reason that you should be overheating at an auto X, especially in Canada. I would check the fan clutch, fan, belts, radiator fins, AC condensor fins, ducting to radiator, thermostat, hoses. Flush and refill with new coolant and you should be good to go.

On a driving note I try very hard not to shift down to first on any course. I try to carry momentum and stay in 2nd.

Eagle7

1st gear will put you into a different RPM range. Maybe you're running lean up there.

peejay

I ran into a similar problem in an N/A 12A. I traced it to water pump cavitation. Was only a problem with sustained speeds over 6000rpm.

How old is your water pump? If it's OEM it's theoretically possible that the fins are eroded and it's not doing much.

That said, how long are your autocross courses that you can overheat that quickly?

Rated R1

If I was running in first gear long enough to overheat I would pack my stuff an head home.

Kentetsu

All of the courses that I have run have been in 2nd gear. I would guess that your belts are loose, causing slippage at high rpms.

Kill No Cone

iTrader: (6)

I am with Peejay, and would think about an underdrive pully to reduce water pump cavitation.

BradSingh

Besides a lot of white smoke out of my tailpipe how can i tell if there is a damaged waterseal in the engine.

During a pressure test, i see no fluid leaks and the there is no white smoke from the tailpipe anyone know where the leak could be?

Larz

Could be a bad pressure cap.

Unseen24-7

The courses i've run are anywhere from 50 seconds to 2 minutes (average times), usually with at least one corner where you pretty much have to use 1st.

I've thought about getting underdrive pulleys...i've heard they're tricky to install, you have to keep some pin in the e-shaft falling out or something.

DamonB

Water pump cavitation. Water pump cavitation. Water pump cavitation.

At high rpm with stock pullies the water pump cavitates and stops pumping coolant efficiently. In first gear the engine is turning big RPM under load, speed is low so there is little air coming through the radiator and the coolant is going basically no where due to pump cavitation. Temps go up in a hurry.

Mahjik

iTrader: (1)

There are two ways to underdrive your accessories:

1. Make the main pulley smaller
2. Make the accessory pulley larger

or a combination of both. Basically, the idea is to have the main pulley have to make more turns to make a single turn of your accessory (so at the higher rpm's, your accessory isn't spinning as hard). It's possible to underdrive your accessory without changing the main pulley.

bean13

iTrader: (1)

I had problems with that with my ITS car when I first built it. Above 4000 or so rpm the water pump cavitates and the stock radiator is a bit small. I changes to RacingBeats underdrive pullys and a big *** AFCO radiator and never had a problem again. I have run at road america in a 93* day and she never tipped the needle over 203ish. Good luck!!!

bean13

iTrader: (1)

oh yeah, installing the main pully isnt that difficult. What the other gentleman was refering to is the torrington bearing falling out of place. This is a bearing that allows the forces to be displaced when the cluth is in, that is when there is pressure against it so if you take the opposing pressure away, the main bolt, there is a chance that it can slip out of place and fall behind a spacer. What I did was cut a 2x4 and stuff it between the seat and the clutch to hold it all the way to the floor and keep pressure on the bearing. The onlyother problem I had was getting the main bolt off, after 20 years and a lot of corrosion she is one tight mother. I had an extra pully around so I welded a bar to it that would hit the frame rail and not allow the engine to spin, hopefully yours wont be so tight. Mine was so tight it would move the car in gear with the parking break on and the wheels chalked. I even tried an impact (3/4) and that wouldnt even budge it. I kinda think mine was a issolated case, but just a heads up.