I finally brought the SA to life. Steady idle, a bit high and lots of back firing when reving. The big issue is this: it can idle all day long or I can rev it as much as I want, but as soon as I drive it the temp rises quickly. I havent let it overheat but it would if I let it. Im thinking some form of exhaust restriction but im not sure. Any ideas?

 

You're running lean under load, which is raising your coolant temps. Not enough fuel or perhaps timing is advanced too much.

 

what makes you believe its overheating? maybe your gauge is reading wrong? have you checked the fan clutch? is it working properly? do you have enough coolant? is there enough in the system? is your water pump working? your thermostat stuck? start at the top and work your way down.

now why it would be fine idling and not driving you got me there ....

 

When it comes to overheating, I always side with the gauge. Better safe than sorry.

Backfiring while trying to rev is very indicative of a timing problem but can also be fuel starvation. Running lean definitely has a big effect on engine temps. When I took my cruising AFR from mid 14's to below 12 with a primary jet change, I noticed a big drop in engine temp when cruising down the interstate in the summer.

 

yeah, I'll mess with anything BUT overheating (and low oil pressure), if the gauge says it's hot, then its hot. And it is. The upper radiator hose gets too hot to touch with my left hand. This test has always worked for me in the past. See I'm a burn victim, and one of the unique side effects is an above average tolerence to heat on my left side, so if something is too hot for my left hand, it's too hot.

As for the lean condition bit, i'm confused: I thought back-firing was a sign of rich condition. As for the fan, how would I test this: the fan spins while the car is running, aside from that I'm a bit unclear how the fan clutch works.

 

I agree with rotor venom.... fan clutch, thermostat, and coolant. backfiring can also indicate timing off as well. temperature rising while moving indicates bad thermostat or radiator partially clogged....

Hopefully it's not the dreadful coolant seal at worst case scenario. Good Luck!

 

So heres what I would do, in this order:

1. Make sure the coolant is fresh and the topped up.
2. Verify the thermostat opens by checking the temp of that top hose, it will be cold at startup
the get hot once the temp guage is rising.
3. Make sure the timing is set correctly.
4. Check the tail pipe and make sure theres a good flow of exhaust out of it when revved.
5. Make sure the oil is topped up and fresh.

Its probably not a cooling system problem, but if the bottom radiator hose stays cool, then
it may be a radiator issue.

The other thing that will cause an SA to overheat is a blocked FMOC, which it should have.
It could be blocked or one of the lines is clogged. When the lines get 30+ years old they
disintegrate internally and can swell shut. My SA was having hot running problems and I
fixed it by replacing the old lines with the RB ones. Instantly fixed it.

 

The oil cooler is another thing I didn't think about. An easy test is to see if both end tanks get hot, and both lines get hot. If they have a thermostat like the FC cooler then that can get stuck closed as well.

 

timing and the rusty radiator sounds very probable. i would guess the oil cooler is the culprit though. once my buddy installed an feabay l FMIC on his fc and the thing could not run on the fwy without overheating. the oil cooler kept getting hot.

i would venture to guess thats why it would be getting hot while under load. and not while idling it isnt building much oil pressure. i ma just a newb so correct me if im wrong but that sounds like the best bet.

 

Possibilities:

1. Loss of leading ignition (check for spark)
2. Fan clutch failure (check manual for procedure to check this)
3. Radiator restriction (might flow enough for idling, but not enoug for when under load)
4. Pinched hose supplying coolant to oil cooler
5. Water pump belt is loose (probably most likely, definitely easiest to check)

Most likely cause of backfiring is a leaky exhaust system.


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